Gas-liquid chromatographic-mass spectrometric confirmation of endosulfan and endosulfan sulfate in apples and carrots

A gas-liquid chromatography-mass spectrometric (GLC-MS) procedure is described for the confirmation of endosulfan I, endosulfan II, and endosulfan sulfate in apples and carrots. After extraction, cleanup, and determination by electron capture gas-liquid chromatography using current AOAC methodology, residues are confirmed by GLC-MS. The chemical ionization (CI) mode is used with methane as a reagent gas. Each residue is confirmed by a scan of only 4 regions of its mass spectrum rather than the full mass range. The 4 mass regions for the 2 endosulfan isomers are 274-280, 340-346, 368-374, and 404-412 atomic mass units (amu). For endosulfan sulfate, the mass regions are 286-294, 322-330, 384-392, and 420-428 amu. Four ions and their chlorine isotopic distributions are detected for each compound by this scanning technique. This method was developed by using carrots and apples to which had been added 0.1 ppm (50% of the current legal tolerance on carrots) of each of the 3 pesticides. The gas chromatographic retention times and the mass spectra of the 4 mass regions specified for the 3 pesticides were compared to those of reference standards injected under identical GLC-MS conditions and were used as the basis for confirming identity of the 3 compounds.

Improved cleanup technique for estimation of endosulfan residues from fish tissues under tropical conditions

A new solvent system 1% and 2% acetone in hexane, was developed for chromatography on partially inactivated Florisil to facilitate the separation of isomers of endosulfan and its metabolites from fish tissues under tropical conditions. By using the colorimetric method of Maitlen et al. (1963), the minimum detectable limit for each isomer of endosulfan in various fish tissues is 5 micro g. With this solvent system, the 2 isomers present in the technical material can be separated, so their toxicity to fish can be assessed separately.

Gas-liquid chromatographic studies on residues of endosulfan on chilli fruits

Studies on the residues of endosulfan were undertaken by GLC so as observe the dissipation of endosulfan and its isomers on green fruits of chilli, Capsicum annuum Linn. and also to know the effect of washing the fruits on the residues. The pattern of dissipation of endosulfan was conventional showing half-life less than two days. The waiting periods worked out were 5 and 7 days after protecting the crop with four sprays of 0.03 and 0.08% endosulfan respectively. The dissipation of alpha isomer was found faster than that of beta isomer. Washing of fruits from treated crop was found quite effective in reducing the level of residues on the fruits.

Relative toxicity of endosulfan, its isomers, and formulated products to the freshwater fish Labeo rohita

The relative toxicity of endosulfan, its isomers, and formulated products to the freshwater fish Labeo rohita was tested. The 96-h LC50 values showed that toxicity decreased in the following order: isomer A, 35% emulsifiable concentrate, technical endosulfan, 4% dust, and isomer B. The principal method of detoxification was by formation of endosulfan ether in the liver, Endosulfant, at both sublethal and lethal doses, enhanced oxygen consumption in L. rohita. Histological studies showed minor changes in the liver only.

Distribution of endosulfan in plasma and brain after repeated oral administration to rats

Rats were fed endosulfan (5 or 10 mg/kg) containing alpha- and beta-isomers in the ratio of 2:1, daily for 15 days. The distribution pattern of endosulfan, its isomers and metabolite, endosulfan sulfate, was estimated in the plasma and brain of the rats. On day 16, the alpha-isomer in rats receiving 5 mg/kg was highest in the cerebrum (3.76 microgram/g) followed by the remaining part of the brain (2.66 microgram/g), and the cerebellum (2.04 microgram/g). The concentration of the beta-isomer was 0.06 microgram/g in the cerebrum and 0.02 microgram/g in the cerebellum; no beta-isomer was detected in the remaining part of the brain. The plasma concentration of alpha- and beta-isomers was 2.26 and 0.46 microgram/ml, respectively. No metabolite other than endosulfan sulfate was detected in plasma. No significant changes in brain tissue were observed in any of the groups under treatment. On day 30 (15 days after the last treatment), the concentration in plasma declined more rapidly than that in the brain tissue. At a higher dose (10 mg/kg), the distribution pattern of isomers and its metabolite, endosulfan sulfate, followed almost the same trend except that the concentration was higher than in rats receiving lower doses.

Collaborative study of the determination of endosulfan, endosulfan sulfate, tetrasul, and tetradifon residues in fresh fruits and vegetables

A method for the determination of endosulfan I, endosulfan II, endosulfan sulfate, tetrasul, and tetradifon residues in fresh fruits and vegetables was studied collaboratively. The method consists of extraction of the product with acetonitrile, ether and elution from a Florisil column with mixtures of hexane, methylene chloride, and acetonitrile, and determination of the residues by electron capture gas-liquid chromatography. This method was studied by 8 collaborators, using apples and cucumbers as the samples. Each sample was spiked with 2 levels of each pesticide. The average per cent recoveries for apples and cucumbers, respectively were as follows: endosulfan I, 103.6 and 101.5; endosulfan II, 102.9 and 100.0; endosulfan sulfate, 100.9 and 92.9; tetrasul, 98.8 and 102.2; and tetradifon, 106.4 and 101.9. The method has been adopted as official first action.

Improved cleanup technique for the estimation of endosulfan and endrin residues

An improved cleanup technique has been developed for the extraction of endosulfan and endrin from crops. The technique involves the use of Nuchar C-190N as adsorbent and a mixture of n-hexane and acetone (4+1) as the eluting solvent. The mean percentage recoveries of endosulfan (I and II) and endrin from plant tissue extracts fortified at levels of 0.5-2.0 ppm varied from 86 to 102 and 97 to 100, respectively.