Mobile troubleshooting

In order to evaluate the process, analytical methods need to be in place which monitor the process performance and troubleshoot the process. Analytical methods are needed to determine the feed composition, the column effluent or product-pool composition, the mobile-phase composition and the regeneration-solution composition. 

Many detectors track the number of hours the lamp is ignited. Although the lamp life may vary, the detector s meter reading can be a helpful guide for troubleshooting. Lamps can sometimes operate for more than 2000 h. To distinguish a lamp problem from air bubbles, one should stop the mobile phase flow. A lamp problem will persist when the flow is stopped, whereas, if the problem is due... 

If initial SST fails, the analyst should stop the sequence immediately, diagnose the problem, make necessary adjustments or repairs, and re-perform SST. Analysis of actual samples should commence only after passing all SST limits, not only the failed criteria. Most SST failures are traced to problems from the autosampler, pump, column, or mobile phase (see Chapter 10 on troubleshooting hints). If one of the interspersed SSS injections fails, data from all samples after the last passing SSS become invalid and must be repeated.15... 

Chapter 7 helps you gain confidence in yourself by preparing you to troubleshoot difficult interview situations that may arise. In other words how to anticipate problems before they happen. Now that you know how to mobilize your success stories in order to show your talents in the best light, you need to know what types of questions you will be asked and the best way to answer them. Chapter 7 provides a road map that shows you all the pitfalls, hairpin curves, and detours. 

Retention can also be influenced by other components of the mobile phase present in small concentrations. The user may not be aware of the presence of these components. In such a case, troubleshooting can be quite difiicult. A common example of this problem is water in normal-phase chromatography. Water is always present in all solvents (see Table 9.3) and can shift retention substantially. However, this is not the only example. For instance, a contamination of methanol with amines that influences the retention of basic analytes in reversed-phase chromatography has been observed. To avoid this situation, the use of HPLC-grade solvents is generally recommended for HPLC applications. 

The most common cause of extra peaks in the chromatogram is the sample itself. The source of the sample may be different, it may have decomposed or aged otherwise. It should be easy to verify whether a particular sample is the source of the extra peak by comparison with samples from other sources or the injection of standards or blanks. If the injection of standards or blanks results in extra peaks, we should next troubleshoot the injector and the mobile phase. 

While one is engaged in troubleshooting, it is necessary to consider the source of the problem and to examine how the problem might have arisen. Additional problems might arise from the sample composition and the mobile phase, and these also need to be considered. It should be noted that problems can present themselves in many different ways, and what might appear to be a pump-related problem can quite easily be a result of something else entirely. 

High quality fluoroscopy a high-quality fluoroscopy system is a mainstay for lead extraction. Visualization of small lead components (such as stretched conductor coils, screws and embolized lead fragments) is fundamental to the safe performance of lead extraction. The equipment may be a fixed fluoroscopic system or a mobile high quality C-arm. Personnel specifically able to operate and troubleshoot this equipment are also required. 

Detwiler, W.L. 1988. Troubleshooting with a Digital Multimeter. Mobile Radio Technology, Intertec Pub-hshing. Overland Park, KS. 

And of course, accidents are much worse if created on purpose. We are now much more at risk of any type of accidents resulting from software-controlled systems because of our trend toward open, interconnected, and networked systems. Throw into that cloud computing and mobile technology (mobile devices are now very common in troubleshooting industrial systems), and we can see that software is much more important to safety today than just a few years ago. Probably, one of the best examples is the new trend in smart cities, putting an entire city s control under software and cyber systems. 

Other polar phases, i.e., silicas with covalently bonded nitrile, nitro, amine, or diol groups, are valuable alternatives to silica. They are less polar (hence the mobile phase can be weaker) and have different selectivities. However, in most cases, they are used in the reversed-phase mode with aqueous mobile phases. Normal-phase applications of some importance are the separation of aromatics on nitro-derivatized phases, and of non-ionic surfactants on diol-derivatized phases. The theoretical plate numbers are usually lower than with non-derivatized sUica. Activity control (see Section 2.2.4 on troubleshooting of NP separations) is not necessary. The stability of the chemical bonding can be limited. 

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