Qualitative and quantitative analysis of organochlorine insecticide residues were conducted in water, sediment, aquatic plants and animals from 3 freshwater reservoirs. Ninety water samples, 90 sediment samples, 397 aquatic plants samples and 121 aquatic animals samples were collected during March-April and August-September 1989. There were about 14 kinds of aquatic plants, such as water hyacinth, water lettuce, algae and water lilly etc. Aquatic animals are fish, shrimps and snails, but most of them are fish. They are striped snake-head fish, carp and catfish etc. Total samples of 698 were analyzed by using gas chromatographic techniques at Agricultural Toxic Substances Division. The results indicated that 5 kinds of insecticides were found in most samples. They were lindane, heptachlor, aldrin, dieldrin, DDT and derivatives. Dieldrin was detected at higher concentration and found in all samples. The residue level of dieldrin ranged from 0.01-0.12 ppb in water, 0.005-0.036 ppm in sediment, 0.001-0.138 ppm in aquatic plants and 0.001-0.037 ppm in aquatic animals respectively. The accumulation of dieldrin residue in water and aquatic plant samples from all reservoirs are not different but the level of dieldrin residue in sediment samples from Bueng Boraphed is higher than the other 2 reservoris. However the levels of dieldrin residue in sediment, aquatic plant and aquatic animal samples higher than those in water samples respectively.

The study objects were 6 samples of vitamin premixes and 28 samples of food products enriched in vitamins. The methods allow determining the content of vitamins B1, B2, B6, B12, PP, B5, B9, C, B8 in powdery, liquid and solid samples. Sample preparing involved water extraction, filtration, centrifugation. For electrophoresis separation there was used a capillary electrophoresis system Agilent was used with a diode-matrix detector, quartz capillary HPCE stndrd cap Leff/Lgen=475/56 cm. Detection was performed with wavelength of 210, 254, 270 and 292 nm, taking the spectrum 190-400 nm. The optimum conditions for analyzing were experimentally selected. The working buffer having the most effective separating capacity was used (borate buffer in the concentration of 100 mM, pH9.3). The detection limit of vitamins varied from 1.0 to 10.0 mg/kg, the quantitative determination from 4.0 to 30.0 mg/kg. The systematic error was not more than 10%. The results obtained by the developed method and by high effective liquid chromatography highly coincided. The proposed method was characterized by simplicity, high rate and especially suits for determining vitamins in milk and fermented milk products | Объектами исследования служили 6 образцов витаминных премиксов и 28 образцов продуктов питания, обогащенных витаминами. Методика позволяет определять содержание витаминов B1, B2, B6, B12, PP, B5, B9, C, B8 в порошкообразных, жидких или твердых образцах. Пробоподготовка включала экстракцию водой, фильтрование, центрифугирование. Для электрофоретического разделения применяли систему капиллярного электрофореза Agilent с диодно-матричным детектором, кварцевый капилляр HPCE stndrd cap Lэфф/Lобщ=47,5/56 см. Детектирование проводили на волнах длиной 210, 254, 270 и 292 нм, снятие спектра – 190-400 нм. Опытным путем были подобраны оптимальные условия анализа: ввод пробы под давлением 50 мбар в течение 10 с, напряжение (отрицательное): 0 мин – 0 кВ, 60 с – 25 кВ, 90 с – 30 кВ, температура термостата – 25 град. С, продолжительность разделения – 5 мин. Использовался рабочий буфер с наиболее эффективной разделяющей способностью (боратный буфер в концентрации 50 мМ, содержащий натрия додецилсульфат в концентрации 100 мМ, pH 9,3). Предел обнаружения витаминов варьировал от 1,0 до 10,0 мг/кг, количественного определения – от 4,0 до 30,0 мг/кг (для рибофлавина и фолиевой кислоты соответственно). Систематическая ошибка составила не более 10%. Результаты, полученные разработанным методом и методом высокоэффективной жидкостной хроматографии, в высокой степени совпали (коэффициенты корреляции составили 0,9955 для рибофлавина и 0,9985 для пиридоксина гидрохлорида). Предлагаемый метод отличается простотой, высокой скоростью и особенно подходит для определения витаминов в молочных и кисломолочных продуктах