Biomedical subjects

H J Sievert

Publications and source records attributed to H J Sievert.

2 recordsLinked to original sources

PubMed1994

Diode array detection in capillary electrophoresis.

Diode array detection (DAD) in capillary electrophoresis (CE) offers similar advantages over single-wavelength detection as it does in high performance liquid chromatography (HPLC). Thus, confirmation of compound identity and establishment of peak purity are critical issues in CE, necessitating sensitive and specific detection. With an optimized optical system, DAD yields sensitivity comparable to that of single or variable wavelength detectors. Sensitivity can be further improved three to five times by use of expanded pathlength capillaries employing the so-called bubble cell. Optimization of optical design, as well as maintenance of spectral fidelity, will be discussed in this work. A variety of applications of CE, and specifically of micellar electrokinetic capillary chromatography (MEKC), with emphasis on quantitative analysis, sensitivity, linearity, spectral identification, and peak purity verification will be presented. The use of spectral information for peak tracking in MEKC method development and for the assessment of purity of electrodistorted peaks will also be illustrated.

Chromatography, High Pressure Liquid↗

PubMed1990

Automated evaluation of tryptic digest from recombinant human growth hormone using ultraviolet spectra and numeric peak information.

UV spectra were successfully employed in identifying peptide fragments from a tryptic digest of recombinant-DNA-derived human growth hormone (r-hGH). It was possible to distinguish very similar peptides utilizing a digital comparison of the UV spectra. An automated procedure was developed to generate a calibration library for the tryptic digest of a reference standard. The calibration library was then evaluated for reproducibility and selectivity and found to provide superior performance in correctly identifying ambiguous peaks as compared to the use of a conventional calibration table. Spectral match factors together with numerical information, derived from peak retention time, area and height, were used to arrive at a "peak score" descriptive of the similarity between standard and sample peaks. "Peak scores" could be combined to calculate a "sample score" indicative of overall similarity between an unknown and a standard. The scoring procedure was automated to generate a final report without operator intervention and successfully assigned appropriate scores to similar as well as dissimilar samples, e.g., native and oxidized r-hGH.

Algorithms↗