Effect of 2019-nCoV Inactivation Method on Serum Methotrexate Concentration in Children with Acute Lymphoblastic Leukemia Detected by Enzyme Immunoassay

OBJECTIVE To study the effects of ultraviolet and heating inactivation of 2019-nCoV on the detection of methotrexate(MTX) concentration by enzyme immunoassay, then to explore the application of this method in epidemic prevention and control. METHODS The blood collection tubes sent to clinical inspection were surface-sterilized with 75% ethanol. After low-speed centrifugation, the serums were divided into non-inactivated, ultraviolet-inactivated and heat-inactivated groups. Then, the ultraviolet-inactivated group was prepared by irradiating the MTX quality control solution and serum samples in a secondary biological safety cabinet under ultraviolet lamp for 30 min. The inactivation method for the heat- inactivation group was heating the quality control solution and serum samples in a seal bag under water bath at 56℃ for 30 min. RESULTS Compared with non-inactivation group, there were no significant difference in MTX detection results of both ultraviolet inactivation and heat-inactivation groups. The results of 91%-95.5% concentration point distribution of the non-inactivated group, ultraviolet-inactivated group and heat-inactivated group were within the 95% concordance interval of the Bland-Altman plot. The correlation coefficients of the non-inactivation group, ultraviolet inactivation group and heat-inactivation group were all >0.98(P<0.001), indicating that the results of the three groups had good consistency. CONCLUSION The inactivation of blood samples in blood vessels by ultraviolet ray for 30 min or heating at 56℃ for 30 min have no effect on the detection of MTX concentration by enzyme immunoassay, which can be used to monitor the concentration of MTX for children with acute lymphoblastic leukemia during the epidemic prevention and control.