Standardization of the method

Standardization is carried out immediately after preparation of the working solution and the photometric standards. To each of six 200 mL Erlenmeyer flasks with glass stoppers are added 10 mL of potassium iodide solution and 10.00 mL of potassium iodate solution, exactly the same amount to each flask, and 1 mL of sulphuric acid 50 mL of the sulphide working solution are pipetted into three of the flasks with a calibrated pipette, and 50 mL of oxygen-free water into the other three flasks. The flasks are set aside for about 10 min. Their contents are then titrated with thiosulphate solution using soluble starch as indicator  

The titers of triplicates should agree to within 0.05 mL. The amount of H2S present is calculated using the formula 

A = mean of the titers of the three solutions without sulphide, in mL B = mean of the titers of the three solutions with sulphide, in mL  

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Analysis of Standards The analysis of a standard containing a known concentration of analyte also can be used to monitor a system s state of statistical control. Ideally, a standard reference material (SRM) should be used, provided that the matrix of the SRM is similar to that of the samples being analyzed. A variety of appropriate SRMs are available from the National Institute of Standards and Technology (NIST). If a suitable SRM is not available, then an independently prepared synthetic sample can be used if it is prepared from reagents of known purity. At a minimum, a standardization of the method is verified by periodically analyzing one of the calibration standards. In all cases, the analyte s experimentally determined concentration in the standard must fall within predetermined limits if the system is to be considered under statistical control. 

The methods used for the quantification of generic bioequivalence have evolved significantly in the past 15 years or so. There is no reason to believe that this evolutionary process will not continue. Thus, it is indeed likely that the present methods will be further refined. It is also likely that the processes of globalization and harmonization will assist in the further standardization of the methods approved for the determination of bioequivalence in different jurisdictions. 

Besides his fundamental research in the carbohydrate field, the functions of Courtois as the head of a hospital laboratory for many years led him to publish a number of papers dealing with clinical chemistry, among which may be cited determination of ethyl alcohol, proteins, acidic phosphatases, and trehalase in blood determination of the basic groups of proteins by phytic acid study of the phytosoluble glycoproteins in biological fluids and identification and determination of scyllitol in urine. Under the aegis of the International Pharmaceutical Federation, he participated in the standardization of the methods proposed for the assay of such enzymes as cellulases and hemicellulases. 

Study Group for the Standardization of the Methods of Testing Explosives , Propellants and Explosives 2 (1977), 1—3 and 7—20... 

The iodine affinity is due to the formation of colored complexes with amylose. The color of this complex depends on both the concentration of the iodine in the solution and the kind of starch. Amylose binds 20% (v/v) of iodine, to develop a blue color, whereas amylopectin binds only O.S to 1% (v/v) of iodine to give a red-violet eolor. Starch which does not contain any amylose gives a red color with iodine. Thus, evaluation of the degree of dextrinization based on the observations of Komm and Martin needs standardization of the method and approach, because ofthe variability in the origin of the starch. Table XVI shows that methods in use to date are not equivalent to one another. The color-development characteristics are again dependent on the origin of the starch. ... 

In this book, experts from academia and industry outline relevant aspects of chemistry, biology, and molecular informatics which are the cornerstones of chemogenomics. General introductory chapters are combined with chapters describing methods and protocols, which are the gold standard of the Methods in Molecular Biology book series. 

Several issues arise with the conduct and interpretation of time-kill kinetic studies. The first is lack of standardization of the method as described in the... 

Very few collaborative studies between accredited doping laboratories are available to determine their variances. As such determinations are rather complex, some of the experimental parameters are most of the time left uncontrolled. Great attention should be given to standardization of the methods. Matrix problems are known during calibration and best results can be obtained with the systematic use of good quality deuterium-labeled internal standards. The... 

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