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At least 991 records · Page 55Linked to original sources
PubMed1979

[Microdetermination of lead and cadmium in blood and urine by graphite furnace atomic absorption spectrophotometry (author's transl)].

A microtechnique is described for determination of lead and cadmium in blood (0.1 ml) and in urine (0.2 ml) using extraction into methyl isobutyl-ketone after chelation by ammonium pyrrolidine dithiocarbamate. Mineralization, precipitation of proteins or addition of hemolysing reagents are not necessary. Blood is hemolysed by addition of deionised water. pH of urine is fixed by a pH 5 buffer. This microtechnique is simple, rapid, reproducible and suitable for routine analysis. In healthy subjects it gives values comparable to data of other workers: blood 158 microgram/l lead (s = 40, n = 18); 0.7 microgram/l cadmium (s = 0.3, n = 10); urine 16 microgram/l lead (s = 9.4, n = 10); 0.5 microgram/l cadmium (s = 0.3, n = 10).

Cadmium↗
PubMed1981

Direct determination of plasma fibrinogen levels by heat precipitation. A comparison of the technique against thrombin clottable fibrinogen with spectrophotometry and radial immuno-diffusion.

We have studied the Thorp method for precipitation of fibrinogen from diluted plasma, using a specific buffer (pH 6.3) at 56 degrees C, and the preferred anticoagulant (EDTA). Nephelometric or turbidimetric measurements of the precipitate were compared with the results obtained by radial immunodiffusion, or by thrombin clotting, of fibrinogen. In the absence of prior proteolysis (as indicated by the presence of fibrinogen and fibrin degradation products), correlations between the methods were excellent (r > 0.99). We conclude that the method of heat precipitation, which is simple to operate and inexpensive, gives results equally as good as the more difficult and time-consuming techniques.

Bilirubin↗
PubMed1982

A micromethod for the analysis of zinc in plasma or serum by atomic absorption spectrophotometry using graphite furnace.

A micromethod is described for the analysis of zinc in plasma or serum by electrothermal atomisation and graphite furnace utilising less than 20 microliters sample volume. The sample matrix introduced an error when aqueous standards were used. Therefore standards were made up in serum which had been treated with Chelex 100 to remove as much zinc as possible. The residual zinc (less than 0.125 mg/l) was determined by flame analysis using the method of additions and each standard assigned a value equal to the sum of the residual zinc and the amount added. Furnace analyses using standards made up in Chelex-treated serum compared favourably with flame analyses over the whole range, and recovery experiments gave 98 +/- 2% of the expected value with 95 +/- 6% recovery of the added zinc. The within-batch coefficient of variation was 2.5%, day-to-day variation 5.6%. The mean concentration of zinc in paired samples of plasma and serum from 50 adults analysed by flame with viscosity-matched aqueous standards were: plasma (mean +/- SD) 0.821 +/- 0.085 mg/l; serum 0.821 +/- 0.07 mg/l. The same samples were analysed in the graphite furnace using serum standards, and the results were: plasma 0.812 +/- 0.082 mg/l; serum 0.815 +/- 0.08 mg/l. In contrast to earlier reports we were unable to demonstrate a significant difference between plasma and serum zinc concentration in the paired samples.

Adult↗
PubMed1985

Quantitative measurement of plasma hemoglobin by second derivative spectrophotometry.

The development and validation of a second derivative spectrophotometric assay for hemoglobin in plasma is reported. Using the oxyhemoglobin absorbance peak at 578 nm, the method was found to be linear for standard samples in the range of 3-2,000 mg/l oxyhemoglobin. Because of one dilution step this range is doubled for plasma samples. Correlation with an enzymatic assay was excellent (r2 = 0.985). Within-run and between-run precision analysis showed CV values ranging from 0.5-6.5% for specified calculation conditions. Icteric or lipemic backgrounds did not influence the results. All calculations of derivative spectra were carried out for three different wavelength intervals. The largest interval (delta gamma = 6 nm) showed the best performance. The method is simple and rapid and it has been introduced successfully in our laboratory for routine clinical use.

Hemoglobins↗
PubMed1987

Determination of selenium in human spermatozoa and prostasomes using base digestion and electrothermal atomic absorption spectrophotometry.

A method for the determination of selenium in human spermatozoa and prostasomes is described. The samples were digested with 25% (w/v) tetramethylammonium hydroxide (TMAH) in methanol and analyzed by atomic absorption spectrometry with electrothermal atomization and Zeeman background correction (ET-AAS). Nickel was used as a matrix modifier. Calibration was performed using the matrix-based calibration curve. The TMAH-digestion method agreed well with a conventional digestion procedure using concentrated nitric acid. The TMAH-digestion does not require heating or strong acids and it was suitable for small biological samples. The average recovery of added selenium in spermatozoan digests was 95.1 +/- 5.2% (n = 5). The coefficient of variation was 9.1% (n = 21). The accuracy of the method tested with the NBS standard 1577 (bovine liver, certified at 1.1 +/- 0.1 micrograms Se/g) resulted in a value of 0.98 +/- 0.10 micrograms Se/g (n = 16). The method was further tested in an interlaboratory comparison study.

Animals↗