Internationally, certified ethanol reference materials are required to calibrate breathalysers and blood-alcohol measurement instruments. The CSIR National Metrology Laboratory of South Africa provides certified aqueous ethanol solutions with traceability to the SI. Ethanol solutions in the concentration range 10 mg/100 g to 20 g/100 g are prepared gravimetrically by mixing ethanol and reagent quality water. To verify the concentration of the ethanol it is oxidized to acetic acid with potassium dichromate in the presence of sulphuric acid. The unreacted potassium dichromate is back-titrated with sodium thiosulphate. The method utilizes gravimetry and titrimetry, which are both primary methods. This paper addresses aspects of ethanol-certified reference materials that have not been previously published: traceability, stability of unpreserved ethanol solutions, homogeneity, quality control measures and the effect of reproducibility on the measurement uncertainty
Reference:
Archer, M, De Vos, BJ and Visser, MS. 2007. Preparation, assay and certification of aqueous ethanol reference solutions. Accreditation and Quality Assurance, Vol. 12(3-4), pp 188-193
Archer, M., De Vos, B., & Visser, M. (2007). Preparation, assay and certification of aqueous ethanol reference solutions. http://hdl.handle.net/10204/834
Archer, M, BJ De Vos, and MS Visser "Preparation, assay and certification of aqueous ethanol reference solutions." (2007) http://hdl.handle.net/10204/834
Archer M, De Vos B, Visser M. Preparation, assay and certification of aqueous ethanol reference solutions. 2007; http://hdl.handle.net/10204/834.
