[A new HPLC method for determination of main constituents of the streptothricin complex. Analysis of nourseothricin, grisin and kormogrisin].

A simple and reliable HPLC method for quantitative analysis of complex antibiotics consisting of a mixture of streptothricins F, E, D and C in a biological matrix was developed. The method is based on ion-pair separation of streptothricins on the reversed-phase C18 analytical column with UV detector (210 nm). Aqueous solution of acetonitrile containing trifluoroacetic acid and octane-1-sulfonic acid sodium salt was used as eluent.

[Comparative analysis of degradation of native avermectins and spinosyns by UV-HPLC].

Degradation rates and compositional changes in active ingredients of the two crop protection insecticides, Fitoverm and Spinosad, have been compared by using a reverse-phase HPLC with UV detection (250 nm). Decay of the major components of active ingredients: spinosyns A and D (Spinosad) and avermectins A1a, A2a, B1a and B2a (Fitoverm) was studied in the thin dry layer on the glass at sunlight at regular day/night changes of temperature. The following results were obtained: 1) 50% degradation time for spinosyns was about two times shorter than that for avermectins: at 40 degrees C day-time temperature it was 6 hours and 10 hours, respectively, while at 23 degrees C these times increased approx.