THE ERRORS IN THE CLAIMED CONCENTRATIONS OF STANDARD GASES USED IN THE OBSERVATION OF REACTIVE GASES AND RECOMMENDED SOLUTIONS

Under strict quality assurance and quality control measures,quantitative comparisons of a number of domestic standard gases with NIST-traceable standard gases were carried out in the laboratory.The results show a large range of deviations between the claimed concentrations of the domestic standard gases and those of the NIST-traceable standards,particularly for SO2 and NO,which were produced by different manufacturers or by the same manufacturer but in different time.In all the results,2/3 and 1/3 of SO2 standard gas samples exceeded the relative deviation of ±5% and ±10%,respectively,nearly 30% of the NO standard gas samples exceeded the relative deviation of ±5%,while CO standard gases show relatively smaller deviations.Therefore,to ensure the comparability among the observed data obtained in different times or at different locations,the errors of standard gas concentration must be addressed.In view of the present quality situation for the domestic standard gases,quality control measures are recommended to reduce the test error and promote the comparability of test data,which is crucial in the long-term operational monitoring.