Ultra-violet diode array detection

Procyanidins can usually not be completely separated from each other, from phenolic acids and from accompanying flavonoids by sample clean up and/or chromatographic procedures. The differentiation between these individual compounds can therefore only by accomplished by the selectivity of a suitable detection method. UV-DAD (ultra violet diode array detection), electrochemical and mass spectrometry detection have been used for the identification and quantitative determination of procyanidins. 

J Slobodnik, AJH Louter, JJ Vreuls, I Liska, UAT Brinkman. Monitoring of organic micropollutants in surface water by automated online trace-enrichment-liquid-and-gas-chromatographic systems with ultra-violet diode-array and mass-spectrometry detection. J Chromatogr A 768 239-258, 1997. 

Complete MCP s can be stacked to provide even higher gains. For response in the vacuum ultra-violet spectral region (50-200 nm) a SSANACON, self-scanned anode array with microchannel plate electron multiplier, has been used (36). This involves photoelectron multiplication through two MOP S, collection of the electrons directly on aluminum anodes and readout with standard diode array circuitry. In cases where analyte concentrations are well above conventional detection limits, multi-element analysis with multi-channel detectors by atomic emission has been demonstrated to be quite feasible (37). Spectral source profiling has also been done with photodiode arrays (27.29.31). In molecular spectrometry, imaging type detectors have been used in spectrophotometry, spectrofluometry and chemiluminescence (23.24.26.33). These detectors are often employed to monitor the output from an HPLC or GC (13.38.39.40). 

Among the chromatographic techniques, LC with octadecyl silica (Cig) columns and ultra-violet/visible (UVA IS) spectrometry detection or by using a diode-array detector (DAD) has been widely employed. It is worth mentioning the paper published by Zhou et al. (2004), in which the inhibition effect on luminol-dimethylsulfoxide chemiluminiscence was exploited as a detection system. 

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