Post analytic Chapter

The standard operating procedure (SOP) manual contains the procedures validated by the laboratory it is a complete set of instructions for pre-analytical, analytical and post-analytical methodology and also procedures for quality assurance/control, chain-of-custody and security. Each step in the handling of the specimen should be evaluated, optimized where possible and documented in the SOP. Important steps in the analytical process include collection, transport and accessioning of the specimen, sample preparation, isolation and detection of the analytes, production of the report and disposal of the specimen. This chapter focuses on the quality assurance and control issues for analytical method development and validation as well as statistical representation of the data. 

Descriptions of analytical methods for strong acid and acidic sulfate content of atmospheric aerosols have been reviewed (6-10). Methods for acidic aerosol determination are reviewed in this chapter according to the measurement principle either filter collection and post-collection extraction, deriv-atization or thermal treatment, and analysis or in situ collection (real-time or stepwise) and analysis. 

Mass spectrometric detectors for capillary electrophoresis are necessarily post-column detectors and must be interfaced to the cathodic end of the capillary. These detectors consist of four main components the interface, that joins the capillary to the ion source, the ion source, that generates ionic fragments from neutral analyte species, the mass analyzer, that distinguishes ions by their mass/charge (m/z) values, and the ion detector, that measures and amplifies the signal. The principles and instrumentation of bioanalytical MS are explained in Chapter 15. 

This text fills the need for a handbook that is current with respect to the philosophy of analytical chemistry support for drug discovery, development, and post-market support. It is our intention to present the role of analytical research and development as a part of the overall process. For this reason, the chapters are organized in more of a process-driven manner rather than pure function or technique. In all cases, a large number of references are provided for those readers desiring a more in-depth discussion of a particular subject. 

John Wiley Sons, Inc. maintains a website for Analytical Chemistry that contains additional supplemental material, which may be updated or added to from time to time. Any text errors that are noted will be posted on this site. Materials on the website include supplemeiital materials for different chapters that expand on abbreviated presentations in the text. Chapters from The Encyclopedia of Analytical Chemistry on Literature Searching Methodology " and Analytical Problem Solving Selection of Analytical Methods are included. The website URLs in the text are also listed on this site and may be updated. All figures and tables in the text are posted on the website and can be downloaded for preparation of transparencies. You may access the website at www.wiley.com/college/christian. 

Tandem mass spectrometry (MS/MS) is very useful for the amino acid sequencing of peptides, and has been used widely in both protein biochemistry and pro-teomics to identify proteins, to deduce the sequence of a peptide, and to detect and locate post-translational modifications. Until around a decade ago, the concept of amino acid sequencing by MS-technologjes was synonymous with ESI-MS/MS, but today MALDI-MS/MS techniques are implemented in high-performance instruments such that the quality of MALDI tandem mass spectra is comparable with that of ESI-MS/MS spectra. Currently, MALDI tandem mass spectrometers exist in a number of geometries, including TOF-TOF, Q-TOF, ion trap and orbitrap analyzers that each provide unique analytical features for the sequencing of peptides and proteins by MS/MS (details of the instrumentation for different types of MS/MS are provided in Chapter 2). 

QqQ in MRM mode and enables use of shorter chromatography columns and shorter run times (and thus increased throughput), while the additional selectivity provided by MRM detection can permit simplification of sample preparation procedures (Chapter 3). In practice, usually for each target analyte just one reaction channel (sometimes referred to as an MRM transition) is used to provide the quantitative data while one or two others are sometimes monitored simultaneously in order to provide confirmation of analyte identity via the relative responses (essentially a check on the selectivity of the analytical method. Section 9.4.3b). In contrast with the QqQ, the 3D ion trap has a poor duty cycle in MRM mode and the full scan product ion scan method is the method of choice if this analyzer is used for quantitation, since it is often possible to acquire 10 such scans across a chromatographic peak with adequate S/B values. Additional post-acquisition data processing is required to obtain quantitation data from such full scan MS/MS experiments. 

As noted in the previous chapters, when an EC detector is used in a flowing system, such as HPLC, it is simply one type of post-separation reaction detector. As with all post-colunm reaction detectors some knowledge of the chemistry involved in the detection process is essential in order to be able to use such detectors successfully. For maximum sensitivity with an EC detector, it is necessary to optimise conditions, such as the pH and composition of the reaction medium, the energy input, the time allowed for the reaction and the nature of the catalytic surface. However, when ED is used in conjunction with chromatography, the EC reaction conditions usually have to be a compromise with the chromatographic conditions necessary to achieve optimum resolution of the analytes, in particular the pH and the composition of the chromatographic eluent, as well as the need to maintain column stability. 

As will be illustrated in Chapters 5 and 6, SIMS is able to effectively circumvent many of these complications through the optimization of analytical methods and post-processing procedures suited to the substrate and information of interest. Note Understanding the potential sources of error is, however, of prime importance in setting up such optimized analytical conditions, which in most cases are substrate and information content specific. 

Post ionisation and desolvation, analyte ions are separated according to their m/z ratio by a mass analyser. The analyte ions are usually separated using static or dynamic electric/magnetic fields. An exception to this would be time-of-flight which does not utilise a magnetic/electric field, excepf if a reflection is used, which employs a static electric held. Although many mass analysers and their variants have been developed, only the principles of a quadrupole and time-of-flight mass analysers will be described in this section in accordance with the techniques used in later chapters. 

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