Research On Technology For Traceability Of Value Of Liquid Particle Counter

The metrology and detection of particles is a new subject to measure the particle size and number concentration in liquid,which is applied widely in the medicine,aerospace and environmental protection.For example,particle size and number concentration of intravenous injection are strictly stipulated in pharmacopoeia of many countries,otherwise it can seriously harms human health;In our country,sewage discharge is divided into three grades,in which suspended particle number concentration is taken as an important quality control standard after wastewater treatment.Liquid particle counter is a precision instrument for the characterization of particle size and number concentration,due to the different mathematical models are established by different instrument manufacturers,there is no unified standard to evaluate the accuracy of measurement results.In addition,the device of liquid particle counter will be aging after using for long time,resulting in poor repeatability of measurement results.Therefore,the liquid particle counter must be regularly verification or calibration with the certified reference materials for particle number concentration to ensure the accuracy and traceability of value of measurement results.Based on this,this paper developed a series of water-based certified reference materials for particle number concentration,the main contents are as follows:(1)The candidate choice of certified reference materials.Stable of chemical property,density is closed to water and excellent sphericity are basic requirements of certified reference materials,the cross-linked polystyrene compared with polystyrene has better heat resistance and solvent resistance,the three-dimensional network structure make it more stable of physical and chemical properties,therefore,this paper selects the cross-linked polystyrene as candidate of certified reference materials.(2)Certified for certified reference materials.This paper adopts the method that can be traced to the relevant national primary standards to certify for particle size and number concentration of certified reference materials.(3)Test of uniformity and stability.It is necessary for certified reference materials to test the uniformity and stability,and this paper test them through F-test and t-test,through data analysis,uniformity and stability of certified reference materials we developed conform to the requirements of country about development of certified reference materials.(5)Uncertainty evaluation of certified reference materials.It is important to analyze the sources of uncertainty and establish appropriate measurement model,this paper analyzes the uncertainty of the certified about particle size and number concentration,finally gives its expanded uncertainty,and its relative expanded uncertainty is all lower than 10%,indicating that the certified is accurate and reliable.