Validation of these Methods

The validation of the microwave-assisted extraction technique was performed by comparing the values obtained to that of the standard samples and by performing conventional prescribed official methods associated with each products under study. Table 2 presents a summary of data presented in references [19] and [20]. The results demonstrate that, in all cases, the microwave-assisted extraction procedures yielded data that were, for all practical purposes, similar to the accreditation values of fat content obtained for the same samples using conventional official methods. These results support the current trend whereby several microwave-assisted extraction methods are being evaluated for accreditation purposes. This trend is not exclusive to food analysis [27]. 

Fat content (%) of various food products obtained by MAP compared to other conventional methods of determining fat 

Notes a) % RSD = % Relative standard deviation = standard deviation / mean (triplicate) x 100 b) Fat content (%) as obtained from Agriculture and Agri-Food Canada (corresponds to the accreditation values) c) Labelled value and d) Value obtained by conventional method. 

Whenever possible, users should select solvents for their ability to dissolve the target compound and for their relative transparency to the microwaves. This will result in the most energy-efficient applications possible, while maintaining relatively mild conditions, thus minimising the possibility of 

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Many texts have been written going in to great detail on the development and validity of these methods. Some of these references are given in the bibliography. We will proceed with the assumption that the methods discussed here are mathematicaily valid and have been proved valuable through many years of use. 

C. Pudelko-Korner, Quantitative Near-Infrared-Reflection-Spectroscopy of Sennosides in Sennae fructus angustifoliae in Processing and Quality Control as well as Validation of these Methods, Pharma Technol. J., 19(1), 57-67 (1998). 

Thermal desorption studies have the attraction of comparatively simple experimentation, but face severe problems in the evaluation of unambiguous, unique rate parameters from the measurements. The subject has been reviewed several times recently (see, for example, refs. 57—61), particularly in relation to gas—metal systems, so here we will concentrate on its specific applications to semiconductors, where it has been used almost exclusively to study metal absorbate-isemiconductor surface interactions. Since this topic provides the subject matter for Sect. 5, we will limit the discussion in this section to the basic experimental approach and available methods of data analysis. We will leave to Sect. 5 the critical appraisal of the validity of these methods as applied to solid adsorbates, and the interaction models which have been postulated. 

The analytical procedures to assess stability must encompass the elements common to validating analytical assays. The methods must be validated according to the parameters of accuracy, precision, robustness and specificity, limits of detection and quantitation, linearity of active ingredient assays, degradants, and other reaction products. More information on how to develop stability indicating methods is discussed in Chapter 7. Validation of these methods is discussed in Chapter 8. 

A good agreement is observed between experimental and calculated values by both Miedema s and Merio s approaches, confirming the validity of these methods. On the contrary, the values calculated by Zen s law are always higher, CaPd showing the maximum contraction. 

Juvekar and Sharma (50) also took into consideration the pressure variation along the column. However, the validity of these methods is far from beeing tested experimentally verified and in view of the great industrial importance of plate columns, experimental evidence in support of them is certainly required. 

Methods of determining the flow of pressurizing gas, the time to fill tanks by condensation and the condensation rates in tanks surrounded by liquid-nitrogen baths and at different pressures are presented. Experimental results to prove the validity of these methods are also shown. 

Active Centre Determination. A number of recent publications involving the use of molecular weight data, tritium quenching, - and CO radio tagging " have appeared recently in the scientific literature. Since the validity of these methods has been assessed recently by the present author" no further details will be given in this Report. The as yet unsettled controversy concerning the use of "CO tagging method should be noted. ... 

Methods for toxicological safety assessments are multiple and varied - some are more reliable than others, some more radical than others, but all are important. Their nature greatly depends on their endpoints, namely, the degree of practical safety they attempt to attain. Unfortunately, the true validity of these methods can only be assessed retrospectively, that is to say, by the record of cases of health impairment they were able to prevent over a reasonable period of time. Because of this and the uncertainty inherent in any extrapolation technique, the final products expressed in numerical form can only be considered as opinions. Some important toxicological opinions presented in numerical form are the LD50 the quantitative risk assessments, the threshold limit values (TLV), and the acceptable daily intakes (ADIs). 

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