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

Abstract

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.

Determination of Sulfur in Bioethanol Certified Reference Material

“…Certified components are water 11) , methanol, sulfur and copper 12) which are regulated by JIS K 2190 1) . Certified values are 1688 26 mg kg -1 for water 11) , 482 23 mg kg -1 for methanol, 2.43 0.23 mg kg -1 for sulfur, and 0.0537 0.0041 mg kg -1 for copper 12) , where plus or minus values are the expanded uncertainty. To determine the sulfur certified value, combustion ultraviolet fluorescence and combustion ion chromatography analysis were used.…”

Development of a reliable method to determine water content by headspace gas chromatography/mass spectrometry with the standard addition technique

“…31,32 Results and discussion Hydranal-Coulomat AG-H and CG were used as the anolyte and catholyte solutions, respectively.…”

Certification of water content in NMIJ CRM 4222-a, water standard solution 0.1 mg g−1, by coulometric and volumetric Karl Fischer titration

“…HYDRANAL-Composite 1 and HYDRANAL-Methanol Dry were obtained from Sigma-Aldrich Japan (Tokyo, Japan). NMIJ CRM 8301-a (bioethanol) 15,16 was used for the titre determination of the KF reagent.…”

“…The titre determination of the KF reagent was performed using NMIJ CRM 8301-a (water content: 1.688 AE 0.028 mg g À1 ). 15,16 The CRM was placed in the gas-tight sample lock syringe, weighed following the same procedure as for coulometric KF titration, and 2 mL (ca. 1.7 g) of the aliquot was injected into the KF cell.…”