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The use of small scale renewable sorbent material for automated solid phase extraction of multi-residue pharmaceuticals in environmental samples exploiting the sequential injection analysis-bead injection with direct coupling to liquid chromatography-electrospray ionization tandem mass spectrometry (SIA-BI-μSPE-LC-ESI-MS/MS) is presented to determine beta-blockers, namely atenolol, sotalol, pindolol, acebutolol, timolol, metoprolol, labetalol, carazolol, propranolol and betaxolol. These compounds yielded the same product ions, therefore were affected in terms of quantification when flow injection analysis-mass spectrometry (FIA-MS) was used. Thus, analytes and matrix present in the sample travel together into the ionization source which can seriously affect the ionization efficiency and analyte signals due to monitoring over a short time period. Graphical abstract A two-dimensional analysis involving a time dimension (retention time) and an m/z dimension (fragmentation ion) is promising for the various sample types. Using the developed method, absolute recoveries percentages of 10 mL of sample loading volume were >91% for all β-blockers with enrichment factor of 62-74, limits of detection of 0.005-0.07 μg L(-1), limits of quantification of 0.01-0.23 μg L(-1), enrichment factor of 62-72 and repeatability within range 7-12%. This developed method is suggested to be used as quantitative screening technique for drugs of abuse or persistent contamination using different kinds of sorbent materials and complex matrix such as biological fluid sample as well.

Fritless columns were fabricated by encapsulating packing material within monolith for capillary electrochromatography. They were applied for separation of 3,4-methylenedioxymethamphetamine and metabolites. The packing material was suspended in polymerisation mixture and then forced into a pre-treated capillary following by polymerisation. This made the preparation much easier, saved time, cost and showed less tendency towards bubble formation with better resolution than with packed column. Using this fritless column, migration time of all analytes increased with buffer concentration and amount of organic component in mobile phase, but decreased on increasing the pH from 3.0 to 4.5 and then increased above pH 4.5.

Capillary electrochromatography (CEC) is classed as a hybrid technique between CE and HPLC and it combines the advantages of both these techniques. However, in some cases the disadvantages are also brought to light and some of these are difficult to resolve. For example the analysis of basic compounds using CEC. The problems of tailing peaks during HPLC analysis of basic compounds was resolved by end capping the residual silanol groups, but in CEC these are the groups that generate the electroosmotic flow. The analysis of basic compounds is crucial within the pharmaceutical industry where a high percentage of the drug actives are basic. Specially designed Continuous Beds stationary phases (CB) can mean that each application can have a specific stationary phase. In order to overcome the problem associated with the analysis of basic compounds using electrochromatography, we have designed a CB stationary phase with a positive charge, which could be operated using negative voltage. The resulting chromatography showed almost gaussian peaks for bases like nortriptyline which tail significantly using stationary phase typically used in CEC.

Capillary electrochromatography (CEC) is a versatile new technique used to complement other separation techniques like HPLC. The main advantage of CEC over HPLC is the electrically driven flow, which generates a flat flow profile and provides sharper peaks and better efficiencies. In CEC the flow profiles within the channels between the particles are plug-like (as in CE), In HPLC (pressure driven flow) the flow profiles within similar channels are parabolic leading to band broadening. Hence efficiencies seen in HPLC are not as good as those obtained from CEC. This advantage along with the suitability of CEC with miniaturisation has led to extensive development of the technique. CEC has progressed significantly in recent years and numerous examples of CEC applications have been published. However most of the work has been carried out in a research environment. In order to progress the technique in the pharmaceutical industry it is necessary to demonstrate that CEC can be a robust and reliable technique. In this article we discuss the validation and robustness testing of a capillary electrochromatography method used for the determination of impurities in a potential drug substance. The CEC method was developed and validated in accordance with the ICH guidelines. The data generated was compared with the data from the existing HPLC method. Overall results show that CEC can be used in a highly regulated environment.

Separations of compounds in plasma were performed on a Hypersil Duet C18/SCX capillary electrochromatography (CEC) column, utilizing an automated injection system combined with a short in-house designed and fabricated micro-electrospray CEC mass spectrometer interface. Protein precipitation was used prior to the CEC separations. More than two hundred separations of the corticosteroids Dexamethasone and Betamethasone 17-valerate, and Fluticasone Propionate in complex plasma matrix were performed on a single column under isocratic conditions. The method demonstrated good reproducibility, selectivity, sensitivity and high efficiencies. Linear calibration with good correlation was typical. Estimated detection limits in the low micromolar and nanomolar range for all compounds were obtained using UV-Vis absorbance (UV) and Electrospray Mass Spectrometric (ES/MS) detection respectively. Efficiencies for all compounds were typically 87,500 plates on a 25 cm column (350,000 plates m−1) and increased with the number of plasma samples injected, up to 250,000 plates per column (1,000,000 plates m−1). These very high observed plate counts may be artificially enhanced by the inadequate scan possibilities of the MS over very narrow chromatographic peaks.

1Department of Comparative Molecular Medicine, School of Veterinary Science, The University of Liverpool, Liverpool, UK. 2Manchester Centre for Integrative Systems Biology, Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, UK. 3Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, UK. 4National Institute for Biological Standards and Guidelines for reporting the use of column chromatography in proteomics