Final answer:
Preanalytical variables in laboratory testing include factors such as sample collection, storage and preparation, as well as the stability and selectivity of the analytical methods used.
Step-by-step explanation:
Preanalytical variables in laboratory testing refers to factors that can affect the accuracy and reliability of the test results before the actual analysis takes place. These variables include factors such as sample collection, storage and preparation, as well as the stability and selectivity of the analytical methods used.
For example, in the context of pharmacokinetic investigations, preanalytical variables may include the stability of stock solutions, the extraction procedure for samples, calibration curve parameters, and the validation of the analytical method.
By carefully considering and controlling these preanalytical variables, scientists can ensure that the test results are accurate and meaningful.