Meaning
Statistical correction accounts for the variance introduced when using a known substance to calibrate the measurement of an unknown compound. The internal standard uncertainty factor is used in the chemical analysis of polymers to improve the accuracy of additive quantification. By adding a fixed amount of a standard to the sample, the lab can compensate for losses that occur during extraction or injection into the chromatograph.
Error Compensation
Variations in the detector response or the volume of the sample injected are the primary sources of measurement error. Using an internal standard uncertainty factor allows the chemist to normalize the signal of the target additive against the signal of the standard. If the standard peak is smaller than expected, the calculation automatically scales the results for the other compounds to match.
This correction is vital when dealing with complex resin matrices that might trap migrants during the initial solvent extraction step.
Analytical Precision
Choosing a standard that is chemically similar to the target migrant is essential for reducing the margin of error. The internal standard uncertainty factor must be calculated for each batch of samples to ensure that the data is defensible. This is particularly important when testing for complex mixtures in recycled plastics where the background noise is high.
Result Reliability
Applying the factor ensures that the final concentration reported in the compliance dossier is as close to the true value as possible.
