Papain adulteration in 11-nor-Delta9-tetrahydrocannabinol- 9-carboxylic acid-positive urine samples

J Anal Toxicol. 2008 Jul-Aug;32(6):438-43. doi: 10.1093/jat/32.6.438.


The adulteration of urine samples is an ongoing problem in forensic drug-testing laboratories, even in the military where the practice of observed collections is performed. These adulterants are used to produce a false-negative result when samples are analyzed for drugs of abuse. It has been reported that papain, a cysteine protease, could be successfully used as a urine adulterant, altering the concentration of 11-nor-Delta9-tetrahydrocannabinol-9- carboxylic acid (THCCOOH) in urine samples. The current study analyzes the effects of latex papain (Sigma, 10 mg/mL) and Lawry's Adolph's Meat Tenderizer (papain is an active ingredient, 10 mg/mL) on immunoassays (FPIA, EMIT, KIMS) and gas chromatography-mass spectrometry (GC-MS) analysis for biological samples. The samples were analyzed initially between 2 and 4 h and then at 1-, 3-, 7-, and 10-day time intervals after the addition of papain. A decrease in response averaged over the course of the study was observed with FPIA (Abbott, 22%) and EMIT (Syva) Dade Behring, 26%, Microgenics, 10%) screening assays by the addition of latex papain to the samples. An increase in response was found using the KIMS (Roche) assay (156% increase). In addition, the GC-MS results (27% decrease) demonstrate that papain affects both the screening and confirmation assays. The addition of meat tenderizer caused decrease in the FPIA (Abbott, 11%) screening assay and GC-MS results (22%) similar to the latex papain while having varied results on the other screening assays. This study confirms papain could be a potential problem for urine drug-testing programs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Dronabinol / analogs & derivatives*
  • Dronabinol / urine
  • Drug Contamination*
  • Gas Chromatography-Mass Spectrometry
  • Humans
  • Papain / urine*
  • Reference Standards
  • Substance Abuse Detection*


  • 11-nor-delta(9)-tetrahydrocannabinol-9-carboxylic acid
  • Dronabinol
  • Papain