We describe the performance of a colorimetric reagent kit (Diagnostic Systems Laboratories, Inc., Webster, TX 77598) for measuring calcium directly in urine, serum, and ultrafiltered serum, and compare the results with those obtained with atomic absorption spectrophotometry. The CV for within-run precision was 2.8 and 2.1% for urine and whole serum, respectively (n = 10 each). Between-run preci...

Conventional matrix characterization by visible spectrophotometry technique required sample destruction and limited to drug content assay. This study investigated the capacity of visible spectrophotometry technique to characterize both drug content and molecular characteristics of solid nifedipine-hydroxypropylmethylcellulose films stored at 25 and 50 % relative humidities in their intact form....

OBJECTIVE The objective of this study was to develop a reproducible method of establishing the concentration of yeast cells per milliliter of solution. METHODS Three methods of determining the number of yeast cells in solution were compared: Neubauer's counting chamber, spectrophotometry, and nephelometry. RESULTS All three methods were comparable and reproducible. The following formulas we...

Articles about the development of derivative spectrophotometric methods and analytical applications of derivative spectrophotometry (DS) published in the last nine years (since 1994) are reviewed.