Stability of γ-Hydroxybutyrate in Blood Samples from Impaired Drivers after Storage at 4°C and Comparison of GC–FID–GBL and LC–MS-MS Methods of Analysis

TY - JOUR

T1 - Stability of γ-Hydroxybutyrate in Blood Samples from Impaired Drivers after Storage at 4°C and Comparison of GC–FID–GBL and LC–MS-MS Methods of Analysis

AU - Jones, Alan Wayne

AU - Gladh, Sven-Åke

AU - Windberg, Charlotte Norup

AU - Johansen, Sys Stybe

N1 - © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: [email protected].

PY - 2015/5/1

Y1 - 2015/5/1

N2 - The stability of γ-hydroxybutyrate (GHB) was determined in 50 blood samples from impaired drivers after storage at 4°C for up to 12 months. GHB was determined in whole blood by gas chromatography-flame ionization detector (GC-FID) after conversion into γ-butyrolactone (GBL) and results were compared with LC-MS-MS. Both analytical methods showed a linear response (R2 > 0.99) to GHB concentrations from 2 to 250 mg/kg. The mean decrease in concentration after storage was 4.8 mg/kg, with extreme changes of 113 mg/kg or 229 mg/kg. Results by the GC-FID-GBL method (y-variate) and the LC-MS-MS method (x-variate) were highly correlated (R2 5 0.974). The regression equation was y 5 0.85x 1 2.2 and residual standard deviation (SD) was 7.8 mg/kg. The y-intercept (2.2 mg/kg) was not significantly different from zero (P > 0.05), although the slope of the regression line (0.85) differed from unity (P < 0.001), indicating a proportional bias of 15%. The LC-MS-MS method tended to give higher results than the GC-FID-GBL method. The mean difference (bias) was 12 mg/kg (P < 0.001). The SD of individual differences was 11.3 mg/kg and 95% limits of agreement were 211 to 133 mg/kg. The results of this study show that concentrations of GHB in whole blood are stable during storage at 4°C for up to 6 months.

AB - The stability of γ-hydroxybutyrate (GHB) was determined in 50 blood samples from impaired drivers after storage at 4°C for up to 12 months. GHB was determined in whole blood by gas chromatography-flame ionization detector (GC-FID) after conversion into γ-butyrolactone (GBL) and results were compared with LC-MS-MS. Both analytical methods showed a linear response (R2 > 0.99) to GHB concentrations from 2 to 250 mg/kg. The mean decrease in concentration after storage was 4.8 mg/kg, with extreme changes of 113 mg/kg or 229 mg/kg. Results by the GC-FID-GBL method (y-variate) and the LC-MS-MS method (x-variate) were highly correlated (R2 5 0.974). The regression equation was y 5 0.85x 1 2.2 and residual standard deviation (SD) was 7.8 mg/kg. The y-intercept (2.2 mg/kg) was not significantly different from zero (P > 0.05), although the slope of the regression line (0.85) differed from unity (P < 0.001), indicating a proportional bias of 15%. The LC-MS-MS method tended to give higher results than the GC-FID-GBL method. The mean difference (bias) was 12 mg/kg (P < 0.001). The SD of individual differences was 11.3 mg/kg and 95% limits of agreement were 211 to 133 mg/kg. The results of this study show that concentrations of GHB in whole blood are stable during storage at 4°C for up to 6 months.

U2 - 10.1093/jat/bkv007

DO - 10.1093/jat/bkv007

M3 - Journal article

C2 - 25652881

SN - 0146-4760

VL - 39

SP - 294

EP - 299

JO - Journal of Analytical Toxicology

JF - Journal of Analytical Toxicology

IS - 4

ER -