Analysis of morphine and codeine in samples adulterated with Stealth

Stealth is an adulterant used to avoid detection of drug abuse. The product does have an effect on the ability to detect several drugs of abuse, including the opiates morphine and codeine. It has previously been shown that low concentration (2500 ng/mL morphine) samples adulterated with Stealth tested negative by both Roche OnLine and Microgenics CEDIA immunoassays, but those spiked with higher concentrations (6000 ng/mL of codeine and morphine glucuronide) were positive. Initial results showed confirmation analysis was also sometimes negatively impacted by this adulterant. Urine samples were spiked with 6000 ng/mL of codeine and/or morphine glucuronide to assess the effect of Stealth. Each individual sample was split into separate aliquots. One aliquot of each was adulterated with Stealth following package directions. The samples were then tested by immunoassay and gas chromatography-mass spectrometry (GC-MS). The control and adulterated aliquots were positive by both immunoassays. Results of GC-MS analysis of the Stealth-adulterated aliquots following standard procedures using deuterated internal standards proved unsuccessful in several cases. In 4 of 12 cases (33%), neither the drugs nor internal standards were recovered despite repeated attempts. In one other sample, recovery was dramatically reduced, making accurate quantitation impossible, whereas the unadulterated aliquots of the same samples posed no problem with recovery. Addition of sodium disulfite to the aliquots prior to extraction allowed recovery of the drugs and internal standards from all samples. Analysis of the samples showed the concentration of morphine and codeine decreased in some by as much as 17 and 30%, respectively. In other cases, there was essentially no difference in the concentration seen before and after adulteration, with or without disulfite treatment. Unless the initial concentration of opiate is near the cutoff, samples containing opiates are likely to be immunoassay positive, it is important to consider this procedure as an option for samples that screen positive but the opiates and their respective internal standards are not recovered for GC-MS analysis.