INVESTIGATION OF DIAZINON DEGRADATION IN MODEL SOLUTIONS USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Aim of our war was to investigate the degradation of diazinon in the model mixture in comparison with the experimental preparation. Methyl alcohol was used as a basis for the manufacture of diazinon drops and the model mixture. The concentration of diazinon was determined by reversed-phase high performance liquid chromatography on the third, fourteenth and twenty-first day after preparation of the model mixture and experimental preparation when stored at room temperature. Despite the large number of publications studying the degradation of diazinon under the influence of various factors, there is a need to study this process in mixtures of a specific composition, in particular in new veterinary drugs that have not yet been studied. This article presents the results of determining the content of diazinon in 10% of the drug and the model mixture based on methyl alcohol. The analyzes were performed on a Knauer liquid chromatograph with a spectrophotometric detector equipped with a Luna® Omega Polar C 18 150 × 4.6 mm column filled with a 5 μm particle sorbent from Phenomenex with a universal C 18 pre-column 4 × 3.0 mm ID. Mobile phase: degassed mixture of acetonitrile: water in the ratio 65:35, flow rate was 1.1 ml/min, temperature of the column was ambient. Diazinone was detected at 245 nm. Injection volume was 0.050 ml and the time of one separation – 20 minutes. The appearance of an unknown peak on the 3 min chromatogram of the solution of the production experimental preparation was revealed. On the twenty-first day of storage of the experimental drug, the content of diazinon decreased to 34 % of the stated amount. On the third and twenty-first day of storage of the model mixture, a decrease in the content of diazinon by 16 % and 79%, respectively, and the appearance of an additional peak were observed. The use of methyl alcohol with other components is likely to be a factor in the breakdown of diazinon in the drug. According to the recipe of the drug, methanol is about half the content of ingredients. This composition does not provide stability of the proposed dosage form of the drug. The next step will be to study the effect of other solvents on maintaining the stated concentration of diazinon.