Biomedical subjects

K Jacob

Publications and source records attributed to K Jacob.

89 records · Page 5Linked to original sources

PubMed1980

Diagnosis of porphyrias by ion-pair high-performance liquid chromatography.

Ion-pair reversed-phase high-performance liquid chromatography together with fluorescence detection is useful in the analysis of urinary porphyrin carboxylic acids. The sensitive and quantitative detection facilitates the clinical diagnosis of porphyrias. The method described permits the detection of porphyrins down to 0.1 ng directly from urine without laborious sample pre-treatment. A linear response curve was obtained from 0.2 up to 200 ng for coproporphyrin I. The within-assay correlation coefficients ranged from 2.5 to 10.1%. Recovery experiments gave an accuracy of 89-109%. The rapidity and simplicity of the method allows its application to the routine analysis of urinary porphyrins in the clinical laboratory.

Chromatography, High Pressure Liquid↗

PubMed1978

Quantitation of adrenaline and noradrenaline from human plasma by combined gas chromatography--high-resolution mass fragmentography.

A gas chromatographic--high-resolution mass fragmentographic method for the simultaneous determination of adrenaline and noradrenaline from human plasma is presented. The catecholamines are separted by adsorption on alumina and converted by a selective, two-step procedure to the corresponding N-trifluoroacetyl-N-trimethylsilyl derivatives. The benzylic fragment C16H31O3Si3 (m/e 355.1568) of these derivatives is detected at a mass spectrometric resolving power of 5000. This high resolution detection was necessary to differentiate this fragment from others with the same nominal mass of 355 originating from the biological matrix and/or the bleeding from column and septum.

Epinephrine↗

PubMed1978

Mass spectrometry of dimethylthiophosphinates of aromatic hydroxy compounds.

The mass spectra of 20 differently substituted dimethylthiophosphinic esters of aromatic hydroxy compounds are presented. Fragmentation routes were investigated using high resolution mass measurements, decoupled metastable determinations and deuterium labelling. All compounds exhibited abundant molecular ions and typical phosphorus-containing ions. Characteristic elimination processes strongly dependent upon the respective type of substitution were observed. Due to their high stability, their great ease of formation and their good gas chromatographic properties these new types of derivatives are of special interest for establishing gas chromatography mass spectrometry profiles of acidic catecholamine metabolites.

Gas Chromatography-Mass Spectrometry↗

PubMed1977

[The mechanization of the enzyme immunological determination of phenytoine with the Centrifichem (author's transl)].

The separation of free from bound antigen is not required in homogeneous enzyme immunoassays (EMIT). Therefore this technique can easily be mechanized. For the mechanization of the enzyme immunological determination of serum levels of Phenytoine the fast analyzer (CENTRIFICHEM) was found most satisfactory in our laboratory. The marked advantages over manual methods are: 1. The amount of sample and reagents needed can be reduced by half. 2. The intra- and interassay variance are significantly better compared to values found with manual techniques. 3. 60 samples can be determined in duplicate in under two hours.

Autoanalysis↗

PubMed1976

Steroid phosphorus compounds. V--Mass spectrometry of phosphinic esters of monohydroxy steroids.

The mass spectra of the dimethylphosphinic, dimethylthiophosphinic and dimethylphosphinous ester derivatives of several monohydroxy steroids are reported. The fragmentations of the derivatized steroids largely depend on the nature of the phosphorus-containing ester group. Phenolic ester derivatives exhibit the base peak at the molecular ion, whereas the spectra of the secondary phosphinic esters are dominated by very intense protonated phosphinic acid ions [Me2P(XH)(OH)]+ at m/e 95 (X =O) or at m/e 111 (x = s). The present results also indicate the low ionization potential for the phosphinic ester group. Due to their good gas chromatographic properties, these steroid derivatives appear to be particularly suitable for gas chromatographic mass spectrometric analysis of biochemical materials.

Androsterone↗

PubMed1975