The determination for the multicomponent residues of organophosphorus pesticides was performed by gas liquid chromatography (GLC) with a flame photometric detector. The GLC under the temperature-programmed operation on the column of 4% OV-101 could provide sufficient information for the screening and the isothermal analyses on the columns of 4% OV-101 and 10% QF-1 could determine individually 38 pesticides.
A modified method for the simultaneous determination of 33 organophosphorus pesticides in agricultural crops was presented. After extraction of samples with acetonitrile, the pesticides are transfered into 20% dichloromethane in benzene, cleaned up by charcoal column chromatography, and then determined simultaneously by the gas liquid chromatography with a flame photometric detector using the column of 4% OV-101 and 10% QF-1. The efficiency of the method was evaluated by analyzing water and 7 kinds of crops fortified with the pesticides. The average recoveries of the pesticides from crops were ranged from 72.0% (fenthion) to 108.0% (tetrachlorvinphos) and those from water were quite satisfactory for all pesticides.
An investigation was carried out on the application of lead-selective ion electrode for the determination of sulphate in food coal-tar dyes with the aim of adopting it as the routine method for product examination. Promising results were obtained. Coal-tar dye solution was titrated with 0.01M lead nitrate solution to form precipitate of lead sulphate and then the presence of an excess of lead was selectively detected with lead electrode. Since lead sulphate was slightly soluble in water which might lead to an indistinct end-point, 50% dioxane solution was chosen as the suitable solvent. Since three xanthene dyes (Food Red No. 3, No. 104 and No. 105) formed precipitate with lead nitrate solution, removal of these dyes was indispensable before titration; and so an aliquot of the filtrate obtained by the filtration of dye acid precipitate formed by the addition of nitric acid was used. Remarkable jumping of electrode potential was observed when the pH was adjusted neutral before titration. Presence of copper and chloride was known to show interference on the titration, but the permissible level of the presence of them in food coal-tar dyes was not so deadly effective as to disturb the reading of the end-point. The methods finally adopted were compared with the contemporarily adopted routine method (turbidimetry) on 8 kinds of food coal-tar dyes, from the results it became clear that the ion electrode titrimetry was superior to turbidimetry both in recovery and repeatability.
Direct determination of trace dimethylamine (DMA) by gaschromatography was investigated. DMA was extracted with water or 1N hydrochloric acid from sample (rubber). The extract was evaporated to driness under acidified condition. The residue was dissolved in isopropanol solution of potassium hydroxide. Methanol and ethanol were not suitable for the solvent, because those gaschromatographic peaks overlaped to that of DMA, and n-propanol and butanol were as same, and these required much more time to release them from the column. iso-Propanol was found to be a most appropriate solvent, because of good separation of DMA from ammonia, methylamine, trimethylamine and ethylamine, and of a short time to analysis. DMA could be measured by gaschromatography with FID and a stainless column packed Chromosorb 103 using nitrogen gas as carrier at 130°C. Recovery Of DMA by the presented method was 96 to 101%, and high reproducibility was obtained. This method is a simple pretreatment procedure and DMA can be determined in the range of 1-20μg/ml.
It has been occasionally observed that white crystalline particles deposited by standing on inside walls of a coffee mill's adaptor or pepper container madefrom imported narra wood. This study was carried out to conform the chemical structures of the particles deposited and ensure the safety from a food hygienic viewpoint. Chopped samples of dried narra wood or containers made from it were steam distilled. The distillate was extracted with petroleum ether to obtain an essential oil. The gas chromatographic preliminary experiments revealed that there were five principal components in the oil. Having been considered that two components of which corresponded to main ones of the particles deposited in the containers, we have attempted isolations of them by further purification of the essential oil. The oil was subjected to an alumina column chromategraphy. By a following silica gel (silver nitrate impregnated) column chromatography, two major fractions were obtained. One of the fractions was purified by sublimation under reduced pressure, and a purified white crystal was obtained. The purified material was analysed by various physical and spectral methods, such as, IR, NMR, GC-MS and others, and identified as β-eudesmol. Another fraction treated in a similar manner was determined as α-eudesmol. Finally, it became clear that principal components of the white particles deposited in the containers were β-eudesmol with a small amount of its α-isomer.
Migration of Dibutyl hydroxy toluene (BHT) to food-simulative solvents from synthetic resins was studied. BHT in synthetic resins such as polypropylene, polyethylene, polystyrene, polyvinyl chloride or polyvinylidene chloride and migrated BHT into food-simulative solvents such as water, 4% acetic acid, 20% ethanol or n-heptane were determined by gas chromatography. With this experiments, the migration of BHT to food-simulative solvents except n-heptane from synthetic resins was not recognized.
The effect of various proteins and amino acids and of the extracts from some foods on the tissue accumulation and the transport of cadmium in the in vitro rat small inte stine was studied. The proteins and amino acids used decreased considerably the accumulation of cadmium in the intestinal tissue. Ovalbumin and glycinin decreased significantly the transport of cadmium. In contrast with such proteins, L-cysteine and L-histidine, which form relatively stable complexes with cadmium, increased the transport of the metal. However, other amino acids, which have a relatively weak affinity for cadmium, had little effect on the transport of the metal. The extracts from soybeans, ivory-shells, and oysters depressed remarkably the accumulation of cadmium in the intestinal tissue. The transport of cadmium considerably decreased by both extracts from soybeans and ivory-shells and, on the contrary, significantly promoted by the oyster extract. These results suggest that the transport of cadmium across the rat small intestine is considerably influenced by the food components such as proteins and amino acids.