Determination of silicate in water by ion exclusion chromatography with conductivity detection

2000 ◽  
Vol 874 (1) ◽  
pp. 143-147 ◽  
Author(s):  
Hua-Bin Li ◽  
Feng Chen
Keyword(s):  
Conductivity Detection ◽  
Ion Exclusion Chromatography ◽  
Ion Exclusion ◽  
Exclusion Chromatography

scholarly journals Improvements in Amperometric Detection of Sulfite in Food Matrixes

1997 ◽  
Vol 80 (6) ◽  
pp. 1374-1380 ◽  
Author(s):  
Michele B Wygant ◽  
John A Statler ◽  
Alan Henshall
Keyword(s):  
Amperometric Detection ◽  
Method Performance ◽  
Pulsed Amperometric Detection ◽  
Ion Exclusion Chromatography ◽  
Working Electrode ◽  
Ion Exclusion ◽  
Before And After ◽  
Exclusion Chromatography ◽  
The Stability

Abstract 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.

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