%0 Journal Article %T Improved Analytical Methods for Determination of Residues of Nitrapyrin and 6-Chloropicolinic Acid in Different Crop Matrices by Liquid Chromatography-Tandem Mass Spectrometry %A Fabiola G. Zuno-Floriano %A Riza L. Reyes-Punongbayan %A Matt J. Hengel %J Journal of Agricultural Chemistry and Environment %P 263-281 %@ 2325-744X %D 2024 %I Scientific Research Publishing %R 10.4236/jacen.2024.133018 %X Novel analytical methods were developed for the determination of nitrapyrin and 6-chloropicolinic acid (6-CPA) residues in agricultural products. Nitrapyrin was extracted with hexane: toluene (1:1, v/v) and 6-CPA with 0.1 N sodium hydroxide (NaOH). For nitrapyrin, samples were cleaned with silica solid phase extraction (SPE) and for 6-CPA with C18 or carbon SPE. Analysis was performed by liquid chromatography-tandem mass spectroscopy (LC-MS/MS) with external calibration (0.010 to 0.0010 µg∙mL−1 for nitrapyrin and 0.0050 to 0.00025 µg∙mL−1 for 6-CPA). Recoveries for nitrapyrin and 6-CPA were 68% - 102% and 66% - 90%, respectively. Nitrapyrin was detected in celery and onion (<0.020 to 0.15 µg∙g−1) and 6-CPA in onion, mustard greens and lettuce (<0.050 - 0.19 µg∙g−1). Lower level method validation (LLMV) for nitrapyrin and 6-CPA was 0.020 µg∙g−1 and 0.050 µg∙g−1, respectively. The methods presented in this study are robust and were utilized for the registration of nitrapyrin on agricultural commodities in the United States. %K Herbicide %K Agricultural Products %K External Calibration %K LC-MS/MS %K Registration %U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=134485