Principles of Quality Control Charting

Control charting is a powerful and a simple tool for the daily quality control of routine analytical work. Statistical control pursues to verify the stability of operation. For such verification the laboratory analyzes control samples together with the routine samples in every analytical run. The results of the analyses of control samples can be interpreted following different ways, including the use of control charts.

Though there are several types of control charts, these two are the most important used for the internal quality control in XRF laboratories:

• X-charts
  
  
• Range-charts