title: False-positive ethyl glucuronide immunoassay screening caused by a propyl alcohol-based hand sanitizer.
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 EtG immunoassay results have to be controlled by mass-spectrometry, in clinical cases at least if ethanol intake is denied by the patient.
authors.affiliation: Bioscientia Institut für Medizinische Diagnostik GmbH, Ingelheim, Germany. torsten.arndt@bioscientia.de
authors.forename: Torsten
authors.initials: T
authors.lastname: Arndt
authors.forename: Joachim
authors.initials: J
authors.lastname: Grüner
authors.forename: Stefanie
authors.initials: S
authors.lastname: Schröfel
authors.forename: Karsten
authors.initials: K
authors.lastname: Stemmerich
mesh_terms: D000433:1-Propanol / Q000032:analysis*; D000428:Alcohol Drinking; D015415:Biomarkers / Q000652:urine; D002853:Chromatography, Liquid; D004202:Disinfectants / Q000737:chemistry*; D005189:False Positive Reactions; D053593:Forensic Toxicology; D005965:Glucuronates / Q000652:urine*; D006235:Hand Disinfection; D006801:Humans; D007118:Immunoassay; D013058:Mass Spectrometry
chemical_list: D015415:Biomarkers; D004202:Disinfectants; D005965:Glucuronates; C093924:ethyl glucuronide; D000433:1-Propanol