Detectors molar extinction coefficient

One cm3 of the reactant/product/catalyst mixture was sampled periodically during the reaction for the transmission infrared analysis (Nicolet Magna 550 Series II infrared spectrometer with a MCT detector). The concentrations of reactants and products were obtained by multiplying integrated absorbance of each species by its molar extinction coefficient. The molar extinction coefficient was determined from the slope of a calibration curve, a plot of the peak area versus the number of moles of the reagent in the IR cell. The reaction on each catalyst was repeated and the relative error for the carbamate yield measured by IR is within 5%. 

The following table provides some comparative data for the selection and operation of the more common detectors applied to high-performance liquid chromatography.15 In general, the operational parameters provided are for optimized systems and represent the maximum obtainable in terms of sensitivity and linearity. In this table, the molar extinction coefficient is represented by s. 

Since its introduction at the end of the 1950s, gas chromatography (GC) has developed into a versatile tool in the analysis of natural products. Clear advantages of GC are the high resolution and high sensitivity of the most common detection method, the flame ionization detector (FID), and the fact that the detector response of similar compounds will be about the same, i.e., peak areas may be directly compared for quantification. This is in contrast to high performance liquid chromatography (HPLC), in which the detector response in the most common detection mode, ultra violet (UV)"absorption, may vary widely for different compounds since the molar extinction coefficients can be very different. 

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