The 5-day sodium carbonate-ammonium nitrate extraction assay (5-day method) has been recognized by the American Association of Plant Food Control Officials as a validated test method to identify fertilizers or beneficial substances that provide plant-available silicon (Si). The test method used the molybdenum blue colorimetric assay to quantify percentage Si; however, laboratories may use induc...

SIMPLE, RAPID TEST-TUBE EXIRACTION TECHNIC for the determination of urinary 17-ketosteroids has seen developed in our laboratories. A complete urinary 17-ketosteroid determination was carried out in a glass stoppered photometer cuvet by combining this extraction technic with a colorimetric method. Three colorimetric methods, Zimmermann (1), (2), Pincus (3), and Cohen and Kaluszyner (4) were com...

A colorimetric method using a tetrazolium compound, 3,4,5-dimethylthiozalil-(1 or 2),2,5-diphenyltetrazolium bromide (TTBr), was developed for studying the growth activity of yeast-phase Histoplasma capsulatum. Materials extracted in phosphate buffer, pH 7.0, from cells at different stages of growth reduced TTBr. Colorimetric changes were correlated with enzymatic activity. Under standardized c...

BACKGROUND Visual assessment of cerebrospinal fluid (CSF) for xanthochromia (yellow color) is practiced by the majority of laboratories worldwide as a means of diagnosing intracranical bleeds. METHODS Colorimetric and spectrophotometric analysis of CSF samples for recognizing the presence of bilirubin either in low concentrations or in the presence of hemolysed blood. RESULTS The experiment...