Acid , generally extraction, quantitative analysis

The stability of the reagent in acid solution, together with its ability to complex a wide range of metals, make it a very useful general extracting reagent, especially for heavy metals. The chief applications of APDC in quantitative analysis are as follows ... 

The reaction of biogenic amines with DNS-C1 is analogous to that for amino acids (Section 4.2.1.1.1). Generally, primary and secondary amines react quantitatively in acetone-water systems containing sodium bicarbonate. The major differences from the analysis of amino acids are the absence of some side reactions reported for amino acids [97], the easier extraction of the amine derivatives from aqueous systems and the chromatography. BNS-C1 reacts with biogenic amines in a similar manner to DNS-C1 under the conditions described below. 

Several reviews covering different aspects of bile acid analysis have appeared in recent years (1-15). These articles cover a wide range of techniques with particular emphasis on thin-layer and gas chromatography. In this chapter we will try to present established methods for bile acid analysis as they can be combined to form a complete analytical procedure, including extraction, purification, identification, and quantitation. It has not been possible to include all methods and the various modifications of standard procedures that have been published. References to most of these can be found in the reviews (1-15). Early development in the field is described in Sobotka s books on bile acids and steroids (16, 17). Whenever equally efficient or similar methods exist we have generally preferred to describe those of which we have personal experience. Many of the techniques used for bile acids are similar to those used in steroid analysis and advance in this area is highly relevant for workers in the bile acid field. 

In aqueous simulants, the extraction yields for controls were lower than that of the samples in the same experimental scheme. A sonication treatment of the controls during the extraction led to extraction yields similar to that of the samples. Both samples and controls (as well as blanks were therefore subsequently sonicated in the extraction step, both in the cases of 15% ethanol and of 3% acetic acid, and for all time-temperature exposures. The yields from the extraction for the samples in aqueous solutions ranged from 70 to 100%. Yields of extraction were generally lower for the exposure of 1 hour at reflux temperature compared with 10 days at 40 °C. The analysis of the three additives from aqueous simulants is represented in Figure 6.8. The SML concentrations for the different compounds analysed was sufficient to yield reproducible peaks and quantitation. 

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