Abstract:

Objective To study the influence of hemolysis on the results of plasma catecholamines [epinephrine（E）,norepinephrine（NE） and dopamine（DA）] and their metabolites [metanephrine（MN）,normetanephrine（NMN） and 3-methoxytyramine（3-MT）] by liquid chromatography-tandem mass spectrometry （LC-MS/MS）.Methods The standard solutions of catecholamines and their metabolites were added to normal plasma and plasma with different degrees of hemolysis [the levels of hemoglobin（Hb） were 0.75 g/L（mild hemolysis）,1.50 and 3.00 g/L（moderate hemolysis） and 7.50 g/L（severe hemolysis） to make the samples with low and high levels of catecholamines and their metabolites. All the samples were subjected to weak cation-exchange solid phase extraction with 3 replicates. The catecholamines and their metabolites in extraction solutions were analyzed by LC-MS/MS.Results No matter the levels of MN,NMN,3-MT were high or low,the levels of MN,NMN and 3-MT had no statistical significance among normal samples and all hemolytic samples（P>0.05）,except the signal of 3-MT could not be determined in severely hemolytic samples（the level of Hb was 7.50 g/L）. The coefficients of variation（CV） of MN,NMN and 3-MT in high-level samples from 3 replicates were <15%. When the levels of Hb were 1.50 g/L for low-level 3-MT and 7.50 g/L for low-level NMN,the CV were >15%. When the level of Hb was 3.00 g/L,DA,E and NE were not determined in low-level or high-level samples. When the level of Hb was ≤1.50 g/L,the results of E,NE and DA in low-level samples and the results of DA and NE in high-level samples had no statistical significance among normal samples and hemolytic samples（P>0.05）,but the result of E in high-level samples decreased,when the level of Hb was 1.50 g/L（P<0.05）. The CV of E,NE and DA in low-level and high-level samples were all <15%,when the level of Hb was ≤1.50 g/L.Conclusions Moderate and severe hemolysis has influence on the results of catecholamines and their metabolites by LC-MS/MS.

Key words: Catecholamine, Metabolite, Hemolysis, Hemoglobin, Liquid chromatography-tandem mass spectrometry