False-positive ethyl glucuronide immunoassay screening caused by a propyl alcohol-based hand sanitizer

• Published in: Forensic science international 2012-11, Vol.223 (1), p.359-363
• Main Authors: Arndt, Torsten, Grüner, Joachim, Schröfel, Stefanie, Stemmerich, Karsten
• Format: Article
• Language: English
• Subjects: 1-Propanol - analysis; Alcohol; Alcohol Drinking; Alcohols; Biological and medical sciences; Biomarkers - urine; Chromatography, Liquid; Disinfectants - chemistry; Disinfection & disinfectants; Ethanol; Ethyl alcohol; Ethyl glucuronide; Exhaust systems; False Positive Reactions; False-positive; Forensic medicine; Forensic sciences; Forensic Toxicology; General aspects; Glucuronates - urine; Hand Disinfection; Humans; Immunoassay; Inhalation; Investigative techniques, diagnostic techniques (general aspects); LC–MS/MS; Mass Spectrometry; Medical sciences; Pathology; Propanol; Public health. Hygiene; Public health. Hygiene-occupational medicine; Recipes; Screening; Substance abuse treatment; Urine
• ISSN: 0379-0738; 1872-6283
• DOI: 10.1016/j.forsciint.2012.10.024

Abstract Background Urine ethyl glucuronide (EtG) is considered as a specific marker of recent ethanol consumption. We describe false-positive DRI® EIA EtG enzyme immunoassay results caused by propyl glucuronides in urine after using a propanol-based hand sanitizer. Methods EtG screening was done with the DRI® EIA EtG assay (Microgenics), using a cut-off of 0.5 mg/L as recommended by the manufacturer and of 0.1 mg/L as demanded by the German Regulations for Reissuing Drivers Licenses. Confirmatory EtG analysis was done with the ClinMass® EtG LC–MS/MS testkit (Recipe), extended by the mass transitions 235.1 → 75.1, 235.1 → 85.1, and 235.1 → 113.1 for the detection of the 1- and 2-propyl glucuronides. Self-experiments were done by staff members of our lab ( n = 7), using 3 mL Sterillium® Classic Pure (30 g/100 g 1-propanol and 45 g/100 g 2-propanol) for hand sanitation every quarter of an hour for 8 h according to DIN EN 1500:2011-05 with and without an exhauster and by passive inhalation of the sanitizer vapor. Spot urine samples were taken immediately before and up to 24 h after the first sanitizer use. Results False-positive immunoassay results of up to 4 mg/L or 2.3 mg/g creatinine were obtained after normal use of the sanitizer and also after passive inhalation of the sanitizer vapor (up to 0.89 mg/L or 0.61 mg/g). Immunoassay results were positive even after 4-fold use of the sanitizer (up to 0.14 mg/L or 0.38 mg/g) and up to 6 h after the last sanitizer contact (maximum 0.63 mg/L and 0.33 mg/g for sanitizer users and 0.25 mg/g after passive inhalation). Spiking of EtG-free urine with 1-propyl glucuronide (Athena Environmental Sciences) between 0.05 and 10 mg/L clearly demonstrated a cross reaction of the immunoassay of approx. 10% as compared to EtG. LC–MS/MS of urines with a positive immunoassay EtG result did not show EtG signals, but distinct signals of 1-propyl glucuronide (n-propyl glucuronide) and 2-propyl glucuronide (iso-propyl glucuronide). An exhauster effectively prevented the inhalation of the sanitizer vapor, the formation of propyl glucuronides and thus false-positive DRI® EIA EtG screening results, proving that propyl alcohols are almost exclusively taken up by respiration. Conclusions The widespread use of propanol-containing products such as hand sanitizers may lead to sufficient uptake of propyl alcohols and excretion of significant amounts of propyl glucuronides to yield false-positive DRI® EIA EtG screening results. Thus, positive