Optimization of experimental parameters in single-drop microextraction-gas chromatography-mass spectrometry for the determination of periodate by the Malaprade reaction, and its application to ethylene glycol.

The aim of present work was to optimize the experimental parameters in single drop microextraction under solution immersion (SDME) and headspace (HS-SDME) extraction modes for the determination of periodate using guaifenesine [3-(2'-methoxyphenoxy)-1,2-propane diol] and norephedrine (phenylpropanolamine) as new and alternative reagents for the Malaprade reaction. The reactions were complete within 5min resulting in the formation of 2-(2'-methoxyphenoxy)-acetaldehyde and benzaldehyde, respectively. SDME/HS-SDME of oxidation products with 2mul of anisole or 1mul of toluene, respectively, has permitted the determination of periodate at mugl(-1) concentration levels. The results indicated that HS-SDME (range 0.01-10mgl(-1), r(2)=0.9990; limit of detection 1.55mugl(-1)) was more sensitive than SDME (range 0.05-50mgl(-1), r(2)=0.9984; limit of detection 3.42mugl(-1)), and was inexpensive, rapid and convenient. Tolerance of excess of iodate has permitted the application of this method in the determination of ethylene glycol in motor oil; the average recovery on spiked sample was 98.6% with R.S.D. of 4.2%.