Potential problems, instrument design

FIAZOP is a formally struetured method of systematieally investigating eaeh element of a system for all ways where important parameters ean deviate from the intended design eonditions to ereate hazards and operability problems. The HAZOP problems are typieally determined by a study of the piping and instrument diagrams (or plant model) by a team of personnel who eritieally analyze eflfeets of potential problems arising in eaeh pipeline and eaeh vessel of the operation. 

The on-line hyphenation of CEC and MS has several potentially challenging instrumental aspects which complicate the successful combination of these two techniques. The first arises due to the absence of a CEC column outlet electrolyte reservoir and the need to achieve electrical continuity for the CEC system, and, in the case of ESI, also for the ESI ion source. Another consideration is the requirement to efficiently remove the mobile phase and simultaneously generate gas phase ions from the analyte, which have to be transferred with high efficiency into the vacuum of the mass analyzer. Because of this situation, numerous designs have been advanced which solve to various degrees these related problems and are discussed individually below. 

The take-home message from this work (Briscoe 2007) appears to arise from two aspects that, when combined, can potentially cause problems, namely the role of QC samples in monitoring the integrated variability of the entire analytical method and the potential for instrumental drift in response of LC-MS/MS instruments for a variety of reasons (e.g. accumulation of contamination). Thus system suitabihty checks conducted only before an analytical run is started may not suffice to guarantee validity of data obtained and should be designed to monitor instrument performance regularly in the course of an analytical run. 

Hazard and operability study (HAZOP) is a method for systematically comparing each element of a process system against its potential for critical parameters deviation from the intended design conditions that could create hazards and operability problems. An HAZOP analysis team studies the process piping and instrument diagrams and/or plant model then analyzes the effects of potential deviations from design conditions in process flow, temperature, pressme, and time. Keywords, such as more of, less... 

An important point to be considered when the instrument is used for A.C. voltage measurement is the terminal connections. One terminal will be clearly designated as the high-potential connection, and this should be adhered to. The HT terminal will have a low value of capacitance to other bodies and to earth while the corresponding capacitance of the other is high. If the instrument is in a metallic case this should be connected to the mains earth as a safety precaution. In some cases, the low-voltage terminal is also connected to the metallic case. If this is so, the instrument will effectively earth the circuit under test, which may give rise to problems. 

Small drug molecules have not been extensively researched with microchip electrophoresis devices despite the great potential achieved in conventional CE systems. One reason is that most of the small drug molecules possess chromophores thus, UV absorbance detection is the most popular detection mode but it is not universally available for a microchip device such as LIE is because of sensitivity problems. Because of the radiation danger imposed by UV light, proper instrumental setup specific to the microchip format is required. In addition, UV transparent material such as fused silica or fused quartz is required to fabricate the microchip device. Because UV absorbance is much less sensitive than LIE, a special design is necessary to increase the optical path length of the detection flow cell. This has been achieved by some clever approaches pioneered by Harrison and co-workers.Recently, a commercial microchip electrophoresis system with UV detection was released by Shimadzu, which will drive the application of microanalytical techniques to a wide variety of molecules of pharmaceutical interest. 

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