Determination of the concentration of very long chain fatty acids in serum by liquid chromatography-tandem mass spectrometry / 中华检验医学杂志

ABSTRACT

Objective To establish a method for very long chain fatty acids( VLCFA )with liquid chromatography-tandem mass spectrometry( LC-MS/MS ). Methods One hundred and one healthy cases and 35 suspected ALD patients collected from April to June in 2009 were enrolled into this study. Quantitative analyzed the concentrations of VLCFA in serum was performed using liquid chromatography-tandem mass spectrometry. The precision, accuracy and recovery were analyzed, and the stability of VLCFA concentration of sample under room temperature and repeated freeze-thawing were also investigated. Serum levels of VLCFA in 101 normal cases were determined and analyzed statistically. The results for the 35 randomly chosen serum samples were compared with those from MDI in Germany. Results Serum VLCFA were separated well under these gradient condition with small interference. The linear range of C220 was from 2 mg/L to 64 mg/L, the recovery was 99. 92% -102. 05%, and the relative standard deviation ( RSD ) of intra-day and inter-day was less than 6% and 9% respectively. For C240 they were 2-64 mg/L. 95. 12%-100. 44%. ≤6%, ≤7%,respectively. For C260, they were 0-8 mg/L, 92.21%-103.71%, ≤7%, ≤8%, respectively. The accuracy of C22 0,C240 and C260 were among 85% to 115%. The samples could be stable within 12 h at room temperature and repeated 10 times freeze-thawing. The values of VLCFA in 101 normal cases followed a normal distribution and the measured values were C220 =( 19. 43 ±4.43 ) mg/L,C240 =( 19. 10 ±4. 58 )mg/L, C260 = ( 0. 21 ± 0. 11 ) mg/L, the ratio of C24 0/C220 and C260/C22 0 were ( 0. 99 ± 0. 13 )and ( 0. 01 ±0. 01 ) respectively. The statistical analysis showed the concentration of C260 in adults ( 0. 18±0. 10 ) mg/L and children ( 0. 21 ± 0. 08 ) mg/L, C24 0/C220 in adults ( 1.01 ± 0. 10 ) and children ( 0. 99 ±0. 14 ) has no significant( t values were 1. 439,0. 806, respectively, all P ＞ 0. 05 ); the ratio of C240/C220 in male (1.05 ± 0. 10 ) and female (0.97 ± 0. 10 ) has significant difference ( t =3. 394,P =0. 001 ). Compared the values determined by MDI laboratory, the results of C22 0( 16. 93 ±4. 30 ) mg/L,C24 0( 19. 57 ± 6. 40 ) mg/L by this method and C220 ( 13.85 ± 3. 17 ) mg/L, C240( 16. 10 ±5.84 ) mg/L by MDI have significant differences( t = 8. 401 ,P =0. 000;t =9. 914,P =0. 000 ),but C260( 0.68 ±0.48 ) mg/L, C240/C220( 1.20 ±0.40 ), C26 0/C220 ( 0.04 ±0.04 )by this method and C26 0( 0. 65 ± 0. 67 ) mg/L, C240/C22 0( 1.19 ± 0. 43 ), C260/C22 0 ( 0. 05 ± 0. 05 )by MDI have no differences( t values were 0. 372,0. 317,0. 945 ,respectively ,all P ＞0. 05 ). Conclusions The quantitative analysis method for serum very long chain fatty acid using LC-MS/MS is accurate, sensitive,specific and stable. It could provide important biochemistry information for diagnosis in clinic.