Standard Interpretation Procedure

To learn to use the variety of information that is available in the mass spectrum, you should follow the outline of this book step by step in interpreting an unknown spectrum. This Standard Interpretation Procedure is set forth inside the back cover in the form of a checklist to be used when you are interpreting an unknown. This is a general, simplified approach applicable to the average El mass spectrum. With experience the first several steps will be fast and largely automatic. While you are learning, however, each step should be done in this order, and your postulations, assignments, and conclusions from each step should be recorded, preferably on the spectrum. If more than one explanation appears possible for a particular spectral feature, be sure to note all possibilities. 

OE ions have a special mechanistic significance, as discussed in Section 4.4. Because of this you should indicate all important OE ions, making these directly on the spectrum (in the Figures of this chapter these mass numbers are circled). This is the next step in the Standard Interpretation Procedure (inside back cover). The importance of a peak, after one has corrected its abundance for contributions of ions containing less-common isotopes, generally increases with ... 

Follow the Standard Interpretation Procedure in attempting to assign structures to Unknowns 5.14 and 5.15. 

Follow all the applicable steps of the Standard interpretation procedure (inside the back cover) covered in the text. The solutions will follow this order, although space limitations prohibit a discussion of every point for each unknown. 

The rehability of these analytical methods may be questionable when chemical shift differences of derivatives are of the same magnitude as variations encountered from solvent, concentration, and temperature influences. Reported fluorine chemical shift ranges for tnfluoroacetylated alcohols (1 ppm), p-fluorobenzoylated sterols (1 ppm), and p-fluorobenzoylated ammo acids (0.5 ppm) are quite narrow, and correct interpretation of the fluonne NMR spectra of these denvatized mixmres requires strict adherence to standardized sampling procedure and NMR parameters. 

To assure consistency and speed in multidisciplinary structure analysis of low-MW compounds involving various techniques (IR, NMR, MS, etc.) most industrial laboratories use a Standard Operating Procedure (SOP). In such schemes IR analysis is frequently used as a cheap filter for a quick starting control and as a means for verification. As IR detects only structural units identification of an unknown compound on the basis of IR is difficult. Mass spectrometry is used as the prime identification tool and is especially important in the determination of the exact mass and gross formulae. While structural prognostication on the basis of MS is difficult for the non-expert, a posteriori interpretation is quite feasible. H NMR is both easy and cheap, however requires greater sample quantities than either... 

The Sherlock Holmes stories often are read as the triumph of the scientific method of deduction. There is, though, another, darker interpretation to be advanced. That is the frustration of science and technology in changing everyday social practice. Throughout the canon, Holmes is consistently thwarted by the standard operating procedures of the Scotland Yard "regulars." He also is annoyed—and even disturbed—by the inability of Victorian... 

Similarly, ethos, the testimonial dependent upon the expertise and credibility of the witness, is critical. Evidence supplied by an impartial and credentialed observer may estabhsh comphance with control standard operating procedures (SOPs), accuracy of documentary evidence, and suitability of code design. Whereas the accuracy of logos transcends its interpretation, however, ethos proof must be evaluated on the basis of its source. Who said so , How does he or she know , and Why should he or she be trusted become the key questions. It is upon the importance of ethos that the important issues of independent, quality assurance (QA), and confirmatory investigation hes. Most ethos testimony takes the form of reports, observational records, and certifications. 

There is some evidence to suggest that, depending upon the phase volume ratios employed, the emulsification technique used can be of greater importance in determining the final emulsion type than the H LB values of the surfactants themselves [434], As an empirical scale the HLB values are determined by a standardized test procedure. However, the HLB classification for oil phases in terms of the required HLB values is apparently greatly dependent on the emulsification conditions and process for some phase-volume ratios. When an emulsification procedure involves high shear, or when a 50/50 phase volume ratio is used, interpretations based on the classical HLB system appear to remain valid. However, at other phase-volume ratios and especially under low shear emulsification conditions, inverted, concentrated emulsions may form at unexpected HLB values [434]. This is illustrated in Figures 7.4 and 7.5. 

However, the sensibility of the Caco-2 monolayers to the different standard operation procedures used for its culture increases the inter-laboratory variability and complicates the combination of data coming from different laboratories and the interpretation of results. Animal in vivo models reproduce the real situation better, as those models include all the physiological variables but, of course, have a low throughput capacity and are not adequate for screening a high number of compounds. 

A common reason for large variability of results is a lack of detail in the procedure which leads to different interpretations of what needs to be done. A solution to this particular problem is to produce a comprehensive document called a standard operating procedure. 

The earlier experimental EFISH studies have often been linked to analysis of the results by the semi-empirical SOS method. An examination of the exact SOS formulae used to interpret the data can provide confirmatory evidence of the convention that has been adopted. The standard SOS procedure, for the electronic contribution to the first hyperpolarizability for frequency doubling, is summarized below. 

Establishment of Common Protocols and Standard Operating Procedures It is essential that all factors relevant to the conduct of the alternative method that may affect the results, the collection of data, and interpretation of the alternative method results be clearly defined before the study begins. These are best documented in the study protocol and SOPs that define the alternative methods. In order to assess the adequacy of the SOPs, they should be examined to determine if they contain three key elements. First, each SOP must have a detailed step-by-step description of how to conduct the assay. Enough details need to be provided such that any appropriately trained and competent laboratory technician need use only this document as the guide to run the assay. Second, the SOP must indicate the steps used to calculate the endpoint of the assay and the number of replicates necessary. Any data transformation or algorithms applied to the data should be clearly documented and consistently applied across all laboratories conducting a particular assay. Third, the protocol must specifically describe the prediction model being tested in the validation study. 

Each immunoassay must have a standard operating procedure (SOP). The SOP must address the entire analytical procedure (i.e., extraction, cleanup, detection, and data analysis and interpretation). Reagent stability and procedural precautions must also be included in the SOP. 

However, what is true for a carcinogenicity study may be wrong for an analytical chemistry study what can be applied to an in vitro genotoxicity study could be completely out of question for a field study. Therefore, it would seem to be important to interpret these definitions flexibly and with well considered regard to the study type and the experimental activities connected with it. Thus, it would seem that in order to arrive at a clear situation, the Standard Operating Procedures for the conduct of the various study types, or at least the study plan, should address these issues and define the dates in a concrete way. 

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