Diphenylcarbazide

Abstract: A method is described for the routine determination of free fatty acids (FFA) in plasma. The extraction medium used contains chloroform-heptane-methanol mixture with a phosphate buffer. This extraction mixture gives a sufficient extraction of FFA from serum and contamination with interfering agents is avoided. The copper soaps of FFA are determined colorimetrically with diphenylcarbazide. The recovery of free fatty acids is 100.4%. The standard deviation of double determinations is 0.013 mmoles per litre. The reference range calculated from 50 normal persons of varying age is 0.100 to 0.660 mmoles per litre.

Abstract: A colorimetric micromethod, based on the formation of FFA-Cu soaps, was developed for determining free fatty acids (FFA) in 50 μl of plasma FFA was extracted with chloroform-heptane-methanol Silicic acid was used to eliminate interference by the phospholipids Diphenylcarbazide was chosen for the colorimetric determination of copper These modifications render the method more sensitive than other available colorimetric methods The method requires only capillary samples and is therefore suitable for repeated registration of the concentration of FFA during experimental conditions

Abstract: While chitosan biopolymer from crustacean shells is recognized as a good adsorbent of metals from aqueous solutions, chemical cross-linking is necessary to avoid biopolymer solubility in acidic medium. Adsorption of chromium onto cross-linked chitosan is realized by means of analysis of pH influence, particle size, adsorbent weight, concentration and oxidation state of metal. Concentrations of chromium in solution are determined by Flame atomic absorption spectrometry and colorimetric method with diphenylcarbazide. Optimum pH of adsorption is 4.0 while chromium(VI) is partially reduced in the range pH ≤ 3.0. The lower affinity of chitosan by chromium(III), 6 mg/g, differs with the high capacity developed with chromium(VI), 215 mg/g, due to highly protonated active sites in the acidic range of pH. Equilibrium data fit to both Langmuir and Freundlich isotherms.

Abstract: The use of diphenylcarbazide as an electron donor coupled to the photoreduction of 2,6-dichlorophenolindophenol by tris-washed chloroplasts or subchloroplast fragments provides a simple and sensitive assay for photosystem 2 of chloroplasts. By varying the concentration of tris buffer at pH 8.0 during an incubation period it is shown that the destruction of oxygen evolution activity is accompanied by a corresponding emergence of an ability to photooxidize diphenylcarbazide, as evidenced by absorbance changes due to diphenylcarbazide at 300 nm. The temperature-sensitive oxidation of diphenylcarbazide is inhibited by DCMU and by high ionic strengths. This activity appears to measure the primary photochemical reaction of photosystem 2.

Abstract: A sensitive micromethod for the colorimetric determination of free fatty acids (FFA) in plasma has been developed. FFA are extracted with chloroform-heptane-methanol with silicic acid being added to eliminate interfering phospholipids. Diphenylcarbazide containing diphenylcarbazone has been chosen as color-developing reagent, since the chromophore formed in the presence of FFA-Cu complex is stable and sensitive. Comparison of the proposed method and a non-routine reference procedure involving, among other steps, isolation of FFA on thin-layer chromatography would indicate that the efficiency of extraction of FFA in the proposed method was 90% that of the reference procedure. The proposed method offers the sensitivity, convenience, and accuracy needed for the determination of FFA in situations where the size of sample available is limiting, as with small rodents.