SOFT 2004 Meeting Abstracts - Society of Forensic Toxicologists

A66
DETERMINATION OF SODIUM AZIDE IN BODY FLUIDS AND BEVERAGES BY ION
CHROMATOGRAPHY
Yukari Hirata', \ Saori Ishida l , Hitoshi Tsuchihashi 2 , Makoto Hamajima l , Kanako Watanabe 3 , Hiroshi
Seno 4 , Rina Kaneko I,Akira Ishii!, IDepartment of LegaJ Medicine, Fujita Health University School of
Medicine, Japan, 2Forensic Science Laboratory, Osaka Prefectural Police Headquarters, Japan, 3Department
ofLegal Medicine, Hamamatsu University School of Medicine, Japan, 4Department of Legal Medicine,
Aichi Medical University, Japan
Background: Sodium azide, which is widely used as a bactericide in protein samples in clinical or research
laboratories, is highly toxic. Actually, its oral LD50 value is estimated to be 45 mg/kg, which is only 5
times greater than that potassium cyanide. In 1998, several mass poisoning cases with sodium azide
occurred in Japan. It was then regulated as a poison by the Poisonous and Deleterious Substances Control
Law. It is thus important to determine azide in body fluids and beverages with high sensitivity. We have
succeeded in determining azide in different materials by ion chromatography.
Methods: Azide ion in various samples was extracted using a Conway microdiffusion cell. Hydrazoic acid
was vaporized from 1 mL sample (plasma or beverages) by adding 1 mL of 5% sulfuric acid in the outer
groove, and absorbed in 250 ~L of 0.1 M NaOH solution in the central round basin. After the cell was
incubated at 37°C for 30 min, a 20-j..tL aliquot of 0.1 M NaOH was injected to an ion chromatography
system equipped with a suppressor and a conductivity detector (Dionex DX 500 system). The guard and
separation columns used were a Dionex AG15 (50 x 2 mm Ld.) and an AS 15 (250 x 2 mm Ld.) column.
The mobile phase was 38 mM NaOH and the flow rate was set at 0.4 mLimin.
Results: The retention time of azide ion was about 10 min. In human plasma samples, the calibration curve
gave good linearity in the range of 50 ng/mL and 10 ~g/mL; its detection limit was about 30 ng/mL. The
intraday and interday CV values for 5 ~g/mL plasma were 2.8 and 8.8 %, respectively. We have tried
several internal standards, but the use of an internal standard did not improve the reproducibility in
quantitation of azide. Also, similar experiments were performed in different beverage samples spiked with
sodium azide. It gave good linearity in the range of 50 ng/mL and 5 llg/mL; its detection limit was about
10 ng/mL.
Conclusion: Combination of the microdiffusion method and a semi-microcolumn has enabled the detection
of azide with 3 to 4 times higher sensitivity compared to the methods previously reported. Thus, the
present method can be applicable for clinical and forensic toxicology, because of its simplicity and
sensitivity .
Keywords: Azide, Ion chromatography, Microdiffusion method
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