What factors will affect the accuracy of phytosterol determination? How to avoid it?

These factors will affect the accuracy of phytosterol determination and should be avoided in this way.

0 1, sampling quality

The sample is a part of substances selected from a large number of substances;

The measurement result of the sample is the estimated value of the overall characteristic quantity;

Due to the non-uniformity of the population, it is inevitable to introduce an error to infer the population from the measurement results of the sample, which is called sampling error.

02, sample processing and recovery rate

In the process of sample treatment, incomplete dissolution, separation and enrichment may occur, or negative systematic errors may occur due to the volatilization and decomposition of the tested components; On the other hand, due to the pollution of instruments, chemical reagents, environment and operators to the tested components, positive systematic errors will occur. Even if there is no obvious systematic error in sample processing, a large random error will be introduced.

03, analysis of blank control and correction

(1) Analysis blank and its function;

Analysis blank and its variability play a decisive role in the accuracy and precision of trace and ultra-trace analysis results and the detection limit of analytical methods.

(2) Control of analysis blank:

There are mainly the following points:

① Eliminate or control the pollution of the experimental environment to the samples;

(2) The pollution of chemical reagents to the tested components in the sample varies with the purity and dosage of the reagents;

(3) If the materials are impure or not cleaned, the instruments used for storing and processing samples may pollute the samples;

(4) Avoid the pollution of the samples by analysts.

(3) Blank test:

According to the blank test value and its standard deviation, the measured value of the sample is blank corrected.

04. Applicability of measurement methods

(1) Categories and grades of measurement methods:

There are thousands of existing standard methods, which can be roughly divided into three types:

① General standard method for testing product technical specifications.

(2) the standard method for implementing some laws and regulations is called the official method.

(3) Basic standard methods, such as those formulated by the American Society for Testing Materials (ASTM).

(2) Main technical parameters and control indexes of the measurement method:

Including: linear range, accuracy, precision, sensitivity, detection limit and so on.

05, calibration of measurement methods

Making accurate and effective calibration curves is an important prerequisite for obtaining accurate and reliable measurement results.

(1) Use accurate and reliable measurement standards.

(2) Eliminate or measure the influence of interference and matrix effect.

(3) Control the experimental conditions and design the experiment reasonably.

The experiment should be designed according to the following principles:

① In order to make the experimental conditions of measuring samples as consistent as possible with those of making calibration curves, the calibration curves should be made and used in a short time interval;

② The number of experimental points on the calibration curve should be more than 5, and the range of experimental points should be as wide as possible to improve the reliability and stability of the calibration curve;

(3) It is best to take the average value of repeated measurements at each experimental point, at least at the end of the calibration curve, so as to reduce the experimental error.

06. Standardization of analytical methods

Standard analytical method, also known as analytical method standard, is one of the technical standards. There are often many alternative methods for the determination of an item, and the sensitivity of these methods is different. The requirements for instruments and operations are different. Moreover, due to the different methods and principles, the interference factors are different, and even the meaning of the results is different.

Laboratories attach importance to inspection work and meet the quality requirements of society for inspection data. It is necessary to comprehensively control the so-called human, machine, sample, method, environment, traceability and other factors that affect inspection data as an organic whole. Only by systematically and harmoniously controlling the interrelation and connection between the whole inspection process and various activities in the process of quality formation, can the accuracy, fairness, truthfulness and reliability of inspection data be guaranteed, and the quality of laboratory analysis and testing can be continuously improved and improved.