2,4-D, dicamba and 4-CPA with auxin-like activity have been intensively used in agriculture, for the control of unwanted broadleaf weeds. An analytical method involving HPLC coupled with UVD was developed for the simultaneous analysis of these three analytes in Chinese cabbage, apple and pepper fruits (representative non-fatty samples) and brown rice and soybean (representative fatty samples) using liquid-liquid partitioning and column cleanup procedures. The residues were confirmed via tandem mass spectrometry (MS/MS) in ion electrospray ionization (ESI) mode. The standard curves were linear over the range of the tested concentrations (0.25-10 microg/mL), as shown by a marked linearity in excess of 0.9999 (r(2) ). The average recoveries (mean, n = 3) ranged from 94.30 to 102.63 in Chinese cabbage, from 94.76 to 108.47 in apple, from 97.52 to 102.27 in pepper, from 76.19 to 101.90 in brown rice, and from 74.60 to 107.39 in soybean. The relative standard deviations (RSDs) were <9% in all tested matrices. The limits of detection and quantitation were 0.006 and 0.02 mg/kg, respectively. Samples purchased from local markets were analyzed to evaluate the applicability of the methods developed herein. The concentration of the 2,4-D residue was measured at 0.102 mg/kg in the soybean sample; however, this level is exactly the same MRL set by the Korea Food and Drug Administration. This developed method deserves full and complete consideration, as it clearly displays the sensitivity, accuracy and precision required for residue analysis of 2,4-D, dicamba and 4-CPA in food crops.

The effects of drying on nine pesticides (chlorfenapyr, clothianidin, diethofencarb, folpet, imidacloprid, indoxacarb, methomyl, methoxyfenozide, and tetraconazole) in chili peppers were studied. The mean concentration factor calculated from weight reduction after drying by water loss was 5.28 for field 1 and 5.41 for field 2 (n = 10). Processing factors for pesticide residues in/on chili peppers after drying were 2.45-5.14 for field 1 and 1.71-4.53 for field 2, indicating that pesticide residues remaining in/on chili peppers were concentrated by usual drying process for pepper powder. The reduction factors reflecting net loss of pesticide residues during drying were 0.50-0.98 for field 1 and 0.44-0.98 for field 2. Drying caused a large reduction (37-49 %) in clothianidin, diethofencarb, imidacloprid, and tetraconazole; moderate reductions (16 and 22 %) in methomyl and methoxyfenozide; while did not affect the levels of chlorfenapyr, folpet, and indoxacarb (using conservative higher reduction factors from the two field trials).

This study was carried out to evaluate the residual characteristics of azoxystrobin in fresh ginseng and calculate its processing factors in processed products, such as dried ginseng, red ginseng and their extracts. Azoxystrobin was sprayed annually onto four-year-old ginseng according to its pre-harvest interval (PHI) for two years. Harvested ginsengs were processed according to the commercially well-qualified conventional methods provided by the Korea Ginseng Corporation. Limits of detection (LODs) of azoxystrobin in fresh ginseng and its processed products were 0.001 and 0.002 mg/kg, respectively. Also limits of quantitation (LOQs) in fresh ginseng and its processed products were 0.003 and 0.007 mg/kg, respectively. Recoveries of the analytical methods in fresh ginseng and its processed products ranged from 69.3 to 114.8%. Highest residue amounts in fresh ginseng and its processed products were 0.025 and 0.118 mg/kg, respectively. Processing factors of the processed products ranged from 1.85 to 3.17 in four-year-old ginseng and from 2.48 to 5.84 five-year-old ginseng.

No abstract

Orysastrobin is a new strobilurin-type fungicide to control leaf and panicle blast and sheath blight in rice. An analytical method was developed to determine the residues of orysastrobin and its two isomers, the main metabolite F001 and the major impurity F033, in hulled rice by the use of high-performance liquid chromatography with ultraviolet photometry (HPLC-UV) and liquid chromatography with tandem mass spectrometry (LC-MS/MS). All compounds were extracted with acetone from hulled rice samples. The extract was diluted with saline water, and an extraction step using dichloromethane/n-hexane partition was used to recover analytes from the aqueous phase. An n-hexane/acetonitrile partition and Florisil column chromatography were employed to further remove interfering coextractives prior to instrumental analysis. An octadecylsilyl column was successfully applied to identify orysastrobin and its isomers in sample extracts. Net recovery rates of orysastrobin, F001, and F033 from fortified samples ranged from 80.6 to 114.8% using HPLC-UV and LC-MS/MS. Relative standard deviations for the analytical methods were all <20%, and the quantification limits of the method were in the 0.002-0.02 mg/kg range. The proposed methods were reproducible and sufficiently accurate to evaluate the terminal residue of orysastrobin and its isomers in rice.