GB/T 5750.3-2023Standard examination methods for drinking water—Part 3: Water analysis quality control (English PDF)

4.1

The purpose of quality control is to reduce the error in the analysis to a certain limit in order to obtain accurate and reliable test results.

4.2

Quality control should be throughout the entire process of water quality analysis, such as sample collection and preservation, sample analysis, data processing, etc. Physical and chemical indicators microbial indicators, radioactive indicators test quality control should be in line with GB/T 5750.1 and GB/T 5750.2 and related indicators test methods and related requirements.

4.3

The laboratory should be validated before the first use of standard methods.

4.4

quality control is the discovery, control and analysis of the process of generating sources of error, used to control and reduce errors, can be achieved by using standard substances or quality control samples, comparison tests (such as personnel comparison, method comparison, instrument comparison, sample retesting, etc.), participation in proficiency testing programs or inter-laboratory comparison, parallel double sample method, spiked recovery method and other effective technical methods to ensure that the analytical results The accurate and reliable.

5.1

Classification of errors in the analysis of the error there are three categories: errors caused by the influence of systematic factors, errors caused by the influence of random factors and errors caused by negligent behavior.

5.2 Representation of the error

6.6 Calibration and Regression

6.6.1 Calibration Curve

Calibration curve describes the quantitative relationship between the concentration or content of the substance to be measured and the response value of the detection instrument or the indicated amount, divided into "working curve" (standard solution processing procedures and analytical procedures are identical to the sample) and "standard curve" (standard solution processing procedures (the standard solution procedure is omitted compared with the sample, such as sample pretreatment)

7.1 Quality control chart method

The most important control charts used in chemical analysis laboratories are of two types, i.e. X-charts (single value or mean value charts) and R-charts (extreme difference charts). Blank value-X-plots and recovery X-plots are special applications of X-plots. Figure 1 shows the most commonly used X-plot drawn from mean values.

8.1 Judgment and processing of outliers

8.1.1

Outliers are judged and processed according to the implementation of GB/T4883.

8.1.2

Grubbs (Grubbs) test can be used to test the consistency of the mean value of multiple measurements and remove outliers in the mean value of multiple measurements, can also be used to test the consistency of a group of measurements and remove outliers in a group of measurements, the number of detected outliers does not exceed 1.

8.2 Measurement results of numerical modifications

8.2.1

Measure the value of the results in accordance with GB/T8170 implementation.

8.2.2

Valid numbers are used to indicate the effective meaning of the measurement figures. Refers to the actual number of measurements can be measured, the value of the valid numbers, the penultimate digit above the number should be reliable (certain), only the last digit is suspicious (uncertain). The number of digits of valid numbers cannot be arbitrarily added or deleted.

9.1

measurement results should be measured using the People's Republic of China legal units of measurement.

9.2

chemical analysis indicators of the measurement results are generally expressed in milligrams per liter (mg / L), the concentration is lower, then micrograms per liter (jag / L) 9.3 The measurement results of radioactive indicators are expressed in Bq per liter (Bq/L).