Photochemical quantum yields using chromatographic data

2 Photochemical quantum yields using chromatographic data 

According to eq. (5.27) a relationship between the concentrations a, of reactants and the signals M, exists, whereby the proportionality constant 1/m, is to be determined by calibration. According to 

Separation of stilbene-1 by HPLC chromatography bottom left, trans-cis photoreaction by irradiation at 365 nm forming the cis product top right, the cis-trans photoreaction 

If the initial concentration a,(0) is known, the values of the signals Af which depend on the reactants and reaction times 7, can be obtained without knowledge of the calibration factors m,-. The only requirement is the experimental ability to separate all the reactants at the chromatographic conditions [110,186]. 

In a closed HPLC loop, the injected amount of substances should stay constant until detection at the end of the column. That means the peak areas Ai or the signal M, should be directly proportional to the concentration a, of the reactant i for a constant flow FW. Under these conditions the overall absorbance of the /th reactant for a defined injection volume is given for a selected time by 

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