Search results for "pesticide residues"

Determination of organochlorine pesticide residues in honey from the central zone of Portugal and the Valencian community of Spain

2004

In this study nine organochlorine pesticide residues ([alpha]-, [beta]-, and [gamma]-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), aldrin, p,p'-DDE, p,p'-DDD, o,p'-DDT, and p,p'-DDT) in forty nine samples of honey collected from markets of Portugal and Spain during 2001 and 2002, respectively, were evaluated. For this evaluation, three analytical procedures were studied. The analytical procedure, based on LLE extraction with ethyl acetate followed by gas chromatography-electron-capture detection (GC-ECD) for quantification, and mass spectrometry (GC-MS) for confirmation, has been selected. Recoveries of spiked samples ranged from 68%, for [beta]-HCH, and 126% for p,p'-DDT, for forti…

Evaluation by HPLC-UV of Polar Pesticides in Rice Fields

1999

Comparison of liquid chromatography using triple quadrupole and quadrupole ion trap mass analyzers to determine pesticide residues in oranges.

2005

Liquid chromatography-triple quadrupole/mass spectrometry (LC-TQ/MS) and liquid chromatography-quadrupole ion trap/mass spectrometry (LC-QIT/MS) for determining bupirimate, hexaflumuron, tebufenpyrad, buprofezin, pyriproxyfen, and fluvalinate in fruits have been compared. The differences in the mass spectra obtained by triple and ion trap quadrupoles are discussed, showing how both of them provide interesting features. The evaluation of the two instruments was carried out by ethyl acetate extraction of oranges spiked with the studied pesticides at LOQ and 10 times the LOQ. Results obtained by LC-TQ/MS correlated well with those obtained by LC-QIT/MS. Recoveries were 70-94% by LC-TQ/MS and 7…

Retrospective screening of pesticide metabolites in ambient air using liquid chromatography coupled to high-resolution mass spectrometry

2015

A new methodology for the retrospective screening of pesticide metabolites in ambient air was developed, using liquid chromatography coupled to Orbitrap high-resolution mass spectrometry (UHPLC-HRMS), including two systematic workflows (i) post-run target screening (suspect screening) and (ii) non-target screening. An accurate-mass database was built and used for the post-run screening analysis. The database contained 240 pesticide metabolites found in different matrixes such as air, soil, water, plants, animals and humans. For non-target analysis, a "fragmentation-degradation" relationship strategy was selected. The proposed methodology was applied to 31 air samples (PM10) collected in the…

Analytical Methods for Pesticide Residue Determination in Bee Products

2002

Monitoring pesticide residues in honey, wax, and bees helps to assess the potential risk of these products to consumer health and gives information on the pesticide treatments that have been used on the field crops surrounding the hives. The present review seeks to discuss the basic principles and recent developments in pesticide analysis in bee products and their application in monitoring programs. Consideration is given to extraction, cleanup, chromatographic separation, and detection techniques.

Aldicarb residues in citrus soil, leaves and fruits

1990

Aldicarb was applied to the soil of Late Valencia orange field plots. A comparative study between four analytical methods is reported, the NPD-gas chromatography method being the best choice. The work also reports the study of accumulation and persistence of aldicarb and its biologically active metabolites in the soil, leaves and fruits (rind and pulp, separately). Residue content, at the ppb level, was found in the order leaves much greater than rind greater than pulp. Carbamate was found to accumulate mainly in its oxidized forms. Residues had reached a maximum level in about 90 days after application.

Liquid chromatography/atmospheric pressure chemical ionization-mass spectrometric analysis of benzoylurea insecticides in citrus fruits.

2000

A liquid chromatography (LC) method for the quantitative determination of three benzoylurea insecticide residues (diflubenzuron, flufenoxuron and hexaflumuron) in citrus fruits is described. Residues were successfully separated on a C18 column by methanol/water gradient elution. Detection was by negative-ion, selected-ion monitoring atmospheric pressure chemical ionization-mass spectrometry (APCI-MS); the main ions were [M - H]-, and the secondary fragment ions were [M - H - HF]-. Useful confirmatory information can thus be obtained at low extraction voltages from losses of HF. Detection limits for standard solutions were 10 fg injected and good linearity and reproducibility were obtained. …

Pesticide residues in oranges from Valencia (Spain)

2001

One hundred and fifty citrus samples from an agricultural co-operative of the Valencian Community (Spain) were analysed for pre- and post-harvest pesticide residues using high performance liquid chromatography and gas chromatography. Among the residues from post-harvest treatments, imazalil was detected in 112 (74.7%) samples at a mean level of 1.2 mg/kg, thiabendazole in 21 (14.0%) samples at a mean level of 0.47 mg/kg and carbendazim in 5 (3.3%) samples at a mean level of 1.05 mg/kg. Among the residues from pre-harvest treatment, dicofol was detected in 28 (18.7%) samples at a mean level of .28 mg/kg chlorpyriphos in 19 (12.7% samples at a mean level of 0.16 mg/kg and endosulfan in 11 (7.…

Impact of maize mucilage on atrazine mineralization andatzC abundance

2005

Soil was amended with maize mucilage, a major rhizodeposit, to study its role on the number of culturable soil micro-organisms, the structure of the bacterial community, atrazine mineralization and atzC abundance. The maximal percentage of atrazine mineralization was lower for mucilage-amended than for water-amended soil. Total culturable soil bacteria and 16S rDNA copy number, measured by RT-PCR, presented similar values and were not significantly (P < 0.05) different among treatments. Mucilage applied at a rate of 70 mu g C g(-1) dry soil day(-1) over two weeks did not modify the abundance of the total soil microflora. Global structure of soil bacterial communities revealed by RISA analys…

Site-heterologous haptens and competitive monoclonal antibody-based immunoassays for pyrimethanil residue analysis in foodstuffs

2015

Pyrimethanil is a widely used post-harvest fungicide whose residues are commonly found in fruits and vegetables. We herein report the synthesis of two new functionalized derivatives of pyrimethanil carrying an equivalent spacer arm at different positions of the molecule. The influence of the linker tethering site on the affinity of monoclonal antibodies was shown. Moreover, the development of competitive immunoassays in different formats and with high sensitivity to the target analyte - IC50 values below 0.3μg/L - is described. Optimized assays were characterized by the determination of the limit of quantification, trueness, and precision using water-diluted QuEChERS extracts of fruits and …