In this work, a green and simpler method for photometric determination of sulfite based on a flow injection-gas diffusion (FI-GD) system using a natural reagent extracted from roselle (Hibiscus sabdariffa L.) was proposed. Despite the fact that the employed reaction is not selective to sulfite, its sensitivity is high, and the selectivity can be improved by coupling a GD unit to the FI system. The method involves monitoring a decrease in absorbance of the reagent solution that is used as an acceptor solution. When a standard solution or sample solution was injected into an acidic donor stream, the liberated sulfur dioxide diffuses through a gas-permeable membrane of the GD unit into the acceptor solution, causing color fading of the reagent. A linear analytical curve in the range of 5–100 mg L⁻¹ was obtained with a detection limit of 2 mg·L⁻¹. Relative standard deviations of 0.9%, 0.6%, and 0.6% were obtained for the determination of 30, 70, and 100 mg·L⁻¹ SO₃^2- (n = 11). The developed method was applied to wine samples, giving results that agreed with those obtained with the Ripper titrimetric method. The proposed method offers advantages of simplicity, cost-effectiveness, and being environmentally friendly such as reduced chemical consumption and less waste generation.

中文翻译：

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以玫瑰茄提取物为天然试剂的光度测定葡萄酒中亚硫酸盐的环保型流动注射气体扩散系统

在这项工作中，提出了一种绿色和更简单的方法，该方法基于流动注射气体扩散（FI-GD）系统，该系统使用从玫瑰茄（Hibiscus sabdariffa L.）提取的天然试剂进行光度法测定亚硫酸盐。尽管事实是所采用的反应对亚硫酸盐不是选择性的，但其灵敏度高，并且可以通过将GD单元偶联至FI系统来提高选择性。该方法包括监测用作受体溶液的试剂溶液的吸光度的降低。当将标准溶液或样品溶液注入酸性供体流中时，释放的二氧化硫会通过GD单元的透气膜扩散到受体溶液中，从而导致试剂褪色。在5–100 mg L ^-1范围内的线性分析曲线检出限为2 mg·L ^-1。测定30、70和100 mg·L ^-1 SO ₃ ^2-的相对标准偏差为0.9％，0.6％和0.6％（n  = 11）。将开发的方法应用于葡萄酒样品，其结果与用开膛手滴定法获得的结果相符。所提出的方法提供了简单，成本效益以及对环境友好的优点，例如减少了化学消耗并且减少了废物的产生。