Avoiding Compound Losses and Assuring Safe Operation in Automated High-Throughput Sample Purification T. Piecha, W. Niedner, F. Arnold*, Dionex Softron GmbH, Munich, Germany * Author to whom correspondence should be addressed. E-mail address: [email protected] Abstract Automated high-throughput sample purification has become a powerful tool for the delivery of pure compounds for biological activity screening in the pharmaceutical discovery process. With the large number of samples delivered by combinatorial chemistry, modern autopurification systems often have to work fully automated and unattended for 24 hours a day. In this operation mode, several security aspects have to be considered to meet industrial safety requirements. The potential loss of samples in case of unexpected system disturbances is an additional concern. Safety Features for Operators and Instrumentation The Safety System Platform not only enables optimal storage and organization of all system components and supplies, but also provides a number of sophisticated design elements for safe operation. Both surface levels of the platform are divided into three individual sections, each containing several drain channels. This design restricts the area of solvent pools in case of spillages reducing a liquid’s evaporation rate. During the development of a new purification system, we paid particular attention to safety and reliability aspects. It was our goal to prevent sample losses or hazardous conditions with advanced diagnostic and safety functions. This presentation describes the diagnostics and safety functions implemented in our APS Autopurification Systems. They include a system platform with ventilated eluent and waste cupboards, a fume hood, and a leak detection system; sensors for waste and eluent level monitoring; a computer-failure detection system; monitoring of several pressure limits and of proper operation of the flow splitting and detection systems; and several system wellness functions built into the instruments. These functions allow safe, smooth, and reliable unattended system operation over long time periods. They increase system uptime and reduce cost of operation. Introduction Preparative high performance liquid chromatography (HPLC) applications apply to the production of compounds in the µg to g range. Contrary to analytical HPLC, these methods require high solvent flow rates ranging from 10 mL/min up to several hundred mL/min. The large amounts of pumped solvents imply a much higher risk potential for operators and instruments in case of system disturbances. Today, legislation and industry set high standards regarding work and environmental safety. In order to prevent hazardous conditions in the laboratory, reliable and immediate safety actions have to be performed to protect users and instruments. Figure 1. The two-leveled Safety System Platform provides optimized arrangement of all modules for maximum performance and safety. The spillways (Figure 2) on the surface guide liquids quickly and safely to the waste container via drainholes (Figure 3). Another important consideration is the safety of the handled samples. Quite often the raw products to be purified are the result of a laborious process that required large amounts of expensive labor time and chemicals. For this reason, a purification system must not lose or waste samples if any interference occurs. PITTCON 2006 Presentation PITTCON 2006 Presentation Eluent Level Sensors Separated Sections Drain Channels Figure 2. Spillways of platform surface sections. Ventilation Orifice Grounded Floor Drain Hole Figure 4. Grounded and ventilated solvent cabinet. Drainage System Figure 3. Drainhole and drainage system of Safety System Platform. Figure 5. Rear view of solvent cabinet with ventilation. Below the instrument levels, the platform holds two cabinets for the storage of eluent and waste casks (Figure 4). Grounding of the cupboards prevents spark formation caused by electrostatic discharge. The solvent compartments consist of flame resistant material and can be connected to a ventilation system (Figure 5). A fume hood (Figures 1 and 6) is specially designed to remove larger amounts of toxic vapors quickly without compromising sample and system accessibility. It covers the Sample and Fraction Manager (SFM™) and hence the area where larger amounts of open solvents are regularly present. This further enhances the comprehensive passive safety features of the APS. Avoiding Compound Losses and Assuring Safe Operation in Automated High-Throughput Sample Purification Figure 8. Waste level sensor with specialized adapter. Figure 6. Fume hood providing toxic vapor removal and all around system access. The main active safety element of the purification system is the Safety and Solvent Monitor (SSM). This independent device monitors the eluent levels, the waste level, and provides leakage and computer failure detection (Figure 7). In case of a computer failure, the software loses control of the system and the pumps might continue pumping until they run out of eluent. The SSM’s computer failure detection recognizes communication errors between hardware and software and is able to automatically shut down the complete system. The individual modules that make up an APS system, such as the UltiMate™ 3000 pumps, the UltiMate 3000 UV detectors, and the Sample and Fraction Manager (SFM), offer numerous wellness functionalities that allow continuous status monitoring of critical wear parts and detect small problems long before they become big problems. The following list provides an overview of the most important wellness features: UltiMate 3000 Pump Series Figure 7. Safety and Solvent Monitoring Module SSM. The SSM’s solvent-level sensor alerts the software if an eluent shortage occurs and enables Chromeleon® to stop the batch. This prevents damage to the instrumentation due to the system running out of eluents. Overfilling the waste container is prohibited by a reliable resonating sensor. The system detects the waste level reaching its maximum in time to finish the current run. A uniquely designed adapter for the waste containers allows the use of the very same sensor also for leakage detection. In case of a spillage the sensor requires only a few mL of liquid to send a signal to the system control software, thus triggering immediate action (Figure 8). • Patented piston-seal monitoring detects piston-seal aging • Active rear-seal wash system extends the lifetime of pistons and piston seals • Programmable upper and lower pressure limits prevent instrument damage as warnings prevent the instrument from extreme operating conditions • A leak sensor detects leakages and warns operators of module damage • A self-test procedure upon pump start checks for module integrity and prevents an operator from using a defective device • Acoustic signals warn operators of malfunctions PITTCON 2006 Presentation UltiMate 3000 Variable Wavelength and Photo Diode Array Detectors • Counters for the number of lamp ignitions, the lamp intensity, and the lamp age provide updates regarding detector performance • Counters detect the cumulated operation time of the detector optics and of the installed flow cell • Leak sensors detect leakages and warn operators of module damage SFM Sample and Fraction Manager • Counters for injection valves and syringe plungers monitor the workload put on these wear parts • Unique anti-collision management assures safe operation of the analytical and preparative arm at the same time • In case of a system failure, the SFM can put back a previously drawn sample from the syringe into the respective vial. There is no need for manual interference and no danger of cross contamination during the recovery of a sample from a syringe • Programmable acoustic signals provide information about system actions even if the user is not actively observing the system Safety Features for Sample Handling In addition to the active and passive security features for the protection of operators and instrumentation, we have developed additional elements to avoid the loss of precious samples. The APS series offers fraction collection from crude sample mixtures either in manual or automatic mode. Although there are sophisticated safety features and software controls, it is still possible to lose a sample if, for example, a user chooses improper fraction collection thresholds. An operator can utilize a manual switching valve (Figure 9) to direct the effluent after the fraction collector into a separate beaker instead of into the waste container. In case of an unexpected malfunction the user can still recover valuable samples from this extra container. Manual Switching Valve Figure 9. Manual Switching Valve for saving effluent from going into waste. The intelligent reaction to hazardous conditions with flexible software programming is an exceptionally powerful tool and a perfect completion of the hardware related safety and wellness features. Chromeleon enables the definition of “triggers” that perform user defined commands as soon as certain conditions become true. The instrument method editor provides a convenient dialog for the creation of triggers. A trigger example is shown in Figure 10. Figure 10. Trigger example in Chromeleon. This trigger switches a valve into position 1 as soon as the signal value of the UV channel 1 exceeds 200 mAU for 2 s. Avoiding Compound Losses and Assuring Safe Operation in Automated High-Throughput Sample Purification With the help of triggers, it is possible to flexibly respond to requirements not already covered by the features described above. The following list provides an overview of additional sample protection features we implemented in the APS Autopurification series using triggers: • Additional upper and lower pressure limits as an early-warning system. If the system reaches these limits it can still complete a sample run and does not lose the sample by immediate pump shutdown • Recognition of disturbances in splitter, injection, and detection system. If Chromeleon detects no peaks meeting the collection criteria in several consecutive runs, an alert results and the batch can be stopped automatically • Monitoring of available fraction tubes. Prior to the start of a purification run, Chromeleon checks if enough fraction collection capacity remains Due to the flexible and unlimited use of Chromeleon triggers, users can develop even more solutions for their individual requirements. Time-stamped audit trails record all trigger executions and system actions making system monitoring and troubleshooting easy. Prior to the start of a batch, the Chromeleon Ready Check verifies if it is actually possible to perform automated batch processing. Within a couple of seconds, the software checks critical parameters such as device communication, required files, disk memory, and estimated eluent consumption. This procedure ensures that all instruments, methods, and resources are available and operating correctly, thus avoiding sample loss because of user or instrument errors. Conclusion Unattended and automated operation of preparative purification systems is a common task in the pharmaceutical, chemical, and biochemical industries today. Compared to analytical HPLC, the safety and reliability requirements of preparative applications are even more demanding because users have to handle considerable amounts of toxic and flammable chemicals. For preparative systems, it is crucial to protect operators, samples, and instrumentation from hazardous conditions. In order to fulfill these requirements, we implemented the following features during the development of the APS Autopurification Systems: • Proper module arrangement and accessibility for optimum system performance and maintenance • Intelligent solvent handling, quick management of solvent spillages, and rapid removal of flammable and toxic vapors to avoid instrument damage and health risks • Prevention of electrostatic discharges to reduce explosion hazards • Continuous status monitoring of critical wear parts to avoid unexpected disturbances and to allow scheduled maintenance • Flexible and scaleable software containing freely programmable triggers for maximum automation and operator convenience The Dionex APS Autopurification Systems, with the single point Chromeleon control, provide preparative chromatographers with a turnkey solution for safe and reliable unattended operation of their complex purification tasks. SFM and UltiMate are trademarks and Chromeleon is a registered trademark of Dionex Corporation. Passion. Power. Productivity. Dionex Corporation North America Europe Asia Pacific 1228 Titan Way P.O. Box 3603 Sunnyvale, CA 94088-3603 (408) 737-0700 Sunnyvale, CA (408) 737-8522 Westmont, IL (630) 789-3660 Houston, TX (281) 847-5652 Atlanta, GA (770) 432-8100 Marlton, NJ (856) 596-0600 Canada (905) 844-9650 Austria (43) 1 616 51 25 Belgium (32) 3 353 4294 Denmark (45) 36 36 90 90 France (33) 1 39 30 01 10 Germany (49) 6126 991 210 Italy (39) 06 66 51 5052 The Netherlands (31) 161 43 43 03 Switzerland (41) 62 205 99 66 United Kingdom (44) 1276 691722 Australia (61) 2 9420 5233 China (852) 2428 3282 India (91) 22 28475235 Japan (81) 6 6885 1213 Korea (82) 2 2653 2580 www.dionex.com LPN 1801-01 04/06 PITTCON 2006 Presentation ©2006 Dionex Corporation