Determination of sulfur in biodiesel microemulsions using the summation of the intensities of multiple emission lines

A method for the determination of sulfur in biodiesel samples by inductively coupled plasma optical emission spectrometry which uses microemulsion for sample preparation and the summation of the intensities of multiple emission lines has been developed. Microemulsions were prepared using 0.5mL of 20% v/v HNO(3), 0.5mL of Triton X-100, 2-3mL of biodiesel sample, and diluted with n-propanol to a final volume of 10mL. Summation of the emission intensities of multiple sulfur lines allowed for increased accuracy and sensitivity. The amounts of sulfur determined experimentally were between 2 and 7mgL(-1), well below legislative standards for many countries. Recoveries obtained ranged from 72 to 119%, and recoveries obtained for the 182.562nm line were slightly lower. This is most likely due to its lower sensitivity. Using microemulsion for sample preparation and the summation of the intensities of multiple emission lines for the successful determination of sulfur in biodiesel has been demonstrated. (C) Elsevier B.V. All rights reserved.