AGFD 63 |
| Perchlorate (ClO4-) has been known as an environmental contaminant for a number of years. It is a component part of rocket propellants, road flares, air bags, along with other industrial processes. From a health standpoint, it has been linked to problems with the thyroid functions, where it inhibits iodide uptake, at high levels. Ion Chromatography (IC) with conductivity detection has been used as a primary technique for ClO4- analysis. However, high ionic strength of anions, such as chloride, in food matrices tends to complicate the analysis using IC and leads to misidentifying perchlorate and the inability to detect perchlorate at trace levels. High performance liquid chromatography (HPLC) in conjunction with quadrupole mass spectrometry (LC/MS/MS) with elecrospray in the negative ion mode is capable of detecting anions at trace levels. The National Food Processors Association (NFPA) has developed a LC/MS/MS method to analyze perchlorate in milk at parts per billion (ppb) levels. The method includes sample acidification for elimination of protein interference from milk, sample cleanup using solid phase extraction and a MS/MS analysis for identification and quantification. Milk samples obtained from different sources, such as milk purchased from local grocery stores, were used for this study. Two different HPLC columns (C-18 and IC columns) were also studied to compare their performance. All milk samples were spiked with 10 g/L of ClO4-. The recovery range was between 85 and 105 %. The detected levels of perchlorate in the studied milk samples were between 3.8 to 11.9 ppb. The limit of quantitation, based on 10 times the signal-to-noise ratio, is about 2 ppb. This study demonstrates that the LC/MS/MS technique is superior to the IC with a conductivity detector since the MS/MS technique can eliminate matrix interference and produce more reliable quantitative data. |
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Sci-Mix
8:00 PM-10:00 PM, Monday, 14 March 2005 Convention Center -- Sails Pavilion, Sci-Mix
Division of Agricultural & Food Chemistry |