An improved extraction method of rapeseed oil sample preparation for the subsequent determination in it of azole class fungicides by gas chromatography

Abstract

a b s t r a c tThe distribution of 19 azole class pesticides in hexane/aqueous-organic mixtures systems and rapeseed oil (or oil solution in hexane)/organic solvents has been studied at 20 ± 1°C. The distribution constants (P) and coefficients (D) between hydrocarbon and polar phase are calculated. It is found that all the studied pesticides are hydrophobic, i.e., in hexane-water system log P ) 0. Replacement of water by organic solvents results in sharp log P falling, and their values become negative. It is revealed that solutions of strong inorganic acids in anhydrous acetonitrile extract azole class pesticides from hexane and vegetable oils most fully and selectively. In particular, the acidification of acetonitrile causes a drop of D values in 50-2000 times for the majority of the studied pesticides. This phenomenon was used for the development of the improved technique for the quantitative analysis of a widely used azole class pesticides, which can be presented at trace levels in rapeseed oil. The proposed methodology is based on dissociation extraction (DE) of azoles using perchloric acid in anhydrous acetonitrile, with following clean-up of acetonitrile extract from organic impurities by hexane and aqueous solution of dipotassium hydrogen orthophosphate, and final GC-ECD (gas chromatography with electron capture detection) determination of azole fungicides. The values of obtained recoveries were between 85% and 115% with RSD values below 10%. The obtained limits of quantitation, ranged from 3.0 to 300 lg kg À1 , are below the maximum residue levels (MRLs) set by the European Union for the majority of pesticides. The developed method was successfully applied to different rapeseed oil samples.

Transfer Assessment of Carbendazim Residues from Rape Flowers to Apicultural Products

“…However, rapes easily suffered from diseases damage during whole growth period, which are significant factors threatening the rapeseed yield [ 5 ]. In agricultural practice for rape fields, fungicides as certain category of pesticides are always used for protecting rapes [ 6 ].…”

Transfer and Metabolism of Triadimefon Residues from Rape Flowers to Apicultural Products

“…In addition, rape is the main nectar source for bees in the region. However, rape is susceptible to insect pests especially fungal diseases during its entire growth period, which can significantly impact yield [ 6 ]. While spraying with insecticides and fungicides protects the crop [ 7 ], it conversely leads to the contamination of apicultural products.…”

Degradation of triadimefon and residue levels of metabolite triadimenol: tracing rapeseed from harvesting and storage to household oil processing

“…Rape plants are widely planted in the Yangtze River Basin. However, rape plants are susceptible to fungal diseases during their entire growth period, which is one of the factors threatening the rapeseed yield . In agricultural practice, fungicides are always used to protect rape plants .…”

“…However, rape plants are susceptible to fungal diseases during their entire growth period, which is one of the factors threatening the rapeseed yield. 6 In agricultural practice, fungicides are always used to protect rape plants. 7 As a common chloroarene fungicide, triadimefon and its metabolite triadimenol have been simultaneously detected in edible vegetable oil.…”