Characterization of water in methylcyclohexane as a certified reference material for determination of trace water content in liquids

Abstract

To ensure the accurate measurement of the water content in various materials, certified reference materials (CRMs) which are traceable to the International System of Units (SI) are required. The National Metrology Institute of Japan (NMIJ) has developed a CRM, water in methylcyclohexane (0.02 mg g−1), for quality control of trace water analyses in liquids. The water content of the CRM was determined by coulometric Karl Fischer titration as a primary method of measurements. The traceability of the electric charge applied on the titration was ensured to realize metrological traceability of the certified value to the SI. The uncertainties due to the analytical method, homogeneity, and long-term and short-term stabilities were evaluated and reflected in the uncertainty of the certified value. The certified value of the CRM was 0.018 mg g−1 and its expanded uncertainty, calculated using a coverage factor of k = 2, was 0.005 mg g−1. The new CRM can be applied for the validation of measurement instruments and procedures used in analyzing trace water. The technical details of the characterization of water in NMIJ CRM 4229-a are described in this paper.

Об Аттестации Стандартных Образцов В Фармации: Метод Баланса Масс

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Development and Application of Certified Reference Materials of Light Crude Oil for Water Content

“…Reference materials (RMs) for water content have certified values and can be used to validate the accuracy of analytical methods. ,,− Margolis et al have developed RMs of light sour crude oil (SRM 2721) and heavy sweet crude oil (SRM 2722), which had reference water content values of 134 and 99 mg/kg, respectively. , The reference values were determined using a modified KFCT method . When SRM 2721 was measured using the traditional KFCT method as described by the ASTM standard method (ASTM D 4928), the measured value was 941 mg/kg, which was much greater than the reference value (134 mg/kg), because of the side reactions of reducing compounds with iodine. , These two RMs were determined using only one method (the modified KFCT method), which does not conform to the requirements for the certification of RMs specified by ISO guide 35 .…”

Accurate Determination of Trace Water in Organic Solution by Quantitative Nuclear Magnetic Resonance

“…Accurate determination of water content is mandatory in fundamental research such as in the pharmaceutical, petroleum products, chemical reagents, and food industries . Especially, trace water in aviation kerosene is easy to freeze into ice when the aircraft flies in cold temperature, leading to intermittent supply of aviation kerosene and thus endangering flight safety .…”