![handle is hein.journals/injlegame111 and id is 1 raw text is: G. Skopp - L. Potsch - I. Konig - R. Mattern
A preliminary study on the stability of benzodiazepines in blood
and plasma stored at 4* C
Received: 16 March 1997 / Received in revised form: 7 May 1997
Abstract An approach to determine the stability of ben-
zodiazepines and some of their metabolites (n = 13) by
means of a routinely applied gas chromatographic method
using electron capture detection was made in this prelim-
inary study. Validation data of the method are given. Spiked
blood and plasma samples were stored at 4° C and analysed
at selected times up to 240 days. The concentrations of all
analytes had decreased to at least 60% of the original lev-
els at the end of the observation period. A clear pattern of
breakdown could not be established. The data obtained
suggest that results from long-term stored samples should
be interpreted cautiously. Further investigations concern-
ing the stability of drugs in blood and plasma samples, ad-
ditional methods of identification and determination as
well as the establishment of optimal storage conditions
seem necessary.
Key words Benzodiazepines Storage condition-
Long-term stability Forensic toxicology-
Gas chromatography
Introduction
The knowledge of time-dependent decreases in drug con-
centrations in blood or plasma samples is of considerable
significance in legal cases. Frequently, there is already a
delay of several days between sampling, determination of
blood alcohol and initial presumptive drug screening. The
subsequent confirmation may not be performed until the
case goes to court for trial and may be done many days or
weeks after the blood has been taken, especially when
analysis for blood alcohol and drug monitoring of the
G. Skopp (®) I. Konig R. Mattern
Institut fur Rechtsmedizin, Ruprecht-Karls-Universitat,
Vosstrasse 2, D-69115 Heidelberg, Germany
L. Potsch
Institut fur Rechtsmedizin, Johannes-Gutenberg-Universitat,
Am Pulverturm 3, D-55131 Mainz, Germany
same sample is done by separate institutions and at sev-
eral places, a situation already present in Baden-Wurttem-
berg and Rheinland-Pfalz. Usually, additives and preserv-
atives had not been added and sometimes, serum had been
separated from blood and stored separately. Sample stor-
age at 4° C is most favoured over freezing because it is
more feasible for long-term storage of a large number of
specimens. This procedure is in accordance with the offi-
cial regulations. In Germany the forensic laboratories have
to keep all blood samples in a cool place for a time period
of at least 2 years [28] to enable reanalysis if possible.
Some data have been reported on the stability of foren-
sically relevant drugs including cocaine [1], benzoylecgo-
nine [19], 11-nor-A9-tetrahydrocannabinol-9-carboxylic
acid [19], phencyclidine [3] and amphetamines [21]. Re-
cently, a comprehensive stability study has been published
on drugs of abuse in authentic blood samples stored at
ambient temperature [6]. Information on the influence of
long-term storage on the stability of benzodiazepines in a
biological matrix is rare [8, 9, 13, 16], although benzodi-
azepines are the most widely prescribed drug substances
being heavily used and abused [12, 15, 27, 29] and play
an important role in screening blood samples of conspicu-
ous motorists.
It was the aim of this preliminary study to investigate
the stability of some commonly used benzodiazepines in
blood or plasma that were refrigerated at 4° C for various
time periods up to 240 days by a routine gas chromato-
graphic method.
Materials and methods
Experimental design
Analysis in the present study was performed on drug-free unpre-
served fresh blood (250 mL) and frozen plasma (250 mL) samples
obtained from two healthy volunteers from the blood bank of the
University of Heidelberg (Germany). Blood as well as plasma
were divided into three portions (60 mL), spiked with mixtures I-
III (Table 1) of benzodiazepines and aliquoted. For concentration,
the upper therapeutic range of the particular substance was chosen
(Table 1).
Int 7 Legal Med (1998) 111: 1-5
© Springer-Verlag 1998](ViewImageLocal?handle=hein.journals/injlegame111&div=1&collection=&method=preview&ext=.png&size=3)
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