On-line chemical vapor generation for determination of total sulfur dioxide in wine samples using an atomic fluorescence spectrometer

摘要

Sulfur dioxide (SO_2) is used as a universal additive to wine due to its excellent antioxidative, antimicrobic, and anti-brown characteristics and also because it is the product of natural fermentation of grapes. The concentration of SO_2 in wine is strictly regulated since SO_2 at high concentrations can damage tissues, organs, and various systems of human beings. In this study, an atomic fluorescence spectrometer (AFS) was used for the determination of SO_2 by measuring its molecular fluorescence signal excited by a zinc hollow cathode lamp (Zn HCL, 213.8 nm) under simple and mild conditions without igniting the atomizer. The instrumental settings were first optimized by detecting gaseous SO_2 prepared in advance. Under the optimal conditions, the instrumental limit of detection (LOD) for SO_2 was found to be 0.17 μg, and the relative standard deviation (RSD) of 200 μg SO_2 was 1.3%. The method was developed for determining the total SO_2 in wine samples extracted by sodium hydroxide and generated in the form using sulfuric acid. The LOD of 0.79 μg mL~(-1) for this method was achieved for the total SO_2 analysis of wine samples with a 5.2% RSD at a concentration level of 30 μg mL~(-1) The advantages of this method are simplicity, high throughput, less interference, relatively low cost, and less chemical consumption.