Adulterants causing false negatives in illicit drug testing.

Abstract

Illicit-drug users may attempt to falsify results by in vitro adulteration of specimens. We investigated eight additives (NaCl, Visine, handsoap, Drano, bleach, vinegar, golden-seal tea, and lemon juice) claimed by drug users to invalidate enzyme immunoassay (EIA) drug assays. We also analyzed adulterated urine specimens to determine if they could be identified, adding adulterants at several concentrations to 222 EIA-positive specimens confirmed by gas chromatography and mass spectrometry (GC/MS) to contain illicit drugs. To identify adulterated urines, we monitored pH, relative density, and urine color and turbidity at adulterant concentrations that falsified EIA results. Specimens contaminated with NaCl had relative densities greater than 1.035. Liquid Drano, bleach, and vinegar shifted urine pH outside the physiological range. Golden-seal tea caused a dark appearance, and specimens containing liquid soap were unusually cloudy. Lemon juice had no effect on the assays. Visine was the only adulterant not detected. The adulterants interfered somewhat differently with each of the drug assays. EIA assays for illicit drugs can be invalidated by specimen adulteration producing false-negative results. Therefore, if urine drug testing is to be conducted, pH, relative density, and appearance should be assessed and suspect specimens should be rejected. Not all adulterants can be detected, so observed collection is strongly recommended.

Determining the effects of adulterants on drug detection via enzyme‐linked immunosorbent assay and adulterant tests strips

“…Other researchers have observed the same type of effect, with either a false negative result being returned or decreased immunoassay sensitivity for other immunoassay techniques, ie, EIA, CEDIA, EMIT, or FPIA. [16][17][18] Most of the literature regarding the effects of these oxidizing agents on immunoassay analysis primarily focuses on the capability of oxidizing agents to decrease drug/metabolite concentration and the mechanisms behind their ability to alter either the immunoassay or the urine matrix, or oxidize and destroy the drugs/metabolites. 18,30 The active ingredient in bleach is sodium hypochlorite, which is a common oxidizing agent that has been shown to alter various immunoassay results by disrupting physicochemical properties of the urine samples.…”

“…[16][17][18] Most of the literature regarding the effects of these oxidizing agents on immunoassay analysis primarily focuses on the capability of oxidizing agents to decrease drug/metabolite concentration and the mechanisms behind their ability to alter either the immunoassay or the urine matrix, or oxidize and destroy the drugs/metabolites. 18,30 The active ingredient in bleach is sodium hypochlorite, which is a common oxidizing agent that has been shown to alter various immunoassay results by disrupting physicochemical properties of the urine samples. [16][17][18]30 Similarly, Drano® contains sodium hypochlorite along with sodium hydroxide, both of which are strong oxidizers.…”

“…18,30 The active ingredient in bleach is sodium hypochlorite, which is a common oxidizing agent that has been shown to alter various immunoassay results by disrupting physicochemical properties of the urine samples. [16][17][18]30 Similarly, Drano® contains sodium hypochlorite along with sodium hydroxide, both of which are strong oxidizers. It has been theorized that these oxidizing agents can affect the immunoassay and/ or the drug antigen through several mechanisms but that the interference mechanism appears to be related to the uniqueness of the drug's chemical and physical properties.…”

“…1,8 However, this accuracy decreases significantly when the urine samples have been adulterated. [13][14][15] Previous studies related to adulterated drug samples have been carried out on other immunoassay techniques including RIA, 5 cloned enzyme donor immunoassay, 16,17 enzyme immunoassay, 18 FPIA, 7 and EMIT. [19][20][21] In a separate study, eye drops, liquid bleach, and vinegar were used to adulterate urine samples at a 10% v/v concentration and analyzed using FPIA, demonstrating that these adulterants significantly interfered with the accurate detection of cannabinoids.…”

Influences of Seven Taiwan‐Produced Adulterants on Gas Chromatographic‐Mass Spectrometric (GC‐MS) Urinalysis of Amphetamines

“…Since test results stand alone as the sole evidence in most of the cases concerning drug abuse, it is paramount that urine drug testing leaves no question as to the validity of results. With the increasing application of drug urinalysis, however, sample substitution, 1 dilution, [1][2][3] or adulteration [4][5][6][7][8] by the testee with the intention to avoid detection of previous drug use is becoming a serious problem. Over the past several years, there have been an increasing number of chemical adulterants marketed on the Internet and in counter-culture, pro-drug use magazines.…”