PubMed · 10314720
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R A Bageant. 1976. Oxygen analyzers.. https://pubmed.ncbi.nlm.nih.gov/10314720/
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In caseogram prints, a type of zymogram which is designed for the detection of acid proteases, enzyme activity is detected in an overlay gel of agarose containing skim milk. The use of this technique for protease quantification was investigated in this study using pepsinogen as an example protease. The area of caseogram bands was found to be logarithmically related to protease activity whereas the intensity of the bands was no reliable measure for activity. A reproducible quantification procedure was described. Accuracy and variation were acceptable over a 128-fold range whose lower border was the detection limit (35 pg pepsinogen).
To investigate the environmental fate, food chain bioaccumulation, and toxicity of organic chemicals, it is often preferable to measure the chemical's fugacity rather than its concentration. However, simple methods to do this are rare. This paper presents a novel yet simple method to measure fugacities of a range of poorly volatile hydrophobic organic chemicals ranging in octanol-air partition coefficients from 10(5.6) to 10(9.2). Thin films of ethylene vinyl acetate coated on glass surfaces are used as solid-phase samplers of contaminated biological tissues. The technique is applied to fish tissue samples and spiked fish diets to determine method feasibility, equilibration times, reproducibility, and property characteristics of the thin films. It is concluded that the method provides an attractive technique to measure chemical fugacities in biological tissues without requiring solvent extractions and cleanup. The method is further expected to be applicable to investigate the fugacity of semivolatile and poorly volatile organic chemicals in air, water, sediments, and soil.
An ITP method for the simultaneous determination of Fe(II) and Fe(III) in waters, based on separation of their EDTA and fluoride complexes, respectively, was developed. The leading electrolyte used consists of chlorides, La(III) as co-counter ion and is buffered with beta-alanine to pH = 3.5. The terminating electrolyte contains caproic acid and L-histidine (pH = 4.5). The method was validated and tested with samples of artificial, ground and treated water with good results, comparable to those obtained by other analytical techniques. Fe(II) and Fe(III) up to 20 mg/L were measured with an RSD = 1.4-1.5% and detection and determination limits of 0.8-0.9 and 3.0-3.5 mg/L, respectively. The ITP method can be recommended for routine utilization in hydroanalytical laboratories.