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Washington State University FEQL Study No. 0313
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Maximum Residue Levels with Decline for Three Insecticides on
Highbush
Blueberry after Mistigation and Airblast Treatments
Authors
Jane LePage and Vince Hebert
Testing Facility
Food and Environmental Quality Laboratory
Department of Entomology
Washington State University
2710 Crimson Way
Richland, WA 99354-1671
FEQL Study No.: 0313
Principle Field Investigators
Lynell K. Tanigoshi1, Beverly S. Gerdeman
1 and Wei Yang
2
1 Washington State University Mount Vernon Northwestern
Washington Research &
Extension Center (WSU-NWREC), 16650 State Route 536 Mount
Vernon, WA 98273 2
North Willamette Research and Extension Center (OSU-NWREC),
15210 NE Miley Rd.,
Aurora, OR 97002
Collaborators
Steve Erikson, CEO, Pan-American Berry Growers, Salem OR
Study Timetable
Study Initiation Date: 7/15/13
Experimental Termination Date: 2/20/14
Report Date
4/20/2014
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Certification
The undersigned hereby declares that this study was performed
according to the procedures
described herein, and that this report provides a true and
accurate record of the results obtained.
Associate Research Scientist: Date: 04/17/2014
Dr. Vince Hebert, Food and Environmental Quality Laboratory
Washington State University, Tri-City Campus, Richland WA
Analytical work performed by:
Jane LePage Research Analyst
Archives (Location of Raw Data)
The original raw data, correspondence logs, and all relevant
information for the study titled:
“Maximum Residue Levels with Decline for Insecticides on
Highbush Blueberry after
Mistigation and Airblast Treatments,” FEQL project number 0313,
along with certified originals
of the signed analytical summary report will be maintained by
the testing facility for a period of
3 years. Exact copies of the analytical summary report and
relevant information for the
construction of this study can be made available to the
principle field investigators or
collaborators on request.
Associate Research Scientist Dr. Vincent Hebert
Testing Facility: Food and Environmental Quality Laboratory
Washington State University
2710 Crimson Way
Richland, WA 99354-1671
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Table of Contents
Page
Certification 2
Archives (location of raw data) 2
Table of Contents 3
Executive Summary 4
Analytical Summary 8
I. Objective/Introduction 8 II. Sample Inventory & History
8
III. Standard Preparation 16
IV. Analytical Procedure 17
A. Residue Method 17 B. Analytical Limits 18 C. Instrumentation
18 D. Quantitation 19 E. Interferences 20 F. Confirmatory
Techniques 21 G. Time Required for Analysis 21 H. Modifications or
Potential Problems 21
V. Results 22
A. Method Validation and Recovery Results 22 B. Storage
Stability 24 C. Residue Results 24
Appendix A: Protocol 35
Appendix B: Working method 43
Appendix C: Sample Chromatograms 46
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Executive Summary
International pesticide maximum residue level (MRL) issues will
remain a major concern
for blueberry growers seeking effective season-long Spotted Wing
Drosophila (SWD)
control. Although many US and foreign agricultural agencies are
working towards global
MRL harmonization, developing an effective resistance management
spray program remains
a challenge to our PNW growers, especially when exporting to the
Pacific Rim where vastly
different MRL requirements exist. Until there is more uniformity
in MRL setting,
understanding season-long insecticide field decline and
appropriately planning spray
programs on a customer-by-customer basis for now may be the best
insurance to avert crop
rejection concerns.
To better understand season-long field decline, from July
through late September 2013, a
weekly insecticide application program was performed on
late-season ripening Aurora
highbush blueberries as part of a program to control SWD at
Pan-American Berry Growers
(PBG), Salem, OR (see Figure 1). During the SWD spray season,
multiple applications of
Malathion AquaTM
, Mustang Maxx™
, and a single late season DanitolTM
application were
conducted at commercial rates (Table 1).
Analytical Summary Report
Figure 1: Plot locations for Salem Oregon 2013 blueberry decline
study
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Table 1: Salem OR SWD Spray Program and Sampling Events
Treatment Insecticide Application Interval Sampling
Week 1 Malathion Aqua (1.25 pts 100 GPA; 1 day PHI**)
-1 through 14 DAT*
Week 2 Mustang Maxx (4.0 fluid oz 100 GPA ;1 Day PHI)
-1 through 14 DAT
Week 3 Malathion Aqua (1.25 pts 100 GPA; 1 day PHI)
-1 through 14 DAT
Week 4 Mustang Maxx (4.0 fluid oz 100 GPA ;1 Day PHI)
-1 through 14 DAT
Last week Danitol (16 fluid oz 100 GPA; 3 Day PHI) ***
-1 through 24 DAT
* DAT = Days after treatment
** PHI = Preharvest Interval
*** Because of the lack of a label use for mistigation, an
airblast application was
solely evaluated for Danitol decline
This insecticide decline study examined pesticide residues on
marketable fruit after
pesticide application by two commercial application techniques
being used by the grower,
chemigation using misters (mistigation; M) and airblast
(AB).
Malathion and Mustang Maxx M and AB chemical applications were
conducted on the
same day to compare if there are residue decline differences due
to application method.
Marketable berries were sampled before chemical application
(-1), and at 0, 1, 3, 5, 7, 10,
and 14 days after treatment (DAT; see Table 1). There is no
label allowed use for mistigation
using Danitol and here only AB residue decline was evaluated.
Since we anticipated that
Danitol could decline at a slower rate, we continued field
sampling through 24 DAT. Two
composited berry samples were collected from each of the above
AB and M treatment plots
on the above DATs. A separated control block (C, see Figure 1)
did not receive any of the
three insecticide treatments and was sampled similarly to
treatment blocks at the above
DATs. After sampling, the composit treatment and control berry
samples were stored at the
OSU North Willamette Research and Extension Center (NWREC) USDA
IR-4 freezer
facilities until vehicle transport by ACDS refrigerated trucking
services to the WSU Food
and Environmental Quality Laboratory (WSU-FEQL) in Richland
WA.
Quality Control: When generating residue decline data, it is
essential to reliably
demonstrate precision in both field sampling and chemical
analysis. To show field sampling
precision, duplicate composited berry field samples were taken
from 20 randomly selected
highbushes in each of the M, AB, and C treatment locations on
each sampling interval day.
To demonstrate precision in chemical analysis, fortified control
blueberry samples were
prepared with each analytical set. For this study, over 129
quality control results were
calculated to support the 148 multi-residue malathion Aqua,
Mustang Maxx, and Danitol
decline measures reported in this seasonal decline study. We
also followed season-long field
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M and AB applications for Imidan (phosmet) with appropriate
quality control to evaluate if
berry residues approached Pacific Rim MRL values.
MRL and Field Decline Results:
Malathion: Figure 2, page 26 shows field residues before and
after malathion applications
occurring in late July and early August 2013. The
reproducibility among the duplicate
composited berry sample data points at each interval date for M
(in green) and AB (in blue)
demonstrates a high degree of uniformity when gathering berries
for our residue
determinations. Thirty-nine laboratory fortifications (spikes)
resulted in an overall average
recovery of 102 +
8%. The high precision in both field sampling and laboratory
analysis
indicate actual residues on berries in the field over the July
28 through mid-August study
decline period.
The fairly rapid residue decline for malathion as well as other
organophosphorus
insecticides in field crops has been understood for quite some
time. Our decline results are
also very similar to a recent decline study conducted at similar
rates on sweet cherries
(Haviland and Beers 2012). For malathion, the allowable maximum
use is 5 pints per acre
per year where up to 2.5 pints can be applied for any one
application. Although this is data
from a single field study, it is reasonable to state that 4
seasonal blueberry applications at
1.25 pints/acre will not trigger MRLs in the US (8 ppm), or
Korea (10 ppm). However, other
Pacific Rim MRLs may be exceeded. Japan’s current MRL is 0.5 ppm
where Taiwan’s is
more conservatively set at 0.1 ppm. When developing a harvest
program for malathion, the
grower may choose to delay picking 3-5 days later than the
allowed 1 day PHI to better
insure that field residues will not trigger a Japan MRL concern.
However, this data is only
from one season and risks of exceeding the MRL can still
exist.
Mustang Maxx: Figure 3, page 26 shows field residues before and
after applications in early
to late August 2013. The good reproducibility among the
duplicate composited berry sample
data points for M and AB applications at each interval date and
consistent recovery among
35 fortified samples (89 +
15%) indicate that testing laboratories should find similar
concentrations in marketable berries. Mustang Maxx berry
residues (as zeta-cypermethrin)
were found at much lower than US (MRL = 8 ppm) and Pacific Rim
MRLs from Korea and
Japan (respectively 10 and 0.5 ppm). It is important to note
that Taiwan does not currently
provide an MRL for the active ingredient zeta-cypermethrin in
Mustang Maxx. As such, any
detected residue may trigger a trade barrier concern. The
appreciably slower rate of residue
decline when compared to organophosphorus insecticides is
typical of pyrethroid insecticides
and again similar to recent cherry decline work by Haviland and
Beers (2012). We did
observe a consistently higher level of Mustang Maxx residues
after the second air blast
application. Although results from one-season decline study make
it difficult to precisely
predict residues that may occur under differing climatic and
growing conditions, it is
reasonable to state that growers should be wary of making too
many consecutive applications
of this substance if planning to export to counties such as
Japan.
Danitol: This substance can currently be only applied twice in
any one growing season and
was used in late August as a clean-up application. Because of
its longer-lasting efficacy on
SWD (Lynell Tanigoshi, personal communication), we anticipated
that this pyrethroid
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chemistry would decline slowly in the field as is evident in
Figure 4 on page 27. Decline
on/in blueberry was similar to the recent decline study
conducted at a similar rate on sweet
cherries by Haviland and Beers (2012). Although the Danitol data
again represents a single
PNW field study, it is reasonable to anticipate that Danitol
applied at the commercial rate of
16 fluid oz per acre should not trigger MRLs in the US (8 ppm),
Japan (5 ppm), or Taiwan (3
ppm). However, Korea MRLs may likely be exceeded well after the
3 day PHI.
Fenpropathrin, the active ingredient in Danitol appears to be a
longer lasting pyrethroid. The
grower may consider using this substance as a start and late
season finish SWD treatment
since current label use of this material (as of 2013) only
allows two seasonal applications.
Cumulative Season-long Field Residues: Malathion, Mustang Maxx,
and Danitol blueberry
residues were measured in the field on 32 separate sampling
events from late July through
mid-September. Residues of Imidan (phosmet) were also assessed
over the 48 day spray
period. Figure 5, page 27 provides the residue data for the 4
compounds. This profile
suggests that cumulative residues over the growing season may be
effective in controlling
SWD field populations thus reducing the need for weekly
applications. As a result, the
grower should consider season-long residual pesticide field
concentrations together with
scouting as part of the SWD spray management program.
The results from this one-year seasonal decline study
suggests
• Pesticide residues for the three evaluated active ingredients
at commercial application rates can sometimes exceed MRLs for
certain Pacific Rim exporting markets.
• Blueberry field decline is similar for these active
ingredients to other PNW small fruits.
This study also suggests:
• For certain Pacific Rim markets, delay harvesting longer than
the label specified PHI. • Consider season-long residual pesticide
field concentrations as part of the SWD spray
management program.
• Start and finish the spray season with a longer-lasting active
ingredient.
Reference:
Haviland D. Beers E. 2012 chemical control programs for
Drosophila suzukii that comply
with international limitations on pesticide residues for
exported sweet cherries. J. Integ. Pest
Mngmt. 3(2): 2012; DOI: http://dx.doi.org/10.1603/IPM11034
http://dx.doi.org/10.1603/IPM11034
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Analytical Summary
I. Objective/Introduction
Pesticides were applied weekly on high bush blueberries
(Vaccinium corymbosum) at Pan-
American Berry Growers (PBG), Salem, OR as part of a program to
control spotted wing
drosophila, Drosophila suzukii (Matsumura; SWD). This study
specifically monitored the
pesticide residue on marketable fruit after pesticide
application.
From July through September, 2013, malathion (Malathion Aqua®,
1.25 pts 100 gallons per
acre (GPA); 1 day pre-harvest interval (PHI)), zeta-cypermethrin
(Mustang Maxx™
; 4.0 fluid oz
100 GPA; 1 day PHI) were applied at the maximum allowed grower
use rates using chemigation
(mistigation; M) and air blast (AB) spray methods. Applications
by these two methods occurred
on the same day; marketable berries were sampled at -1, 0, 1, 3,
5, 7, 10, and 14 days after
treatment (DAT) to evaluate decline of pesticide residues. In
addition, in September Danitol®
(active ingredient: fenpropathrin) was applied by airblast to
that treatment plot. Berries were
sampled for fenpropathrin residue decline at -1, 0, 1, 2, 4, 8,
12, 15, and 24 DAT. Phosmet was
also monitored in field samples as a secondary pesticide of
interest.
The generated residue information in tandem with WSU-NWREC SWD
bioassay efficacy
foliage data (Project Number 0313-B) provides growers with a
regional reference tool to decide
on an appropriate harvest day that controls crop injury while
reducing uncertainty of exceeding
international maximum residue levels (MRLs).
II. Sample Inventory & History
A separate control block of Aurora high bush blueberries was
designated at the start of this
study (see Figure 1). This plot received no malathion,
zeta-cypermethrin or fenpropathrin
pesticide applications during the study. Control blueberries
were collected from the control block
on each sampling day. At the treatment blocks, berries were
picked at low, mid, and high cluster
locations from at least 20 randomly selected high bush blueberry
plants for a composite sample
which represented commercial harvesting practices. Duplicate
treatment samples were collected
on each sampling day.
Samples were labeled according to the protocol (FEQL 0313, see
Appendix A) with M, AB,
or C to designate treatment block (mistigation, airblast or
control), the sampling date and T or
TD for treatment or treatment duplicate.
The control and treated blueberry samples were stored in
freezers at PBG or the North
Willamette Research and Extension Center (OSU-NWREC) until
transport to the WSU-Food
and Environmental Quality Laboratory (FEQL). Samples were
shipped by ACDS freezer truck
on 8/12/13, 9/13/13 and 10/15/13. On arrival at the laboratory
all samples were placed in a
freezer (ID Dasher) until processing and analysis. Samples were
processed by pulverizing frozen
berries with dry ice using Robot Coupe Processor. The entire
sample was processed and returned
to the freezer. Table 2 provides the sample inventory and dates
for subsequent handling of the
samples in frozen storage at FEQL. The sample names represent
the name on the sample upon
arrival appended with the FEQL project number, 0313.
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Table 2 FEQL Blueberry Sample Inventory
Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Arrival at FEQL
Date processed
Weighed for extraction
Date of extraction
Days in frozen storage
Set
0313-C-072713 7/27/2013 M(-1) 8/13/2013 8/13/2013 9/12/2013
9/23/2013 58 set2re
0313-M-072713-T 7/27/2013 M(-1) 8/13/2013 8/15/2013 9/12/2013
9/23/2013 58 0313-M-072713-TD 7/27/2013 M(-1) 8/13/2013 8/15/2013
9/12/2013 9/23/2013 58 0313-AB-072713-T 7/27/2013 M(-1) 8/13/2013
8/15/2013 9/12/2013 9/23/2013 58 0313-AB-072713-TD 7/27/2013 M(-1)
8/13/2013 8/15/2013 9/12/2013 9/23/2013 58 0313-C-072813 7/28/2013
M0 8/13/2013 8/13/2013 10/7/2013 10/7/2013 71 set11re
0313-M-072813-T 7/28/2013 M0 9/14/2013 10/2/2013 10/7/2013
10/7/2013 71 0313-M-072813-TD 7/28/2013 M0 9/14/2013 10/2/2013
10/7/2013 10/7/2013 71 0313-AB-072813-T 7/28/2013 M0 9/14/2013
10/2/2013 10/7/2013 10/7/2013 71 0313-AB-072813-TD 7/28/2013 M0
9/14/2013 10/2/2013 10/7/2013 10/7/2013 71 0313-C-072913 7/29/2013
M1 8/13/2013 8/13/2013 10/11/2013 10/11/2013 74 set14
0313-M-072913-T 7/29/2013 M1 8/13/2013 8/15/2013 10/11/2013
10/11/2013 74 0313-M-072913-TD 7/29/2013 M1 8/13/2013 8/15/2013
10/11/2013 10/11/2013 74 0313-AB-072913-T 7/29/2013 M1 9/14/2013
10/10/2013 10/11/2013 10/11/2013 74 0313-AB-072913-TD 7/29/2013 M1
9/14/2013 10/10/2013 10/11/2013 10/11/2013 74 0313-C-073013
7/30/2013 M2 8/13/2013 8/14/2013 9/12/2013 9/23/2013 55 set3RE
0313-M-073013-T 7/30/2013 M2 8/13/2013 8/19/2013 9/12/2013
9/23/2013 55 0313-M-073013-TD 7/30/2013 M2 8/13/2013 8/19/2013
9/12/2013 9/23/2013 55 0313-AB-073013-T 7/30/2013 M2 8/13/2013
8/19/2013 9/12/2013 9/23/2013 55 0313-AB-073013-TD 7/30/2013 M2
8/13/2013 8/19/2013 9/12/2013 9/23/2013 55 0313-C-073113 7/31/2013
M3 8/13/2013 8/13/2013 9/23/2013 9/24/2013 55 set4RE
0313-M-073113-T 7/31/2013 M3 8/13/2013 8/15/2013 9/23/2013
9/24/2013 55 0313-M-073113-TD 7/31/2013 M3 8/13/2013 8/15/2013
9/23/2013 9/24/2013 55 0313-AB-073113-T 7/31/2013 M3 8/13/2013
8/15/2013 9/23/2013 9/24/2013 55
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Arrival at FEQL
Date processed
Weighed for extraction
Date of extraction
Days in frozen storage
Set
0313-AB-073113-TD 7/31/2013 M3 8/13/2013 8/15/2013 9/23/2013
9/24/2013 55 0313-C-080213 8/2/2013 M5 8/13/2013 8/14/2013
9/23/2013 9/24/2013 53 set5RE2
0313-M-080213-T 8/2/2013 M5 8/13/2013 8/19/2013 9/23/2013
9/24/2013 53 0313-M-080213-TD 8/2/2013 M5 8/13/2013 8/19/2013
9/23/2013 9/24/2013 53 0313-AB-080213-T 8/2/2013 M5 8/13/2013
8/19/2013 9/23/2013 9/24/2013 53 0313-AB-080213-TD 8/2/2013 M5
8/13/2013 8/19/2013 9/23/2013 9/24/2013 53 0313-C-080313 8/3/2013
MM(-1) 8/13/2013 8/14/2013 9/23/2013 9/25/2013 53 set6RE
0313-M-080313-T 8/3/2013 MM(-1) 8/13/2013 8/14/2013 9/23/2013
9/25/2013 53 0313-M-080313-TD 8/3/2013 MM(-1) 8/13/2013 8/14/2013
9/23/2013 9/25/2013 53 0313-AB-080313-T 8/3/2013 MM(-1) 8/13/2013
8/14/2013 9/23/2013 9/25/2013 53 0313-AB-080313-TD 8/3/2013 MM(-1)
8/13/2013 8/14/2013 9/23/2013 9/25/2013 53 0313-C-080413 8/4/2013
M7, MM0 8/13/2013 8/14/2013 9/30/2013 9/30/2013 57 set7
0313-M-080413-T 8/4/2013 M7, MM0 8/13/2013 8/19/2013 9/30/2013
9/30/2013 57 0313-M-080413-TD 8/4/2013 M7, MM0 8/13/2013 8/19/2013
9/30/2013 9/30/2013 57 0313-AB-080413-T 8/4/2013 M7, MM0 8/13/2013
8/19/2013 9/30/2013 9/30/2013 57 0313-AB-080413-TD 8/4/2013 M7, MM0
8/13/2013 8/19/2013 9/30/2013 9/30/2013 57 0313-C-080513 8/5/2013
MM1 8/13/2013 8/14/2013 9/30/2013 10/1/2013 57 set8
0313-M-080513-T 8/5/2013 MM1 8/13/2013 8/19/2013 9/30/2013
10/1/2013 57 0313-M-080513-TD 8/5/2013 MM1 8/13/2013 8/19/2013
9/30/2013 10/1/2013 57 0313-AB-080513-T 8/5/2013 MM1 8/13/2013
8/19/2013 9/30/2013 10/1/2013 57 0313-AB-080513-TD 8/5/2013 MM1
8/13/2013 8/19/2013 9/30/2013 10/1/2013 57 0313-C-080713 8/7/2013
M10, MM3 8/13/2013 8/14/2013 9/30/2013 10/1/2013 55 set9
0313-M-080713-T 8/7/2013 M10, MM3 8/13/2013 8/14/2013 9/30/2013
10/1/2013 55 0313-M-080713-TD 8/7/2013 M10, MM3 8/13/2013 8/14/2013
9/30/2013 10/1/2013 55 0313-AB-080713-T 8/7/2013 M10, MM3 8/13/2013
8/14/2013 9/30/2013 10/1/2013 55
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Arrival at FEQL
Date processed
Weighed for extraction
Date of extraction
Days in frozen storage
Set
0313-AB-080713-TD 8/7/2013 M10, MM3 8/13/2013 8/14/2013
9/30/2013 10/1/2013 55 0313-C-080913 8/9/2013 MM5 8/13/2013
8/14/2013 9/30/2013 10/1/2013 53 set10
0313-M-080913-T 8/9/2013 MM5 8/13/2013 8/15/2013 9/30/2013
10/1/2013 53 0313-M-080913-TD 8/9/2013 MM5 8/13/2013 8/15/2013
9/30/2013 10/1/2013 53 0313-AB-080913-T 8/9/2013 MM5 8/13/2013
8/15/2013 9/30/2013 10/1/2013 53 0313-AB-080913-TD 8/9/2013 MM5
8/13/2013 8/15/2013 9/30/2013 10/1/2013 53 0313-C-081013 8/10/2013
M(-1) 8/13/2013 8/14/2013 9/11/2013 9/11/2013 32 set1re
0313-M-081013-T 8/10/2013 M(-1) 8/13/2013 8/15/2013 9/11/2013
9/11/2013 32 0313-M-081013-TD 8/10/2013 M(-1) 8/13/2013 8/15/2013
9/11/2013 9/11/2013 32 0313-AB-081013-T 8/10/2013 M(-1) 8/13/2013
8/15/2013 9/11/2013 9/11/2013 32 0313-AB-081013-TD 8/10/2013 M(-1)
8/13/2013 8/15/2013 9/11/2013 9/11/2013 32 0313-C-081113 8/11/2013
M0, MM7 9/14/2013 9/25/2013 10/8/2013 10/8/2013 58 set12
0313-M-081113-T 8/11/2013 M0, MM7 9/14/2013 10/7/2013 10/8/2013
10/8/2013 58 0313-M-081113-TD 8/11/2013 M0, MM7 9/14/2013 10/7/2013
10/8/2013 10/8/2013 58 0313-AB-081113-T 8/11/2013 M0, MM7 9/14/2013
10/7/2013 10/8/2013 10/8/2013 58 0313-AB-081113-TD 8/11/2013 M0,
MM7 9/14/2013 10/7/2013 10/8/2013 10/8/2013 58 0313-C-081213
8/12/2013 M1 9/14/2013 10/2/2013 10/8/2013 10/10/2013 59 set13
0313-M-081213-T 8/12/2013 M1 9/14/2013 10/8/2013 10/8/2013
10/10/2013 59 0313-M-081213-TD 8/12/2013 M1 9/14/2013 10/8/2013
10/8/2013 10/10/2013 59 0313-AB-081213-T 8/12/2013 M1 9/14/2013
10/8/2013 10/8/2013 10/10/2013 59 0313-AB-081213-TD 8/12/2013 M1
9/14/2013 10/8/2013 10/8/2013 10/10/2013 59 0313-C-081313 8/13/2013
M2 9/14/2013 9/26/2013 10/15/2013 10/15/2013 63 set16
0313-M-081313-T 8/13/2013 M2 9/14/2013 10/14/2013 10/15/2013
10/15/2013 63 0313-M-081313-TD 8/13/2013 M2 9/14/2013 10/14/2013
10/15/2013 10/15/2013 63 0313-AB-081313-T 8/13/2013 M2 9/14/2013
10/14/2013 10/15/2013 10/15/2013 63
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Arrival at FEQL
Date processed
Weighed for extraction
Date of extraction
Days in frozen storage
Set
0313-AB-081313-TD 8/13/2013 M2 9/14/2013 10/14/2013 10/15/2013
10/15/2013 63 0313-C-081413 8/14/2013 M3, MM10 9/14/2013 9/30/2013
10/14/2013 10/14/2013 61 set15
0313-M-081413-T 8/14/2013 M3, MM10 9/14/2013 10/9/2013
10/14/2013 10/14/2013 61 0313-M-081413-TD 8/14/2013 M3, MM10
9/14/2013 10/9/2013 10/14/2013 10/14/2013 61 0313-AB-081413-T
8/14/2013 M3, MM10 9/14/2013 10/10/2013 10/14/2013 10/14/2013 61
0313-AB-081413-TD 8/14/2013 M3, MM10 9/14/2013 10/10/2013
10/14/2013 10/14/2013 61 0313-C-081613 8/16/2013 M5 9/14/2013
9/25/2013 10/16/2013 10/16/2013 61 set17
0313-M-081613-T 8/16/2013 M5 9/14/2013 10/15/2013 10/16/2013
10/16/2013 61 0313-M-081613-TD 8/16/2013 M5 9/14/2013 10/15/2013
10/16/2013 10/16/2013 61 0313-AB-081613-T 8/16/2013 M5 9/14/2013
10/15/2013 10/16/2013 10/16/2013 61 0313-AB-081613-TD 8/16/2013 M5
9/14/2013 10/15/2013 10/16/2013 10/16/2013 61 0313-C-081713
8/17/2013 MM(-1) 9/14/2013 9/30/2013 10/17/2013 10/17/2013 61
set18
0313-M-081713-T 8/17/2013 MM(-1) 9/14/2013 10/16/2013 10/17/2013
10/17/2013 61 0313-M-081713-TD 8/17/2013 MM(-1) 9/14/2013
10/16/2013 10/17/2013 10/17/2013 61 0313-AB-081713-T 8/17/2013
MM(-1) 9/14/2013 10/16/2013 10/17/2013 10/17/2013 61
0313-AB-081713-TD 8/17/2013 MM(-1) 9/14/2013 10/16/2013 10/17/2013
10/17/2013 61
0313-C-081813 8/18/2013 M7, MM14, MM0 9/14/2013 9/30/2013
10/21/2013 10/21/2013 64 set19
0313-M-081813-T 8/18/2013 M7, MM14, MM0 9/14/2013 10/17/2013
10/21/2013 10/21/2013 64
0313-M-081813-TD 8/18/2013 M7, MM14, MM0 9/14/2013 10/17/2013
10/21/2013 10/21/2013 64
0313-AB-081813-T 8/18/2013 M7, MM14, MM0 9/14/2013 10/17/2013
10/21/2013 10/21/2013 64
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Arrival at FEQL
Date processed
Weighed for extraction
Date of extraction
Days in frozen storage
Set
0313-AB-081813-TD 8/18/2013 M7, MM14, MM0 9/14/2013 10/17/2013
10/21/2013 10/21/2013 64
0313-C-081913 8/19/2013 MM1 9/14/2013 9/26/2013 10/22/2013
10/22/2013 64 set20
0313-M-081913-T 8/19/2013 MM1 9/14/2013 10/9/2013 10/22/2013
10/22/2013 64 0313-M-081913-TD 8/19/2013 MM1 9/14/2013 10/9/2013
10/22/2013 10/22/2013 64 0313-AB-081913-T 8/19/2013 MM1 9/14/2013
10/9/2013 10/22/2013 10/22/2013 64 0313-AB-081913-TD 8/19/2013 MM1
9/14/2013 10/9/2013 10/22/2013 10/22/2013 64 0313-C-082113
8/21/2013 M10, MM3 9/14/2013 9/30/2013 10/24/2013 10/24/2013 64
set22
0313-M-082113-T 8/21/2013 M10, MM3 9/14/2013 10/23/2013
10/24/2013 10/24/2013 64 0313-M-082113-TD 8/21/2013 M10, MM3
9/14/2013 10/23/2013 10/24/2013 10/24/2013 64 0313-AB-082113-T
8/21/2013 M10, MM3 9/14/2013 10/23/2013 10/24/2013 10/24/2013 64
0313-AB-082113-TD 8/21/2013 M10, MM3 9/14/2013 10/23/2013
10/24/2013 10/24/2013 64 0313-C-082313 8/23/2013 MM5 9/14/2013
9/30/2013 10/28/2013 10/28/2013 66 set23
0313-M-082313-T 8/23/2013 MM5 9/14/2013 10/10/2013 10/28/2013
10/28/2013 66 0313-M-082313-TD 8/23/2013 MM5 9/14/2013 10/10/2013
10/28/2013 10/28/2013 66 0313-AB-082313-T 8/23/2013 MM5 9/14/2013
10/10/2013 10/28/2013 10/28/2013 66 0313-AB-082313-TD 8/23/2013 MM5
9/14/2013 10/10/2013 10/28/2013 10/28/2013 66 0313-C-082413
8/24/2013 D(-1) 9/14/2013 9/25/2013 10/23/2013 10/23/2013 60
set21
0313-M-082413-T 8/24/2013 D(-1) 9/14/2013 10/22/2013 10/23/2013
10/23/2013 60 0313-M-082413-TD 8/24/2013 D(-1) 9/14/2013 10/22/2013
10/23/2013 10/23/2013 60 0313-AB-082413-T 8/24/2013 D(-1) 9/14/2013
10/22/2013 10/23/2013 10/23/2013 60 0313-AB-082413-TD 8/24/2013
D(-1) 9/14/2013 10/22/2013 10/23/2013 10/23/2013 60
0313-C-082513 8/25/2013 M14, MM7, D0 9/14/2013 10/2/2013
10/29/2013 11/5/2013
10/30/2013 11/5/2013
61 67
set24 set 24r for zeta-cypermethrin
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Arrival at FEQL
Date processed
Weighed for extraction
Date of extraction
Days in frozen storage
Set
0313-C-083013 8/30/2013 D5 9/14/2013 9/25/2013 10/29/2013
11/5/2013
10/30/2013 11/5/2013
61 67
set24 set 24r for zeta-cypermethrin
0313-M-083013-T 8/30/2013 D5 9/14/2013 10/29/2013 10/30/2013
11/5/2013
10/30/2013 11/5/2013
61 67
0313-M-083013-TD 8/30/2013 D5 9/14/2013 10/29/2013 10/30/2013
11/5/2013
10/30/2013 11/5/2013
61 67
0313-AB-083013-T 8/30/2013 D5 9/14/2013 10/29/2013 10/30/2013
11/5/2013
10/30/2013 11/5/2013
61 67
0313-AB-083013-TD 8/30/2013 D5 9/14/2013 10/29/2013
10/30/2013 11/5/2013
10/30/2013 11/5/2013
61 67
0313-C-090113 9/1/2013 D7, MM14 9/14/2013 9/25/2013 10/31/2013
10/31/2013 60 set25
0313-M-090113-T 9/1/2013 D7, MM14 9/14/2013 10/21/2013
10/31/2013 10/31/2013 60 0313-M-090113-TD 9/1/2013 D7, MM14
9/14/2013 10/21/2013 10/31/2013 10/31/2013 60 0313-AB-090113-T-A
9/1/2013 D7, MM14 9/14/2013 10/21/2013 10/31/2013 10/31/2013 60
0313-AB-090113-TD-A 9/1/2013 D7, MM14 9/14/2013 10/21/2013
10/31/2013 10/31/2013 60 0313-AB-090113-T-B 9/1/2013 D0 9/14/2013
10/24/2013 10/31/2013 10/31/2013 60 0313-AB-090113-TD-B 9/1/2013 D0
9/14/2013 10/24/2013 10/31/2013 10/31/2013 60 0313-C-090213
9/2/2013 D1 9/14/2013 10/2/2013 11/5/2013 11/6/2013 65 Set26
0313-AB-090213-T 9/2/2013 D1 9/14/2013 10/30/2013 11/5/2013
11/6/2013 65 0313-AB-090213-TD 9/2/2013 D1 9/14/2013 10/30/2013
11/5/2013 11/6/2013 65 0313-C-090313 9/3/2013 D2 9/14/2013
9/26/2013 11/5/2013 11/6/2013 64 set26
0313-AB-090313-T 9/3/2013 D2 9/14/2013 10/24/2013 11/5/2013
11/6/2013 64 0313-AB-090313-TD 9/3/2013 D2 9/14/2013 10/24/2013
11/5/2013 11/6/2013 64 0313-C-090513 9/5/2013 D4 9/14/2013
10/28/2013 11/7/2013 11/7/2013 63 set27
0313-AB-090513-T 9/5/2013 D4 9/14/2013 10/28/2013 11/7/2013
11/7/2013 63
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Arrival at FEQL
Date processed
Weighed for extraction
Date of extraction
Days in frozen storage
Set
0313-AB-090513-TD 9/5/2013 D4 9/14/2013 10/28/2013 11/7/2013
11/7/2013 63 0313-C-090913 9/9/2013 D8 9/14/2013 9/30/2013
11/7/2013 11/7/2013 59 set27
0313-AB-090913-T 9/9/2013 D8 9/14/2013 11/6/2013 11/7/2013
11/7/2013 59 0313-AB-090913-TD 9/9/2013 D8 9/14/2013 11/6/2013
11/7/2013 11/7/2013 59 0313-C-091313 9/13/2013 D12 9/14/2013
9/26/2013 11/12/2013 11/12/2013 60 set28
0313-AB-091313-T 9/13/2013 D12 9/14/2013 10/30/2013 11/12/2013
11/12/2013 60 0313-AB-091313-TD 9/13/2013 D12 9/14/2013 10/30/2013
11/12/2013 11/12/2013 60 0313-C-091613 9/16/2013 D15 10/17/2013
11/7/2013 11/12/2013 11/12/2013 57 set28
0313-AB-091613-T 9/16/2013 D15 10/17/2013 11/5/2013 11/12/2013
11/12/2013 57 0313-AB-091613-TD 9/16/2013 D15 10/17/2013 11/5/2013
11/12/2013 11/12/2013 57 0313-C-092513 9/25/2013 D24 10/17/2013
11/7/2013 11/12/2013 11/12/2013 48 set28
0313-AB-092513-T 9/25/2013 D24 10/17/2013 11/6/2013 11/12/2013
11/12/2013 48 0313-AB-092513-TD 9/25/2013 D24 10/17/2013 11/6/2013
11/12/2013 11/12/2013 48
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III. Standard Preparation
Linearity standards in control matrix were prepared with each
sample set to compare sample
residues to a linear regression calculated from four standard
concentrations. When necessary,
samples were diluted to fit the range of linearity standards.
Table 3 lists the test substances,
spiking solutions, and standard dilutions used throughout this
study.
Table 3: Test Substances and Standards
Compounds
Use Reference
No. Purity Source
Expiration
Date
Malathion Test Substance 1436 99.5% ChemService 5/31/16
Phosmet Test Substance 1437 99.5 ChemService 11/30/15
Zeta-cypermethrin Test Substance 1438 99.4 ChemService
3/31/18
Fenpropathrin Test Substance 1441 99.3 ChemService 6/30/18
Solutions & Dilutions of Test Substances
Compound Use Solution
No. Conc. Solvent
Expiration
Date
Malathion
Spiking 14361 1 mg/mL acetonitrile 5/22/14
Spiking 143611 100 ug/mL acetonitrile 5/22/14
Spiking 143612 10 ug/mL acetonitrile 5/22/14
Std verification 14362 1 mg/mL acetonitrile 6/10/14
Std verification 143621 100 ug/mL acetonitrile 6/10/14
Std verification 143622 10 ug/mL acetonitrile 6/10/14
Zeta-cypermethrin
Spiking 14371 1 mg/mL acetonitrile 5/22/14
Spiking 143711 100 ug/mL acetonitrile 5/22/14
Spiking 143712 10 ug/mL acetonitrile 5/22/14
Std verification 14372 1 mg/mL acetonitrile 5/22/14
Std verification 143721 100 ug/mL acetonitrile 5/22/14
Std verification 143722 10 ug/mL acetonitrile 5/22/14
Fenpropathrin
Spiking 14381 1 mg/mL acetonitrile 5/22/14
Spiking 143811 100 ug/mL acetonitrile 5/22/14
Spiking 143812 10 ug/mL acetonitrile 5/22/14
Std verification 14382 1 mg/mL acetonitrile 5/22/14
Std verification 143821 100 ug/mL acetonitrile 5/22/14
Std verification 143822 10 ug/mL acetonitrile 5/22/14
Phosmet
Spiking 14411 1 mg/mL acetonitrile 7/5/14
Spiking 144111 100 ug/mL acetonitrile 7/5/14
Spiking 144112 10 ug/mL acetonitrile 7/5/14
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Mixed Solutions
Compounds Solution No. Conc. Solvent Expiration
Data
Malathion; Zeta-cypermethrin;
Fenpropathrin; Phosmet
M0313T-8 100 µg/mL each acetonitrile 5/22/14
Malathion; Zeta-cypermethrin;
Fenpropathrin; Phosmet
M0313T-10 10 µg/mL each toluene 5/22/14
Malathion; Zeta-cypermethrin;
Fenpropathrin; Phosmet
M0313T-22 1 µg/mL toluene 5/22/14
Malathion; Zeta-cypermethrin;
Fenpropathrin; Phosmet
M0313T-23 0.5 µg/mL toluene 5/22/14
Malathion; Zeta-cypermethrin;
Fenpropathrin; Phosmet
M0313T-24 0.2 µg/mL toluene 5/22/14
Malathion; Zeta-cypermethrin;
Fenpropathrin; Phosmet
M0313T-25 0.1 µg/mL toluene 5/22/14
Malathion; Zeta-cypermethrin;
Fenpropathrin; Phosmet
M0313T-26 0.05 µg/mL toluene 5/22/14
All standard solutions were stored in the freezer at
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PSA and magnesium sulfate. This tube was then mixed and
centrifuged again. Finally, 4 mL
of the resulting organic solvent was solvent exchanged to
toluene and brought to final
volume for analysis.
B. Analytical Limits
The working method was validated by fortifying and recovering
malathion, zeta-
cypermethrin, phosmet and fenpropathrin from control
blueberries. The method was
validated in triplicate at three concentration levels: 0.05
ug/g, 0.5 ug/g and 5 ug/g (6 ug/g for
zeta-cypermethrin). Results from the method validation are
presented in Section V. Results.
C. Instrumentation
Pesticide residue concentrations were determined using one of
three instruments. Instrument
conditions are presented below.
A Varian 3400 CX gas chromatograph with pulsed flame photometric
detection (GC/PFPD)
and 8200 CX autosampler was used for malathion and phosmet
determination. Integration of
chromatographic data was performed using the Star Workstation
software.
Column: Alltech EC-1, 15m x 0.53mm, 1.2 μm film thickness
Carrier gas: Ultrapure helium, flow ca. 12 mL/min.
Temperatures: Detector: 300°C
Injector port: 225 to 250°C at 250°C/min
Oven program
Initial: 100°C
ramp 30°C/min to 300°C, hold 1 min.
Injection volume: 2 μl
Detector: Air
Hydrogen
Nitrogen makeup gas
Retention time: Based on the observed retention times of
external calibration
standards in each set.
An Agilent 6890N gas chromatograph with micro-electron capture
detection (GC/µECD) and
7683 Autosampler was used for fenpropathrin detection and
quantification. Integration of
chromatographic data was performed using Chemstation
software.
Column: DB-5ms, 30m x 0.32mm, 0.25 μm film thickness
Carrier gas: Ultrapure helium, constant flow 2.2 mL/min.
Temperatures: Injector port: splitless, 250°C
Oven program
Initial: 100°C
ramp 25°C/min to 150°C,
ramp 10°C/min to 300°C, hold 2 min.
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Injection volume: 2 μl
Detector: µECD 250°C; hydrogen 2 mL/min; air 60 mL/min;
nitrogen makeup 30 mL/min
Retention time: Based on the observed retention times of
external calibration
standards in each set.
An Agilent 6890N gas chromatograph with mass spectrometry
detection (GC/MS) and 7683
Autosampler was used for zeta-cypermethrin detection and
quantification. Integration of
chromatographic data was performed using Chemstation
software.
Column: DB-5ms, 25m x 0.25mm, 0.25 μm film thickness
Carrier gas: Ultrapure helium, constant flow 2.2 mL/min.
Temperatures: Injector port: 250°C
Oven program
Initial: 100°C
ramp 25°C/min to 150°C,
ramp 10°C/min to 300°C, hold 2 min.
Injection volume: 2 μl
Detector: Source 230 ˚C, Quad 150 ˚C
SIM Zeta-cypermethrin: 91 m/z, 163 m/z, and 181 m/z
Retention time: Based on the observed retention times of
external calibration
standards in each set.
To verify the reliability of the GC instruments, calibration
standards were inserted into the
sample set during each GC analysis. The peak area counts and
retention times for the
compounds were assessed for reproducibility and accuracy.
Additionally, extracts were
injected in duplicate. If extract peak areas agreed within 20%
then the average of the two
results were used to calculate concentrations.
D. Quantification
The quantification of pesticide residues in 15 g blueberry was
performed by electronic peak
area measurement of each pesticide and comparison to the linear
regression from at least four
standards in the concentration range of sample extracts. To
assure high quality during GC
operation, all samples were bracketed with external calibration
standards during the
analytical set. For each analytical set, linearity and
calibration standards were used to
construct the calibration curves using a spreadsheet program
(Excel®).
The residue concentration in the blueberry samples is calculated
by multiplying the
calculated concentration by the equivalent final volume of the
sample extract, and then
dividing by the weight of berry sample. Results are reported as
total concentration of each
individual pesticide in blueberry.
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For example, set-24, sample 0313-SO-FS33, the malathion linear
regression line of best fit,
computed from the combined linearity and calibration standards
of this set (n=15, R2=0.999)
is expressed by equation 1:
Eq. 1 Y =m X + B
Where Y is peak area, m is the slope of the line, X is detected
concentration, and B is the
intercept.
Y = 9017.934196 x X – 44.6356526
4 mL of the acetonitrile extract was exchanged to toluene for
analysis and brought to a final
volume of 2 mL. This is equivalent to 4 g of crop in 2 mL. The
average peak area count from
two injections of the sample was 8959.5. Because this is a
fortified sample, the peak area of
the control is subtracted from the peak area of the fortified
sample. However, there was no
malathion detected in the corresponding control sample in this
set. The concentration (in
µg/mL) of malathion in the extract is calculated according to
Eq. 1:
8959.5 = 9017.934196 x X – 44.6356526
X=0.998 µg/mL malathion
The concentration of malathion in the blueberry sample is then
figured by multiplying by the
ratio of the final volume to the sample weight:
(0.998 µg/mL malathion)(2 mL/4 g) = 0.50 µg/g malathion
To assess overall analysis precision and percent recovery on a
per-set basis, control samples
were fortified with a known amount of standard prior to
extraction. For each analytical set,
percent recovery for the fortified sample was calculated
according to Equation 2. When
necessary, control-sample peak area was subtracted from
fortified recovery sample peak of
similar dilution for fortified-residue determination.
Eq. 2 % Recovery = (amount detected*) x 100
Amount fortified
* amount detected is calculated from fortified peak area minus
control peak area.
For example, sample 0313-SO-FS33 was a fortified sample spiked
with 7.5 µg malathion
(0.5 µg/g in blueberry). The percent recovery of malathion in
the extract is then calculated by
eq. 2.
% Recovery = (0.50 µg/g) x 100 = 100%
µg/g
The same calculation method was used for each of the pesticides
in this study.
E. Interferences
The GC/PFPD analysis for malathion and phosmet was very straight
forward and sensitive.
The quantitation of phosmet often required additional sample
dilutions and reanalysis to suit
the range of standards.
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In the case of zeta-cypermethrin there was a large interfering
peak at the retention time of the
compound which prevented use of µECD for quantitation. The use
of GC/MS-single ion
monitoring overcame this problem but the interference still
existed to some degree. The zeta-
cypermethrin peak is a cluster of four isomers of the compound.
To adequately quantify the
compound the integration program was set to force the peak and
sum all peak areas within
the retention time window.
Typical for ECD chromatography, the µECD chromatograms have some
interfering peaks at
the lower concentration levels, making integration of the peak
of interest difficult.
Additionally, matrix enhancement was present which required the
use of matrix-matched
standards for all berry sample analyses.
F. Confirmatory Techniques
Matrix-matched analytical standards were used to confirm the
presence of malathion, zeta-
cypermethrin, fenpropathrin, and phosmet by retention times.
G. Time Required for Analysis
The time required for an experienced person to work up a set of
samples (generally five
samples, one control, and one fortified sample) was
approximately 6 hours. The duration of
the GC analyses of each set depended on which compounds were of
interest in the samples.
Sample sets were analyzed on multiple instruments after
extraction. Each sample set was
injected using the auto sampler associated with the
instrument.
H. Modifications or Potential Problems
High-quality reagents, pesticide grade or better, must be used
throughout the study to avoid
chromatography problems and contamination in the control.
Method development work indicated a significant matrix
enhancement effect characterized
by improved peak shape and peak response in the presence of
matrix compared to the
analytical standards made in pure solvent. To overcome the
influence of the matrix, matrix-
matched standards were created for each set.
The QuEChERS method was quick and easy and yielded reliable
extraction results. The
method uses far less solvent than traditional liquid-liquid
extraction, however the method
introduces a lot of salt and co-extractable components to the
sample extracts. The
consumption of disposable supplies, need for matrix standards
and the greatly increased
maintenance requirements on the GC inlet and column make this
method less than ideal for a
project of this magnitude. It is highly recommended that a
better extraction method be used
for future blueberry MRL studies.
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V. Results
A. Method Validation and Recovery
All reagents and instruments used during the course of this
study are commercially available
and typical of what would be present in most analytical
laboratories. The working method
was validated at three concentration levels, 0.05 µg/g, 0.5 µg/g
and 5 µg/g. The low end
fortification of 0.05 µg/g was designated as the method’s limit
of quantitation (mLOQ) for
malathion, zeta-cypermethrin, fenpropathrin, and phosmet. The
method limit of detection
(mLOD) was empirically estimated at approximately 0.01 µg/g for
malathion, fenpropathrin
and phosmet. However, due to background in the control samples
which was occasionally as
high as the equivalent of 0.02 µg/g zeta-cypermethrin the LOD
for that compound was
empirically determined at half the mLOQ, or 0.025 µg/g
zeta-cypermethrin. Table 4 lists the
method validation results. Table 5 provides the concurrent
recovery results for malathion,
zeta-cypermethrin, fenpropathrin, and phosmet in the fortified
samples extracted with each
set.
Table 4
Method Validation
Percent Recoveries
Sample ID
Fortificatio
n Level
(µg/g) Malathion Phosmet Fenpropathrin
Zeta-
cypermethrin
0313-Y2-MV11 0.05 113.1% 112.3% 102.1% rejected
0313-Y2-MV11re1 0.05 102.0% 100.6% 100.5% 86.6%
0313-Y2-MV12 0.05 112.5% 112.5% 106.0% 85.7%
0313-Y2-MV13 0.05 111.6% 115.6% 104.9% 79.7%
0313-Y2-MV14 0.5 93.4% 91.4% 90.1% 86.3%
0313-Y2-MV15 0.5 96.4% 92.4% 92.6% 89.1%
0313-Y2-MV16 0.5 97.1% 92.2% 93.2% 84.9%
0313-Y2-MV17 5 102.8% 103.0% 102.0%
0313-Y2-MV18 5 96.5% 96.5% 98.0%
0313-Y2-MV19 5 95.4% 91.9% 97.3%
0313-Y2-MV20 6 112.7%
0313-Y2-MV21 6 99.9%
0313-Y2-MV22 6 96.9% 1 re = this set was re-extracted a second
time due to initially high (rejected) zeta-cypermethrin
recovery
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Table 5
Concurrent Fortified Samples
Percent Recoveries
Sample ID
Fortification
Level
(µg/g) Set Malathion Phosmet Fenpropathrin
Zeta-
cypermethrin
0313-Y-FS10 0.05 SET1RE1 118.4% 118.6% NA 78.1%
0313-Y-FS11 0.05 SET2RE 101.1% 106.0% NA 37.1%2
0313-Y2-FS12 0.05 SET3RE 104.5% 113.3% NA 53.2%2
0313-Y-FS15 0.05 SET6RE 109.5% 105.5% NA 86.2%
0313-SO-FS16 0.05 set7 101.7% 110.1% NA 104.9%
0313-SO-FS21 0.05 set12 101.2% 87.4% NA 86.8%
0313-SO-FS22 0.05 set13 114.6% 106.7% NA 77.7%
0313-SO-FS24 0.05 set15 94.2% 96.2% NA 103.6%
0313-SO-FS26 0.05 set17 105.3% 112.1% NA 113.4%
0313-SO-FS27 0.05 set18 103.7% 109.4% NA 96.3%
0313-EFO-FS36 0.05 set27 103.4% 105.9% 110.9% 100.9%
0313-SO-FS28 0.1 set 19 108.2% 104.0% NA 79.0%
0313-SO-FS29 0.1 set20 102.7% 106.2% NA 102.0%
0313-SO-FS30 0.1 set21 100.5% 100.5% 94.8% 79.6%
0313-SO-FS32 0.1 set23 98.1% 104.2% NA 89.6%
0313-Y-FS13 0.5 SET4RE 99.8% 104.8% NA NA
0313-Y-FS14 0.5 SET5RE2 99.6% 103.0% NA NA
0313-SO-FS17 0.5 set8 96.2% 100.6% NA 89.0%
0313-SO-FS18 0.5 set9 78.4% 78.5% NA 75.8%
0313-SO-FS19 0.5 set10 90.3% 91.3% NA 76.6%
0313-SO-FS20R 0.5 set11re 93.5% 97.7% NA 84.1%
0313-SO-FS23 0.5 set14 113.3% 124.9% NA NA
0313-SO-FS25 0.5 set16 101.7% 130.3% NA 83.2%
0313-SO-FS31 0.5 set22 110.0% 122.8% NA 114.2%
0313-EFO-FS33 0.5 set24 99.8% 118.2% 98.0% 95.4%
0313-EFO-FS34 0.5 set25 114.4% 115.9% 93.8% 95.8%
0313-EFO-FS35 0.5 set26 92.6% 98.9% 97.5% 98.0%
0313-EFO-FS37 0.5 set28 100.9% 108.6% 96.9% 97.8%
0313-072713-C-FS1 0.5 Storstab 100.3%
89.8% 85.3%
Overall Average Recovery 102.0% 105.0% 98.1% 88.7%
Standard Deviation 8% 11% 6% 15%
Total Count (includes validation) 39 38 17 35 1 re = these sets
were re-extracted due to one or more poor recoveries.
2 These recoveries accepted. Results were low due to high
control peak which was subtracted
from the fortified sample peak for calculation.
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B. Storage Stability
To verify stability of malathion, zeta-cypermethrin,
fenpropathrin, and phosmet on
blueberries during frozen storage, FEQL fortified organic
control berries purchased from a
grocery store at 0.5 µg/g on 9/4/2013. These storage stability
samples, were maintained in
the freezer (ID Dasher) with study samples. Storage stability
samples were extracted on
3/19/2014 according to the analytical method to verify the
stability of the pesticides of
interest in frozen storage. This storage interval represents 196
days of demonstrated storage
stability. All berry samples from this study were extracted
within 74 days of sampling. Table
6 provides the storage stability recovery results for malathion,
zeta-cypermethrin,
fenpropathrin, and phosmet on blueberry.
Table 6
Storage Stability Samples
Percent Recoveries
Sample ID Fortification
Level
(µg/g) Malathion Phosmet
1 Fenpropathrin
Zeta-
cypermethrin
0313-Y2-SS1 0.5 89.5% 87.1% 87.0% 78.7%
0313-Y2-SS2 0.5 86.7% 80.1% 93.0% 88.7%
0313-Y2-SS3 0.5 87.4% 87.2% 97.1% 93.7% 1
Phosmet quantified against prepared standards because matrix
control had detectable levels of phosmet.
C. Residue Results
This project monitored the pesticide residue on marketable fruit
from two different
application methods one day before application through
approximately 14 days after
application. Figures 2-4 illustrate the individual pesticide
decline after application. Figure 5
is a plot of all monitored pesticides for the duration of the
study that also included Imidan.
Table 7 provides the results for the analyzed MRL blueberry
samples. All residues are
expressed as micrograms of pesticide per gram of blueberry (µg/g
or ppm). Results below the
method limit of detection are listed as
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per year where up to 2.5 pints can be applied for any one
application. Although this is data
from a single field study, it is reasonable to state that 4
seasonal blueberry applications at
1.25 pints/acre will not trigger MRLs in the US (8 ppm), or
Korea (10 ppm). However, other
Pacific Rim MRLs may be exceeded. Japan’s current MRL is 0.5 ppm
where Taiwan’s is
more conservatively set at 0.1 ppm. When developing a harvest
program for malathion, the
grower may choose to delay picking 3-5 days later than the
allowed 1 day PHI to better
insure that field residues will not trigger a Japan MRL concern.
However, this data is only
from one season and some level of risk of exceeding the MRL can
still exist.
Mustang Maxx: Figure 3 shows field residues before and after
Mustang Maxx
applications in early to late August 2013. The good
reproducibility among the duplicate
composited berry sample data points for M and AB applications at
each interval date and
consistent recovery among 35 fortified samples (89 +
15%) indicate that testing laboratories
should find similar concentrations in marketable berries.
Mustang Max berry residues (as
zeta-cypermethrin) were found at much lower than US (MRL = 8
ppm) and Pacific Rim
MRLs from Korea and Japan (respectively 10 and 0.5 ppm). It is
important to note that
Taiwan does not currently provide an MRL for the active
ingredient zeta-cypermethrin in
Mustang Maxx. As such, any detected residue may trigger a trade
barrier concern. The
appreciably slower rate of residue decline when compared to
organophosphorus insecticides
is typical of pyrethroid insecticides and again similar to
recent cherry decline work by
Haviland and Beers (2012). We did observe a consistently higher
level of Mustang Maxx
residues after the second air blast application. Although
results from any one-season decline
study make it difficult to precisely predict residues that may
occur under differing climatic
and growing conditions, it is reasonable to state that growers
should be wary of making too
many consecutive applications of this substance if planning on
exporting to countries such as
Japan.
Danitol: Currently, this substance can only be applied twice in
any one growing season
and was used in late August as a clean-up application. Because
of its longer-lasting efficacy
on SWD (Lynell Tanigoshi, personal communication), we
anticipated that this pyrethroid
chemistry would decline slowly in the field as is evident in
Figure 4. Decline on/in blueberry
was similar to the recent decline study conducted at a similar
rate on sweet cherries by
Haviland and Beers (2012). Although the Danitol data again
represents a single PNW field
study, it is reasonable to anticipate that Danitol applied at
the commercial rate of 16 fluid oz
per acre should not trigger MRLs in the US (8 ppm), Japan (5
ppm), or Taiwan (3 ppm).
However, Korea MRLs may likely be exceeded well after the 3 day
PHI. Fenpropathrin, the
active ingredient in Danitol appears to be a longer lasting
pyrethroid. The grower may
consider using this substance as a start and late season finish
SWD treatment since current
label use of this material (as of 2013) only allows two seasonal
applications,.
Cumulative Season-long Field Residues: Malathion, Mustang Maxx,
and Danitol
blueberry residues were measured in the field on 32 separate
sampling events from late July
through mid-September. Residues of Imidan (phosmet) were also
assessed over the 48 day
spray period. Figure 5 provides the residue data for the four
compounds. This profile
suggests that cumulative residues over the growing season may be
effective in controlling
SWD field populations thus reducing the need for weekly
applications. As a result, the
grower should consider season-long residual pesticide field
concentrations together with
scouting as part of the SWD spray management program.
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Figure 2: Malathion applications on 7/28/2013 and 8/11/2013
Figure 3: Mustang Maxx (zeta-cypermethrin) applications on
8/4/2013 and 8/18/2013
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Mal
ath
ion
(p
pm
)
Malathion Applications
Field Control (ppm)
Mistigation-T(ppm)Mistigation-TD(ppm)Airblast-T (ppm)
Airblast-TD (ppm)
0.000
0.050
0.100
0.150
0.200
0.250
0.300
zeta
-Cyp
erm
eth
rin
(p
pm
)
Mustang Maxx Applications
Field Control(ppm)Mistigation-T(ppm)Mistigation-TD(ppm)
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Figure 4: Danitol (fenpropathrin) application by airblast
sprayer on 9/1/2013
Figure 5: Cumulative pesticide concentrations, monitored
7/27/2013-9/25/2013
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Fen
pro
pat
hri
n (
pp
m)
Danitol Application
Field Control(ppm)Airblast-T (ppm)
Airblast-TD(ppm)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
Pes
tici
de
(pp
m)
Date Malathion Mistigation (ppm) Phosmet mistigation
(ppm)Zeta-cypermethrin mistigation (ppm) Malathion Airblast
(ppm)Phosmet airblast (ppm) Zeta-cypermethring airblast (ppm)
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Table 7
Analysis Results
Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Date of extraction
Set Malathion
(µg/g) Phosmet
(µg/g) Fenpropathrin
(µg/g)
Zeta-cypermethrin
(µg/g)
0313-C-072713 7/27/2013 M(-1) 9/23/2013 set2re ND 0.32 NA
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Date of extraction
Set Malathion
(µg/g) Phosmet
(µg/g) Fenpropathrin
(µg/g)
Zeta-cypermethrin
(µg/g)
0313-M-073113-TD 7/31/2013 M3 9/24/2013
0.10 0.18 NA NA
0313-AB-073113-T 7/31/2013 M3 9/24/2013
0.37 0.41 NA NA
0313-AB-073113-TD 7/31/2013 M3 9/24/2013
0.49 0.34 NA NA
0313-C-080213 8/2/2013 M5 9/24/2013 set5RE2 ND 0.64 NA NA
0313-M-080213-T 8/2/2013 M5 9/24/2013
0.06 0.18 NA NA
0313-M-080213-TD 8/2/2013 M5 9/24/2013
0.06 0.21 NA NA
0313-AB-080213-T 8/2/2013 M5 9/24/2013
0.28 0.48 NA NA
0313-AB-080213-TD 8/2/2013 M5 9/24/2013
0.18 0.46 NA NA
0313-C-080313 8/3/2013 MM(-1) 9/25/2013 set6RE ND 0.85 NA
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Date of extraction
Set Malathion
(µg/g) Phosmet
(µg/g) Fenpropathrin
(µg/g)
Zeta-cypermethrin
(µg/g)
0313-M-080713-TD 8/7/2013 M10, MM3 10/1/2013
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Date of extraction
Set Malathion
(µg/g) Phosmet
(µg/g) Fenpropathrin
(µg/g)
Zeta-cypermethrin
(µg/g)
0313-M-081313-TD 8/13/2013 M2 10/15/2013
0.15 0.19 NA
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Date of extraction
Set Malathion
(µg/g) Phosmet
(µg/g) Fenpropathrin
(µg/g)
Zeta-cypermethrin
(µg/g)
0313-AB-081813-T 8/18/2013 M7, MM14, MM0
10/21/2013
0.15 0.19 NA
0.18
0313-AB-081813-TD 8/18/2013 M7, MM14, MM0
10/21/2013
0.13 0.20 NA
0.15
0313-C-081913 8/19/2013 MM1 10/22/2013 set20 ND 1.43 NA
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Date of extraction
Set Malathion
(µg/g) Phosmet
(µg/g) Fenpropathrin
(µg/g)
Zeta-cypermethrin
(µg/g)
0313-C-082513 8/25/2013 M14, MM7, D0
10/30/2013 11/5/2013
set24 set 24r for zeta-cypermethrin
ND 0.91 ND
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Sample IDs Sampling
Date
Treatment Status
Days after Treatment
Date of extraction
Set Malathion
(µg/g) Phosmet
(µg/g) Fenpropathrin
(µg/g)
Zeta-cypermethrin
(µg/g)
0313-AB-090213-TD 9/2/2013 D1 11/6/2013
0.12 0.09 0.52 0.07
0313-C-090313 9/3/2013 D2 11/6/2013 set26 1.34 0.63
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Appendix A: Protocol
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Appendix B: Working Method
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Appendix C: Sample Chromatograms
Figure C1 - Malathion & Phosmet 0.5 ug/mL standard in
blueberry extract matrix
malathion 0.5 ug/mL
phosmet 0.5 ug/mL
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Figure C2 – Malathion & Phosmet: Control berry extract,
0313-EFO-C33 in 2 mL
malathion expected
retention time ~4.5 min;
phosmet expected retention
time ~6.0 min
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Figure C3 – Malathion & Phosmet: fortified recovery sample,
0313-EFO-FS33 in 2 mL
malathion, 0.998 ug/mL in 2 mL
extract, equivalent to 0.5 ug/g;
phosmet, 1.18 ug/mL in 2 mL
extract, equivalent to 0.59 ug/g
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Figure C4 – Malathion & Phosmet: mistigation sample,
0313-M-083013-T in 2 mL
malathion, 0.092 ug/mL in 2 mL
extract, equivalent to 0.05 ug/g;
phosmet, 0.099 ug/mL in 2 mL
extract, equivalent to 0.05 ug/g
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Figure C5 – Malathion & Phosmet: airblast sample,
0313-AB-083013-T in 4 mL
malathion, 0.832 ug/mL in 4 mL
extract, equivalent to 0.83 ug/g;
phosmet, 0.121 ug/mL in 4 mL
extract, equivalent to 0.12 ug/g
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Figure C6 – Malathion & Phosmet: field control sample,
0313-C-083013 in 2 mL
malathion, ND in 2 mL extract,
equivalent to 0.83 ug/g;
phosmet: Sample later diluted and
reanalyzed for phosmet, 0.67 ug/g
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Figure C7 - Zeta-cypermethrin 0.5 ug/mL standard in blueberry
extract matrix
Zeta-cypermethrin 0.5 ug/mL
SIM, cluster of peaks at 15.68 min
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Figure C8 - Zeta-cypermethrin Control berry extract,
0313-EFO-C33R in 2 mL
Zeta-cypermethrin background,
0.02 ug/g in control
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Figure C9 - Zeta-cypermethrin fortified recovery sample,
0313-EFO-FS33R in 2 mL
Zeta-cypermethrin 0.954 ug/mL in 2
mL extract, equivalent to 0.48 ug/g
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Figure C10 - Zeta-cypermethrin mistigation sample,
0313-M-083013-TR in 2 mL
Zeta-cypermethrin 0.072 ug/mL in 2
mL extract, equivalent to
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Figure C11 - Zeta-cypermethrin airblast sample,
0313-AB-083013-TR in 2 mL
Zeta-cypermethrin 0.224 ug/mL in 2 mL
extract, equivalent to 0.11 ug/g
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Figure C12 - Zeta-cypermethrin field control sample,
0313-C-083013R in 2 mL
Zeta-cypermethrin 0.056 ug/mL in 2 mL
extract, equivalent to
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Figure C13 – Fenpropathrin 0.5 ug/mL standard in blueberry
extract matrix
Fenpropathrin 0.5 ug/mL
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Figure C14 - Fenpropathrin Control berry extract, 0313-EFO-C37
in 2 mL
Fenpropathrin, expected retention
time 14.77 min
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Figure C15 – Fenpropathrin fortified recovery sample,
0313-EFO-FS37 in 2 mL
Fenpropathrin 0.969 ug/mL in 2 mL
extract, equivalent to 0.48 ug/g
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Figure C16 – Fenpropathrin airblast sample, 0313-AB-092513-T in
2 mL
Fenpropathrin 1.03 ug/mL in 2 mL
extract, equivalent to 0.52 ug/g
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Figure C17 – Fenpropathrin field control sample, 0313-C-092513
in 2 mL
Fenpropathrin 0.057 ug/mL in 2 mL
extract, equivalent to