Author
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King, Jerry |
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Submitted to: American Laboratory
Publication Type: Review Article Publication Acceptance Date: 4/1/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The analysis of pesticides and antibiotics in many foods is a complex and time consuming process. In addition, traditional analysis has utilized large quantities of organic solvents in the laboratory to isolate and purify extracts from the sample prior to analysis. Many of the solvent intensive methods utilize flammable and carcinogenic solvents. A highly compressed gas, carbon dioxide, has been used as a substitute for organic solvents to extract trace level toxicants from meats, fruits and vegetables. Unfortunately, extraction of these sample matrices with compressed carbon dioxide (also referred to as supercritical carbon dioxide, SC-CO2), extracts many unwanted substances; particularly coextracted fat and lipid material. To introduce more specificity into the extraction, several extract cleanup techniques were developed to ideally yield an extract that would permit direct analysis by conventional analytical methods. Among the techniques developed are the addition of an adsorbent to and after the extraction cell to hold back lipophilic coextractives. In addition, another compressed gas, fluoroform, has also been found to be more specific for target analytes while having a low propensity for lipids. The use of binary fluids such as mixtures of carbon dioxide and nitrogen can also be optimized to yield very low lipid contaminated extracts that are amenable to direct gas chromatography (GC) and high performance liquid chromatographic (HPLC) injection. It should be noted that a new sample cleanup method called inverse supercritical fluid extraction has been integrated into the extraction step. This technique allows for the isolation of the target analyte on a sorbent with subsequent removal of unwanted compounds that interfere in the final assay method. |
