Jerome H. Epstein

Bio: Jerome H. Epstein is an academic researcher from George Washington University. The author has contributed to research in topics: Blood serum & Excretion. The author has an hindex of 2, co-authored 3 publications receiving 903 citations.

Chapter III Chemical Analysis of Microbial Cells

Abstract: Publisher Summary This chapter discusses the chemical analysis of microbial cells. The preparation of material for analysis is discussed, because changes in the chemical composition of cells may occur as a result of the washing and storage conditions used. Wet- and dry-weight determinations of bacterial samples and assay of total cell numbers are described, because analytical results must refer to one or other of these values. Selection of an analytical procedure is a subjective process, because the number of suitable methods is large and each will have different merits and defects. Primary considerations are sensitivity, specificity, reproducibility, and absolute accuracy. Automatic methods for performing biochemical analyses, already widely accepted in hospitals and in industry, are beginning to make their way into the research laboratory. All automatic analyzers developed so far may be classified as either “continuous-flow” or “discrete” types. All of them use colorimetric methods exclusively and contain some form of automatic colorimeter for final read-out. The first and best-known is the Technicon “AutoAnalyzer,” which is of the continuous-flow type.

[12] Colorimetric analysis of sugars

Abstract: Publisher Summary This chapter presents a procedure for the calorimetric analysis of sugars for the identification and determination of small quantities of carbohydrates obtained from biological materials. In general, such tests have been devised by heating aqueous solutions of the sugar with a strong acid, thereby converting it to furfural or a derivative of furfural. A color is then produced by the addition of an organic developer such as indole, orcinol, diphenylamine, or carbazole. Many of the reagents commonly employed for the determination of a specific class of sugars are suitable, with slight modifications, to measure total carbohydrates. Thus, orcinol, carbazole, indole, and diphenylamine have all been used for this purpose. Although these reactions logically require a separate classification, therefore they are discussed individually to prevent unnecessary duplication. For the determination of inulin diphenylamine reaction is employed, which is based on the Ihl-Pechmann reaction for fructose and is not to be confused with the diphenylamine test for DNA. In arsenomolybdate method of Nelson a colorimetric determination of the reaction product replaces the conventional iodometric titration of the reduced copper found in the Somogyi reagent, thus facilitating the handling of serial assays. In addition to the methods discussed in the chapter for the determination of pentoses, there are several alternate procedures which may be of value under special circumstances. The more important of these seem to be the methods of Roe and Rice and of Tracey employing p-bromoaniline and aniline, respectively, as the color-producing agent. These reactions are appreciably less affected by the presence of hexoses and uronic acids than is the case with orcinol.