Post-column complexation

Warner, C. R., S. Selim, D. H. Daniels, Post-column complexation technique for the spectro-photometric detection of poly(oxy-l,2-ethanediyl) oligomers in steric exclusion chromatography,/. ChwmatogK, 1979,173, 357-363. 

The on-line measurement of reducing capacity can be performed with either a single or a series of electrochemical detectors, and linear correlations have been demonstrated between total antioxidative activities determined by the electrochemical detection and those determined by DPPH- reduction or by the ORAC assay (Guo et al, 1997 Peyrat-Maillard et al, 2000). The reducing capacity must also be quantified by post-column reactions, either with DPPH- or by the reduction of phosphomolybdenum complexes followed by UV-VIS-detection (Bandoniene and Murkovic, 2002 Cardenosa et al, 2002). A combination of HPLC and semi-automatic ORAC analysis has also been described (Caldwell, 2001). 

Cardellechio, N., Cavalli, S., Ragone, P., and Riviello, J. M., New strategies for determination of transition metals by complexation ion-exchange chromatography and post column reaction, ]. Chromatogr. A, 847, 251, 1999. 

Methods used for the detection of PAs in cmde or partially purified extracts can also be adapted for post-column analysis after fractionation (see below). Direct quantitative analysis of PAs in crude grape phenolic extracts is often impossible due to the complex sample matrix. Thus, fractionation or purification is often necessary before analysis. The Folin-Ciocalteu and Pmssian Blue assays are widely used for the quantification of total polyphenols in plants [27,28]. These methods are not specific for PAs due to the reaction of other phenolic compounds with these reagents. 

Shi S-Y, Zhou H-H, Zhang Y-P, Jiang X-Y, Chen X-Q, Huang K-L. Coupling HPLC to on-line, post-column (bio) chemical assays for high-resolution screening of bioactive compounds from complex mixtures. Trends in Analytical Chemistry. 2009 28(7) 865-877. 

M. A. Fotopoulou and P. C. Ioannou, Post-Column Terbium Complexation and Sensitized Fluorescence for the Determination of Norepinephrine, Epinephrine and Dopamine Using High-Performance Liquid Chromatography, Anal. Chim. Acta 2002,462, 179. 

Post-column detection of chlorophyll derivatives is often accomplished by ultraviolet and visible spectroscopic techniques, which take advantage of the strong electronic absorption spectra of these pigments (units F4.3 F4.4). While these methods have enjoyed wide application (Schwartz et al., 1981 Khachik et al., 1986), a major advance was made with the introduction of photodiode array (PDA) detection. Multichannel photodiode array detection allows for simultaneous monitoring of multiple wavelengths, resulting in the generation of online electronic absorption spectra of a compound as it elutes from the HPLC column. Because of the uniqueness of electronic absorption spectra of individual chlorophyll derivatives, these techniques have enjoyed extensive application for tentative identification of components from complex mixtures and extracts... 

Fentin, cyhexatin and fenbutatin oxide fungicides have been determined in soil by high-performance liquid chromatography with a CN column combined with UV photoconversion and post-column morin complexation followed by fluorescence detection [539]. 

Some investigators have produced organic chelate complexes from the metals after they have been separated in the inorganic form on the column, but before entry into the detector, ie post-column derivatisation, while other investigators form the organic complexes before the sample is applied to the separation column, ie pre-column derivatisation. 

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