Mechanism of Action of Chemical Adulteration

Chemical adulterants may act by destroying the drug moieties. In a study on the action of PCC, potassium chromate, and sodium chromate, Paul et al. found that the drug moiety was destroyed by these oxidants. The oxidative properties are shown to result from the chromate ions. PCC affected mainly 11-nor-A9-tetrahydrocannabinol-9-carboxylic acid (THC-acid). PCC also affected morphine at very low pH (8). Further study suggested that the effects of oxidizing agents depended on the reduction potential (E0), pH, temperature, time of reaction, and urine constituents. Compounds like potassium chromate, sodium nitrite, potassium permanganate, periodic acid, potassium persulfate, Oxone®, hydrogen peroxide/ferrous ammonium sulfate, and sodium oxychloride destroyed THC-acid within 48 h (9).

Chemical adulterants may also act by interfering with the extraction procedures in gas chromatography(GC)-mass spectrometry (MS). In a study on the effect of Stealth on morphine and codeine, Cody et al. found that the adulterant affects the extraction procedures in the GC-MS process (10). Tsai et al. studied the effect of nitrite adulteration on immunoassays and GC-MS and found that nitrite has no significant effect on laboratory and on-site drug screens. However, it interferes with the GC-MS extraction of THC-acid so that adulterated samples that were tested THC-positive by screening tests would not be confirmed (11).

Adulterants can also target the enzymatic assays of the laboratory drug screens. Wu et al. studied the effects of Urine Luck containing PCC and found that it decreased the response rates for several laboratory drug screens, leading to false-negative results partly as a result of the low pH induced by PCC (12).

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