Wygant M B, Statler J A, Henshall A
Dionex Corp., Sunnyvale, CA 94086, USA.
J AOAC Int. 1997 Nov-Dec;80(6):1374-80.
Sulfite is added to foods as an antimicrobial, antibrowning agent, or antioxidant. It also can occur naturally, and is often used in the production of beer and wine. For years the standard methodology for determination of sulfite in foods has been the Monier-Williams method, which is a combination of acid distillation and titration. Recently, AOAC adopted a chromatographic method based on a method developed by Kim and Kim for the determination of sulfite. The method combines ion exclusion chromatography with direct-current (DC) amperometric detection to provide more convenient and accurate quantitation of sulfite. However, fouling of the platinum working electrode results in a rapid decrease in method sensitivity. As a result, standards must be injected before and after every sample, and the electrode must be polished frequently to maintain adequate detection limits. Pulsed amperometric detection overcomes electrode fouling problems by repeatedly and continuously applying cleaning potentials to the working electrode. Using this technique, a reproducible electrode surface can be maintained, and injection-to-injection repeatability is greatly improved. A comparison of method performance for both DC and pulsed amperometric detection is presented. Also investigated was the stability of sulfite samples at varying pH, and in the presence or absence of a preservative.
亚硫酸盐作为抗菌剂、防褐变剂或抗氧化剂添加到食品中。它也可天然存在，常用于啤酒和葡萄酒的生产。多年来，食品中亚硫酸盐测定的标准方法一直是莫尼尔 - 威廉姆斯法，该方法是酸蒸馏和滴定的结合。最近，美国官方分析化学师协会（AOAC）采用了一种基于金和金开发的方法的色谱法来测定亚硫酸盐。该方法将离子排斥色谱与直流（DC）安培检测相结合，以更方便、准确地定量亚硫酸盐。然而，铂工作电极的污染会导致方法灵敏度迅速下降。因此，必须在每个样品前后注入标准品，并且必须频繁抛光电极以维持足够的检测限。脉冲安培检测通过向工作电极反复连续施加清洁电位来克服电极污染问题。使用该技术，可以维持可重复的电极表面，并且进样间的重复性大大提高。本文对直流和脉冲安培检测的方法性能进行了比较。还研究了亚硫酸盐样品在不同pH值以及有无防腐剂情况下的稳定性。
