An HPLC Method with UV Detection, pH Control, and Reductive Ascorbic Acid for Cyanuric Acid Analysis in Water

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• 作者：Ricardo Cantú ; Otis Evans ; Fred K. Kawahara ; Jody A. Shoemaker ; and Alfred P. Dufour
• 刊名：Analytical Chemistry
• 出版年：2000
• 出版时间：December 1, 2000
• 年：2000
• 卷：72
• 期：23
• 页码：5820 - 5828
• 全文大小：128K
• 年卷期：v.72,no.23(December 1, 2000)
• ISSN：1520-6882

文摘

Every year over 250 million pounds of cyanuric acid (CA)and chlorinated isocyanurates are produced industrially.These compounds are standard ingredients in formulations for household bleaches, industrial cleansers, dishwasher compounds, general sanitizers, and chlorinestabilizers. The method developed for CA using high-performance liquid chromatography (HPLC) with UVdetection simplifies and optimizes certain parameters ofprevious methodologies by effective pH control of theeluent (95% phosphate buffer: 5% methanol, v/v) to thenarrow pH range of 7.2-7.4. UV detection was set at theoptimum wavelength of 213 nm where the cyanuric ionabsorbs strongly. Analysis at the lower pH range of 6.8-7.1 proved inadequate due to CA keto-enol tautomerism,while at pHs of <6.8 there were substantial losses inanalytical sensitivity. In contrast, pHs of >7.4 provedmore sensitive but their use was rejected because of CAelution at the chromatographic void volume and due tochemical interferences. The complex equilibria of chlorinated isocyanurates and associated species were suppressed by using reductive ascorbic acid to restrict theproducts to CA. UV, HPLC-UV, and electrospray ionization mass spectrometry techniques were combined tomonitor the reactive chlorinated isocyanurates and tosupport the use of ascorbic acid. The resulting method isreproducible and measures CA in the 0.5-125 mg/Llinear concentration range with a method detection limitof 0.05 mg/L in water.