Determination of buprenorphine and norbuprenorphine in hair by GC-MS

Buprenorphine is a synthetic derivative of thebaine
used as a substitute of heroin in detoxification pro¬
grams. Buprenorphine was introduced for this applica¬
tion in May 2000 in Italy and its use for this therapeu¬
tic purpose has increased of more than 30 % in three
years. The aim of this study was to extend the method
routinely applied in our laboratory to detect heroin
metabolites, cocaine and amphetamines also to bupre¬
norphine (BPR) and its metabolite norbuprenorphine
(norBPR) in order to monitor BPR administration in
detoxification programs as well as to detect drug abuse
during detoxification. The analytical procedure was as
follow: after a washing-step with methanol, hair was
finely cut and incubated in HC1 0.1N (45° C, over¬
night). Nalorphine was chosen as internal standard.
Purification of analytes was executed by solid phase
extraction (Bond Elut Certify®) which provided reco¬
veries higher than 80 % for both BPR and norBPR;
purified extract was derivatised with N-methyl, N-trimethylsilyl
trifluoroacetamide (MSTFA) and the ana¬
lysis was performed by GC-MS in SIM mode. Ions
monitored were: m/z 450, 482, 506 for BPR, m/z 468,
500, 524 for norBPR and m/z 455, 414, 324 for inter¬
nal standard (underlined ions were used as quantifiers).
Method validation was performed by: evaluation of
accuracy and precision; analysis of seven drug-free
hair; testing of linearity (0-0.5 ng/mg, n=5). Intra-day
(n=7) and inter-day (n=3 on 5 different days) precision
were better than 8.8 % for both analytes and accuracy
better than 15 %. The limit of detection was 0.005
ng/mg and the limit of quantitation. was 0.01 ng/mg.
This method was applied to hair samples collected
from patients in withdrawal treatment program and demostrated its good applicability in routine analysis.