Simple Determination of 4-Methylimidazole in Soft Drinks by Headspace SPME GC-MS

A simple method to detect 4-methylimidazole in soft drinks is described. This method is based on headspace solid-phase micro-extraction and gas chromatography-mass spectrometry (HS-SPME GC-MS). The HS-SPME parameters (selection of fiber, extraction temperature, heating time, and pH) were optimized and selected. Under the established condition, the detection and the quantification limit were 1.9 and 6.0 mu g L-1 using 4 mL of the liquid sample, respectively. The relative standard deviation for five independent determinations at 100.0 and 500.0 mu g L-1 was less than 8 %. The calibration curve was y = 0.6027x-0.0033 with a linearity of r (2) = 0.997. Using the proposed method, the levels of 4-MEI were detected in a range from 94.0 to 324.8 mu g L-1. The comparison of liquid chromatography tandem mass spectrometry (LC-MS/MS) with the proposed method was performed and the agreement with LC-MS/MS for all samples was acceptable.