examination and comparison of glass evidence - teafteaf.fiu.edu/training_downloads/module 4a_intro...

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.

Source: http://www.corrosionsource.com/handbook/periodic/periodic_table.gif

SEM- EDX

SEM/EDX

• Elemental ratios are used for classification: Mg/Ca

• Ryland suggests Ca/Mg > 15 to be container

• Fe can’t be detected (need XRF)

• non-destructive• No sensitive enough for

trace elements

SEM spectra and figures of merit(16 keV, low vacuum)

ANALYSIS OF WINDOW GLASSES BY SEM-EDS Limitation is 1000 ppm (0.1 %)

accelerating voltage=16KV time of collection=100slow vacuum pressure=29 Pawork distance=9 mmsingle point spot size=50back scatter detectorresolution=1024x800 magnification=110

Element 1831a 1831b 1831c Mean SD RSD Certified Values (as % Oxides) uncertaintySi 65.70 65.64 65.56 65.63 0.07 0.11 73.08 0.08Na 14.82 14.91 15.25 14.99 0.23 1.51 13.32 0.05Ca 10.31 10.38 10.32 10.34 0.04 0.37 8.2 0.05Mg 4.53 4.63 4.71 4.62 0.09 1.95 3.51 0.05Al 2.46 2.44 2.48 2.46 0.02 0.81 1.21 0.04K 0.64 0.55 0.53 0.57 0.06 10.22 0.33 0.02S 0.41 0.55 0.56 0.51 0.08 16.55 0.25 0.01Fe 0.38 0.21 0.32 0.30 0.09 28.42 0.087 0.003Ti 0.00 0.12 0.28 0.13 0.14 105.36 0.019 0.002Sn 0.49 0.37 0.00 0.29 0.26 89.10 0

99.85 100.01

SEM Analysis of NIST 1831 (Float Glass) at 16 keV

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

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

-- cts/sec or % --Si Ca Fe Sr Zr Sr/Zr

J23a 4224 37343 29095 2041 6188 0.330J23b 4347 37440 31189 1582 5501 0.288J23c 4331 37375 28813 1407 4535 0.310Mean 4307 37386 29699 1677 5408 0.309StdDev 55 49 1298 327 830 0.021%RSD 1.29 0.13 4.37 19.5 15.4 6.79

ICP methods

ICP Methods (ICPOES and ICPMS)

NORMAL ANALYTICAL ZONE (blue)

INITIAL RAD. ZONE (red)

INDUCTION REGION

OUTER GAS FLOW

AEROSOL GAS FLOW INTO AXIAL CHANNEL

LOADCOIL

TORCH

Processes in ICP methods

Molecule Atom Ion

Aerosol

Particle

Emission process

Nebulization

Desolvation

Vaporization

Atomization

Ionization

Mass analyzer

liquid sample

ICP-OES ICP-MS

ICP-AES

ICP-AES

• Advantages• Multi-element quantitative

results• Excellent accuracy and

precision• Easy data handling via

computer output

• Disadvantages• Large sample size requirements• Sample preparation is

complicated• Destructive• High cost of instrument and

operator

[Zr] ICP-AES calibration curve

0

0.5

1

1.5

2

2.5

3

3.5

0 0.1 0.2 0.3 0.4 0.5 0.6

Emission Lines

Element λ (nm) Conc. Range g/mLFe 238.204 0.005 - 0.600Mn 257.610 0.004 - 0.100Mg 279.553 0.020 - 10.00Zr 339.198 0.020 - 0.600Sc 361.384 50.0 (Internal Std)Ti 368.520 0.010 - 0.400Ca 393.366 0.250 - 20.00Al 396.152 0.050 - 4.00Sr 407.771 0.004 - 0.200Ba 455.403 0.004 - 0.100Na 589.592 0.40 - 20.00

Elemental Analysis of Glass by ICP-AES

• Weigh ~5 mg glass fragments to the nearest .01 mg for dissolution with HF/HNO3 at 800 C.

• Heat to drive off excess HF.

• Add HCl, 5 ppm Sc (Internal Standard) and deionized/distilled water to a volume of 5.00 ml.

• Use multi-element solutions of Al, Ba, Sr, Fe, Ti, Mg, Mn, Ca, Na, Zr as external standards for calibration.

• Standard Reference Glasses from NIST (620, 621, 1830 and 1831) are run in every set to check for accuracy.

Precision of ICP-AES Results for Three Samples of a Sheet Glass

-- % -- -- ppm --Ca Na Mg Fe Al Sr Mn Ba Ti

H33a 6.33 10.60 2.315 0.356 474 37.6 25.5 10.1 63.3

H33b 6.18 10.48 2.315 0.347 469 37.2 23.3 9.6 63.6

H33c 6.43 10.82 2.300 0.343 456 37.7 21.2 8.9 65.3

Mean 6.31 10.63 2.310 0.348 466 37.5 23.3 9.5 64.0

St Dev 0.13 0.17 0.009 0.007 9.6 0.3 2.2 0.57 1.1

% RSD 1.9 1.6 0.3 1.9 2.0 0.7 9.2 6.0 1.6

ICP-AES Results for Two Sheet Glasses Indistinguishable by RI and XRF

Element Sample 22 Sample 27

Ca, % 6.00, 6.08, 6.10 6.14, 6.11, 6.28Fe 0.302, 0.308, 0.302 0.302, 0.300, 0.300Mg 2.34, 2.38, 2.36 2.29, 2.29, 2.32Na 8.4, 8.8, 9.9 8.6, 9.5, 8.7

Al, ppm 587, 591, 587 602, 575, 578Ba 13, 15, 13 13, 14, 17Mn 17.3, 16.1, 16.7 14.2, 13.0, 14.6Sr 27.4, 28.5, 27.3 76.5, 73.1, 75.8Ti 61, 58, 51 60, 57, 49

ICP-MS

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)


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.


10% HNO3, 30 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 ”

50 µm

Laser Ablation Diagram

Monitor

TiSi CCD camera

Motorized zoom

Mirror

Illuminator

Ablation chamber

Carrier gas(He)

Ar gas

ICP/ MS

Sample

Nd YAG laser

Monitor

TiSi CCD camera

Motorized zoom

Mirror

Illuminator

Ablation chamber

Carrier gas(He)

Ar gas

ICP/ MS

Sample

Nd YAG laser

TiSi CCD camera

Motorized zoom

Mirror

Illuminator

Ablation chamber

Carrier gas(He)

Ar gas

ICP/ MS

Sample

Nd YAG laser

Glass Standard

25Mg 55Mn 85Rb 88Sr 90Zr 137Ba 139La 140Ce 146Nd 178Hf

NIST 612 (ppm) 2.2 0.32 0.11 0.062 0.094 0.30 0.061 0.075 0.19 0.22

NIST 1831 (ppm) 2.1 0.32 0.10 0.072 0.10 0.24 0.053 0.065 0.17 0.21

FGS02 (ppm) 3.4 0.31 0.093 0.060 0.083 0.23 0.040 0.052 0.15 0.21

50 µm spot size 266 nm (9 mJ), 10 Hz, 50 sec. ablation (500 shots)

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.

LODs with the New Wave UP 213 LA-ICP-MS

Limits of Detection ComparisonLOD (ns-LA-ICP-

MS)[ppm]

Typical Concentration Range [ppm]

Element

0.7925064 – 43136Mg0.82485 – 8116Al2.80*51 – 463Ti0.2710 – 79Mn0.050.23 – 7Rb0.0621 – 91Sr0.0520 – 271Zr0.235 – 64Ba

0.251.27 – 37Pb0.190.79 – 8Hf0.022 – 23Ce0.061.20 – 12La

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

9

w132

w142

w143

w152

w153

w165

w174

w193

w204

w206

w232

Sample number

[Sr]

(in

pp

m)

Miami Junkyard Sample Collection (August 2005)

A total of 41 glass samples were collected from 14 different vehicles in junk yards

Selected vehicles were manufactured from 1995 to 2005

LA-ICP-MS Discrimination by Isotopes

142 (17%)49Ti176 (21%)85Rb191 (23%)137Ba

8 (1%)All (14 isotopes)

76 (9%)88Sr127 (15%)90Zr

255 (31%)57Fe303 (37%)140Ce

Number of indistinguishable pairs (out of 820 possible pairs)

Isotope

List of indistinguishable pairs by LAICPMS

inside windshield2001Grand CherokeeJeep38

outside windshield2001Grand CherokeeJeep378

outside windshield2004Expedition Eddie BauerFord29

inside windshield2004Expedition Eddie BauerFord287

inside windshield1998StratusDodge24

outside windshield1998StratusDodge236

inside windshield2003CavalierChevrolet21

outside windshield2003CavalierChevrolet205

inside windshield2000NeonDodge14

outside windshield2000NeonDodge134

inside windshield1998IntrigueOldsmobile12

outside windshield1998IntrigueOldsmobile113

rear window2004CavalierChevrolet9

side window2004CavalierChevrolet82



Sample LocationYearVehicle modelVehicle makeSample #Pair #

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

inside windshield1998StratusDodge24

outside windshield1998StratusDodge236



inside windshield2000NeonDodge14

outside windshield2000NeonDodge134

inside windshield1998IntrigueOldsmobile12

outside windshield1998IntrigueOldsmobile113

rear window2004CavalierChevrolet9

side window2004CavalierChevrolet82



Sample LocationYearVehicle modelVehicle makeSample #Pair #

XRF Intensity vs LA-ICP-MS

R2 = 0.9911

0

2

4

6

8

10

12

14

16

18

20

0 20 40 60 80 100 120 140

[Sr] LA-ICP-MS Results (ppm)

(XRF data from Ryland)

Correlation of LA-ICPMS and XRF (Sr)

LIBS Developments

Number of publications over the last 40 years (but still less mature than ICP and XRF as an analytical method)

Source: M. Sabsabi from Cremers and Radziemsk, 2006

Named as a“superstar technique”Professor Winefordner

Laser ablation: LIBS

Lasersam

ple

spectrometer

LIBS signal

Wavelength (nm)

Intensity

samplesample

Shock WaveShock Wave

hot, highhot, high--pressure pressure Strongly absorbing Strongly absorbing PlasmaPlasma

Laser PulseLaser Pulse

LIBS for Forensics• Advantages

• Large amount of information obtained

• Qualitative and quantitative

• Almost non-destructive direct solid sampling

• Speed, versatility, ease of operation, affordability and portability

• Good detection limits (~ 10 ppm - 50 ppm)

• Challenges• Calibration• Matrix effects

NIST Standard Reference Material610 = 515 ppm Sr1831 = 89 ppm Sr

What are the key factors to decide on a technique for elemental analysis?

• From a scientific point of view

• Good Sensitivity and selectivity

• Non destructive of the sample

• Low instrument maintenance desirable

• Easy to use• Fast• Reliable (accurate,

precise)• Good discrimination• Multiple applications

• From an administrative

point of view• Lowest cost possible!• Fast• Good discrimination• Multiple applications

• From our end user : JUSTICE

• Provide the best discriminating data possible in the minimum time possible

Forensic Glass Analysis

Source: Almirall, JR; Trejos, T. Forensic Science Review, 2006, 18,2, 2006, 74-95.

Para m et er SE M/ EDS EP MA XRF LIBS ICP -O ES ICP -M S LA -ICP -MS

Samp le pene tration

~ 5 microns

micron s<< 1

~100 microns

~50 -100 micron s (operator contro lled)

bulk bulk ~ 80 micron s (operator contro lled)

Lim it of det ection on glass

1000 ppm (0.1%)

100 pp m (0.01%)

50 -100 ppm (0.01%)

10 -50 ppm < 100 ppm on glas s . (01 -1 ppb in solu tion)

< 2ppm on glas s (<0.01ppb in sol u tion)

< 1ppm

Samp le throughput

low low medi u m high high high high

Pr ecision Poor

Fair

G ood

Fair -good

Exc ellent Exc ellent Exc ellen t

Acc uracy Qua litative

Se m i-quant ita tiv e

Se m i-quant itativ e

Se m i-quant itativ e

Quant itat ive Quant itat ive Quant itat ive

Tim e of analysis

Slow

Slow

Very Slow

Very Fast

Very Slo w conside ring sam p le prepara tion

Very Slow conside ring sam p le prepara tio n

Fast

Samp le cons u mption

non -destru ctiv e

non -destru ctiv e

non -destru ctiv e

alm o st non -destru ctiv e

Destr u ctive (5 -8mg per repl icate)

Destr u ctive (2mg per repl icate)

alm o st non -destru ctiv e (~280ng per repl icate)

Eas e of use Easy to Use

Comp lica ted

Ea sy to use Very Easy to U se

Relativ ely Comp lica ted

Comp lica ted

Comp lica ted

Cost $200 ,000

$600,000

$120,000

$60,000

$100,000 $150,000 $250,000

Dis crim inatio n powe r

Poor

Fair

Very Good

Good -very good?

Very Good Exc ellent Exc ellent

Sample penetration

Parameter SEM/EDS EPMA XRF LIBS ICP-OES ICP-MS * 5 LA-ICP-MS *5

Sample penetration

~ 5 microns

microns<< 1

~100 microns

~50-100 microns (operator controlled)

n/a n/a ~ 80 microns (operator controlled)

This will determine if we are doing “bulk” or surface analysis

Homogeneity issues at micro-scale have to be considered to defineSampling strategies and match criteria


Limit of detection on glass

1000 ppm (0.1%) *1

100 ppm (0.01%)

100 ppm (0.01%)

10-50 ppm *2

< 100 ppm on glass. (01-1 ppb in solution)

< 2ppm *3 on glass (<0.01ppb in solution)

< 1ppm *4

Precision Poor

Fair

Fair-good

Fair-good

Excellent Excellent Excellent

Accuracy Qualitative

Semi-quantitative

Semi-quantitative

Semi-quantitative

Quantitative Quantitative Quantitative

Sample consumption

non-destructive

non-destructive

non-destructive

almost non-destructive

Destructive (5-8mg per replicate)

Destructive (2mg per replicate)

almost non-destructive (~280ng per replicate)

Discrimination power

Poor

Fair

Good

Good Very Good Excellent Excellent

This are KEY factors that will determine the qualityof the data and discrimination power.

They will define also the application to different evidence

This parameters may determine at the end the applicability to Forensic laboratories


Sample throughput

low low medium high high high high

Time of analysis

Slow

Slow

Very Slow

Very Fast

Very Slow considering sample preparation

Very Slow considering sample preparation

Fast

Sample consumption

non-destructive

non-destructive

non-destructive

almost non-destructive

Destructive (5-8mg per replicate)

Destructive (2mg per replicate)

almost non-destructive (~280ng per replicate)

Ease of use Easy to Use

Complicated

Easy to use Very Easy to Use

Relatively Complicated

Complicated

Complicated

Cost $250,000

$600,000

$120,000

$60,000

$100,000 $150,000 $250,000

examination and comparison of glass evidence - teafteaf.fiu.edu/training_downloads/module 4a_intro...

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