ECCO

Induced Breakdown Spectroscopy (LIBS)

ECCO

Identifying Methamphetamine Precursors

Using LIBS to identify methamphetamine precursors

Methamphetamine production and use have become a scourge of many countries worldwide. This in part is due to the ready availability of the precursor chemicals for its manufacture. This makes it possible for small-scale production in Clandestine Laboratories to be carried out.

Typical synthetic routes encountered involve reduction of the hydroxyl group in Ephedrine / Pseudoephedrine, commonly found in over the counter decongestants. The reduction can be facilitated by Hydroiodic (HI) that is generated from Iodine (I2), Water and Phosphorous (P). This is known as the red-phosphorous “cook” method. The other method, known as the birch method, involves using Lithium Metal and Ammonium Nitrate to facilitate the reduction. The reaction is shown below.

Lithium is typically obtained from Lithium batteries, and Phosphorous can found in flares, and matchbox striking plates. Iodine can be purchased from pharmacists/drug stores. The identification of these chemicals recovered from suspect laboratories can provide useful evidence in proving illicit drug manufacture. Here we show that the ECCO Elemental Composition Comparator can detect and identify lithium, phosphorous and iodine. Lithium with atomic number 3 is particularly difficult to detect by other analytical methods.

Lithium

Figure 1 - Spectra of Lithium metal from a battery and a thin film of Lithium hydroxide. The line broadening is due to a combination of self-absorption (for the bulk metal) and stark broadening.

Iodine

Figure 2 – solid Iodine shows a complex pattern of peaks in 500 – 560 nm range.

Phosphorous

Figure 3 – Phosphorous shows 2 prominent peaks in the UV spectral region, at 253.6 and 255.5 nm. The same peaks albeit weaker in intensity are visible in the spectrum of the match striker plate.

Discriminate Paint Chips

Discriminate Paint Chips using Laser-Induced Breakdown Spectroscopy

Common methods for the forensic examination of paint chips involve physical examination, microspectrophotometry, FTIR, SEM-EDS. Here we show how LIBS can be used effectively in the forensic examination of paint.
LIBS spectra of small sections (< 1mm ) of paint from various sources were recorded. 10 one-shot spectra of each sample were averaged.
All LIBS spectra were acquired using the ECCO laser-induced breakdown spectrometer. This consisted of an air-cooled actively Q-switched flashlamp pumped Nd:YAG laser delivering 60 milliJoule, 7 nanosecond pulses of 1064 nm of laser radiation at a repetition rate of 0.5 Hz. The spectrometer range was 225 – 600 nm. The spectrometer contained 3 CMOS sensors. The gate delay between the laser firing and the CMOS sensors shutters opening was 1 microsecond.
All LIBS spectra were recorded in an Argon atmosphere, with a flow rate of approximately 6 liters/minute.
Spectra were compared qualitatively for the presence or absence of elements, such as Cr, Ba, Ti, Ca, Pb and Sr.

Below are the spectra from 4 different colored paints, including white, grey, red, blue and green.

Figure 1
Blue paints, showing the difference in the proportion of Calcium, Titanium, and Barium

Figure 2
Grey paints, showing the difference in the proportion of Calcium, Titanium, and Barium

Figure 4
Green paints, showing the difference in the proportion of Chromium, Barium, and Calcium.

Figure 5
Red paints, showing a difference in the proportion of Chromium, Calcium, Strontium, and Lead.

Screening for GSR

LIB Spectrometry for the detection of gunshot residues

Gunshot residue consisting of particles containing the elements Barium (Ba), Lead (Pb) and Antimony (Sb) are frequently found on the arms and clothing of a shooter after firearm discharge.
Both presumptive tests and SEM-EDX for imaging and elemental analysis of the particles are used for GSR detection.

Both these techniques have their pitfalls. Nitrate detection which is used in presumptive testing is found not to be very specific due to nitrates being nearly ubiquitous, being found in cosmetics, fertilizers and numerous other commercial products.
SEM-EDX is expensive and time-consuming and is not suited to screening a group of suspects quickly.
Laser-induced breakdown spectroscopy using the Foster+Freeman ECCO has been used to rapidly screen swabs from suspects hands for elements consistent with GSR, by detection of Barium and Lead. The spectrum below of GSR was taken recorded in less than 1 second, and clearly reveals peaks due to Barium and Lead – consistent with GSR.

Discriminating Glasses

LIBS can be used to identify many of the main elements present in the glass as well as minor and trace elements down to concentrations of low PPM. In addition, the ratios of the spectral peaks of minor and trace elements to those of the major elements are often effective in discriminating between glasses which cannot be separated by refractive index. LIBS is also a fast and effective technique for identifying glass type.
In this Application Note, we demonstrate the potential of the ECCO to differentiate between glass samples which cannot be distinguished by the measurement of RI alone.

Discriminating Pencil Lead

LIBS Analysis for the discrimination of pencil leads
Pencil lead is one of the more challenging evidence types encountered by the forensic document examiner.

The inorganic nature of the material means that traditional documents examination techniques such as the Video Spectral Comparison are not applicable.
The differences in the elemental composition of the lead between different brands mean that Laser-Induced Breakdown Spectroscopy is an applicable analytical method for discrimination of pencil lead.

Discriminating Match Heads

Laser-Induced Breakdown Spectrometry for the investigation of arson
One of the goals of the arson scene examiner is to link evidence found on the suspect to that found at the scene of crime.

Burnt match heads offer a source of evidence which may incriminate a suspect.

Discriminating Office Paper

LIBS analysis of paper
Office paper is one of the evidence types frequently encountered by forensic document examiners.

Traditional analysis methods such as UV induced fluorescence, are subjective and can be affected by factors such as the age of the paper and ream variation. Here we present a study utilizing the ECCO-DE laser-induced breakdown spectrometer, to analyze and discriminate A4 office paper based on its elemental composition.

Identifying Security Documents

Elemental comparison of security documents using LIBS
The most commonly applied method for the forensic examination of paper involves close visual inspection, possibly aided by the wide spectral range of the UV, IR and visible light sources in instruments such as the Foster + Freeman Video Spectral Comparator.

Recent studies have been reported, however, in which paper has been examined using elemental analysis techniques. These studies have measured trace elements such as barium and strontium, which occur as impurities in the calcium carbonate and other fillers used in the manufacture of the paper.
Security papers, however, tend to have a quite different composition to normal types of paper and are often devoid of optical brighteners. Instead, uncommon elements, such as manganese or titanium, may be present, either having been added intentionally or occurring incidentally as a constituent of colorants.
This Application Note shows the different elemental profiles of three different types of security paper.

Identifying Counterfeit Coins

The number of counterfeit £1 coins in circulation in the UK has risen steadily over the last few years, probably because of the ease with which coins can now be counterfeited compared with paper banknotes.

Whilst close visual inspection (inconsistencies in the date and design, poor quality of less prominent features, incorrect dimensional tolerances) can often be used to identify counterfeit coins, such methods are not entirely reliable.
Recent studies have been reported, however, in which counterfeit coins can be detected by elemental analysis. The presence or absence of specific trace elements can often distinguish genuine coins from counterfeit.