Concept of response factor in capillary isotachophoresis. Determination of drugs in solution for intravenous injection.

Twenty-six drugs in solutions for intravenous injection were determined by capillary isotachophoresis with only one calibration point for each component. The maximum deviation of the labelled concentration was 2%. A new calibration constant is introduced, viz., the response factor (RF, dimensionless), which is independent of the diameter of the capillary, the construction of the universal detector and the driving current used during detection. It is shown that the RF can be used on different equipment, using different currents during detection. It appears that the RF is usable for routine analysis when a deviation of 5% is acceptable. Daily one-point recalibration, however, improves this value to 1%.

Analysis of the aqueous phase of human cervical mucus by reversed-phase high-performance liquid chromatography and capillary isotachophoresis.

The aqueous phase of human cervical mucus was analysed by reversed-phase high-performance liquid chromatography (HPLC) and capillary isotachophoresis (ITP). With HPLC, seventeen ultraviolet-absorbing and eight fluorescent components and with ITP five anionic and four cationic components could be determined. The sample pre-treatment consisted of a simple ultrafiltration. Ten samples from fertile women and eleven samples from infertile women were analysed. In six samples from the infertile group higher median concentrations of several components were found. This may be an indication of disturbances in the biochemical processes of the cervical mucus of woman with fertility problems.

Screening of UV-absorbing solutes in uremic serum by reversed phase HPLC--change of blood levels in different therapies.

In order to screen UV-absorbing solutes in large numbers of uremic serum samples, an automated liquid chromatographic method was developed. The method proved to be reliable and reproducible in more than 500 analyses. HPLC separation was performed using gradient elution on a 25-cm Ultrasphere Octyl reversed phase column, with 5 microns particles. Characteristic profiles for the uremic state were obtained in the analyses of serum samples of 43 uremic patients before and just after artificial kidney treatment; hemodialysis (n = 14), hemodiafiltration (n = 13) and hemofiltration (n = 16). In these profiles 20-40 peaks were resolved of which nine were 'quantitated' by peak height relative to a standard. Of these solutes creatinine, uracil, uric acid, hypoxanthine, indoxylsulfate, tryptophan and hippuric acid were identified. The heterogeneity of the population of uremic patients, with respect to the UV-absorbing solutes, was estimated. Significant differences of solute blood level changes during hemodialysis, hemodiafiltration and hemofiltration, were observed.