[Atomic absorption determination of heavy metals in the milk and meat from several regions of Bulgaria].

By AAS after wet digestion of the samples the results were 20% higher (for milk) and 41% higher (for meat) in comparison with dry coshing. Cow and ewe milk and pork, beef, and mutton were sampled in six regions of the country and were studied with regard to residual amounts of four trace elements. Highest appeared to be the content of zinc, and lowest--the content of cadmium.

[Pesticide residues in honey].

Investigated were a total of 40 samples of flower honey from seven regions of the country (the districts of Mihailovgrad, Gorna Oryahovitsa, Turgovishte, Plovdiv, Pazarjik, Sliven, and Byala Slatina). In 20 per cent of the samples there were traces of the phosphororganic pesticides trichlorfon and DDVF, and in 32 per cent - traces of chlororganic insecticides - HChCH and DDE. The studies made use of the agar diffusion, thin layer chromatography, and gas chromatography methods.

[Determination of benzoic acid and its salts in food products of animal origin].

A modification of the method for determining benzoic acid and its salts by water-vapour distillation and extraction of the biological material conservant and its titrimetrical determination is proposed. The thin layer chromatography method (TLC) is used parallelly for the identification of the conservant. The advantage of the proposed method consists in that the same distiller is used for quantitative titrimetrical determination and for TLC assessment.

[Determination of sorbic acid, its salts and salicylic acid in food products of animal origin].

A foreign method for quantitative assay of sorbic acid and natrium sorbate in food stuff of plant origin was applied by the authors for food stuffs of animal origin. The conservant of the food stuff was isolated by water vapour distillation. Sorbic acid and natrium sorbate assay was performed on part of the distillate colorimetrically at wave length lambda--532 nm.

[Cyclophosphamide content in the meat and milk after a single application to sheep].

Investigated were two groups of 10 Merino sheep each. The test group were given orally cyclophosphamide, singly, at the rate of 25 mg/kg, while the controls of the second group were not treated but were kept under the same conditions. Both milk and meat of the two groups were investigated by thin layer chromatography and gas chromatography on the 1st, 4th, 9th, 14th, 23rd, and 30th day following the introduction of cyclophosphamide.

[Organochlorine pesticide residues in the eggs from poultry raising farms].

A gas chromatography method was employed to investigate the residual amounts of chlororganic pesticides in a total of 37 average batch samples of eggs taken from 18 large poultry farms. More than two thirds (from 70.3 to 75.

[Thin-layer chromatographic determination of coumarin derivatives].

Described is a thin-layer chromatography method for the demonstration and identification of the cumarin derivatives cumaphos and warfarin. Tested were five solvents and six developers. Best results were obtained by means of Silica gel plates, the toluol-aceton solvent (85:15), and the developer of a diazosalt 0.

[Determination of the concentration of copper, lead, cadmium and zinc in milk by atomic absorption spectrophotometry].

Developed was an atom-absorption method for determining microconcentrations of copper, lead, cadmium, and zink in milk originating from various regions of this country. The study was carried out by means of an atom-absorption spectrophotometer AA-5. Established were the optimal conditions for determining the trace elements reaching the following values of susceptibility: for copper--0.

[Thin-layer chromatographic demonstration of the herbicide zenkor].

Established were the thin-layer chromatography conditions for the demonstration of the herbicide Zenkor as a pure substance and a preparation. Comparative experiments were carried out applying Thomson and Stanley's thin-layer chromatography conditions and the authors' personal ones. Most adequate proved to be the following conditions: sorbent-Kieselgel 60F 254 (Merck); solvent -- chloroform: 1,4-dioxan (9:1); developer -- ultraviolet light (authors' technique).