M. I. R. Mamun

Development and validation of a multiresidue method for determination of 82 pesticides in water using GC

Several methods used for the multiresidue analysis of pesticides from the environment and drinking water have been reported. However, most of these reports dealt with a small number of targeted pesticides or some special groups. A method that is simple, faster, and more cost-effective than the environmental protection agency (EPA) method has been developed for the analysis of 82 frequently used pesticides in water samples obtained from Yeongsan and Sumjin rivers, as well as rice fields located in various locations around the two rivers. The samples were extracted by dichloromethane, and the pesticides were analyzed using a GC-electron capture detector (ECD), followed by confirmation with GC-MS. Recoveries were found to be between 82 and 120.1% for most of the tested pesticides, which were in agreement with the standard values dictated by the EPA. The method was potentially applied to 66 water samples for human consumption and 90 water samples from the rice fields and irrigation ditches that were collected from June to September 2007. Oxadiazon, butachlor, and alachlor were detected in some of the river water samples collected in June, iprobenfos (IBP) was detected in samples collected in August, and no pesticide was detected in September. On the other hand, chlorpyrifos-methyl, IBP, hexaconazole, diazinon, oxadiazon, butachlor, and isoprothiolane were detected at relatively high concentrations in 48 rice paddy field water samples collected between June and September 2007. Alachlor in one sample and procymidone in some of the rice paddy field water samples were also detected in trace amounts. The results were consistent with the temporal pattern of pesticide application in Korean rice fields.

Inert matrix and Na4EDTA improve the supercritical fluid extraction efficiency of fluoroquinolones for HPLC determination in pig tissues.

A supercritical fluid extraction method combined with high-performance liquid chromatography-fluorescence detection was developed for the determination of enrofloxacin, danofloxacin, and ciprofloxacin in pig muscle, lung, and kidney samples. The optimal SFE conditions were 80 degrees C, 300 kg/cm(2), 30% methanol for 40 min as a dynamic extraction time, in addition to 0.2g Na(4)EDTA and 7.0 g sea sand in the extraction vessel. The use of Na(4)EDTA and sea sand on SFE extraction resulted in improvement of the recoveries of ciprofloxacin, a polar and hydrophilic compound, as well as enrofloxacin and danofloxacin. Overall, the recoveries ranged from 86.7 to 113.1% using the Na(4)EDTA/sea sand-assisted SFE extraction method. The Na(4)EDTA/sea sand-assisted SFE-HPLC-FLD validated method was successfully carried out in pig tissues, and proved to be specific, sensitive, reliable, and accurate. The method was also applied satisfactorily for accurate quantitative residue analysis in incurred pig tissues.

Residual pattern of fenhexamid on pepper fruits grown under greenhouse conditions using HPLC and confirmation via tandem mass spectrometry

Fenhexamid (25%, SC) was sprayed on pepper fruits grown under greenhouse conditions at the recommended dose rate of 20g/20L water. Fruit samples were collected randomly at 0 (2h after application), 1, 2, 4, 6, 8, 11, and 14days post-application. The samples were extracted with acetonitrile, partitioned with water, passed through a cleanup procedure, and analysed via HPLC. Residues were confirmed via LC-tandem mass spectrometry (LC-MS/MS) in positive-ion electrospray ionisation (ESI+) mode. The rate of disappearance of fenhexamid on pepper fruits was described as first-order kinetics (r(2)=0.992) with a half-life of 4.7-day. Based on the pattern of decline of the fungicide residues in relation to the estimated maximum residue limits (MRL=5mg/kg), a safety pre-harvest interval of 1day is suggested for peppers at the recommended dosage.

Identification of volatile organic compounds generated from healthy and infected powdered chili using solvent-free solid injection coupled with GC/MS: Application to adulteration

To investigate adulteration in commercial chili powder, the volatile organic compounds of healthy and infected powdered chili pepper were characterized using a solvent-free solid injector (SFSI) coupled with gas chromatography/mass spectrometry (GC/MS). Except for one compound (capillary compound for blank), 43 compounds were identified in healthy and infected chili powder. Specifically, 31, 36, and 41 compounds were identified in healthy, medium-infected, and severely infected chili powder. Among these compounds, acetic acid (13.77%), propanal (2.477%), N-methylpyrrole (1.986%), and 2-methyl-propanal (1.768%) were leading volatiles in the healthy chili powder. In contrast, infected chili powder contained 9,12-octadecadienoic acid, ethyl ester (15.984%), acetic acid (11.249%), hexadecanoic acid, methyl ester (3.3%), N-methylpyrrole (3.221%), and 2-furanmethanol (2.629%) as major compounds. Trimethylamine and isosorbide were detected in both medium and severely infected chili, but not in healthy chili. This means that these compounds could be used as biomarkers to distinguish between healthy and infected chili. The proposed technique was applied to 12 commercial chili powders, and trimethylamine and isosorbide were detected in six samples. These results suggest that a contaminated chili that was added to a healthy one could be successfully identified by a combination of the SFSI and GC/MS.

Development of a multiresidue method for the determination of multiclass pesticides in soil using GC

The principal objective of the present study was to develop a multiresidue analytical method for 62 pesticides in a soil matrix. Soil samples were fortified with known quantities of pesticides at two different concentration levels (0.1 and 0.01 microg/g) and the analytes were extracted via a liquid-solid extraction method. The pesticides were separated on an HP5 capillary column and were detected by gas chromatography coupled to an electron capture detector (GC-ECD). The method was validated, considering its good linearities (r(2) = 0.978-0.999), specificity and recovery characteristics. Recoveries were found between 70.3 and 113.4% for all pesticides except edifenphos (67.5%) and dichlobenil (69.5%) spiked at a 0.1 microg/mL concentration level and 74.5-117% except ethalfluralin (63.3%) and dichlobenil (51.9%) spiked at a concentration of 0.01 microg/mL. The developed method could be utilized as a simple and cost-effective method for the routine analysis of 62 pesticides in soil samples.

Development and validation of a multiresidue method for determination of 37 pesticides in soil using GC‐NPD

In this study, a multiresidue analytical method for the detection of 37 pesticides in a soil matrix was developed and validated. The soil sample was fortified with a known quantity of pesticides at two different concentration levels (0.1 and 0.01 µg/g) and the analytes were extracted via a liquid-solid extraction method. The pesticides were separated on an HP5 capillary column and were analyzed with a gas chromatograph coupled to a nitrogen-phosphorous detector (GC-NPD). Method validation was accomplished with good linearity (r(2) = 0.994-0.999) within a considerable range of concentrations. Satisfactory recoveries (70.5-110.4%) were obtained with 32 pesticides at both spiking concentration levels, whereas five pesticides-dimepiperate, buprofezin, prometryn, pirimicarb, and fludioxonil-were recovered at relatively low levels (43.6-61.8%). The applicability of the method was demonstrated by analyzing field samples collected from 24 different sites around Yeongsan and Sumjin rivers in the Republic of Korea. No residues of the selected pesticides were detected in any of the samples. The developed method could be employed as a simple and cost-effective method for the routine detection and analysis of 37 pesticides in soil samples.

Organochlorine pesticide residues in poultry meats of Bangladesh

Forty poultry meat samples from four large companies were analyzed for the presence of organochlorine pesticides. Homogenized samples were mixed with silica sand and anhydrous sodium sulfate, and extracted with ethyl acetate followed by n-hexane: MTBE. Clean up of samples were done by silica sulphuric acid and analyzed by GC-ECD, and confirmed by GCMS. The limit of detection (LOD) and limit of quantification (LOQ) were 0.5, 0.5 and 0.7, and 2.5, 2.5 and 3.5 ng/g, respectively. The calibration curves were linear and the correlation coefficients (r 2 ) were 0.991, 0.992 and 0.997 for DDE, DDD and DDT, respectively and the recoveries for them were 76%, 78% and 80%. DDT and its metabolites, DDE and DDD were detected in 28 (70%), out of 40 samples and ranged 0.039-0.769 mg/kg.

Bufferized Solvent Extraction and HPLC Fluorometric Detection Method for Sarafloxacin in Pig and Chicken Muscles

In this study, a method for the detection of sarafloxacin in pig and chicken muscles was developed using HPLC-FLD as a regulatory residue technique. Good extraction efficiency was achieved using a mixture of 1% orthophosphoric acid-0.2 m MgCl(2) in water and acetonitrile as an extraction solvent, and n-hexane partitioning and centrifugation for cleanup was used in the absence of dehydration. Specificity, linearity, detection and quantification limits, recovery, accuracy and precision were all validated, and all results were sufficient for the SARA regulatory residue method in pig and chicken muscles. The method developed and described herein was not only simple but also reliable, and was applied to market samples to determine their residue contents.

Characterization of secondary metabolite compounds correlated with the seasons in Artemisia princeps var. orientalis (Pamp.) H. Hara leaves using direct sample injection and gas chromatography-mass spectrometry: contribution to phytotoxicity

Leaves from a natural population of Artemisia princeps var. orientalis (Pamp.) H. Hara were collected monthly from April through October and characterized for composition of secondary metabolite compounds and their phytotoxic effects on seed germination and seedling growth of Achyranthes japonica and Lactuca sativa. The compounds were identified using gas chromatography/mass spectrometry (GC/MS) coupled with a solvent-free solid injector (SFSI). GC/MS analyses of all samples revealed qualitative variability in the composition of secondary metabolites. The greatest number of compounds was identified in July (56) followed by September (30) and April (24), and the lowest number was found in June (2) and August (2). Among 92 compounds, the major compounds were various terpenes (23) (mono-, sesqui, di-, and tri-terpenes) followed by heterocyclic compounds (18) and hydrocarbons (14). The higher the concentration of the secondary metabolites, the lower the seed germination and seedling growth of A. japonica and L. sativa. Plant samples collected in July and August were most detrimental. Taken together, variability in the secondary metabolites compounds of A. princeps var. orientalis was verified during different seasons, and the compounds were successfully identified by a combination of SFSI and GC/MS. Notably, the antimicrobial and antioxidative effects were inconsistent throughout the various seasons.

Simultaneous multiresidue determination of 48 pesticides in Yeongsan and Sumjin River water using GC-NPD and confirmation via GC-MS

In a continuation of our earlier work, a multiresidual analytical method using 48 frequently used neutral pesticides in a water matrix was developed and validated in this study. The samples were extracted with dichloromethane and the pesticides were analyzed via GC-NPD followed by confirmation with GC-MS. Good linearity was detected over a concentration range of 0.01-1.0 microg/mL with correlation coefficients (r(2) ) in excess of 0.982. The recoveries were measured between 70.7 and 111.4% for the majority of the targeted pesticides with relative standard deviations (RSDs) of less than 20%. The LODs and LOQs were in ranges of 0.1-2 and 0.33-6.6 microg/L, respectively. A total of 66 water samples were collected from different locations in Yeongsan and the Sumjin River, Republic of Korea, and were analyzed in accordance with the developed method. None of the water samples were determined to contain any of the targeted pesticides. The method has been shown to be simpler, faster, and more cost-effective than the method established by the Environmental Protection Agency (EPA).