What do you think of the matrix effect?
In chemical analysis, matrix refers to the components in the sample other than the analyte. The matrix often significantly interferes with the analysis process of the analyte and affects the accuracy of the analysis results. For example, the ionic strength of the solution can have an effect on the analyte activity coefficient, these effects and interferences are called matrix effects
1. What is matrix effect?
Matrix refers to the components of the sample other than the analyte. The matrix often significantly interferes with the analysis process of the analyte and affects the accuracy of the analysis results.
The most commonly used method to remove the matrix effect is to establish a calibration curve by using a standard sample with known analyte concentration while keeping the matrix in the sample as constant as possible. Solid samples also have a strong matrix effect, and its correction is particularly important.
For complex or unknown matrix effects, the standard addition method can be used. In this method, the response of the sample is measured and recorded. Add a small amount of standard solution further, and record the response value of the sample again. Ideally, standard additions should increase the concentration of the analyte by a factor of 1.5 to 3, while the solution should remain consistent over several additions. The volume of the standard sample used should be as small as possible to minimize the impact on the matrix during the process.
2. Evaluation method
Relative Response Value Method
A: Response value of pesticide in pure solvent B: Response value of the same amount of pesticide added in sample matrix
Matrix Effect Matrix Effect (%)=B/A×100
Complicated standard curve determination
Prepare 3 sets of standard curves. Group 1 is prepared with an organic solvent to form a standard curve containing a series of concentrations of components to be tested and an internal standard, which can be repeated 5 times. The second group of standard curves was prepared by adding the same serial concentrations of components to be tested and internal standards of the same serial concentration as the first group after extraction of five blank samples from different sources or different varieties. The third group of standard curves was prepared by using the same blank sample as the second group, adding the same serial concentration of the components to be tested and the internal standard as the first group before extraction, and then extracting.
The influence of matrix effect on quantification can be determined by comparing the absolute response values of the components to be tested in the three standard curves, the ratio of the response values of the components to be tested to the internal standard, and the slope of the standard curve. The repeatability of the entire system can be evaluated by the results of the first set of measurements. Compared with the measurement results of the first group, if the relative standard deviation of the response value of the component to be tested is significantly increased in the second group of measurement results, it indicates that there is a matrix effect. For the measurement results of the third group, if the relative standard deviation of the response value of the components to be tested increases significantly, it indicates that there is a common influence of matrix effect and extraction recovery rate due to different sample sources.
3. Why is there a matrix effect if the diluent is wrong when diluting the sample?
When we dilute the sample, we need to consider the effect of matrix effect. The dilution must be carried out in the appropriate matrix. For most determinations, the appropriate matrix is the zero calibration product. If the concentration of the components contained in the analyte dilution matrix effect is not correct , the dilution recovery rate cannot be accurately determined for them, because they will form a new equilibrium with Bing agent after dilution.
4. How to avoid the influence of matrix effect in the determination of chemiluminescence?
(1) The matrix effect in immunochemiluminescence assay is a description of a phenomenon, which refers to interference, antigen-antibody reaction, and non-specific factors that have nothing to do with the analyte itself. The matrix effect of the same matrix state varies with methods and detection conditions .
(2) The matrix effect is absolute. As long as the matrix state of the processed sample and the measured sample are different, there must be a matrix effect, and the matrix effect is relative. As long as the matrix effect of a certain method is recognized, or determined by the matrix If the error introduced by a certain method is at an acceptable level, then when measuring whether another method has matrix effect, methodological comparison should be made. If the distribution of the results of the processed sample and the measured sample are different, it means that the matrix effect is obvious, otherwise it belongs to Acceptable, that is, it can be considered that there is no matrix effect.
(3) Strictly speaking, the matrix effect produced by different batches of reagents is also inconsistent, so manufacturers generally calibrate in batches.
(4) To measure whether there is a matrix effect, or to understand the comparability between different methods, the best sample is a fresh human specimen.
(5) Be sure to understand the difference between single standard solution, calibrator, quality control product and fresh sample, and use them correctly.
(6) The quality control product should not be used as the calibrator to calibrate the instrument. Not only will there be differences caused by matrix effects, but also the values of the calibration product and the quality control product will be inconsistent.
(7) The quality control products used for indoor quality control are only used to control the repeatability and precision in the daily work of each laboratory. Since the test methods of each laboratory are inconsistent with the method of the manufacturer's established value, it is not allowed to use the serum with a fixed value. target value to determine the value.
(8) The only credible way to measure the accuracy and reliability of a certain method or reagent is to use fresh human samples for comparison. Only the measured value of the quality control product is similar or equal to the fixed value, which is not enough to explain the accuracy of the method.
(9) The calibrator is designated by the manufacturer to calibrate a certain measurement system (instrument + reagent + method). It is artificially given the calibration value of the calibrator in consideration of its matrix effect, so the calibrator must be dedicated to a certain Determination system. The laboratory department should try to use the reagents, calibrators and quality control products specified by the manufacturer.
(10) When the same calibrator is used for different instruments, it should have different calibration values, and the calibration value of a certain calibrator cannot be used to calibrate various instruments.
