Current applications of miniaturized chromatographic and electrophoretic techniques in drug analysis

doi:10.1016/j.jpba.2014.03.041

Journal of Pharmaceutical and Biomedical Analysis

Volume 101, December 2014, Pages 194-220

https://doi.org/10.1016/j.jpba.2014.03.041 Get rights and content

Highlights

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The use of miniaturized separation techniques in pharmaceutical field is reviewed.
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For each technique advantages and approaches to overcome the drawbacks are discussed.
•
Examples of applications from literature are illustrated.

Abstract

In the last decade, miniaturized separation techniques have become greatly popular in pharmaceutical analysis. Miniaturized separation methods are increasingly utilized in all processes of drug discovery as well as quality control of pharmaceutical preparation. The great advantages presented by the analytical miniaturized techniques, including high separation efficiency and resolution, rapid analysis and minimal consumption of reagents and samples, make them an attractive alternative to the conventional chromatographic methods for drug analysis. The purpose of this review is to give a general overview of the applicability of capillary electrophoresis (CE), capillary electrochromatography (CEC) and micro/capillary/nano-liquid chromatography (micro-LC/CLC/nano-LC) for the analysis of pharmaceutical formulations, active pharmaceutical ingredients (API), drug impurity testing, chiral drug separation, determination of drugs and metabolites in biological fluids. The results concerning the use of CEC, micro-LC, CLC, and nano-LC in the period 2009–2013, while for CE, those from 2012 up to the review draft are here summarized and some specific examples are discussed.

Graphical abstract

Introduction

Pharmaceutical analysis is an important topic of research widely applied in several areas such as drug discovery and development, assessment of purity and quality of drug formulations, and pharmacokinetic/pharmacodynamic studies [1], [2]. The high demand for analytical tools able to offer high-throughput, reliable and fast methodologies has recently stirred the interest of pharmaceutical industry towards miniaturized separation techniques, which furthermore provide reduced waste production and are cost-effective [3], [4], [5]. This attention has been additionally stimulated by “omics” research and by the introduction of protein-based drugs (e.g., monoclonal antibodies). Such applications essentially need analytical techniques capable to handle with small quantities of sample and to be easily hyphenated, i.e. with mass spectrometer (MS) [2], [3], [6], [7].

Miniaturization of analytical and bioanalytical processes represents an important area of research which involves the implementation of several important tools such as microreactors, sampling, detection, separation systems, including the use of microchip technologies, and microextraction sample techniques [2], [8], [9]. Sample preparation procedures in use in many application areas are, in fact, still tedious and manually intensive protocols making the sample treatment the most time-consuming and error-prone part of the analytical scheme [10].

Taking into account miniaturized separation techniques, capillary electrophoresis (CE), capillary electrochromatography (CEC) and micro/capillary/nano-liquid chromatography (micro-LC, CLC, nano-LC) are those largely promoted, in some instance especially from research laboratories, as valid and convenient alternative to conventional and commonly employed chromatographic techniques such as HPLC and GC. As briefly above mentioned, the common advantages making these methodologies attractive are: (i) the reduced use of reagents, including organic solvents, with consequent decreased environmental pollution and cost; (ii) the need of small sample volumes; (iii) short analysis time; (iv) rapid optimization of experimental conditions, comprising the possibility to perform experiments in parallel [3], [5], [11].

Considering the low flow rate of miniaturized techniques, they are particularly suitable for the coupling with MS without using split flow system. Hyphenated MS techniques are essential for an unequivocal identification of compounds and their structural analysis, possess enhanced selectivity and sensitivity. However it should be mentioned that laboratory-made interfaces often offer better performances than commercially available ones, and especially relating to CEC this coupling still results in experimental complexity [12], [13], [14].

Another drawback related to miniaturized techniques can be the low sample loading due to the small dimension of the separation medium and the low sensitivity related to on-column detection with UV detectors. However, it is possible to resort to different ruses to avoid such an inconvenience, for example on-line focusing and stacking approaches for chromatographic and electrophoretic techniques, respectively, in addition to sample preparation techniques allowing the simultaneous enrichment and purification of the analytes. Being involved the analysis of biological matrices, sample preparation represents a mandatory task for miniaturized techniques, as well, where is of paramount importance to avoid system overloading and/or clocking [8], [15], [16], [17], [18], [19], [20].

Comparing CE with CEC and nano-LC/CLC, the first one is of easier implementation in relation to the separation medium. In fact, few kinds of packed capillary columns (monolithic or particulate) are commercially available for miniaturized version of chromatography and CEC. As a consequence, most research laboratories prepare themselves packed capillary columns in order to amplify the range of selectivity, increase efficiency and speed up analysis, by the use of innovative stationary phases. Another restriction related to CEC is the need of stationary phases able to generate an electroosmotic flow (EOF); this can be easily solved utilizing material that contains charged or chargeable groups [5].

In this review all these aspects will be covered considering the applications of miniaturized separation techniques in the different branches of pharmaceutical field. In this contest, especially noteworthy is the role played by miniaturized techniques in chiral drug analysis [4], [21], [22] to which a specific section is dedicated. Finally, the implementation of such techniques as laboratory-on-chip for pharmaceutical analysis is also discussed.

Considering the previous published review papers [1], [3], [4], [5], [23], [24], this one takes into consideration the applications of CEC, micro-LC, CLC, and nano-LC in the period 2009–2013, while for CE, those from 2012 up to the review draft.

Section snippets

Analysis of pharmaceutical drugs by capillary electrophoresis

Since its early application in drug analysis [25], [26], CE has become an established routine analytical method and together with HPLC, is the most used separation technique in pharmaceutical field. Remarkable features, such as high efficiency, great resolution power, rapid analysis, automation, low sample consumption and low costs as well as the hyphenation with MS detectors, make CE an increasing popular analytical tool for pharmaceuticals analysis. Additionally, the development of various

Analysis of pharmaceuticals by miniaturized chromatography and capillary electrochromatography

Although the advantages mentioned in Section 1, miniaturized versions of liquid chromatography (including CEC) are still no largely exploited in several analytical fields, including the pharmaceutical one. Most preconceptions against nano-/micro-/CLC methodologies originate from the need of new instrumentations, rearrangement of well established and validated methods, knowledge of technical features [3]. However, very low sample required per analysis, easy hyphenation with MS, reduced analysis

Chiral analysis of pharmaceutical drugs by miniaturized techniques

Chiral separations are an important and old task in analytical chemistry, especially in pharmaceutical field where it is estimated that about half of the drugs in use are chiral. It is well known that enantiomers of a racemic drug often differ considerably in their pharmacological activity, pharmacokinetics and toxicity. Only one of the enantiomers can be responsible for the desired activity, while the other may show no therapeutic effects or even side effects and toxicity; in addition the

Conclusions

The aim of this review was to give an update of the role of miniaturized separation techniques in the pharmaceutical field. The necessity of fast analyses and high-throughput methodologies, as well as the great concern about environmental pollution, has brought to the reemergence of these techniques. Miniaturized systems, and specifically CE, CEC and miniaturized versions of chromatography (micro-, C-, and nano-LC), offer several advantages, such as short analysis time, the need of small sample

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ReviewCurrent applications of miniaturized chromatographic and electrophoretic techniques in drug analysis

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Analysis of pharmaceutical drugs by capillary electrophoresis

Analysis of pharmaceuticals by miniaturized chromatography and capillary electrochromatography

Chiral analysis of pharmaceutical drugs by miniaturized techniques

Conclusions

Capillary methods for drug analysis

J. AOAC Int.

Current trends in modern pharmaceutical analysis for drug discovery

Drug Discov. Today

Nano-liquid chromatography in pharmaceutical and biomedical research

J. Chromatogr. Sci.

Enantiomeric separations by means of nano-LC

J. Sep. Sci.

Recent applications in nano-liquid chromatography

J. Sep. Sci.

Advances in nutrigenomics research: novel and future analytical approaches to investigate the biological activity of natural compounds and food functions

J. Pharm. Biomed. Anal.

Integrative omics, pharmacoproteomics, and human body fluids

Microextraction techniques combined with capillary electrophoresis in bioanalysis

Anal. Bioanal. Chem.

A critical review in calibration methods for solid-phase microextraction

Anal. Chim. Acta

Critical overview of selected contemporary sample preparation techniques

J. Chromatogr. A

Miniaturized separation techniques in glycomic investigations

J. Chromatogr. B

Recent advances in sheathless interfacing of capillary electrophoresis and electrospray ionization mass spectrometry

J. Chromatogr. A

CE–MS for proteomics: advances in interface development and application

J. Proteomics

Coupling capillary electrochromatography with mass spectrometry by using a liquid-junction nano-spray interface

J. Chromatogr. A

Recent developments in microcolumn liquid chromatography

J. Chromatogr. A

On-line preconcentration in capillary electrochromatography using a porous monolith together with solvent gradient and sample stacking

Anal. Chem.

On-line preconcentration methods for capillary electrophoresis

Electrophoresis

On-line sample preconcentration techniques in micellar electrokinetic chromatography

J. Pharm. Biomed. Anal.

Combination of two different stationary phases for on-line pre-concentration and separation of basic drugs by using nano-liquid chromatography

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Contemporary sample stacking in CE: a sophisticated tool based on simple principles

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Enantiomer separation of drugs by capillary electromigration techniques

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Enantioseparation of chiral drugs and current status of electromigration techniques in this field

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Current applications of miniaturized chromatographic and electrophoretic techniques in drug analysis

Development and validation of a capillary electrophoresis method with capacitively coupled contactless conductivity detection (CE-C⁴D) for the analysis of amikacin and its related substances