Ott D E, Gunther F A
J Assoc Off Anal Chem. 1983 Jan;66(1):108-10.
A colorimetric technique has been developed which is suitable for use as a field-screening method for detecting above-tolerance levels of parathion on and in citrus fruits. By using this method, a grower should be able to postpone harvesting a crop until parathion residues are below tolerance level, so that the crop is safe to market. The method depends on the reaction of parathion with 4-(p-nitrobenzyl)-pyridine. Parathion is extracted by mixing chopped citrus rind with acetone in a hand-operated homogenizer. The extract is partially cleaned by a partitioning step before final cleanup with a Sep-Pak Florisil cartridge. The colored reaction solution is read at 560 nm by using a portable, rechargeable spectrophotometer. A single test can be completed in about 75 min; the average time per test when several are conducted sequentially is considerably shorter. The analytical system responds readily to less than 5 ppm parathion on or in 1 g navel orange rind, which corresponds to less than 1 ppm in the whole fruit. The present U.S. tolerance for parathion on or in citrus is 1 ppm on a whole fruit basis. Preliminary work indicates that the method should also be suitable for apples.
已开发出一种比色技术，适用于作为一种现场筛选方法，用于检测柑橘类水果表面及内部高于耐受水平的对硫磷。通过使用这种方法，种植者应能够推迟收获作物，直到对硫磷残留量低于耐受水平，从而使作物能够安全上市。该方法依赖于对硫磷与4-（对硝基苄基）吡啶的反应。将切碎的柑橘皮与丙酮在手动匀浆器中混合来提取对硫磷。提取物在通过Sep-Pak弗罗里硅土柱进行最终净化之前，先通过分配步骤进行部分净化。使用便携式可充电分光光度计在560nm处读取显色反应溶液。单个测试大约可在75分钟内完成；依次进行多个测试时，每个测试的平均时间要短得多。该分析系统对1克脐橙皮表面及内部低于5ppm的对硫磷反应灵敏，这相当于整个果实中低于1ppm。美国目前对柑橘类水果表面及内部对硫磷的耐受水平是以整个果实为基础，为1ppm。初步工作表明该方法也应适用于苹果。
