Field amplified separation in capillary electrophoresis: a capillary electrophoresis mode

In field-amplified injection in capillary electrophoresis (CE), the capillary is filled with two buffering zones of different ionic strength; this induces an amplified electrical field in the low ionic strength zone and a lower field in the high ionic strength zone, making sample stacking feasible. The electroosmotic flow (eof) usually observed in CE, however, displaces the low field zone and induces an extra band broadening preventing any CE separation in the field-amplified zone. These limitations have originated the restricted use of field amplification in CE only for stacking purposes. For the first time, in this work it is theoretically shown and experimentally corroborated that CE separation speed and efficiency can simultaneously be increased if the whole separation is performed in the field-amplified zone, using what we have called field amplified separation in capillary electrophoresis (FAsCE). The possibilities of this new CE mode are investigated using a new and simple coating able to provide near-zero eof at the selected separation pH. Using FAsCE, improvements of 20% for separation speed and 40% for efficiency are achieved. Moreover, a modified FAsCE approach is investigated filling the capillary with the high ionic strength buffer up to the interior of the detection window. Under these conditions, an additional 3-fold increase in sensitivity is also observed. The most interesting results were obtained combining the short-end injection mode and this modified FAsCE approach. Under these conditions, a part of a 3-fold improvement in efficiency and sensitivity, the total analysis time was drastically reduced to 40 s, giving rise to a time reduction of more than 7-fold compared to normal CE. This speed enhancement brings about one of the fastest CE separations achieved using capillaries, demonstrating the great possibilities of FAsCE as a new, sensitive, efficient, and fast CE separation mode.     

Capillary electrophoresis time-of-flight mass spectrometry for comparative metabolomics of transgenic versus conventional maize

In this work, capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS) is proposed to identify and quantify the main metabolites in three lines of genetically modified (GM) maize and their corresponding nontransgenic parental lines grown under identical conditions. The shotgun-like approach for metabolomics developed in this work includes optimization of metabolite extraction from GM and non-GM maize, separation by CE, online electrospray-TOF-MS analysis, and data evaluation. A large number of extraction procedures and background electrolytes are tested in order to obtain a highly reproducible and informative metabolomic profile. Thus, using this approach, significant differences were systematically observed between the detected amounts of some metabolites in conventional varieties (Aristis, Tietar, and PR33P66 maize) compared with their corresponding transgenic lines (Aristis Bt, Tietar Bt, and PR33P66 Bt maize). Results point to some of these metabolites as possible biomarkers of transgenic Bt maize, although a larger number of samples needs to be analyzed in order to validate this point. It is concluded that metabolomics procedures based on CE-TOF-MS can open new perspectives in the study of transgenic organisms in order to corroborate (or not) their substantial equivalence with their conventional counterparts.     

Characterization of cheese proteolysis by capillary electrophoresis and reverse-phase HPLC analyses of peptides

 The possibilities of reverse-phase high performance liquid chromatography (RP-HPLC) and capillary electrophoresis (CE) when used for separation of cheese peptides are discussed. A CE method using a coated capillary column and a low pH buffer was developed to analyze the water-soluble fraction of a 6-month-old cow’s milk cheese. The CE patterns were compared with the chromatograms obtained by RP-HPLC using a C18 column and a gradient of acetonitrile in water. The CE method gave shorter analysis times but RP-HPLC provided lower coefficients of variation of the retention times and better detection limits. In addition, the elution behavior of peptides in CE strongly depended on the sample matrix. The results show that both techniques provide complementary information for the analysis of cheese peptides. Received: 10 June 1997 / Revised version: 20 October 1997     

Modelling the effect of temperature and time on the performance of a copper electrowinning cell based on reactive electrodialysis

A temperature- and time-dependent mathematical model for the operation of a laboratory-scale copper electrowinning cell based on reactive electrodialysis (RED) has been developed. The model is zero-dimensional. The cathodic reaction was copper electrodeposition and the anodic reaction was ferrous to ferric ion oxidation. The catholyte was aqueous cupric sulphate and the anolyte was aqueous ferrous sulphate, both in sulphuric acid. Catholyte and anolyte were separated by an electrodialytic anion membrane. The model predicts the effect of temperature and time on: (a) cathodic and anodic kinetics, (b) speciation of catholyte and anolyte, (c) transport phenomena in the electrolytes and (d) ion transport through the membrane. Model calibration and validation were carried out. Its predictions are in good agreement with experiments for: amount of deposited copper, amount of produced Fe(III) species, cell voltage and specific energy consumption.     

The legal status of reverse engineering of computer software

Reverse engineering of computer software has assumed greater importance in recent years because of the need to examine legacy code to remove the year 2000 bug. There are different types of reverse engineering based on the level of abstraction of the code to be reengineered; machine code, assembly code, source code or even CASE code. We describe the different types of reverse engineering and the extent of copyright protection for software. The most common uses of reverse engineering are described. This provides for a comparative overview of the legal standing on reverse engineering at the international level. We propose challenges to the global electronic community in relation to existing and future legislation in the area of reverse engineering and protection of digital works.     

Improved methodology for the characterisation of transgenic Bt-11 maize cultivars using RP-HPLC profiles of albumin,globulin, prolamin,and glutelin protein fractions and chemometric analysis

A clear differentiation between Bt-11 transgenic and isogenic non-transgenic maize cultivars has successfully achieved analysing the perfusion and monolithic RP-HPLC profiles of the albumin, globulin, prolamin, and glutelin maize fractions together with a discriminant analysis. Significant differences between transgenic and isogenic non-transgenic cultivars were observed in the chromatograms obtained from any of the four protein fractions. The application of linear discriminant analysis to the area percentages corresponding to every peak detected in every protein fraction was successfully employed for the classification of transgenic Bt maize lines obtaining a global percentage of correct classification of 100%. For perfusion RP-HPLC, the variables with more discriminant power and prediction capability were the following peaks: peaks 1 and 3 for albumins, peak 2 for globulins, peaks 3 and 6 for prolamins, and peaks 7 and 8 for glutelins. In the case of monolithic RP-HPLC, the variables were peaks 2 and 3 for albumins, peak 5 for globulins, peaks 5, 6, and 7 of prolamins, and peak 10 for glutelins.     

The comparative effect of individually-constructed vs. collaboratively-constructed computer-based concept maps

The researchers investigated the comparative effects of individually-constructed and collaboratively-constructed computer-based concept mapping on middle school science concept learning. One hundred and sixty one students completed the entire study. Using prior science performance scores to assure equivalence of student achievement across groups, students were assigned to three groups: a self-selected study strategy group, an individual-concept mapping group, and a collaborative pairs – concept mapping group. Collaboratively and individually-constructing computer-based concept maps had equally positive effects on seventh grade middle school science concept learning as measured on a comprehension test. However, the students who collaboratively constructed concept maps created significantly higher quality concept maps than those who individually constructed concept maps indicating deeper conceptual understanding.     

Rapid analysis of whey proteins from different animal species by reversed-phase high-performance liquid chromatography.

This paper explores the possibilities of reversed-phase high performance liquid chromatography (RP-HPLC) for analysing whey proteins from the milk of cows and other animal species. An RP-HPLC method is proposed to separate and quantify bovine whey proteins. Using this method, bovine serum albumin, alpha-lactalbumin, beta-lactoglobulin A and beta-lactoglobulin B were separated in less than 7 min. It is demonstrated that irreversible adsorption of bovine whey proteins occurs on unused columns (i.e. those not previously used to separate proteins). Therefore, prior conditioning of the column with whey proteins is required for valid protein quantification. Conditioning can be achieved by eluting a large amount of at least one of the bovine whey proteins through the unused column. The calibration curve (peak area vs. protein concentration) for the main bovine whey proteins was linear. This method also allowed good separation of caprine and ovine whey proteins and separation of some homologous whey proteins of different animal species. Detection of milk mixtures from different animal species was carried out using this method.