Stability studies of principal illicit drugs in oral fluid: preparation of reference materials for external quality assessment schemes.
Author(s): Ventura M, Pichini S, Ventura R, Zuccaro P, Pacifici R, de la Torre R
Publication: Ther Drug Monit, 2007, Vol. 29, Page 662-5
PubMed ID: 17898661 PubMed Review Paper? No
Suggested by: ISBER
Purpose of Paper
The purpose of this paper was to determine the stability of illicit drugs in spiked saliva specimens during storage.
Conclusion of Paper
Storage at 37 or 25 degrees C for 7 days, or storage at 4 or -20 degrees C for up to 2 months, had no effects on amphetamine (AMP), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), benzoylecgonine (BZE), morphine (MOR), or codeine (COD). In contrast, cocaine (COC) and 6-monoacetylmorphine (6-MAM) were degraded after 3 days at 37 degrees C, 7 days at 25 degrees C, 1 month at 4 degrees C, and 2 months at -20 degrees C. The addition of sodium azide and citrate buffer stabilized COC and 6-MAM for up to 7 days at 25 or 37 degrees C and up to 2 months at 4 or -20 degrees C. Up to 3 freeze-thaw cycles had no effects on the stability of any of the drugs.
Studies
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Study Purpose
The purpose of this study was to investigate the stability of illicit drugs in saliva specimens during storage with and without preservative and after freeze-thaw cycling. Normal saliva specimens were spiked with 300 ng/mL each of AMP, MA, MDA, MDMA, BZE, MOR, COD, COC, and 6-MAM.
Summary of Findings:
Storage at 37 or 25 degrees C for 7 days, or storage at 4 or -20 degrees C for up to 2 months, had no effect on AMP, MA, MDA, MDMA, BZE, MOR, and COD. In contrast, COC and 6-MAM were rapidly hydrolyzed to BZE and MOR. After 3 days of storage, at 37 degrees C, 80% of COC had been hydrolyzed and 37% of 6-MAM. After 7 days of storage, at 25 degrees C, 66% of COC and 21% of 6-MAM was hydrolyzed. After 7 days or 1 month at 4 degrees C, significant hydrolysis of COC (23% and 82% respectively) was found. Significant hydrolysis of 6-MAM (15%) was observed only after 1 month of storage at 4 degrees C. After 2 months at -20 degrees C, small but statistically significant changes in COC (5%) and 6-MAM (10%) were observed. The addition of sodium azide and citrate buffer stabilized COC and 6-MAM for up to 7 days at 25 or 37 degrees C and up to 2 months at 4 or -20 degrees C. Up to 3 freeze-thaw cycles had no effects on the stability of any of the drugs.
Biospecimens
Preservative Types
- None (Fresh)
- Other Preservative
- Frozen
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Small molecule GC-MS Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Storage Storage temperature 25 degrees C
37 degrees C
4 degrees C
-20 degrees C
Storage Storage duration 3 days
7 days
1 month
2 months
Storage Freeze/thaw cycling 1 cycle
2 cycles
3 cycles
0 cycles
Biospecimen Preservation Type of fixation/preservation Sodium azide
None (fresh)
Frozen
Biospecimen Preservation Fixative additive/buffer Citrate buffer