Ok-Ja Choi

Simultaneous multiresidue analysis of 41 pesticide residues in cooked foodstuff using QuEChERS: Comparison with classical method

The principal objective of this study was to develop a simple multiresidue method involving a quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method for the identification and quantification of 41 pesticide residues in cooked foodstuffs including cooked potatoes, radishes, and rice using GC-μECD. The analytes were subsequently confirmed via GC-MS. The results were then compared using the classical method established by the KFDA. The quantitation of individual pesticides was based on matrix-matched calibration curves with a correlation coefficient in excess of 0.993 for the 41 pesticides selected herein. Using QuEChERS, the mean recoveries ranged between 68.6 and 130.0% for the majority of the tested pesticides; however, the classical method exhibited low recoveries for dichlofluanid, tetraconazole, oxadixyl, fenbuconazloe, and paclobutrazol. After QuEChERS, the LODs and LOQs ranged between 0.004 and 0.3μg/kg and 0.0125 and 1.0μg/kg, respectively. The proposed method was applied successfully to determine the residue levels in cooked foodstuffs, and none of the samples contained detectable amounts of pesticide residues.

Detection of pyridaben residue levels in hot pepper fruit and leaves by liquid chromatography-tandem mass spectrometry: effect of household processes.

Following quick, easy, cheap, effective, rugged and safe (QuEChERS) and LC/MS/MS analysis, pyridaben residual levels were determined in unprocessed and processed hot pepper fruit and leaves. The linearities were satisfactory with determination coefficients (R(2)) in excess of 0.995 in processed and unprocessed pepper fruit and leaves. Recoveries at various concentrations were 79.9-105.1% with relative standard deviations ≤15%. The limits of quantitation of 0.003-0.012 mg/kg were very low compared with the maximum residue limits (2-5 mg/kg) set by the Ministry of Food and Drug Safety, Republic of Korea. The effects of various household processes, including washing, blanching, frying and drying under different conditions (water volume, blanching time and temperature) on residual concentrations were evaluated. Both washing and blanching (in combination with high water volume and time factor) significantly reduced residue levels in hot pepper fruit and leaves compared with other processes. In sum, the developed method was satisfactory and could be used to accurately detect residues in unprocessed and processed pepper fruit and leaves. It is recommended that pepper fruit/leaves be blanched after washing before being consumed to protect consumers from the negative health effects of detected pesticide residues.

Analysis of 10 systemic pesticide residues in various baby foods using liquid chromatography-tandem mass spectrometry.

Ten systemic pesticides, comprising methomyl, thiamethoxam, acetamiprid, carbofuran, fosthiazate, metalaxyl, azoxystrobin, diethofencarb, propiconazole, and difenoconazole, were detected in 13 baby foods (cereals, boiled potatoes, fruit and milk) using QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) for sample preparation and liquid chromatography tandem mass spectrometry for analysis. The matrix-matched calibration curves showed good linearity with determination coefficients (R(2) ) >0.992. The limits of detection and quantitation were 0.0015-0.003 and 0.005-0.01 mg/kg, respectively. The mean recoveries of three different concentrations ranged from 69.2 to 127.1% with relative standard deviations <20%. The method was successfully applied to 13 actual samples collected from a local market, and none of the samples were found to contain pesticide residues. This method is suitable for the identification and quantification of systemic pesticides with matrix-matched standards in various baby foods.

Separation of multi-class pesticide residues from fatty food matrices prior to analysis using gas chromatography

Separation of pesticides and other chemical contaminants from fatty food matrices prior to subsequent steps in the analytical process remains a challenging issue, and much effort has been invested to further enhance this method. The aim of the present study was to develop a simple multi-residue method involving a quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method for the identification and quantification of 41 pesticide residues in cooked fatty food matrices, including heated soybean oil, roasted sesame, and boiled soybean using gas chromatography-micro/electron capture detector (GC-μECD). The analytes were subsequently confirmed via GC-mass spectrometry (MS). The responses of analytes were linear with excellent correlation coefficients (r2) ranging from 0.993 to 1.000 (calculated from absolute peak areas). For the majority of the tested pesticides, the mean recoveries ranged from 68.5 and 121.4% with relative standard deviations ranging from 0.4 to 18.7%. Instrument limits of detection and quantification ranged from 0.004 to 0.30 μg/kg and 0.0125 to 1.00 μg/kg, respectively. The developed method presented in this study was applied successfully to determine pesticide residue levels in cooked fatty food matrices. None of the samples contained detectable amounts of pesticide residues.