Byeong-Chul Moon

Identification and characterization of matrix components in spinach during QuEChERS sample preparation for pesticide residue analysis by LC–ESI–MS/MS, GC–MS and UPLC-DAD

In this article matrix components in spinach were investigated in detail. The samples were prepared using two QuEChERS (quick, easy, cheap, effective, rugged and safe) methods, AOAC and CEN. Liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS), gas chromatography–mass spectrometry (GC–MS) and ultra performance liquid chromatography-diode array detector (UPLC-DAD), were applied for component identification. The strategies of identification by LC–ESI–MS/MS include accurate mass spectra of the parent ion, comparison with previous literature data and investigation of the mass spectral decomposition pattern. Overall, fourteen components were identified by LC–ESI–MS/MS in each methods of AOAC and CEN, which were phytosteroids, flavonoids, fatty acids and fatty acid amides. Fifty components using AOAC method and fifty-seven components using CEN method were identified in GC–MS by comparing mass data with the National Institute of Standards and Technology (NIST, U.S.) database. The results indicate that the major components of the matrix are terpenoids, fatty acids and fatty acid esters. Moreover, three pigments (neoxanthin, violaxanthin and lutein) in the AOAC method and eight pigments (neoxanthin, violaxanthin, zeaxanthin, lutein, chlorophyll a, chlorophyll b, pheophytin a and beta-carotene) in the CEN method that gave a characteristics peak at 440xa0nm were identified by the UPLC-DAD. According to the sample preparation condition using different amounts of graphitized carbon black (GCB) in this study, the AOAC method had higher matrix component removal efficiency than the CEN method. A better understanding of matrix components would increase the current knowledge for improvement of existing QuEChERS methodology, as well as contribute to new method developments.

Determination of Pyraclostrobin and Trifloxystrobin Residues in Red Pepper Powder Processed from Raw Red Pepper

In this study, we aimed to determine the characteristics of residual pesticides of pyraclostrobin (22.9% emulsifiable concentrate [EC]) and trifloxystrobin (22% suspension concentrate [SC]) in red pepper powder and to determine the processing and reduction factors in red pepper powder during processing. The pesticides were sprayed twice onto red pepper cultivated in an open field at intervals of 10xa0days at the recommended and double doses according to the dilution rate of Korean pre-harvest interval (PHI), and then, the samples were collected. The collected samples were processed by two drying methods, hot air drying in an oven and sunlight drying in a greenhouse without washing, and the samples were analyzed. Recoveries of test pesticides were found to be 70–120% in red pepper and its processed products. Water contents ranged from 79 to 82% in red pepper and from 14 to 16% in dried red pepper. The results of pesticide residue analysis showed that the residual concentration of test pesticides in red pepper dried using the two drying methods was not significantly different. The processing factors of pyraclostrobin and trifloxystrobin in dried red pepper ranged from 4.7 to 5.5 and from 3.7 to 5.4, respectively, indicating that the residual concentration in dried red pepper was increased by drying. However, the reduction factors, which corrected the water content of red pepper, were in the range of 1.0–1.2 and 0.8–1.2, indicating that the amount (ng) of residual pesticides was not different between red pepper and its processed product.

Compensation for matrix effects in GC analysis of pesticides by using cucumber extract

Matrix effects (MEs) can adversely affect quantification in pesticide residue analysis using GC. Analyte protectants (APs) can effectively interact with and mask active sites in the GC system, and are added individually or in combination to sample extracts and calibration solutions to minimize errors related to MEs. Unfortunately, APs cannot sufficiently compensate for MEs in all cases. Plant extracts, containing a broad range of natural compounds with AP properties, can also be used for this purpose. In this study, the applicability of cucumber extract as a natural AP mixture was investigated both alone and in combination with traditional APs. Extracts of two selected difficult matrices (onion and garlic) were prepared according to the citrate-buffered QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure. ME values of 40 representative GC-amenable pesticides were compared when calibrating against standards in pure solvent and in cucumber extract, with and without the addition of APs. Using a GC system with a contaminated inlet liner, the use of a cucumber-based calibration solution decreased MEs remarkably. The combination of APs with cucumber raw extract further decreased MEs, resulting in more than 85% of the tested pesticides showing ≤u200910% ME in onion and ≤u200920% ME in garlic. These results demonstrate that the preparation of calibration standards based on cucumber extracts (with or without the addition of APs) is a very useful and practical approach to compensate for MEs in pesticide residue analysis using QuEChERS and GC-MS/MS. The use of various internal standards is furthermore critically discussed.

Analytical Method for Fenoxasulfone in Agricultural Commodities using High Performance Liquid Chromatography

본 연구에서는 농산물중 fenoxasulfone의 잔류량을 분석하기 위한 분석법을 개발하였다. 농산물에 범용적으로 사용될 분석법을 개발하기 위하여 5가지 대표 농산물(사과, 감자, 고추, 대추, 현미)에 대하여 0.025, 0.25, 1.25 μg/g의 농도 수준으로 회수율 시험을 실시하였다. 시료는 아세톤으로 추출하고 액액분배과정에서 용매별 분배효율을 비교하여 디클로로메탄을 선정하였다. 현미와 대두의 비극성 불순물을 제거하기위해 n-hexane으로 포화된 acetonitrile과 acetonitrile로 포화된 n-hexane이 사용되었다. 추가 정제를 위해 n-hexane/acetone의 조합으로 aminopropyl SPE cartridge 조건을 확립하였다. 기기분석은 HPLC/UVD 240 nm 검출조건에서 acetonitrile과 water을 이동상 조건으로 확립하였다. 개발된 분석법의 검증 결과 회수율은 71.2-89.8%의 범위였으며 상대표준편차(RSD)는 7.2% 이하였다. Fenoxasulfone의 정량한계(LOQ)는 0.025 μg/g이었고 정량곡선의 결정계수(R2)는 1.0000로 양호하였다. 따라서 개발된 분석법은 농산물에서 fenoxasulfone의 잔류량을 분석하기 위한 분석법으로 사용이 가능하리라 판단되었다.본 연구에서는 농산물중 fenoxasulfone의 잔류량을 분석하기 위한 분석법을 개발하였다. 농산물에 범용적으로 사용될 분석법을 개발하기 위하여 5가지 대표 농산물(사과, 감자, 고추, 대추, 현미)에 대하여 0.025, 0.25, 1.25 μg/g의 농도 수준으로 회수율 시험을 실시하였다. 시료는 아세톤으로 추출하고 액액분배과정에서 용매별 분배효율을 비교하여 디클로로메탄을 선정하였다. 현미와 대두의 비극성 불순물을 제거하기위해 n-hexane으로 포화된 acetonitrile과 acetonitrile로 포화된 n-hexane이 사용되었다. 추가 정제를 위해 n-hexane/acetone의 조합으로 aminopropyl SPE cartridge 조건을 확립하였다. 기기분석은 HPLC/UVD 240 nm 검출조건에서 acetonitrile과 water을 이동상 조건으로 확립하였다. 개발된 분석법의 검증 결과 회수율은 71.2-89.8%의 범위였으며 상대표준편차(RSD)는 7.2% 이하였다. Fenoxasulfone의 정량한계(LOQ)는 0.025 μg/g이었고 정량곡선의 결정계수(R2)는 1.0000로 양호하였다. 따라서 개발된 분석법은 농산물에서 fenoxasulfone의 잔류량을 분석하기 위한 분석법으로 사용이 가능하리라 판단되었다.

Herbicide Production (1964 to 2007) for Paddy Field and Aspects of Weed Occurrence

국립농업과학원 농업생물부, 441-707 경기도 수원시 권선구 수인로 150(Department of Agricultural Biology, National Academy of Agricultural Science, RDA., Suwon 441-707, Korea).*연락저자(Corresponding author)：Phone)+82-31-290-0582, Fax)+82-31-290-0508, E-mail)smoh530@hanmail.net(Received June 9, 2011; Examined June 20, 2011; Accepted June 23, 2011)