CATION ANALYSIS OF FERMENTATION BROTH BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY UTILIZING ION INTERACTION

Nutrient information concerning the specific needs of microorganisms in fermentation broth is crucial to the potency and production of an antibiotic. Nutrient analysis is hindered by an array of fermentation broth matrix interferences. These matrix interferences can be effectively removed by ashing the sample, although most of the major interferences can be removed by solid-phase extraction. The ashed sample was extracted using 10(-3) M nitric acid and filtered through a 0.45-mu-m filter. The sample extract was chromatographed on an Adsorbosphere HS C-18 column with conductivity detection. The mobile phase consisted of 40 mM tartaric acid, 2 mM sodium octanesulfonate in 5% methanol adjusted to pH 4.0 with sodium hydroxide. The flow-rate was 0.8 ml/min. Under these conditions, calcium, copper, lead, zinc, nickel, cobalt, cadmium, iron(III), magnesium and manganese are separated in less than 35 min. All analytes, with the exception of calcium and iron, are baseline-resolved. The response is linear for the range 1-1000 ppm. This method is able to monitor the microorganisms' cation consumption from the starting raw materials such as the flours and water used in producing a suitable starting culture to the final fermentation products. The use of post-column derivatization using ultraviolet detection allows for greater minimum detectable quantities (approximately 10(-9)g) with a larger linear dynamic range.