Head-space single drop microextraction combined with gas chromatography with an electron capture detector for determination of iodine in infant formulas

Abstract

Headspace single-drop microextraction (HS-SDME) coupled with gas chromatography with electron capture detection (GC-ECD) was used for quantification of total iodine in milk based samples of infant formula. In this procedure 3 μL of a mixture containing 1-octanol and 3-pentanone was exposed to the headspace of a 5 mL acidic (H2SO4, 2 mol L−1) aqueous solution containing 1.5 mol L−1 ZnSO4 for 30 minutes followed by addition of 1 mL of 1 mol L−1 H2O2 for in situ generation of iodine. Optimization of the microextraction system was carried out using the Taguchi experimental design method. The limit of detection was determined to be 250 ng L−1 with an enrichment factor of 150. The repeatability, expressed as a relative standard deviation, was 1.9% (n = 6). The linear calibration working range was between 0.75 and 2000 μg L−1 (r2 = 0.998). The method was successfully applied for determination of iodine in milk based samples of infant formula.