International Journal of Legal Medicine

, Volume 133, Issue 1, pp 109–116 | Cite as

Comparison of concentrations of drugs between blood samples with and without fluoride additive—important findings for Δ9-tetrahydrocannabinol and amphetamine

  • Christopher WiedfeldEmail author
  • Julia Krueger
  • Gisela Skopp
  • Frank Musshoff
Original Article


Fluoride is a common stabilizing agent in forensic toxicology to avoid the frequent problem of degradation of drugs in blood samples especially described for cocaine. In cases only samples with addition of fluoride are available, it is a crucial question if also concentrations of common drugs other than cocaine (amphetamines, opiates and cannabinoids) are affected by fluoride. So far, there are only rare literature data available on discrepant results especially for Δ9-tetrahydrocannabinol (THC). In this study, comparative analysis of positive tested paired routine plasma/serum samples (n = 375), collected at the same time point (one device with and one without fluoride), was carried out with special focus on cannabinoids. Samples were measured with validated routine liquid chromatography-tandem mass spectrometry methods for THC, 11-hydroxy-THC (THC-OH), 11-nor-9-carboxy-THC (THC-COOH), cocaine, benzoylecgonine, ecgonine methyl ester, morphine, codeine, amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyamphetamine, and 3,4-methylenedioxyethylamphetamine, and results were statistically evaluated. Beside the expected stabilization effect on cocaine and the consequently reduced concentration of ecgonine methyl ester in fluoride samples, benzoylecgonine was elevated compared to respective samples without fluoride. Most importantly, new findings were significantly reduced mean concentrations of THC (− 17%), THC-OH (− 17%), and THC-COOH (− 22%) in fluoride samples. Mean amphetamine concentration was significantly higher in samples with the additive (+ 6%). For the other amphetamine type of drugs as well as for morphine and codeine, no significant differences could be seen. Whenever specified thresholds have been set, such as in most European countries, the use of different blood sample systems may result in a motorist being differently charged or prosecuted. The findings will support forensic toxicologists at the interpretation of results derived from fluoride-stabilized blood samples.


Fluoride Drugs Comparison Limit values Forensic toxicology 


Compliance with ethical standards

Conflicts of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Christopher Wiedfeld
    • 1
    Email author
  • Julia Krueger
    • 1
  • Gisela Skopp
    • 1
  • Frank Musshoff
    • 1
  1. 1.Forensisch Toxikologisches Centrum GmbHMunichGermany

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