crab that produces a gel precipitate with endotoxins. The precipitate is measured by turbidity. The Sandoz system can evaluate 32 samples in 150 min while protecting analytical samples from human endotoxin contamination. During the analysis the robot dispenses reagent standards, makes serial dilutions, incubates samples, and reads turbidity—all with 1% reproducibility. Robots can help not only to attain test results but also to avoid false positives from bacterial contamination. According to Nicholas d'Abeloff of Precision Robots, Inc., a laboratory that annually tests 2000 batches of injectable drugs for bacterial contamination will commonly encounter five batches producing a false positive result. These false positives can cost a pharmaceutical company as much as $100,000 per year from rejected lots, retesting costs, storage, and lost orders. Typically, 20 samples are tested from each batch of several thousand drug vials. A true positive result would find many of the tubes contaminated. However, if just one vial shows bacterial contamination, the analysis is suspect and can be redone. A false positive
is probable and declared if even one tube is found to be contaminated in the retest. Yet the entire batch must be discarded. The government recently banned second retesting and there is the prospect, according to d'Abeloff, of eliminating the first retest. Thus the need for reliable sterility testing is even more urgent. Traditionally, manual sterility testing uses what is termed a body glove box. This costly system has been replaced by a small stand-alone robotic system operating in a sterile laminar air-flow hood. The robot can handle 80 containers per hour, and it replaces two technicians. The only access to the robot is through a bottom door below the laminar air-flow region, preventing the introduction of bacteria. Both robotic and manual sterility testing require cleaning a vial septum and inserting a syringe to draw the sample into a filter/incubation container. Bacterial growth in the container after seven days indicates a positive result. According to d'Abeloff, after four years of using the robotic system no false positives have been declared. A clever application of robots in the biotechnology industry was described
by Steve Hamilton from Lilly Research Labs in Indianapolis. Hamilton and his co-workers automated a procedure for breaking open bacteria and then isolating intact DNA. These are the first two steps in a restriction enzyme analysis that determines whether fermentation broth bacteria are mutating. (The other steps, cleaving the DNA into small segments and running capillary electrophoresis, are done manually.) In automating, the Lilly researchers made minimal changes from the manual method. All the steps are performed in 12 X 75 mm test tubes. The procedure requires reagent additions, chilling, vortex mixing, incubations at three different temperatures, centrifugations, and drying. Some steps are combined: Several reagents are premixed, and vortexers heat or cool samples with a liquid heat exchanger. The Lilly scientists also developed their own 3000-rpm, 1500-g centrifuge. To maximize throughput, they overlapped steps such that samples exit the system every 14 min. However, said Hamilton, "A disadvantage of interleaving steps is that it is virtually impossible to know what is going on in any
NEW GENERATION TIME-OF-FLIGHT SIMS TFS SURFACE ANALYZER Now you can simultaneously image with high mass resolution! Surface Microanalysis of: • Polymers • Pharmaceuticals • Semiconductors • Biomolecules • Ceramics Applications In: • Organic Microanalysis • Tissue Targeting • Wafer Contamination • Particle Analysis
CHARLES EVANS&ASSOCIATES® SPECIALISTS IN MATERIALS CHARACTERIZATION
301 Chesapeake Dr., Redwood City, CA 94063 (415) 369-4567 Telex 172747 FAX (415) 369-7921 See us at PittCon in booth 3209 CIRCLE 35 ON READER SERVICE CARD
ANALYTICAL CHEMISTRY, VOL. 62, NO. 5, MARCH 1, 1990 · 339 A
