MEASUREMENT PRECISION AND 1 F NOISE IN ANALYTICAL INSTRUMENTS/

The recently promulgated uncertainty theory of instrumental analyses w as used to minimize the relative standard deviation of measurements. N aphthalene, acenaphthene, pyrene and perylene in HPLC were used as ill ustrations. For a Gaussian model peak with a width (S.D., sigma) of fi fteen data points, the optimum integration domain was about +/-6 data points (+/-0.4 sigma) around the peak centre on the HPLC baseline exam ined. Two commonly used integration modes were examined: horizontal ze ro line and oblique zero line. The precision was almost the same for b oth modes in the HPLC analysis. The signal shape at the limit of detec tion was also shown for the optimum integration domain. The error acco mpanying the use of the uncertainty theory was evaluated using a Monte Carlo simulation. The practical applicability and limitations of the theory are discussed.