FLORIDA INTERNATIONAL UNIVERSITY INTL. FOFRENSIC RESEARCH INSTITUTE PHONE 305 348 3917 www.ifri.fiu.edu INTRODUCTION TO ELEMENTAL ANALYSIS OF GLASS Lecture #4 Tatiana Trejos, M.Sc Florida International University Department of Chemistry and Biochemistry International Forensic Research Institute Examination and Comparison of Glass Evidence
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FLORIDA INTERNATIONAL UNIVERSITY INTL. FOFRENSIC RESEARCH INSTITUTE PHONE 305 348 3917 www.ifri.fiu.edu
INTRODUCTION TO ELEMENTAL ANALYSIS OF GLASS
Lecture #4
Tatiana Trejos, M.ScFlorida International University
Department of Chemistry and BiochemistryInternational Forensic Research Institute
Examination and Comparison of Glass Evidence
INTRODUCTION TO ELEMENTAL ANALYSIS
•SEM-EDS•XRF and u-XRF•ICP-AES and ICP-MS•LIBS
Glass manufacturing
“An inorganic production of fusion which has cooled to a rigid
condition without crystallizing”
• Main Raw materials:• Sand (SiO2)• Soda Ash (Na2CO3)• Limestone (CaO)
• Not all sand has the proper quality:
• 20 million tons of quartz sand are used annually in North America
• Over 100 glass sand mines in NA
Glass manufacturing
Colourants/ Decolourants
Fe2O3, Cr+, Se+
/As2O3, MnO2, As2O3, CaSO4
Refining agents
Cullet
Formers
SiO2, B2O3
Modifiers
Na2O, CaO, MgO
Sources of trace elements
Raw materials Modifiers addedintentionally
Manufacturing process
How is glass associated to a source?
ICP
Elemental Analysis
SEM XRF
Physical Properties(color, thickness)
Refractive Index
LA-ICP LIBS
Why we do elemental analysis in forensic science?
• Comparison or provenance• Relies on premise that
• minor variations in the elemental composition remains between and within batches
• Variation on the elemental profile of common sources are smaller than variation within the population
Examples: comparison of glass fragments, provenance of gold, wine or diamonds.
Need of selective, sensitive, precise and accurate techniques
and methods
Elemental Analysis of GlassPeer reviewed papers:Hickman, D, Glass types identified by chemical analysis, Forensic Science International, 1986, 33(1), 23-46.
Koons, R; Fiedler, C; Rawalt, R, Classification and discrimination of sheet and container glasses by ICP-AES and pattern recognition, Journal of Forensic Sciences, 1988, 33(1), 49-67.
Becker, S; Gunaratnam, L; Hicks, T; Stoecklein, W. and Warman, G, The differentiation of float glass using refractive index and elemental analysis: Comparisons of techniques, Problems of Forensic Science, Vol. XLVII, 2001, 80-92.
T. Trejos, S. Montero, and J.R. Almirall, Analysis and comparison of glass fragments by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), Journal of Analytical and Bioanalytical Chemistry, 2003, 376: 1255-1264.
Trejos, T and Almirall, J, Effect of fractionation on the elemental analysis of glass using LA-ICP-MS, Analytical Chemistry, 2004,76(5) 1236-1242.
Trejos, T and Almirall, J, Sampling strategies for the analysis of glass fragments by LA-ICP-MS.Part I: micro-homogeneity study of glass and its application to the interpretation of forensic evidence, Talanta, 2005, 67(2) 388-395.
Trejos, T and Almirall, J, Sampling strategies for the analysis of glass fragments by LA-ICP-MS. Part II: sample size and sample shape considerations, Talanta, 2005, 67(2) 396-401.
Latkoczy,C; Dücking, M; Becker, S; Günther, D; Hoogewerff J; Almirall, J; Buscaglia, J; Dobney, A; Koons, R; Montero, S; van der Peyl, G; Stoecklein, W; Watling, J; Zdanowicz, V, Evaluation of a standard method for the quantitative elemental analysis of float glass samples by LA-ICP-MS, J. of Forensic Sciences, 2005, 50 (6), 1327-1341. (NITECRIME WORK PRODUCT)
K. Smith, T. Trejos, R.J. Walting, J.R. Almirall, A guide for the quantitative elemental analysis of glass using laser ablation inductively coupled plasma mass spectrometry, Atomic Spectroscopy 27 (2006) 69-75.
Trace metals in 1831 (Float Glass) (measured by LA-ICP-MS)
element reported
value, µgg-1 average,
µgg-1 Bias, % repeatability-
within, sr (%) reproducibility-between, sR (%)
Ti 114a 123 7.9 3.0 5.8 Mn 15.00 6.6 8.8 Rb 6.11 2.1 9.2 Sr 89.12 2.8 10 Zr 43.36 4.8 11 Sb 2.06b 85 - Ba 31.52 2.4 4.2 Ce 4.54 2.0 7.4 Sm 0.40 7.7 9.9 Hf 1.10 19 5.7 Pb 1.99 10 7.7
SEM penetration profile (sampling)
4 µm
Monte Carlo Dynamics (source: Reimer, Ludwig, Scanning Electron Microscopy, Springer-Verlag, 1985, p. 99)
~ 2 µm for 15 keV and ~ 5 µm for 25 keV
XRF
X-Ray Fluorescence
• Advantages• Small sample size can be
used• Nondestructive• Very rapid
• Disadvantages• Poor accuracy without
elaborate sample preparation
• Poor precision for small, irregularly shaped samples
• Low sensitivity for low atomic number elements
Picture courtesy of Scott Ryland, FDLE
XRF spectra and figures of merit
Courtesy of Scott Ryland, FDLE, Orlando, FL
Rh x-ray tube40 keV beam potential300 micron diameter monocapillary focusing collimatorLi drifted silicone EDS with beryllium windowbeam current adjusted to achieve a 35% dead time factor (approximately 760 microamps)17 microsecond time constantresolution approximately 156 eV
XRF penetration profile (sampling)
Varies greatly depending on material (and energy)
I=Io exp[x]
Io is the original intensity of the beam, is an absorption coefficient and is the mass density of the materialx is the thickness
Expected to be in ~ hundreds of microns (even low mm)
XRF is a bulk analysis method
Flatness of sample, incident angle and SIZE dependence
Precision of XRF peak intensities for three fragments of a glass specimen
AdvantagesMulti-element capability and high sample throughputLow detection limits in solution (< 0.01 µg/L)True quantitative analysisSmall samples (0.5 -2 mg before digestion)Isotopic information
DisadvantagesHigh cost and complexityDestructive (for solution analysis)
Why ICP-MS?
Wash Samples (meOH, 10 min,
10% HNO3, 30 min)
Wash Samples (meOH, 10 min,
10% HNO3, 30 min)Rinse and dry
(DI H2O, dry overnight)Rinse and dry
(DI H2O, dry overnight) Crush and weigh 2-5 mgCrush and weigh 2-5 mg
Dissolve in 600 µL of2:1:1 HF/HNO3/ HCl
Dissolve in 600 µL of2:1:1 HF/HNO3/ HCl
Dry 16-24 hr (block heater 80-85°C)
Dry 16-24 hr (block heater 80-85°C)
Add 800 µL of HNO3 0.8M, 20 µL of Rh 10ppm and 680 µL of H20
Add 800 µL of HNO3 0.8M, 20 µL of Rh 10ppm and 680 µL of H20
Vortex, leave overnight and bring into 4 mL with H20
Vortex, leave overnight and bring into 4 mL with H20
Dilute an aliquot of 50 µL to 5 ml in HNO3 0.8 M ,add 30 µL of Sc 10ppm
Dilute an aliquot of 50 µL to 5 ml in HNO3 0.8 M ,add 30 µL of Sc 10ppm
Sample preparation scheme: Glass dissolution procedure adapted from Parouchais, et al., J.Forensic Sci., 41, 1996, 351.
Wash Samples (meOH, 10 min,
10% HNO3, 30 min)
Wash Samples (meOH, 10 min,
10% HNO3, 30 min)Rinse and dry
(DI H2O, dry overnight)Rinse and dry
(DI H2O, dry overnight)
External Calibration Method
Typical Element Menu
:Trace elements
: Minor elements
LA-ICP-MS
Laser Ablation“Ablation is a progressive and superficial
destruction of a material by melting, fusion, sublimation, erosion and explosion ”
T. Trejos and J.R. Almirall, Effect of fractionation on the elemental analysis of glass using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), Analytical Chemistry, 2004, 76(5) 1236-1242.
21 windows with the same refractive index values and similar chemical composition
[Sr] distribution
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
w23 w33 w49 w62 w79 w83 w95w10
3w10
7w12
9w13
2w14
2w14
3w15
2w15
3w16
5w17
4w19
3w20
4w20
6w23
2
Sample number
XRF spectra and conditions
Courtesy of Scott Ryland, FDLE, Orlando, FL
Ca/Fe, Sr/Zr, and Ca/Mg, Ti and K were used in discrimination scheme to produce 8/820 indistinguishable pairs.
Rh x-ray tube, 40 keV beam potential300 micron diameter monocapillary focusing collimatorSiLi EDS with beryllium windowbeam current @ 35% dead time (approximately 760 microamps)17 microsecond time constant, resolution approximately 156 eV
List of indistinguishable pairs by LAICPMS
inside windshield2001Grand CherokeeJeep38
outside windshield2001Grand CherokeeJeep378
outside windshield2004Expedition Eddie BauerFord29
inside windshield2004Expedition Eddie BauerFord287