Decontaminating illicit drug labs: DART speeds up screening

Drug lab debris

The number of incidents related to illegal meth labs in the US reached 10,247 in 2010, according to the Department of Justice, with the state of Missouri topping the charts. The nature of the manufacturing operation guarantees that vapours, aerosols and particulates circulate the room and deposit on ceilings, walls, floors and other surfaces. A similar distribution of illicit drug residues is known to occur in buildings used regularly for meth smoking.

In labs and residences, the residues remain long after drug activity has ceased, presenting a clear danger of exposure to the general public upon entry or habitation. Households and other buildings used for labs or for regular meth smoking are required by US law to be decontaminated before they are released to the public for sale.

Current NIOSH methods for meth analysis are long-winded, requiring several steps before mass spectrometric analysis. Wiping with gauze swabs is followed by extraction, clean-up and solvent exchange before the analysis itself, which can be carried out by GC/MS or LC/MS. The former technique also involves a derivatisation step.

A duo of scientists from the Environmental Sciences Division of the National Exposure Research Laboratory, ORD, EPA, at Las Vegas, recognised that this official procedure is relatively expensive as well as time consuming, which can limit the number of samples taken for analysis. So, they have proposed an alternative protocol which relies on the growing discipline of ambient mass spectrometry.

Automated DART process for rapid swab testing

Andrew Grange and Wayne Sovocool based their method on sampling with cotton stick swabs which were analysed directly by DART (direct analysis in real time) mass spectrometry on a time of flight instrument. It incorporated a lab-built autosampler constructed from N-scale model railroad flatbed wagons and track with a variable-speed motor.

The use of swabs for sample collection was preferred to fragments of walls, ceiling, floors and furniture due to better reproducibility. Swabs were soaked in solvent and rolled across an area of 100 cm² to get an even distribution of drug on the cotton, which is more representative than pieces of samples and increases the chances of encountering small pockets of drugs. The swabs also offered more consistent shapes for analysis, the rolling action compacting stray cotton fibres back with the bulk of the swab.

During collection, individual swabs were placed in a carrier which contained the core element of the autosampler comprising a long bar with holes along its length. The swabs were covered by glass vials and the whole assembly was covered for transport to the lab and reconnection with the autosampler.

The swabs had dried out during transport and were analysed by DART MS using a high-speed flow of excited helium species to generate ions which were drawn into the mass spectrometer for analysis. The helium temperature was optimised at 150-300°C for particular analytes and the system was operated in positive-ion mode.

The accurate masses of the protonated molecules were measured for each drug and the quantities present were calculated from the two peak areas measured when the leading and trailing edges of the swab passed through the helium beam.

Screening different indoor surfaces

The mass spectrometer parameters were optimised for nine illicit drugs, as well as nicotine and pseudoephedrine, which is used to produce meth. The nine were methamphetamine, amphetamine, cocaine, heroin, morphine, ketamine, phencyclidine, fentanyl and tetrahydrocannabinol (THC).

The observable peak thresholds were 0.1 µg/100 cm² for nicotine, morphine and THC and 0.025 µg/100 cm² for the remaining eight drugs. These levels satisfy the NIOSH method detection limits as well as the lowest decontamination limit set by the state authorities in the USA.

Screening of multiple drugs was demonstrated for wipes of meth, cocaine and THC. The dynamic ranges of eight of the drugs were greater than 100, which were deemed sufficient by the researchers for screening purposes.

The best overall solvent for the wipes was isopropanol, which was most efficient for glass surfaces. The relative paired peak areas for all of the drugs were 100, 43 and 17% for isopropanol, methanol and water from a mirror. However, water was more efficient for removing drugs from one week-old paint surfaces.

Removal of the drugs from paint was about an order of magnitude smaller than from glass, with absorption and/or adsorption playing a key role. However, removal was never complete with a single swabbing. For instance, the successive removal of meth from glass with isopropanol-soaked swabs produced relative peak areas of 100, 69, 40 and 21%, respectively.

This behaviour is not important for screening, where detecting the presence or absence of drugs is the main aim.

The researchers also swabbed other typical household surfaces such as floor tiles, a wooden door, a cloth quilt and a medium-pile nylon carpet, demonstrating a range of recoveries which must be taken into account during screening.

Overall, the system is a rapid alternative for screening illicit drug labs and its low relative cost should remove limitations on the number of samples which can affect more expensive procedures such the established GC/MS and LC/MS methods.

Sampling time is about 2 minutes/wipe and analysis time averaged out to 13 seconds/swab for 27 swabs placed in the autosampler. Only 0.2 mL of solvent was required for each swab and no other solvents or reagents were required, so the method also fulfils green credentials.

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.