Figure 58 : NOTE: these quantitation formulas above are used in most of quantitative calculations in chromatography. BUT: these formulas are based on strictly linear signal over quantity calibration lines, on substance amount independent calibration factors and only in case the standard calibration and substance calibration lines go through ZERO First problem: the pass through zero cannot be checked practically. Second problem: Linearity exist normally never except within very narrow ranges of concentration of a standard enclosing the value of the concentration of the substance of interest short below and short above its true value. Third: what about the real purity of the substance of interest and the standard substance ? If one of both is only at 95% the data have a systematic error of AT LEAST +- 5 %. (??) Click HEREor THERE.