A new colorimetric technique for the estimation of vitamin C using Folin phenol reagent

A new colorimetric technique for the estimation of ascorbic acid by using Folin phenol reagent has been developed. The absorption maximum of the color developed by the interaction of ascorbic acid with Folin reagent is 760 nm. The technique obeys the Beer-Lambert law up to a concentration of 45 μg ascorbic acid as shown by the standard curve. The color developed has been found to be stable up to 18 h. Recovery experiments showed that the technique is almost 100% efficient. The development of the color is not obstructed by glucose, glutathione, bovine serum albumin, urea, cysteine, adenine, guanine, cytosine, uracil, sulfosalicylic acid, thymol, or oxyhemoglobin, which are compounds suspected of interfering in routine analysis. The technique is simple, quick, and efficient and can be employed for the estimation of ascorbic acid in a wide variety of biological materials.     

Protein measurement with neocuproine reactive

Summary A new one-step method for protein measurement based in the copper-neocuproine complex formation is described. A linear response was obtained for different proteins in the range of 0.5 to 40 g/ml with a sensitivity of 0.5 g protein/ml.     

Protein measurement in solid-state fermentation

Summary Membrane filter culture was used as a model system for the investigation of the growth of Rhizopus oligosporus in solid-state fermentation. The biuret method gave more accurate estimations of protein than the Folin-Lowry method. However, due to the change in the protein content of the biomass during the fermentation, protein cannot be considered to be a reliable index of growth in solid-state fermentation.     

Selected problems with phenol toxicity

Some data on the toxicity of phenol are surveyed. Environmental and health hazards are discussed. Pending standards are given. These are 0.3-19 mg/m3 in the air and working places in different countries. Acceptable phenol concentration in the air is 10 mg/m3 in Poland. The same standard for public buildings is 0.012 mg/m3. Toxic effects of phenol were reported in case of occupational exposition to 5 mg/m3 of air. Data concerning urine levels of phenol in children living in the buildings of increased phenol levels in the air and health impact of this are discussed.     

Enzymic degradation of phenolic materials in peatlands — measurement of phenol oxidase activity

The model substrate L-dihydroxy phenylalanine (L-DOPA) was used to measure the activity of phenol-oxidase (PO) in peat from a Welsh riparian wetland. The sensitive and relatively simple technique measured the rate of formation of the red coloured compound 2-carboxy-2,3-dihydroindole-5,6-quinone from the enzymic oxidation of L-dopa. The method was used to test the hypothesis that the large exports of phenolic materials from peatlands into aquatic systems were caused by low phenolic-degrading enzyme activities within the peat matrix. The low oxygen availability and acidic pH of the peat soil were found to be sub-optimal for PO activity. Furthermore, a depth-dependent decline in PO activity was inversely correlated with phenolic concentrations. Thus, the findings supported the above hypothesis.