What are Quality Control Samples?
Quality Control (QC) samples are critical components in the field of
bioanalytical sciences, serving as benchmarks to ensure the accuracy, reliability, and consistency of analytical results. These samples are typically prepared from a biological matrix spiked with known quantities of analytes and are used to monitor the
performance of analytical methods over time.
They help in validating the
analytical methods used for quantifying analytes in biological matrices.
They ensure the
reliability and
consistency of the data generated.
They aid in identifying and correcting any
systematic errors or discrepancies in the analytical process.
They provide a means to assess the
accuracy and
precision of the laboratory's analytical methods.
How are QC Samples Prepared?
QC samples are prepared by spiking a known amount of the analyte into a biological matrix such as plasma, serum, or urine. The concentration levels of the analyte in these QC samples are typically set at multiple levels, including low, medium, and high concentrations, to cover the
dynamic range of the analytical method. These samples are then aliquoted and stored under conditions similar to those used for the actual study samples.
Blank QC Samples: Contain no added analyte and are used to monitor any background noise or contamination.
Low QC Samples: Contain a low concentration of the analyte and are used to assess the method's sensitivity and lower limit of quantification.
Medium QC Samples: Contain a mid-range concentration of the analyte and are used to evaluate the method's accuracy and precision within the linear range.
High QC Samples: Contain a high concentration of the analyte and are used to ensure that the method can accurately quantify high analyte levels.
How are QC Samples Used in Routine Analysis?
In routine analysis, QC samples are analyzed alongside the study samples to ensure that the analytical method remains within acceptable performance criteria. Typically, a set of QC samples is included in each analytical run. The results from these QC samples are then compared to predetermined acceptance criteria, such as accuracy (percentage deviation from nominal concentration) and precision (coefficient of variation). If the QC sample results fall within the acceptable range, the analytical run is considered valid. If not, the run may need to be repeated, and any issues identified and resolved.
Accuracy: The percentage deviation of the measured concentration from the nominal concentration should be within a specified range (e.g., ±15%).
Precision: The coefficient of variation (CV) of replicate measurements should be within a specified range (e.g., ≤15%).
Stability: QC samples should remain stable under the storage and analytical conditions used in the study.
Matrix Effects: The biological matrix can affect the accuracy and precision of the analytical method, making it crucial to use matrix-matched QC samples.
Stability Issues: Analytes in QC samples may degrade over time, leading to erroneous results if not properly stored and handled.
Variability: Inconsistencies in the preparation of QC samples can introduce variability, affecting the reliability of the analytical method.
Conclusion
Quality Control samples are indispensable tools in bioanalytical sciences, providing a means to ensure that analytical methods produce accurate, reliable, and consistent results. Proper preparation, handling, and analysis of QC samples are essential to maintaining the integrity of bioanalytical data, ultimately contributing to the success of drug development and other research endeavors.
