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JA0026 The Use of Dispersive Pipet Extraction (DPX) Tips for the Sample Cleanup of Apples, Pears, and Oranges in the Analysis of Formetanate HCl
来源:Journal of aoaC international | 作者:Lynda V. Podhorniak | 发布时间: 2142天前 | 2201 次浏览 | 分享到:
The U.S. Environmental Protection Agency Analytical Chemistry Laboratory evaluated the effectiveness of dispersive pipet extraction (DPX) tip cleanup and compared the results with the Quick, Easy, Cheap, Effective, Rugged, and Safe dispersive tube cleanup for the sample preparation of three different fruit matrixes analyzed for formetanate HCl (FHCl). Using LC/MS/MS, the target LOD and the LOQ achieved for FHCl with dispersive tubes, 0.1 and 0.3 ng/g, respectively, were similar to the DPX tip sample cleanup. Recoveries at the LOQ ranged from 94 to 109%. A set of 20–40 samples could be prepared in one working day by one chemist.
1 Introduction

For many reasons, the Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) approach to sample preparation has become the method of choice for pesticide residue analysis. The increased speed in sample preparation has been welcomed by many laboratories that analyze thousands of food samples a year. Using a variation of the QuEChERS method, it was possible for two U.S. Environmental Protection Agency (EPA) chemists to analyze 4000 fruit samples for the N-methyl carbamate formetanate HCl (FHCl) over a period of less than 2.5 years. This rate of sample analysis would not have been possible without the QuEChERS approach to sample preparation. In the quest for even shorter sample preparation times and greater sample throughput, a technology was introduced that uses tips instead of tubes for sample cleanup. If MgSO4, primary-secondary amine (PSA) sorbent, and graphitized carbon black (GCB) sorbent in a 15 mL tube provide a sufficient sample cleanup for many matrixes and many pesticide analytes, then MgSO4, PSA sorbent, and GCB sorbent in a dispersive pipet extraction (DPX) tip should also provide a sufficient cleanup. This technique appeared to have the potential to further streamline sample preparation as well as further reduce solvent use. The EPA Analytical Chemistry Branch analyzed 600 additional orange samples collected by the U.S. Department of Agriculture (USDA) Pesticide Data Program (PDP) in an ongoing dietary exposure study of FHCl. The analyses of the 600 samples needed to be completed in the 2 month timeframe by only one chemist. The method used to analyze the 4000 previous samples in the FHCl study was a version .....





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