Analytical Sciences

Membrane Sampling with Microdialysis Coupled to HPLC/UV for On-line Simultaneous Determination of Melamine and Cyanuric Acid in Non-dairy Coffee Creamer

Yu-Ying CHAO,* Yu-Tzu WEI,* Cheuch-Ting LEE,* Hwang-Shang KOU,** and Yeou-Lih HUANG***

*Department of Public Health, College of Health Science, Kaohsiung Medical University, 80708 Kaohsiung, Taiwan
**Graduate Institute of Pharmaceutical Sciences, College of Pharmacy, Kaohsiung Medical University, 80708 Kaohsiung, Taiwan
***Department of Medical Laboratory Science and Biotechnology, College of Health Science, Kaohsiung Medical University, 80708 Kaohsiung, Taiwan

An on-line microdialysis/high-performance liquid chromatography method was developed for the simultaneous determination of melamine and cyanuric acid in non-dairy coffee creamer. To collect these analytes from aqueous samples, the microdialysis system featured a microdialysis probe incorporating a polyarylethersulfone membrane and employed 0.05 M HCl in 0.1% (v/v) MeOH as the perfusate, with optimal efficiency obtained at a flow rate of 1 μL min⁻¹. The chromatographic conditions were optimized when using a reverse-phase phenyl column and a mobile phase of phosphate buffer solution in 10% (v/v) MeOH, buffered at pH 3.0. Good linearity relationship (r² > 0.9987), intra- and inter-day precisions (RSDs < 6.6%), recoveries (96.9 – 105.0%), and limits of detection (melamine, 3 ppb; cyanuric acid, 150 ppb) were observed for the two analytes. This method has been successfully applied to simultaneous determination of melamine and cyanuric acid in commercial creamers with the recoveries in the range of 97.5 to 102.6%.

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