A reversed-phase air-assisted dispersive liquid-liquid microextraction coupled with colorimetric paper-based analytical device for the determination of glycerol, calcium and magnesium in biodiesel samples

摘要

A cheap and simple procedure for the simultaneous colorimetric determination of glycerol, magnesium and calcium in biodiesel samples using a paper-based analytical device (PAD) was developed. A reversed-phase air-assisted dispersive liquid-liquid microextraction (RP-AA-DLLME) approach was proposed and used for glycerol, magnesium and calcium separation from biodiesel samples into aqueous phase (sodium periodate solution). After RP-AA-DLLME the obtained hydrophilic emulsion (biodiesel fuel in water) containing target analytes was introduced to a sample zone of the PAD, and as the emulsion penetrated through hydrophilic cellulose fibers to detection zones its destruction was observed. Colorimetric detection of calcium and magnesium with Eriochrome Black T and derivative of glycerol (formaldehyde) with acetylacetone on the detection zones of the PAD was implemented using conventional scanner and Corel (R) PHOTO-PAINT (TM) X7 software. Under optimal conditions, the calibration curves were linear in the ranges 100-300 mu g g(-1) for glycerol and 1-15 mu g g(-1) for calcium and magnesium. The limits of detection, calculated from a blank test based on 3s, were 30 mu g g(-1) for glycerol and 0.3 mu g g(-1) for calcium and magnesium. The PAD was successfully applied for biodiesel samples analysis.