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Reproducibility (n = 8) Peak 1: 0.10% RSD, Peak 2: 0.05% RSD, Peak 3: 0.07% RSD
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News systematic study Veronika Meyer of the University of Bern (Switzerland) showed that they can affect the analytical results. For this study, Meyer ran simple analytes Combinatorial such as methylethylketone through a remethods to reshape versed-phase HPLC system using a 95% analytical water/5% isopropanol mobile phase at a rate of 1 mL/min with UV detection. Varychemistry? ing amounts of leakage were introduced by loosening the appropriate fittings. Combinatorial chemistry has been hailed Meyer found that leaks between the as a major new approach to rapidly finding new candidate drugs for the pharmaceuti- pump and injection valve led to a broadencal industry, but could analytical chemists ing of peaks, longer retention times, and benefit from this novel technique? "It is an increased peak areas. Leaks between the injection valve and column also increased opportunity to design separation techretention times but lowered peak heights niques," structural biologist Gregory and had only a small influence on peak Petsko of Brandeis University told the area. Leaks between the column and deaudience convening in San Francisco for tector cell have little effect because the HPLC '96. "It will change the shape of typical HPLC detector is concentration your world." dependent and not mass dependent. Combinatorial chemistry is the production of all possible combinations of a basic set of modular components. "It is like playing with Legos," said Petsko, referring to the building block toy. Petsko, a founding Plastic column scientist for the combinatorial chemistry firmArQule, Inc. (Medford, MA), pointed Fused silica has been the most out that combinatorial methods produce widely used column material for CE. thousands of chiral molecules cheaply and However, biopolymers can stick to quickly using automated methods. "These its surface. Plastic materials could are tailor-made materials for separations." offer a solution to this problem, but most studies with plastics have been As an example, prior to the meeting, limited to materials transparent to Petsko chose at random the target analyte UV light. By inserting a fused-silica proteinase K and screened it for affinity detection window into the plastic against a 2000-compound array that ArQule column, Heinz Engelhardt and had previously generated for its drug work. Hanne Bayer of the Univeritat des "We have this library 'on the shelf'," he Saarlandes (Germany) have been said. The library did produce a 'hit', a moleable to broaden their studies to incule with a strong affinity for the proteinclude plastics with poor UV transmitase. This compound could then be the basis tance. Moreover, by modifying the for producing new combinatorial libraries surface, they can develop plastic color the beginning of a new product "The umns with desirable separation propwhole operation took a week to develop this erties, says Bayer. new chromatographic material," said Petsko. For example, the researchers According to Petsko, the combinatorial added polyvinyl alcohol to the revolution has now advanced to a point buffer solution in order to dynamiwhere practitioners, beginning with a mocally coat the surface of EVA (a lecular "scaffold," can directly synthesize in polymer of ethylene and vinylwater or methanol arrays of chiral comacetate) columns and found that pounds, each in a single well with a purity this CE column displayed good sepof 85% or higher. Although this generates arations for basic proteins. This lots of molecules for pharmaceutical or same type of separation chemistry chromatographic testing, it also presents an was observed when nylon surfaces analytical challenge in further purifying were permanently modified using these chiral mixtures, he said. "We need butanediol diglycidylether, which better ways to clean up chiral compounds." then links with hydroxyethyl cellulose. According to Bayer, they have also been able to modify a polyester Leaky science surface to create a column for reverse osmotic flow. For most chromatographers, leaks in the HPLC system are an annoyance, but in a NEWS FROM HPLC '96
