Data acquisition in capillary isotachophoresis

A computer program was developed for data acquisition in capillary isotachophoresis. The program consists of two modules, one for data acquisition and the other for data analysis. The data analysis module calculates zone lengths and step heights automatically. This can also be done by the operator on a graphics screen. The program was tested on the analysis of both a thirteen-component standard mixture and a more complex sample

Aspects of detection and identification in isotachophoresis

The detector response in isotachophoresis is usually associated with qualitative parameters such as mobility (universal detection) and molar absorbance (specific detection). A more specific response (valency) is obtained from the a.c. conductivity detector when using coated electrodes. When using UV absorption of the counter ion, a more universal character of the signal is obtained. A number of anionic and cationic operational systems are suggested. In addition, quantitative accuracy and precision are discussed with special reference to detection principless, detector cell design, driving current stability and electroosmotic disturbance

Analysis of oligomers formed during an emulsion polymerization by means of isotachophoresis

Isotachophoresis is an outstanding technique to determine ionic organic compounds in water. The product of a surfactant free emulsion polymerization of butadiene with potassium persulphate as initiator was analysed and compared with the isotachopherograms of aliphatic sulphates of known structure. This resulted in a qualitative and quantitative analysis of the oligomers with 1-3 monomeric units and one sulphate end group. It seems possible to develop isotachophoresis to become a valuable tool providing insight into initiation, propagation and termination reactions occuring in the water phase, as well as information about the contribution of the oligomers (radicalic and terminated species) to particle formation

Pretreatment of body fluids by preparative isotachophoresis prior to chromatographic analysis

This study focusses attention on the possibilities of preparative isotachophoresis (ITP) as a sample pretreatment technique prior to liquid chromatographic (HPLC) analysis. The increased demand for accurate and less time consuming analysis necessitates that sample pretreatment procedures, should be develop in parallel with other improvements (e. g. in detection and separation) which can be observed. The preparation isotachophoresis was performed on gel slabs and the zones of interest were subsequently cut out, desorbed and the desorbates analyzed by HPLC. In this study satisfactory recoveries of between 85–90% with a standard deviation of 1–5% were observed for blank experiments. For spiked serum and urine samples the recoveries in general decreased with decreasing spiked drug concentrations. These observations are discussed in this paper

Determination of quinine in beverages, pharmaceutical preparations and urine by isotachophoresis

The suitability of isotachophoresis for the determination of quinine in different samples was investigated. The operational conditions were 0.01 M potassium—morpholinoethanesulphonic acid (MES) (pH 6.0) with 0.05% Mowiol as the leading electrolyte and ca. 0.005 M creatinine—MES as the terminating electrolyte. The analyses were carried out at 25 µA in a 0.2 mm I.D. PTFE capillary with UV and conductivity detection. Quinine-containing beverages were degassed by sonification and directly injected. The limit of detection was 5 mg/l with a 4 µl injection volume. The allowed concentrations could be determined with sufficient accuracy. Analgesic preparations were dissolved in a solution of 5 · 10-3M MES with sonification. The quinine levels found agreed well with the declared values. The other constituents of the pharmaceuticals did not interfere with the analysis. Urine samples from volunteers were analysed after consumption of tonic. The samples were extracted with dichloromethane—isopropanol (95:5), vortexed, centrifuged, evaporated to dryness, the residue dissolved in 5 · 10-3M MES and analysed. At a concentration factor of 33, the limit of detection was ca. 60 µg in 48-h urine: 2–15% of the quinine consumed was excreted as the parent compound in the first 48 h after consumption. The combination of the extraction procedure and the operational system makes the method suitable for the determination of a number of other alkaloids in physiological samples