Characterization of water content in biodiesel fuel certified reference material (NMIJ CRM 8302-a)

Abstract

The National Metrology Institute of Japan has issued a certified reference material of biodiesel fuel derived from palm oil (NMIJ CRM 8302-a) for the measurement and quality control of water, methanol, six elements (sulfur, phosphorus, sodium, potassium, magnesium, and calcium), density, and kinematic viscosity. This paper presents the technical details for the characterization of the water content in NMIJ CRM 8302-a. Because the water content in biodiesel is easily affected by ambient humidity, sample handling is extremely difficult. Thus, a sample handling technique that overcomes this limitation was established, and optimized coulometric and volumetric Karl Fischer titrations were performed in order to accurately determine the water content with traceability to the International System of Units. The certified water content and its expanded uncertainty with a coverage factor k = 2 were 393 mg kg−1 and 25 mg kg−1, respectively.