Abstract:
The number of clandestine methamphetamine laboratories discovered in New Zealand is on
the rise, with a total of 211 clandestine laboratories being dismantled in the 2006 calendar
year. These laboratories pose a significant danger to the general public due to their physical,
chemical and environment hazards. This study has developed methods appropriate for
sampling and analysing Iow levels of methamphetamine, pseudoephedrine and iodine under
conditions such as could be encountered at a clandestine methamphetamine laboratory.
Although analysis of methamphetamine and pseudoephedrine is routine, the application of
these analyses to very Iow levels in environmental extracts is not as well developed.
The major part of this study looked at the recovery of pseudoephedrine and methamphetamine
from glass, stainless steel, and a range of other surfaces likely to be found in a clandestine
laboratory (Formica, kitchen top tile, painted metal, varnished wood and floor wood).
Analysis of trace-level pseudoephedrine showed interference from carbonyl-containing
compounds, expecially formaldehyde. In our hands, standard TFAA derivatisation did not
completely react with the pseudoephedrine-formaldehyde coumpound. Therefore, an
alternative derivatisation strategy with cyclohexanone was used, which could analyse both
pseudoephedrine and pseudoephedrine-formaldehyde. The results show that pseudoephedrine
free base has significant volatili• ty at room temperature, wi• th >80% of a 2.5 μg∕/8 0 cm 2 sample
being Iost in two days. The pseudoephedrine hydrochloride salt, while Iess volatile, still
volatilised to a significant extent, with up to 40% being found on a plate positioned above a
surface concentration of 2 μg∕80 cm2. Similar recoveries of pseudoephedrine were observed
for most surfaces examined, although surface painted with polyester cross-linked with
melamine showed much lower recoveries (<10%) suggesting reaction of pseudoephedrine
with the polymer. Our results show that surface wiping with water-dampened filter paper can recover 60-80% of pseudoephedrine immediately after deposition, and at least 50% of the
pseudoephedrine still present on a surface after 2 days.
Analysis of methamphetamine did not show the interference shown by pseudoephedrine, so a
standard TFAA derivatisation could be used. Methamphetamine showed similar volatility to
pseudoephedrine, even though it is theoretically predicted to be more volatile.
Methamphetamine could be recovered by surface wiping with methanol-dampened filter paper
with 60-90% recovery shortly after deposition, and at least 50-60% of the methamphetamine
still present on surfaces could be recovered after 2 days.
The recovery of methamphetamine and pseudoephedrine were not affected by the presence of
iodine in solution or on surfaces using the basic extraction protocol followed by
cyclohexanone (pseudoephedrine) or TFAA (methamphetamine) derivatisation, and GC-MS
analysis. This means that reliable results for these analytes can be obtained from surfaces
showing iodine staining.
A reported method for iodine analysis using ΛζτV-dimethylaniline and GC-MS was adapted for
trace-level analysis and discrimination of airborne and surface I2 and Γ. This method gave
good recoveries (>80%) of airborne iodine, but surface wiping only recovered 20% (filter
paper) or 50% (glass fibre filter paper) of the I2 deposited on an inert surface. These recoveries
were reproducible, so surface wiping could still give indicative results.
Iodine deposited on glass, stainless steel, Formica or kitchen top tile faded rapidly upon the
drying of the solvent. No visible stains were visible after 15 min, and only trace levels of total
iodine (<200 ng 1/100 cm2) could be recovered by surface wipes after two days at room
temperature. This iodine was present as Γ, suggesting that iodine was reduced to iodide even
on a cleaned glass surface.
A direct trapping and derivatisation strategy was used to analyse airborne iodine. The amount
of iodine present in the atmosphere of a glass chamber during evaporation of a 1 mg/mL
solution of iodine in methanol peaked at the time of complete solvent evaporation and then decreased rapidly, indicating Ioss 0fI2 to the container wall. Methanolic iodine stains on vinyl
slowly released I2 to the air over 32 h suggesting that the iodine absorbed by the vinyl was
slowly desorbed. Only trace levels of iodine (mainly present as Γ) were detected from the
surface wipes of this stain suggesting that the iodine is not simply adsorbed on this surface but
that the iodine is dissolved inside the material. Therefore, for such substrates, a surface wipe
may not give adequate indication of iodine staining. The current practice of identifying I2
contamination by visual examination is appropriate, especially for light-coloured surfaces.