J. Sep. Sci. 2007, 30, 579 – 585 L. Sµnchez et al. 579 Laura Sµnchez 1 Ramón Gonzµlez 1 Antonio L. Crego 2 Alejandro Cifuentes 1 1 Institute of Industrial Fermentations (CSIC), Juan de la Cierva 3, Madrid, Spain 2 Departmento de Química Analítica, Facultad de Ciencias, Universidad de Alcalµ, Alcalµ de Henares, Madrid, Spain Original Paper A simple capillary gel electrophoresis approach for efficient and reproducible DNA separations. Analysis of genetically modified soy and maize It is generally assumed that in order to achieve suitable separations of DNA frag- ments, capillary gel electrophoresis (CGE)-coated capillaries should be used. In this work, a new method is presented that allows to obtain reproducible CGE separa- tions of DNA fragments using bare fused-silica capillaries without any previous coa- ting step. The proposed method only requires: (i) a capillary washing with 0.1 M hydrochloric acid between injections and (ii) a running buffer composed of Tris- phosphate-ethylenediamine tetraacetic acid (EDTA) and 4.5% of 2-hydroxyethyl cel- lulose (HEC) as sieving polymer. The use of this new CGE procedure gives highly resolved and reproducible separations of DNA fragments ranging from 50 to 750 bp. The separation of these DNA fragments is accomplished in less than 30 min with efficiencies up to 1.7610 6 plates/m. Reproducibility values of migration times (given as %RSD) for the analyzed DNA fragments are better than 1.0% (n = 4) for the same day, 2.2% (n = 16) for four different days, and 2.3% (n = 16) for four different capillaries. The usefulness of this separation method is demonstrated by detecting genetically modified maize and genetically modified soy after DNA amplification by PCR. This new CGE procedure together with LIF as detector provides sensitive anal- ysis of 0.9% of Bt11 maize, Mon810 maize, and Roundup Ready soy in flours with S/ N up to 542. These results demonstrate the usefulness of this procedure to fulfill the European regulation on detection of genetically modified organisms in foods. Keywords: Capillary electrophoresis / Corn / Food analysis / GMO / Transgenic food / Received: May 11, 2006; revised: May 22, 20066; accepted: May 26, 2006 DOI 10.1002/jssc.200600195 1 Introduction According to the European regulations 1829/2003/CEE and 1830/2003/CEE, any foodstuff containing more than 0.9% of genetically modified organism (GMO, basically corn and soy) derived material must be unambiguously labeled as “GMO containing”. Enforcement of these rules requires the development of appropriate sensitive detec- tion methods for GMOs in food matrices. The easiest and cheapest procedure to carry out such detection is to amplify a DNA fragment specific of the GMO by PCR fol- lowed by agarose gel electrophoresis plus ethidium bro- mide staining of the amplification products. However, the limited sensitivity and resolution of slab gel electro- phoresis imposes important qualitative and quantitative restrictions to this type of analysis [1, 2]. Among the different procedures proposed to analyze GMOs based on specific DNA sequences [1 – 3], capillary gel electrophoresis (CGE) has shown to be an interesting alternative to carry out such analyses. Namely, the use of CGE together with polymer solutions has become one of the main analytical techniques to separate DNA frag- ments [4 – 8], as already demonstrated through the Human Genome Project [9, 10]. The use of CGE together with adequate polymer solu- tions, apart from providing the well-known advantages related to the use of electrophoresis in a capillary format (i. e., speed of analysis, automation, and quantitative anal- ysis), results in efficient separations of ssDNA and dsDNAs. On the other hand, it is well known that in order to achieve well-resolved and reproducible separations in reasonable times, these CGE separations have to be per- Correspondence: Dr. Alejandro Cifuentes, Institute of Industrial Fermentations (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain E-mail: acifuentes@ifi.csic.es Fax: (+34)-91-564-4853 Abbreviations: CGE, capillary gel electrophoresis; EDTA, ethyl- enediamine tetraacetic acid; GMO, genetically modified organ- ism; HEC, 2-hydroxyethyl cellulose; CTAB, N-cetyl-N,N,N-tri- methyl-ammonium bromide; PVA, polyvinylalcohol i 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.jss-journal.com