title: Improved microbiological assay for folic acid based on microtiter plating with Streptococcus faecalis.
abstract: We have developed an improved method, using 96-well microtiter plates, for the microbiological assay of folic acid. With this method, the tedium of conventional microbiological analysis is substantially decreased. Culture volumes have been reduced 33-fold, and pipetting procedures have been simplified. Assay time has been reduced to 14 h, and sensitivity has increased 10-fold (0.1 ng/mL). Analytical recoveries range from 98 to 104%. Intra-assay and interassay variabilities are less than 11%. The assay does not require extensive manipulation of inoculum. Day-to-day variability has been minimized by using saline aliquots of the bacterial suspension stored at 4 degrees C. The procedure is accurate, selective, and useful for direct measurement of folic acid in multivitamin formulations.
authors.affiliation: Indian Statistical Institute, Calcutta.
authors.forename: J
authors.initials: J
authors.lastname: Das Sarma
authors.forename: C
authors.initials: C
authors.lastname: Duttagupta
authors.forename: E
authors.initials: E
authors.lastname: Ali
authors.forename: T K
authors.initials: TK
authors.lastname: Dhar
mesh_terms: D001681:Biological Assay; D013293:Enterococcus faecalis / Q000187:drug effects / Q000254:growth & development; D005492:Folic Acid / Q000032:analysis* / Q000494:pharmacology; D012680:Sensitivity and Specificity; D013997:Time Factors; D014815:Vitamins / Q000032:analysis
chemical_list: D014815:Vitamins; D005492:Folic Acid