Development of certified reference materials of ethanol in aqueous solution resulting from the participation of GUM in EMPIR 16RPT02 ALCOREF project

The measurement of alcohol concentration in exhaled air is used worldwide for sobriety checks by police and other services. Breath alcohol analyzers are instruments for the determination of alcohol (ethanol) mass concentration in exhaled air. These instruments are evaluated and calibrated in many countries (among others in Poland) using wet gas standards produced in situ from aqueous standard solutions in breath simulators. The value of the mass fraction of ethanol in the solution is necessary to determine the concentration of ethanol in the produced gas standard. New reference materials of ethanol in an aqueous solution intended for use in breath simulators for calibration and testing of breath alcohol analyzers were developed as a result of the Central Office of Measures (GUM) participation in the EMPIR 16RPT02 ALCOREF project. CRMs were certified following standard ISO 17034:2016 and ISO Guide 35:2017 ensuring traceability of certified values to SI units and covering ethanol content ranging from 0.129 g/kg to 5.051 g/kg required by OIML R126. The certified mass fractions of the ethanol and expanded uncertainties (k = 2) of the four reference materials representative for the entire range were (0.2588 ± 0.00040) g/kg (GUM 12.2), (0.6470 ± 0.00074) g/kg (GUM 12.3), (1.0352 ± 0.0014) g/kg (GUM 12.4) and (5.0506 ± 0.0092) g/kg (GUM 12.8). The CRMs produced by the procedure presented in this paper have been found to be fit for purpose.