Review MEKC: A powerful tool for the determination of amino acids in a variety of biomatrices The continued publication from year to year of new MEKC formulations for the analysis of amino acids provides evidence that both CZE and MEKC still have a great power of attraction in this area. The present review intends to cover the literature on MEKC of amino acids from 2007 until present: it has been planned to follow the same format of our previous review (Electrophoresis 2008, 29, 224–236) representing its ideal conti- nuation. In addition to methodological developments, the more recent practical appli- cations of MEKC procedures for the determination of amino acids in different matrices will also be described here as an evidence, once again, of the suitability of this technique on samples of different origin. Keywords: Amino acids / Chiral additives / MEKC / Surfactants DOI 10.1002/elps.200900366 1 Introduction Owing to the significant role that free amino acids play in many important areas, their detection/quantification in complex matrices represents a challenging task that may provide useful information in diverse research fields [1–9]. For example, the measurement of trace levels of these components in biological media is often used to study control and regulation processes in living organisms or to predict the likely course of a disease and to monitor and assist in the management of the disease [10–17]. Among the variety of methods that have been developed for their detection [18–34], CE has easily emerged as an excellent technique. The publication over the last two decades of a large number of interesting articles/reviews focused on the application of CE to the separation/detection of amino acid mixtures, has provided considerable evidence that both CZE and MEKC have a great power of attraction in this area [35–40]. Owing to its intrinsic advantages, which include high-resolution power, speed of analysis, and handling of very small sample volumes, CE may suitably respond to the demand of methods even more sensitive, more selective, or simpler to perform. In particular, decisive methodological progress was achieved with MEKC, a CE mode in which the combination of electrokinetic migration and the partitioning mechanism of solute between the bulk solution and the micelles makes the differentiation of analytes with similar physico-chemical properties, for example, of amino acids, very efficient. Hence, no wonder that a good number of protocols dealing with new CE developments in amino acid analysis and novel applications on several types of bioma- trices continues to appear in the literature. This would make the time ripe for the preparation of updated review articles on this topic. In this respect, the present report intends to cover the literature from 2007 until present: it was planned to follow the same format of our previous review [41], representing its ideal continuation. In addition to metho- dological developments, the more recent practical applica- tions of MEKC procedures for the determination of amino Simona Viglio Marco Fumagalli Fabio Ferrari Paolo Iadarola Department of Biochemistry, University of Pavia, Pavia, Italy Received June 8, 2009 Revised July 7, 2009 Accepted July 12, 2009 Abbreviations: 3-bFurl, sodium n-dodecyl 1-thio-b-l- fucopyranoside-3-hydrogen sulphate; BDS, 1-butyl-3- methylimidazolium dodecyl sulphate; BODIPY-FL, fluorescently labelled boron dipyrromethene; Brij 35, polyethylene glycol dodecyl ether; CBQCA, 3-(4-carboxyl- benzoyl)quinoline-2-carboxaldehyde; CDDS, chlorododecyl dimethylsilane; CFSE, 5-carboxyfluorescein succinimidyl ester; DES, desmosines; DHAMAP, 3-[(3-dehydroa- bietamidopropyl)dimethylammonio]-1-propanesulphonate; DNS, dansyl; DOPA, 3,4-dihydroxyphenylalanine; GABA, gamma-aminobutyric acid; HT, Hadamard transformation; IDES, isodesmosine; NBD-F, 4-fluoro-7-nitrobenzo-2,1,3- oxadiazol; NBD-Cl, 4-chloro-7-nitrobenzo-2-oxa-1,3diazol; NDA, naphthalene-2,3-dicarboxaldehyde; PAABS-F, p- acetamidobenzenesulphonylfluoride; PAPS, 3-(N,N- dimethylhexadecylammonium) propanesulphonate; PB, Pacific Blue succinimidyl ester; poly-l-SUCAA, polysodium N-undecenoxycarbonyl-l-amino acidate; poly-l-SUCAAS, polysodium N-undecenoxycarbonyl-l-amino acid sulphates; SIFA, N-hydroxysuccinimidyl fluorescein-O- acetate; SMA, sodium maleopimaric acid; STDC, sodium taurodeoxycholate; TAMRA, carboxytetramethylrhodamine succinimidyl ester; WT, wild-type Correspondence: Professor Paolo Iadarola, Department of Biochemistry, University of Pavia Via Taramelli 3/B, 27100 Pavia, Italy E-mail: piadarol@unipv.it Fax: 139-382-423108 & 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.electrophoresis-journal.com Electrophoresis 2010, 31, 93–104 93