Detectors pulsed amperometric

Figure 1. HPLC analysis of product progression during hydrolysis of 0.25 % polygalacturonate by PGII. Aliquots were withdrawn from the reaction mixture at timed intervals and reactions were stopped by raising the pH of the sample to pH 8.0 by mixing with 1 volume 25 mM Na-phosphate pH 9.5. Gl to G5 indicate the oligogalacturonates with corresponding degree of polymerization. The vertical axis shows the responce of the pulsed amperometric detector and the horizontal axis the elution time. Times of sampling are indicated above the trace.

Figure 5. Selected HPLC elution profile of products obtained after incubation of 0.25% polygalacturonate with PGII, upper trace, and PGII H223A, lower trace, respectively, demonstrating the effect of the mutation on catalysis. G1 to G3 indicate the peaks of the corresponding oligogalacturonates. IS indicates the internal standard, glucuronate. The vertical axis shows the pulsed amperometric detector response while the horizontal axis shows the retention time.

Tabata, S. and Dohi, Y., An assay for oligo-(l—>4) —5(1—>4)-glucantransferase activity in the glycogen debranching enzyme system by using HPLC with a pulsed amperometric detector, Carb. Res., 230,179, 1992. 

A comparative study of the analysis of aliphatic amines by GC-FID, GC-TSD and HPLC with refractive index detector (RID), using isopropylamine as internal standard, gave good results in all cases. Determination of trimethylamine oxide by HPLC with a pulsed amperometric detector was problematic136. 

A unique anion-exchange column has been developed that has a thin (non-diffusion limited) anion-exchange phase coated onto a 10-/nm latex bead. When a mobile phase of 0.15 M NaOH is used, neutral carbohydrates are converted into anions, which are separated on the column. Although the resin has low capacity, and probably causes degradation of the carbohydrates, when it is coupled to a triple-pulsed, amperometric detector, the system provides extremely sensitive, high-resolution separations. 

Historically, R1 detector was widely applied to carbohydrates analysis [52,55,59,66-71], Other approaches involve the use of ED permitting a high sensitivity and selectivity even in the presence of complex matrices further improvement in this method is the use of pulsed amperometric detector [69,70,72-78],... 

In the literature, isocratic solvent systems are found for monosaccharides, and gradient systems are described for oligosaccharides. Table 3.4 gives some gradient systems for carbohydrate separation Table 3.5 illustrates programs for pulsed amperometric detectors. 

Dionex Corporation 1228 Titan Way P.O. Box 3603 Sunnyvale, CA 94088-3603 Pulsed amperometric detector cells and instrumentation... 

Figure 6.10 Chromatograms of debranched amylopectins of (a) A-type starches (b) B-type starches analyzed using anion-exchange chromatography a pulsed amperometric detector and an amyloglucosidase enzyme reactor (HPAEC-ENZ-PAD) and (Continued overleaf)...

The scope of ion chromatography was considerably enlarged by newly designed electrochemical and spectrophotometric detectors. A milestone of this development was the introduction of a pulsed amperometric detector in 1983, allowing a very sensitive detection of carbohydrates [17]. 

With the development of the pulsed amperometric detector (PAD) [13] a new detector cell was also designed. It is schematically shown in Fig. 6-10. To facilitate replacing the... 

RPC = reversed-phase chromatography, IEC = ion-exchange chromatography, NPC = normal-phase chromatography, SEC = size-exclusion chromatography, NARP = nonaqueous reversed-phase, PAD = pulsed amperometric detector, ELSD = evaporative light scattering detector. Pre-column or post-column derivatization required. 

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