The Application And Development Of Several Kinds Of Reference Materials For The Metrology Calibration

Reference materials play an important and basic role in calibrating and measuring instruments and quality control.In the analysis and metrology,It is usually necessary to calibrate the analytical instrument with the standard substance similar to the substrate,the qualitative and quantitative analysis of material composition can be realized to ensure Accuracy,effectiveness and comparability of measurement results,so that the value can be traceable to national or international standards.Therefore,with the development of analytical science,reference material used more widely and became growing demand.The reference material research has become one of the important directions and research topics in the development of chemistry,biology,medical treatment,environment and geology,which has attracted wide attention of scholars.In this paper,the development of reference material for low conductivity solution is studied,which is mainly used to calibrate the on-line conductivity instrument for quality monitoring of pure water/ultra pure water,and to solve the problem of lack of low conductivity solution in our country.To prepare standard solution with better stability and low conductivity,the low electrolytic conductivity(EC)solutions were prepared with mixed solvents of water and organic solvents:n-propyl alcohol,glycerol,ethylene glycol 1,4-dioxane and potassium chloride as solute.The effect of dielectric constant,proportion of mixed solvent,viscosity,temperature and carbon dioxide on low EC solutions were investigated.It demonstrated that 50%glycerol/water system should be a good choice for preparing low EC standard solutions.Thus,low EC standard solution was prepared with glycerin/water mixed solvent and the uniformity and stability of the standard solution were monitored.Finally,the uncertainty were analyzed in this paper.The expansion uncertainty of the reference material solution was 2%.The sample was sent to the National Institute of Metrology for comparison test,and the results were satisfactory.The successful development of this standard material indicates that we have mastered the development of low conductivity solution and filled the blank of reference material in this low conductivity solution in our country.In this paper,the reference material of naphthalene in methanol solution was developed,with a concentration of 1.0×1 0-7 g/mL?1.0×10-4 g/mL,which was used to calibrate the UV detector and diode array detector of liquid chromatography.The results of homogeneity and long term stability show that the homogeneity and stability are satisfactory,and the uncertainty is 3%,which is equal to the level of similar domestic refernence materials,as well as filling up the blank in the field of this item reference material in our province.At the same time,the reference material of n-hexadecane-isooctane solution with concentration of 100 ng/p.L was developed.It is used to calibrate the gas chromatograph for hydrogen flame ionization detector.The uniformity and stability of the reference material were satisfactory,and its uncertainty is 1%.In order to alleviate the lack of reference material for calibration of ion chromatograph in China,the field dilution,water quality,container,environment and other factors may affect the accuracy of value,and a series of concentration gradient solution is developed to meet the requirements of the JJG 823-2014 verification regulation.Two methods of inductively coupled plasma mass spectrometry(ICP MS)and potential titration were used to analyze the purity of raw of the reference material for the calibration of the ion chromatograph,An accurate,reliable and reproducible quantitative analysis method has been established.The reference material of chloride ion and lithium ion(5?100,?g/mL)solution for calibrating ion chromatography(conductance detector)has been prepared,and passed the homogeneity test.