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Errors in Analysis

Introduction

Analytical chemistry is based on reliability, reproducibility and accuracy. However, every measurement has some degree of uncertainty which is called as error in analytical chemistry. The error is nothing but the difference between the experimental mean value and a true value. Errors are classified into two types – determinate and indeterminate errors. Determinate errors can be avoided or corrected and further classified as instrumental errors, operative errors, errors of method, additive and proportional errors. Indeterminate errors are random errors over which analyst has no control. Errors can not be neglected but minimized by calibrating instruments, running blank determination and control determination, standard addition, internal standard or by amplification methods.

Accuracy is defined as the concordance between it and the true value. In other way, it is the closeness of mean test value obtained by the method to the concentration of the analyte. Precision is defined as a series of measurement of the same quantity or the closeness of individual measures of an analyte when the procedure is applied repeatedly to multiple aliquots of single homogenous volume of biological matrix. Accuracy expresses the correctness of a measurement and precision express the reproducibility of a measurement.

Significant figure is a digit which denotes the amount of the quantity in the place in which it stands. In analytical chemistry, standard deviation is the most common statistical terms and is defines as the square root of the mean of the sum of the squares of the differences between the values and the mean of those values.

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