Review: Quantifying the Effectiveness of Cleaning Agents at Removing Drugs from Laboratory Benches and Floor Tiles

Emily C. Lennert





opioids, cleaning, quantification, cocaine, fentanyl, methamphetamine, heroin, MDMA, carfentanil, cyclopropyl fentanyl, LC-MS/MS, TD-DART-MS, GC-FID

Article Reviewed

Sisco, E.; Najarro, M.; Burns, A. Quantifying the effectiveness of cleaning agents at removing drugs from laboratory benches and floor tiles. Forensic Chemistry. 2019, 12, 1-7.


The opinions expressed in this review are an interpretation of the research presented in the article. These opinions are those of the summation author and do not necessarily represent the position of the University of Central Florida or of the authors of the original article.


Research has indicated that forensic laboratory surfaces contain detectable background levels of drugs. Additionally, with the rise of powerful opioids, such a fentanyl, and new psychoactive substances, the prevention of accidental exposure is of high importance. For these reasons, the effectiveness of cleaning agents both in the field and in the laboratory must be evaluated. In-field cleaning agents must be used to render a scene safe for handling, and therefore are required to breakdown drugs such as opioids through chemical processes such as oxidation. In the laboratory, the common purpose of cleaning agents is to remove residual drug material from surfaces to prevent cross contamination. Drug maybe present either as a thin film residue or as particulate material, and cleaning agents and procedures must be effective at removing both of these. The background level of drugs detected on laboratory surfaces commonly falls below the limit of detection for traditional means of analysis, i.e. Gas Chromatography – Mass Spectrometry (GC-MS). However, certain drugs may require more sensitive analytical techniques, e.g. Direct Analysis in Real Time – Mass Spectrometry (DART-MS), and therefore background drug levels may become detectable. The purpose of this study was to quantitatively evaluate the effectiveness of several cleaning agents in a laboratory and in the field, focusing on both particulate and residue drug contamination.

Cocaine, fentanyl, methamphetamine, and heroin were selected for the laboratory benchtop surface residue study. Fentanyl was selected due to its potency and increasing frequency in casework. Cocaine, methamphetamine, and heroin were selected due to their identification as the greatest contributors to drug background in forensic laboratories. Cleaning agents included methanol, Alconox soap and water, OxiClean™, and Super Clean® adhesive followed by methanol. In the laboratory benchtop surface particulate study, four case samples were obtained from the Maryland State Police Forensic Sciences Division: cocaine, cyclopropyl fentanyl, heroin, and 3,4-methylenedioxymethamphetamine (MDMA). The same cleaning agents were used in the laboratory particulate study as were used in the residue study. Particulate studies of cyclopropyl fentanyl and carfentanil were conducted for the in-field simulation. Ceramic floor tiles were used to simulate a first responder scenario surface. OxiClean™ and Dalhgren Decon were evaluated as cleaning agents, due to their reported ability to chemically breakdown fentanyl. Detailed cleaning procedures may be found for each cleaning agent in the study, Section 2.1. A final study was conducted in which the breakdown of opioids, cyclopropyl fentanyl and carfentanil, was quantified in solution using OxiClean™ and Dalhgren Decon.

A laboratory bench was divided into 15 cm x 15 cm squares for the residue and particulate studies. Each square was used for one experiment, e.g. one drug residue with one cleaning agent. Prior to drug application, the surface was sampled with a dry meta-aramid wipe, which was extracted and analyzed via Liquid Chromatography – MS/MS (LC-MS/MS) to establish a background. Details on the application of residues and particulates may be found in section 2.2 of the study. After application and cleaning, the area was sampled again with a new meta-aramid wipe, which was then extracted and analyzed qualitatively by thermal desorption DART-MS (TD-DART-MS) and quantitatively by LC-MS/MS. Similarly, drugs were applied to ceramic floor tiles for the in-field simulation within a chemical fume hood to minimize exposure. The details of application can be found in section 2.3 of the study. Cleaning agents were allowed to sit on the surface for 0, 5, 10, or 30 min prior to finishing the cleaning process and sampling. Samples were extracted then analyzed via TD-DART-MS and LC-MS/MS. The extraction process used for all surface samples is detailed in section 2.4 in the study. Two replicates were obtained for all cleaning agent/drug combinations.

In the benchtop studies, for the residues, each cleaning agent achieved a removal efficiency greater than 97% (Table 2 within the study). Methanol was the least effective. High reproducibility in the replicates was observed, indicating that the removal as consistent for each product. The trace levels of drug that remained on the surface were detectable by both TD-DART-MS and LC-MS/MS. The particulate studies yielded removal efficiencies greater than 98% in all instances, with high reproducibility (Table 3 within the study). In the in-field simulation, removal efficiencies exceeding 97% were observed in all but two instances. The two instances in which removal efficiencies were less than 97% were noted to have had evaporation of the cleaning solution. The authors note that the cleaning solution must not evaporate, as the evaporation of the cleaning solution will lower the removal efficiency of the cleaner. TD-DART-MS and LC-MS/MS analysis indicated detectable levels of intact opioids, supporting earlier research that suggested the incomplete breakdown of opioids by these cleaners.

In the final study, measuring the breakdown of opioids in solution, 1 mg of the opioid was measured into a test tube. Then, 1 mL of the selected cleaning agent was added to the opioid and mixed to dissolve. A small portion of the solution was removed at four timepoints: <1, 5, 15, and 30 min. The removed solution was added to chloroform to extract the remaining opioid, which was then dried and reconstituted in methanol, followed by analysis by GC-flame ionization detector (GC-FID) to determine the amount of remaining opioid. Three replicates were obtained for each time point. OxiClean™ was determined to be 85% effective at breaking down cyclopropyl fentanyl and 95% effective at breaking down carfentanil at the 15 min mark. Dalhgren Decon studies at all time points yielded undetectable levels of the opioids by GC-FID. The limit of detection for the GC-FID method corresponded to a 95% efficiency for carfentail, and a 97.5% efficiency level for cyclopropyl fentanyl. As indicated by the earlier tile studies, the cleaners failed to completely breakdown the opioids.

Scientific Highlights

  • All cleaning agents examined were at least 97% effective at removing drug residues from laboratory benchtops.
  • Despite high removal efficiencies, drugs were still detectable by sensitive instrumentation, e.g. TD-DART-MS.
  • Drying of the cleaning agent lowered the removal efficiency of the cleaner.Relevance

Cleaning agents must be effective to reduce the risk of cross contamination in the lab and to ensure safety in the field. If laboratories do not properly clean the lab bench, there could be the potential of contaminating other samples from other cases.

Potential Conclusions

The studied cleaners were effective at removing drugs from benchtop surfaces and ceramic tiles, however it should not be assumed that all drugs are removed by cleaning.