Pulse-Polarographic Methods

A pulse polarographic method to determine dantrolene sodium and its major metabolites in urine after ethyl acetate extraction has been reported [181]. The ethyl acetate is brought to a residue and the dantrolene plus the total extract-able metabolites are analyzed for reduction of the azomethine linkage at -0.86 V in a DMF-acetate buffer (pH 4.0). The nitro compounds are simultaneously determined in the same media as dantrolene equivalents from the reduction of the nitro group at -0.26 V (see Fig. 26.13). The difference between the two determinations represents the metabolites not containing the nitro group. Levels as low as 0.1 fig/mL can be determined for either functional group. 

For the estimation of traces of proteins in nucleic acid preparations, a pulse polarographic method is more suitable than classical polarography... 

Anodic stripping voltammetry has been used to determine total arsenic spedes . Pulse polarographic methods have been applied to aqueous and non-aqueous solutions of methyl- and dimethylarsenic adds at concentration levels down to 0.1 /rg/ml . These arsenicals are electroactive in aqueous buffers and in non-aqueous media in which the acidic supporting electrolyte, guanidinium porchlorate, is employed. A direct method of analysis, based on differential pulse polarography, is reported. Detection limits of roughly 0.1/xg/ml (for MMAA) and 0.3p[Pg.190]

A highly sensitive differential pulse polarographic method has been developed for the determination of trace levels of sulfa drugs after diazotization and coupling with AM-naphthylethylenediamine dihydrochloride. For the coupled diazo product of sulfacetamide, at pH 1.6 and with 0.01 M KH2PO4 as base electrolyte, the peak current at -0.070V versus SCE is increased linearly in the concentration range... 

The simplicity of the differential pulse polarographic method lies in the fact that the peak height is proportional to the analyte concentration (Fig. 15.33). If adequate resolution... 

A differential pulse polarographic method for the determination of prednisolone in tablets is described. The method is more sensitive than dc polarography and the measurement of diffusion current is greatly simplified. Sorenson phosphate buffer pH 5.6 was used as the supporting... 

What are the three major forms of polarography State the reasons why pulse polarographic methods are more sensitive than classical DC polarography. 

Fig. 22. Scheme of the current components in the differential pulse polarographic method, (a) the potential-time plot, t the waiting time between successive potential pulse applications, tp the pulse width, dEop the pulse amplitude, tj the sampling time, (b) plot of the charging current 1 (c) plot of the faradaic current 2 (d) plot of the total current 3 Al the recorded (sampled) total current difference, the drop life-time. 

With pulse polarographic methods, in particular with the DPP, the resolution in the analysis of electroactive mixtures is much improved as compared to DC polarography. The peaks are well resolved even for differences 30-50 mV. In spite of this, one often has to work... 

Betso and McLean [11] have described a differential pulse polarographic method for the determination of acrylamide and acrylic acid in polyacrylamide. A measurement of the acrylamide electrochemical reduction peak current is used to quantify the acrylamide concentration. The differential pulse polarographic technique also yields a well-defined acrylamide reduction peak at 2.0 V versus SCA (reduction potential), suitable for qualitatively detecting the presence of acrylamide. The procedure involves extraction of the acrylamide monomer from the polyacrylamide, treatment of the extracted solution on mixed resin to remove interfering cationic and anionic species, and polarographic reduction in an 80/20 v/v) methanol/water solvent with tetra-n-butylammonium hydroxide as the supporting electrolyte. The detection limit of acrylamide monomer by this technique is less than 1 ppm. 

The presence of either the nitrate or nitrite ions has been found to markedly enhance the height of the polarographic wave for Yb and a differential pulse polarographic method for the determination of these anions based on this phenomenon has been proposed by Boese et al. (1977). 

Smrkolj P, Germ M, Kreft 1, Stibilj V (2006) Respiratory potential and Se compounds in pea (Pisum sativum L.) plants grown from Se-enriched seeds. J Exp Bot 57 3595-3600 Somer G, Caliskan AC (2007) Selenium and trace elements distribution in astragalus plants developing a differential pulse polarographic method for their determination. Turk J Chem 31 411-422... 

Betso and McLean have described a differential pulse polarographic method for carrying out this determination (method 50). A measurement of the acrylamide... 

This differential pulse polarographic method enables down to 0.02% acrylamide monomer to be determined in polyacrylamide. 

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