China
Africa
Explore chapters and articles related to this topic
Drug Monitoring by Capillary Electrophoresis
Published in Steven H. Y. Wong, Iraving Sunshine, Handbook of Analytical Therapeutic Drug Monitoring and Toxicology, 2017
Electrophoretic mass transport is highly regulated, thus allowing charged solutes to be concentrated (stacked) across an electrolyte discontinuity,8 including that produced initially between sample and running buffer. In CE, this inherent and exclusive feature of electrophoresis may take place when the sample compounds encounter isotachophoretic concentration (isotachophoretic sample stacking is based upon differences in electrophoretic mobilities)8,60 or when the conductivity of the sample is smaller than that of the buffer (field amplified sample stacking).8,61 After hydrodynamic sample introduction, stacking techniques are not only dependent upon sample composition, but also on the sample volume injected and thus limited by the capillary volume. Experimentally determined enhancement factors associated with these in-column stacking techniques typically do not exceed 100. Head-column field amplified sample stacking (also referred to as field amplified sample injection)62 associated with electrokinetic sample introduction takes place at the tip of the column and has no limited injection volume. It is best performed with a sample of low conductivity (Figure 1–5, left electropherograms) and a short plug of water at the capillary inlet. During electroinjection, analytes are stacked at the interface between the low-conductivity zone and the running buffer. Furthermore, little sample solvent is co-injected because the net electroosmotic velocity is typically much smaller than local electrophoretic transport. Using this approach, a 1000-fold sensitivity enhancement can easily be obtained.63 Thus, detection limits in CE are not only dependent on the type of detector used, but also on the matrix of the sample and the injection procedure employed.
Analytical investigation of ternary mixture of phenylephrine hydrochloride, dimetindene maleate and benzalkonium chloride using validated stability indicating HPLC-DAD method
Published in Drug Development and Industrial Pharmacy, 2020
Ahmed G. Abdelhamid, Dina S. El-Kafrawy, Magdi M. Abdel-Khalek, Tarek S. Belal
For DMD, different visible spectrophotometric methods [22,23] and GC [24,25] were published for assay of DMD. Capillary isotachophoresis and chiral capillary electrophoresis method was reported for analysis of DMD and its enantiomers [26,27]. HPLC-UV [27–29] and densitometric method [30] were also published for the determination of DMD.