Characterization of Certified Reference Material for the Quantification of Water in Bioethanol

• Published in: Analytical Sciences Vol. 28; no. 11; pp. 1089 - 1095
• Main Authors: INAGAKI, Shinsuke, NUMATA, Masahiko, HANARI, Nobuyasu, IWASAWA, Ryoko, MATSUO, Mayumi, KATO, Kenji
• Format: Journal Article
• Language: English
• Published: Singapore The Japan Society for Analytical Chemistry 2012; Springer Nature Singapore; Japan Science and Technology Agency
• Subjects: Analytical Chemistry; Chemistry; Coulometers; Ethanol - analysis; Ethanol - standards; Methyl alcohol; Moisture; Reference materials; Reference Standards; Titration; Valves; Water - chemistry; Water - standards
• ISSN: 0910-6340; 1348-2246
• DOI: 10.2116/analsci.28.1089

The National Metrology Institute of Japan has issued a certified reference material of bioethanol (NMIJ CRM 8301-a) for the quantification of water, methanol, sulfur, and copper. This paper presents technical details for the characterization of the water in NMIJ CRM 8301-a. The characterization was performed using coulometric and volumetric Karl-Fischer (KF) titrations. To reduce moisture absorption, sample handling and KF titration were performed in a glove box under a dried nitrogen atmosphere. In addition, a rubber cap with a three-way valve was attached to the ampoule immediately after opening so as to minimize the influence of moisture. Sample aliquots were obtained using a gas-tight microsyringe through the valve, and injected into the KF cell as soon as possible. The certified value of water obtained from coulometric and volumetric KF titrations was 1.688 mg g−1, and the expanded uncertainty (coverage factor, k = 2) was 0.028 mg g−1. This CRM would be suitable for the monitoring of water in bioethanol and similar matrices.