Detection microchemical

Conte, E.D. and Barry, E.F., Gas chromatographic determination of caffeine in beverages by alkali aerosol flame ionization detection, Microchem. J., 48,372,1993. 

Sadek, F. S., and C. N. Reilley Ultramicro Chelometric Titrations with Potentiometric End Point Detection. Microchem. J. 1, 183 (1957). 

Salicylamide can be detected microchemically by means of the formation of the dibromo-derivative (9). Furthermore, the identification of salicylamide by chromatographic analysis are discussed further in the monograph. 

Sato K, Tanaka S. Determination of metal ions by flow injection analysis with peroxy-oxalate chemiluminescence detection. Microchem J 1996 53 93-8. 

Hendrickson, H. R, Anderson, R, Wang, X., Ritlman, Z., and Bobbitt, D. R., Compositional analysis of small peptides using capiUaiy electrophoresis and Ru(bpy)3/3-H-based chemiluminescence detection, Microchem. J., 65,189, 2000. 

S. Martinez-Barrachina and M. del Valle. Use of a solid-phase extraction disk module in a FI system for the automated preconcentration and determination of surfactants using potentio-metric detection. Microchemical Journal 83 48-54, 2006. 

Fujiwara, T., K. Murayama, and T. Imdadullah Kumamaru, 1994. Automated method for the selective determination of gold by online solvent extraction and reversed micellar-mediated luminal chemiluminescence detection. Microchem. J. 49 183-193. 

In principle it is possible to employ physical, microchemical and biological-physio-logical methods for detection in TLC (Fig. 2). 

Microchemical reactions These can be carried out either with universal reagents [11] or with such substances which react with particular functional groups (group-characterizing reagents). If the separation process ensures that only one component occurs at a particular spot on the chromatogram, then this can be detected sub-stance-specifically . But specificity in an unequivocal sense can only be produced by a combination of the separation and the detection process. (The same is true of other forms of detection.)... 

Physical detection methods are based on inclusion of substance-specific properties. The most commonly employed are the absorption or emission of electromagnetic radiation, which is detected by suitable detectors (the eye, photomultiplier). The / -radiation of radioactively labelled substances can also be detected directly. These nondestructive detection methods allow subsequent micropreparative manipulation of the substances concerned. They can also be followed by microchemical and/or biological-physiological detection methods. 

Just like the physical and microchemical methods of detection, the indirect, biological-physiological detection procedures are very selective when apphed to thin-layer chromatography. Here it is not chemical functional groups or particular physical properties that are selectively detected but effects on highly sensitive biodetectors . The following detection techniques have been employed ... 

For the detection and microchemical estimation of these alkaloids, the precipitation, crystalline form and melting-points of the perbromides, periodides, aurichlorides or picrates and the mydriatic test have been used. ... 

Owing to its use as a vermin-killer and to its importance in toxicology, a great deal of attention has been given to methods for the isolation of strychnine from biological materials and the detection of minute quantities. For critical reviews of such methods see Ainsworth Mitchell, Steyn,ii Ward and Munch. A microchemical method for the differentiation of str3 chnine and brucine has been described by Martini. i... 

This volume is divided into two parts which encompass about the same amount of material as Volume 1 a. Thus Part I begins with specific detection methods including the known photochemical, thermochemical and electrochemical activation methods. Here microchemical reactions are described that are carried out without the use of reagents. Detection involves the use of light, heat and electric current. 

The microchemical detection methods are the most economical methods and the simplest for the chemist to carry out. No expensive apparatus is required and in certain circumstances they can be combined with the two detection methods mentioned above. 

Three types of detection methods for TLC may be distinguished, namely physical, microchemical and biological-physiological. The more common detection methods for polymer additives in TLC are given in Figure 4.8. Detection is an off-line process, thus several detection techniques may be used one after the other. 

Thies M, Fischer R (1971) A new colour reaction for the microchemical detection and the quantitative determination of catechins. Mikrochim Acta 1 9-13... 

Further improvement of microchemical methods for proteinaceous media was based on immunological techniques. The high specificity of the antigen-antibody reaction enables the discrimination of the same protein coming from different species, or the detection of multiple antigens in the same sample. Application to the analysis of artwork has been reported in two types of immunological techniques immunofluorescence microscopy (IFM), and enzyme-linked immunosorbent assays (ELISA) [31]. 

Reverse stains In 1974, Wallace et al. developed reverse staining just to improve recovery of proteins for subsequent microchemical characterization. However, reverse stains are not suitable for quantitative analysis and staining of transfer membranes. The procedure is based on detection of proteins as transfer zones on a black background and used for visualization of proteins, passive elution of intact proteins from gels, and analysis by MS. Over the years, several different forms of procedures have been developed for reverse staining (Table 5.2). 

Various microchemical tests are available for the detection of minute quantities of sulphur, both free and combined. The substance under examination may be treated with a little sodium hydroxide solution, the extract evaporated just to dryness, a few drops of aqueous sodium cyanide (0-1 per cent.) added and the evaporation repeated. The residue, moistened with dilute sulphuric acid and a drop of ferric chloride, gives the characteristic ferric thiocyanate colour if sulphur is present.6 In the ease of minerals, traces of sulphur dioxide produced on heating may be detected 6 by the colour change of an alkaline solution of Bromocrcsol Green or by the deeolorisation of starch-iodine solution. 

Calibration curve of Cu(0) dissolution charge as a function of (x) Cu(l) or (o) Cu(ll) concentration in styrene solution containing 0.11 moll-1 THAP at 298.0K and v=50mVs 1. (Reprinted from Microchemical Journal, Vol 77, De Wael et al, Electrochemical detection. .., pp 85-92 (2004), with permission from Elsevier.)... 

T. D. Gibson, Label-free and reversible iminunosensor based upon an ac impedance interrogation protocol, Anal. Chim. Acta, 537 (2005) 163-168. P. Sarkar, One-step separation-free amperometric biosensor for the detection of protein, Microchem. J., 64 (2000) 283-290. 

Christian, G. D. A Sensitive Amperometric Endpoint Detection System for Microcoulometric Titrations. Microchem. J. 9, 484 (1965). 

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