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

Abstract

Sulfur dioxide (SO₂) 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 SO₂ in wine is strictly regulated since SO₂ 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 SO₂ 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 SO₂ prepared in advance. Under the optimal conditions, the instrumental limit of detection (LOD) for SO₂ was found to be 0.17 μg, and the relative standard deviation (RSD) of 200 μg SO₂ was 1.3%. The method was developed for determining the total SO₂ 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 SO₂ 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.