Measurement of Uncertainty for Vaporous Ethanol Concentration Analyzed by Intoxilyzer® 8000 Instruments.
Reporting a measurement of uncertainty helps to determine the limitations of the method of analysis and aids in laboratory accreditation. This laboratory has conducted a study to estimate a reasonable uncertainty for the mass concentration of vaporous ethanol, in g/210 L, by the Intoxilyzer(®) 8000 breath analyzer. The uncertainty sources used were: gas chromatograph (GC) calibration adjustment, GC analytical, certified reference material, Intoxilyzer(®) 8000 calibration adjustment and Intoxilyzer(®) 8000 analytical. Standard uncertainties attributed to these sources were calculated and separated into proportional and constant standard uncertainties. Both the combined proportional and the constant standard uncertainties were further combined to an expanded uncertainty as both a percentage and an unit. To prevent any under reporting of the expanded uncertainty, 0.10 g/210 L was chosen as the defining point for expressing the expanded uncertainty. For the Intoxilyzer(®) 8000, all vaporous ethanol results at or above 0.10 g/210 L, the expanded uncertainty will be reported as ±3.6% at a confidence level of 95% (k = 2); for vaporous ethanol results below 0.10 g/210 L, the expanded uncertainty will be reported as ±0.0036 g/210 L at a confidence level of 95% (k = 2).
New Mexico Department of Health, Scientific Laboratory Division, Toxicology Bureau, Albuquerque, NM, USA rong.hwang@state.nm.us.
Rong-Jen
RJ
Hwang
New Mexico Department of Health, Scientific Laboratory Division, Toxicology Bureau, Albuquerque, NM, USA.
Craig
C
Rogers
New Mexico Department of Health, Scientific Laboratory Division, Toxicology Bureau, Albuquerque, NM, USA.
Jada
J
Beltran
New Mexico Department of Health, Scientific Laboratory Division, Toxicology Bureau, Albuquerque, NM, USA.
Gerasimos
G
Razatos
New Mexico Department of Health, Scientific Laboratory Division, Toxicology Bureau, Albuquerque, NM, USA.
Jason
J
Avery
D000435:Alcoholic Intoxication / Q000175:diagnosis*; D001944:Breath Tests / Q000295:instrumentation*; D002138:Calibration; D002849:Chromatography, Gas / Q000379:methods; D000431:Ethanol / Q000032:analysis*; D005554:Forensic Medicine / Q000295:instrumentation; D006801:Humans; D035501:Uncertainty
D000431:Ethanol