Microbiological turbidimetric methods: linearization of antibiotic and vitamin standard curves.

Procedures were devised to linearize the usually curved calibration lines for turbidimetric microbiological assays. Three new equations relating concentration of drug and turbidity are described; two are for antibiotic assays and one for vitamin assays. One equation is for antibiotic assays employing Klebsiella pneumoniae as the test organism. The accuracy of interpolation from the three equations was studied by means of appropriate mathematical models based on erthromycin, chlortetracycline (K. pneumoniae), and cyanocobalamin assays. The accuracy of the new expressions was significantly superior to those used previously, and they are of general applicability.