Determination of the optimum working range in spectrophotometric procedures.

A brief introduction to the topics of covariance and variance is given in this paper. An abstract vectorial space, the "precision pattern space" is introduced in order to find the general expression for the law of random error propagation. A new approach to the determination of the optimum working range in spectrophotometric procedures has been developed. The method involves the use of the calibration curve and the application of the Laplacian operator to concentration. The general expression reported for the relative error in concentration tends towards the classical photometric error expression in limiting cases.