title: Assessment of the stability of exogenous gamma hydroxybutyric acid (GHB) in stored blood and urine specimens.
abstract: OBJECTIVE
  The aim of this work is to test the stability of exogenous GHB in whole blood and urine samples collected from living and deceased GHB free-users, spiked with known concentrations of GHB and stored at different temperatures (-20°C, 4°C and 20°C) up to 4 weeks.
  
  
  METHODS
  GHB was added to GHB-free ante-mortem blood and urine samples at the concentration of 5 and 10 mg/L, respectively whereas in post-mortem blood and urine specimens at 50 and 10 mg/L respectively. All samples were stored at three different temperatures: -20°C, 4°C and 20°C and extracted and analyzed at three days, 1 week, 2 weeks, 3 and 4 weeks in duplicate. No preservatives were added. GHB was quantified by GC-MS after LLE according to a previously published method.
  
  
  RESULTS
  Post-mortem blood specimens showed a reduction of GHB levels higher than 10% only after a period of 4 weeks of storage for samples kept at +4°C and +20°C, whereas samples stored at -20°C showed a mean reduction of 8.7%. In post-mortem urine samples, there was a mean reduction of GHB levels higher than 20% at all storage temperatures, after 4 weeks of storage. Ante-mortem blood samples showed a reduction of GHB levels lower than 10% only after 3 days of storage at -20°C and at +4°C (samples stored at +20°C showed a mean reduction of 10.4%). After 4 weeks of storage, there was a mean reduction of GHB concentrations higher than 20% at all storage temperatures. Ante-mortem urine samples showed a reduction of GHB levels higher than 10% after just 3 days of storage for samples kept at all tested temperatures. After 4 weeks of storage, there was a mean reduction of GHB concentrations higher than 25% at all storage temperatures.
  
  
  CONCLUSIONS
  According to our findings, it would be useful to perform GHB analysis both in blood and urine specimens within 3 days of sampling and the specimens should be stored at -20°C or 4°C in order to avoid instability issues.
authors.affiliation: Department of Anatomical, Histological, Forensic and Orthopedic Sciences, Sapienza University of Rome, Rome, Italy. simona.zaami@uniroma1.it.
authors.forename: F P
authors.initials: FP
authors.lastname: Busardò
authors.forename: S
authors.initials: S
authors.lastname: Zaami
authors.forename: G
authors.initials: G
authors.lastname: Baglio
authors.forename: F
authors.initials: F
authors.lastname: Indorato
authors.forename: A
authors.initials: A
authors.lastname: Montana
authors.forename: N
authors.initials: N
authors.lastname: Giarratana
authors.forename: C
authors.initials: C
authors.lastname: Kyriakou
authors.forename: E
authors.initials: E
authors.lastname: Marinelli
authors.forename: G
authors.initials: G
authors.lastname: Romano
mesh_terms: D000328:Adult; D001344:Autopsy; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006885:Hydroxybutyrates / Q000097:blood* / Q000652:urine*; D008297:Male; D008875:Middle Aged; D013048:Specimen Handling / Q000592:standards*; D015813:Substance Abuse Detection / Q000379:methods / Q000592:standards*; D019966:Substance-Related Disorders / Q000097:blood / Q000175:diagnosis / Q000652:urine; D013696:Temperature; D013997:Time Factors
chemical_list: D006885:Hydroxybutyrates; C111420:4-hydroxybutyric acid