Issue Date: August 27, 2012
Cautionary Tale For Food Analysis
The methods used by some laboratories to measure arsenic in juice can yield results that are biased high, reported William Mindak, a scientist at the Food & Drug Administration. Last fall, the television program “The Dr. Oz Show” questioned the safety of national apple juice brands, claiming that its analysis showed that some of them contained arsenic concentrations that exceeded the regulatory levels for drinking water. When FDA measured samples from the same lot of one of the brands, Mindak said, its scientists found much lower arsenic concentrations, by a factor of four to five. Mindak undertook a study to figure out why the labs’ results differed so much. He found that the contract lab, which did not regularly perform food analysis, had used a modified wastewater method, which called for larger sample volumes than FDA’s method. As a consequence, the apple juice was inadequately digested to remove carbon, which enhances the arsenic measurement. Mindak cautioned contract labs that are considering moving into food analysis to choose their methods with care, because foods are a more complicated matrix than many environmental samples.
- Chemical & Engineering News
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