Abstract The standard and thermostatted Agilent 1100 Series autosamplers offer the possibility to inject volumes from 0.1 μl to 100 μl with high precision. However, for certain applications, such as semi-preparative HPLC or low con- centrated samples, higher sample vol- umes are required. This technical note describes the enhanced injection volume capabilities, which are possible with the multi-draw upgrade kit, the 900-μl injection upgrade kit, a combination of both kits, and a 5000-μl seat capillary. Injecting large sample volumes with the Agilent 1100 Series using the multi-draw and 900-μl injection upgrade kits Technical Note
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Injecting large sample volumes with the Agilent 1100 Series using
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Abstract
The standard and thermostatted Agilent 1100 Series autosamplers offerthe possibility to inject volumes from 0.1 µl to 100 µl with high precision.However, for certain applications, suchas semi-preparative HPLC or low con-centrated samples, higher sample vol-umes are required.
This technical note describes theenhanced injection volume capabilities,which are possible with the multi-drawupgrade kit, the 900-µl injection upgradekit, a combination of both kits, and a5000-µl seat capillary.
Injecting large sample volumeswith the Agilent 1100 Seriesusing the multi-draw and 900-µl injection upgrade kits
Technical Note
Introduction
The standard and thermostattedAgilent 1100 Series autosamplersoffer the possibility to inject vol-umes from 0.1 µl to 100 µl withhigh precision1. However, for cer-tain applications, such as semi-preparative HPLC or low concen-trated samples, higher sample vol-umes are required.
In semi-preparative HPLC moresample amount is applied to thecolumn. This can be achieved byconcentration or volume over-loading. Concentration overload-ing is only possible if the solubili-ty of the sample compound in theliquid phase is high enough.Otherwise volume overloadingwith injection volumes in the mil-liliter range is necessary.
Samples with low compoundamounts have to be concentratedfor proper detection. This can bedone offline by evaporating thesolvent or online by accumulatingthe compound on the head of thecolumn using an appropriate elu-ent. After the sample is complete-ly applied to the column the eluent is changed and separationand detection can be achieved.Another possibility is to concen-trate the compound on the headof a small column and then flushback the compound onto anothercolumn where the actual separa-tion takes place. This requires acolumn-switching valve, whichcan be built into the Agilent 1100Series thermosatted column com-partment.
Agilent Technologies offers twoupgrade kits to enhance the injec-tion volume:
They can be used independentlyor in combination with each other.Larger injection volumes can beachieved using other seat capillaries of larger volume.
Equipment
All experiments were carried outon the Agilent 1100 Series highpressure gradient system consist-ing of
• an Agilent 1100 Series vacuum degasser,
• an Agilent 1100 Series binary pump,
• an Agilent 1100 Series auto-sampler,
• an Agilent 1100 Series thermostatted column compartment, and
• an Agilent 1100 Series diode array detector.
The system was controlled usingthe Agilent ChemStation software(rev. A.06.03).
The multi-draw upgrade kit, con-sisting of a 400-µl and a 1400-µlextended seat capillary wasinstalled according to theInstallation Note for Multidraw
Upgrade Kit2 which is supplied
with the product.
The 900-µl injection upgrade kit,consisting of a 900-µl analyticalhead, a 900-µl loop extension anda 900-µl needle was installedaccording to the Installation Note
for 900-µl Injection Upgrade Kit3
which is supplied with the product.
Configurations
Various configurations of sampleloop and seat capillary are possibleas listed in table 1. Configurationexamples 1-5 are discussed in thistechnical note.
The configuration of the samplingsystem is shown in figure 1.
Figure 2 shows the sample loopand the seat capillary configura-tions in the Injector Configuration
window of the ChemStation. Herethe sample loop is called Syringe.
* Using an injector program** Seat capillary not included in the multi-draw upgrade kit
Table 1
Overview of configurations
Figure 1
Schematic of the Agilent 1100 Series
autosampler
Figure 2
Injector configuration window
• The 400-µl seat capillary was installed according to the “Installation Note for the
Multi-draw Kit G1313-68711”
• The seat capillary was configured in the Injector
Configuration window.• Maximum injection volume:
500 µl (4 x 100 µl in the seat capillary and 100 µl in the sample loop).
• Draw speed: 200 µl/min, configured in the Setup
Injector window of the ChemStation.
• Sample: Isocratic sample, diluted 1:100 with water/acetonitrile 60:40.
Performance characteristics
Precision of peak areaAfter a certain number of injections of the same sample therelative standard deviation of thepeak areas were determined. Therelative standard deviation showsthe reproducibility of the wholesystem, which is influenced by allsystem components. For preci-sion measurements ten injectionswere performed from the samesample. The relative standard deviationwas calculated using the sequencesummary report of the Chem-Station. Figure 3 shows the preci-sion of the peak area.
4 x 125 mm, 5 µmTemperature: 25 °CDetector: DAD 254 nm/16
(reference:360 nm/100)
Dimethylphthalate
DiethylphthalateBiphenyl
Terphenyl
LinearityAnalysis of samples with differentcompound concentrations givesthe linearity curve of the autosam-pler. The signals of the sampleshave to be in the linear range ofthe detector. For linearity mea-surements at least three injectionvolumes were injected. For each
injection volume ten measure-ments were performed and themean value was used for calculat-ing the linearity correlation coeffi-cient. Linearity is shown in figure 4.
0
500
1000
1500
2000
2500
3000
3500
4000
0 100 200 300 400 500
Dimethylphthalate
Diethylphthalate
Biphenyl
Terphenyl
Correlation: 1.00000
Correlation: 1.00000
Correlation: 1.00000
Correlation: 0.99999
Figure 4
Linearity for configuration example 1
Peak area [mAU x s]
Injection volume [µl]
• The 1400-µl seat capillary was installed according to the “Installation Note for the
Multi-draw Kit G1313-68711”.
• The seat capillary was configured in the Injector
Configuration window.• Maximum injection volume:
1500 µl (14 x 100 µl in the seat capillary and 100 µl in the sample loop).
• Draw speed: 200 µl/min (configured in the Setup
Injector window of the ChemStation).
• Sample: Isocratic sample, diluted 0.7:100 with water/acetonitrile 60:40.
Precision of peak area and linearity are shown in figures 5and 6.
Chromatographic Parameters
Mobile phase: A = waterB = acetonitrile
Gradient: at 0 min 40 % Bat 10 min 80 % Bat 12 min 80 % Bat 13 min 40 % B
4 x 125 mm, 5 µmTemperature: 25 °CDetector: DAD 254 nm/16
(reference:360 nm/100)
Configuration Example 5: 900-µl sample loop and 5000-µl seat capillary
1000
µl
2000
µl
3000
µl
4000
µl
5000
µl
0
1
2
3
RSD [%]
Injection Volume
Figure 12
Precision of peak area for configuration example 5
0
1000
2000
3000
4000
5000
6000
7000
0 1000 2000 3000 4000 5000
Dimethylphthalate
Diethylphthalate
Biphenyl
Terphenyl
Correlation: 0.99955
Correlation: 0.99942
Correlation: 0.99962
Correlation: 0.99933
Figure 13
Linearity for configuration example 5
Peak area [mAU x s�
Injection volume [µl]
Dimethylphthalate
Diethylphthalate
Biphenyl
Terphenyl
Conclusion
The precision and linearity ofpeak area were measured for aAgilent 1100 Series autosamplerconfigured with the multi-drawupgrade kit, the 900-µl injectionupgrade kit, a combination ofboth, and a 5000-µl seat capillary.The results for the precision ofarea and linearity are summarized
in table 2.Precision of area and linearityshow very good values even forhigh injection volumes of 1000–4000 µl. The values become slight-ly inferior only for an injectionvolume of 5000 µl. Therefore, wedemonstrated that the Agilent1100 Series autosampler can beused for precise and reliableinjection of high sample volumes.
Configuration Precision of Area Linearity(RSD) (Correlation of coefficient)