Standard Practice for Using Pre-Control in the Instrumental Analytical Laboratory
|Publication Date:||1 January 1993|
1.1 This practice covers the application of pre-control as a means of statistical process control in an instrumental analytical laboratory.
1.2 "Pre-control," which stands for "prevention control," is based on the laws of probability utilizing strategic sampling schemes to detect shifts and changes in a measurement system or process with respect to an applied tolerance.
1.3 This practice provides direction for the evaluation of the two major characteristics of any system of variation: the center of the distribution from which the statistical sample could have come, and the width of that distribution.
1.4 Pre-control is not a substitute for traditional control charts.
1.5 This practice provides instructions for the application of pre-control to measurement systems such as X-ray fluorescence (XRF) or optical emission (OE) spectrometers.
1.6 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.