Simple headspace device for determination of volatile compounds in food and drug samples

Abstract

This work presented a simple alternative method for simultaneous extraction and determination of volatile compounds in complex matrix samples by combining headspace technique with paper based colorimetric method. The paper loaded with colorimetric reagent that was attached to the liner of the vial cap making a simple headspace device for direct detection of the semi-volatile and volatile compounds in headspace extraction mode. A sample was placed in a vial sealed with the paper-based headspace device. The method was tested for determination of volatile compound using ethanol as a model and semi-volatile compound using iodine as a model in complex matrix samples. Ethanol volatilized and reacted with chromic acid reagent, which was generated by mixing sodium or potassium dichromate with sulfuric acid, on the paper. The orange color of solution containing dichromate (VI) change to green solution containing chromium (III) ions. Iodine was volatilized by using oxidizing agent and react with starch reagent on the paper. The colorless of starch solution change to dark blue color of iodine-starch solution. The image of the paper was taken by the scanner for determination of iodine and by digital camera for determination of alcohol. The images were processing by ImageJ software in RGB mode and the blue intensity was taken for quantification. For determination of alcohol, the sample was heated at 40 o C for 5 min. The method was applied for determination of alcohol content in drug (i.e., stomachic mixtures and Salol et menthol mixture), and beverage sample (i.e., beer). The linear calibration ranged from 0-7 % (v/v) of ethanol with R2 > 0.97 was obtained. The recovery of 94-120% and the relative standard deviation of less than 3% were achieved. For determination of iodine, the treatment of spiked egg sample with 0.4 g/mL TCA was heated at 50 o C for 15 min. The linear calibration ranged from 0-100 ppm of iodine with R2 > 0.98 was obtained. The recovery of 93% and the relative standard deviation of less than 2% were achieved.