It’s a graphic representation to study the variation of results for an analytical method.

In fact, the most important tool in quality control is the use of control charts. The laboratory runs control samples together with the routine samples. The control values are plotted in a control chart. In this way, it is possible to demonstrate that the measurement process performs within given limits. If the control value is outside the limits, no analytical results are reported and remedial actions have to be taken to identify the sources of error, and to remove such errors. 

This guarantees the accuracy and the stability of the results and protects against errors because you can immediately detect a drift.

A control chart is made up of :

• (1) A central line that corresponds to the target value
• (2) Two lines that correspond to the warning limits are located at a distance of +/- two times the standard deviation from the central line
• (3) Two other lines are also drawn at a distance of +/- three times the standard deviation from the central line. These lines are called the control limits.
• (4) The curve of the results obtained by the laboratory.

srepro is the reproductibility standard deviation of the laboratory.

According to the cases, the target value could be :

• The theoretical concentration of the synthetic solution
• The value assigned to the real sample by the laboratory,
• A value within the TITRIVIN confidence interval.

 TITRIVIN can help you to easily create your control chart. So, click here!