Measurement of potency and lipids in monensin fermentation broth by near-infrared spectroscopy

A transmission near-infrared (NIR) spectroscopic method for quantifcation o f potency and lipids in monensin fermentation broth was developed and valid ated. Two multiple linear regression calibration curves were established fo r a set of 100 fermentation samples, correlating the appropriate absorption bands in the NIR spectrum to the laboratory reference methods; high-perfor mance liquid chromatography for potency, and chloroform extraction for lipi ds, During method development, potency was found to be well correlated to N IR absorbances specific for monensin. While acceptable, correlation of NIR absorbances characteristic of oil to the chloroform lipid method was weaker due to a greater amount of relative variation in the lipid measurements. F ollowing establishment of the optimal calibration curves, the NIR method fo r potency and lipids was validated for selectivity, accuracy, precision, an d robustness. In order to investigate long-term drift in the measurement sy stem, samples were tested both by the NIR and the reference methods over a 7-month period. The differences between results from the two measurements w ere calculated and statistically analyzed. (C) 2001 Elsevier Science B.V. A ll rights reserved.