Polyalcohols detection

From studies on numerous compounds in aqueous alkaline solutions, Johnson concluded that all aldehydes, alcohols, polyalcohols, and carbohydrates are electrochemi-cally detected by the pulsed amperometric scheme described above [61-63] these compounds include the oligosaccharides [64, 65]. Detection limits are typically less than 0.1 ppm for early eluting peaks when the sample volume is approximately 50 pL. 

All carbohydrates (aldoses and ketoses) and polyalcohols produce a large anodic peak response at ca. +0.15 V. The peak for glucose corresponds to a reaction with n approaching 10 equiv/mol for fluid velocities typical of flow-through detection cells. This n value is consistent with an oxidative cleavage for the C1-C2 and Cs-C bonds to form two moles of formate and one mole of dicarboxylate dianion [24]. 

There are some persons who stand out prominently in any review of the history of polyesters. As early as in 1911, Meyer [1] found that the saponification of polyesters of polyacids and polyalcohols and the hydrolysis of a glycerol ester proceeds in acid and alkaline solution, and, the hydrolysis can only be detected under certain conditions with heterogeneous saponification. However, he did not mention the molecular weights of the polyesters used. Hermann Staudinger (1881-1965) is recognized as the father of polymer chemistry because of his great contributions to polymer science (Figure 1.1). 

Knappe et al. [40] separate technically important polyalcohols on alumina G layers, using chloroform-toluene-formic acid (80 - - 17 + 3) on silica gel G layers with n-butanol, saturated with 1.5N ammonium hydroxide or on kieselguhr-polyamide layers with chloroform. For detection, they recommend a number of spray reagents made up of a strong oxidising agent and an oxidisable base. 

Anodic detection of the aldehyde and alcohol functionalities in carbohydrates occurs in a potential region where there is only a very small background signal for the concurrent formation of surface oxide. Mode 1. The development of positive peaks for carbohydrates and polyalcohols by Mode 1 in LC-PAD is illustrated in Figure 10.3A by the chronoamperometiic (i—t) response curves generated following the potential step from E ed to det in the PAD waveform. The residual current (curve a)... 

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