Pharmaceutical analysis methods for biological samples include chromatography, radionuclide labeling, immunological and microbiological methods. The assay method with good specificity and high sensitivity should be selected according to the nature of the test substance. Chromatography includes high performance liquid chromatography (HPLC), gas chromatography (GC) and chromatography-mass spectrometry (eg LC-MS, LC-MS/MS, GC-MS, GC-MS/MS methods). In situations where simultaneous determination of multiple compounds in biological samples is required, LC-MS/MS and GC-MS/MS have additional advantages in terms of specificity, sensitivity, and speed of analysis.
Biological sample analysis method inspection index
– Accuracy: the closeness of the measured value to the true value under certain analytical conditions;
– Precision: the degree of dispersion of a series of measurements of a sample of the same concentration in the same medium under defined analytical conditions;
– specificity: the ability of an analytical method to measure and distinguish analytes from coexisting components, which may include metabolites, impurities, breakdown products, media components, etc.;
-Sensitivity: The sensitivity of the biological sample analysis method is characterized by the standard curve, mainly including the lower limit of quantification and the concentration-response function;
– Reproducibility: the degree of dispersion of the results between different laboratories, and the degree of dispersion of the results of the analytical method under the same conditions after a short interval;
– Stability: the chemical stability of an analyte in a given medium for a certain period of time under defined conditions;
– Standard curve: relationship between assay response and analyte concentration. Appropriate weighting and statistical tests should be used to best describe simple mathematical models. The standard curve should be continuous and reproducible and should be based on the minimum percent deviation of the results of the regression calculations;
-Extraction recovery: the extraction efficiency of the analysis process, expressed as the percentage of analyte content before and after sample extraction and processing;
– Biological medium: a substance of biological origin that can be collected and processed in a reproducible manner, such as whole blood, plasma, serum, urine, feces, various tissues, etc.;
– Quantitative range: the concentration range including the upper limit of quantification (ULOQ) and the lower limit of quantification (LLOQ) within which reliable and reproducible quantification can be performed using a concentration-response relationship with acceptable accuracy and precision;
– Mediator effects: direct or indirect effects on the response due to the presence of interfering substances in the sample;
– Analysis batch: a complete set of samples to be tested, an appropriate number of standards and quality control samples. Several analysis batches can be completed in one day, and one analysis batch can be completed for several days;
– Standard sample: a sample prepared by adding a known amount of analyte to the biological medium, used to establish a standard curve, and calculate the analyte concentration in quality control samples and unknown samples;
– Quality control samples: QC samples, which are samples prepared by adding known amounts of analytes to biological media to monitor the repeatability of the bioanalytical method and evaluate the integrity and correctness of the analytical results of unknown samples in each analytical batch sex.
Due to the small sampling amount of biological samples, low drug concentration, endogenous substances (such as inorganic salts, lipids, proteins, metabolites) and individual differences and other factors that affect the determination of biological samples, it must be determined according to the structure of the analyte, biological media and expected concentration ranges, establish appropriate biological sample analysis methods, and validate the methods. It is recommended that an independent person prepare standard samples of different concentrations to check the analytical method.
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