Quality control of gasohol using a micro-unit for membraneless gas diffusion

Abstract

This work describes the development of a new spectrophotometric flow technique suitable for monitoring of ethanol content in gasohol fuel. Membraneless gas-diffusion (MBL-GD) was applied with one-step aqueous extraction of gasohol (1:2 gasohol/water). Segments of aqueous extract and color developing reagent were allowed to flow into two separate channels in the MBL-GD device. Inside the device, ethanol vapor can diffuse across a small headspace between the two channels (donor and acceptor). Introduction of an air-segment behind the zone of acceptor reagent to stop dispersion of the colored zone greatly improves the rapidity of analysis using this MBL-GD technique. Two methods were developed for quality control of gasohol by measuring ethanol content. Method I is suitable for direct calibration of E5 and E10. Method II is recommended for E20. These methods have high accuracy with good precision (% RSD: 1 to 4.9, n=45) and have a sample throughput of 26 samples per hour. E10 samples were compared with analysis using a standard GC method. © 2008 Springer-Verlag.