Developing fast laboratory screening platform for sulfate dioxide in food by surface-enhanced Raman spectroscopy

The direct detection of sulphur dioxide has been realized in various food matrixes with high sensitivity and high selectivity, on the basis of the integration of the high energy resolution of the finger-print spectrum of surface-enhanced Raman spectroscopy and the universal but easy-on-going pretreatment procedure. The characteristic peak of sulphur dioxide at ~630 cm −1 was applied as the qualitative and quantitative standard, which displayed a lowest detectable concentration at the 1 mg kg −1 level for the spiked food samples. The key point of the high sensitivity and selectivity is the effective pretreatment born out of the standard distillation one, which has been improved in the three parts. (1) Using CaCO 3 and Zeolite instead of N 2 gas as the bubbling reagent. (2) Using oxalic acid as the acidic distillation solution to eliminate the hazards from acid volatilization, such as hydrochloric acid. (3) Using diluted sodium hydroxide solution as the absorption reagent instead of lead acetate solution to avoid the secondary pollution. With the three distinguished advantages of environment friendly, high sensitivity and free of matrix interference, the proposed method has great potential to replace the traditional ones for the fast screening of the illegal or abused sulphur dioxide in food.