In-matrix derivatization and automated headspace solid-phase ...

Forensic Toxicol (2006) 24:51–57
DOI 10.1007/s11419-006-0010-6
ORIGINAL ARTICLE
In-matrix derivatization and automated headspace solid-phase
microextraction for GC-MS determination of amphetamine-related
drugs in human hair
Midori Yahata · Akira Namera · Manami Nishida
Mikio Yashiki · Takako Kuramoto · Kojiro Kimura
Received: 20 February 2006 / Accepted: 14 July 2006 / Published online: 18 September 2006
© Japanese Association of Forensic Toxicology and Springer 2006
Abstract A fully automated method for analysis of
amphetamine-related drugs in human hair by gas
chromatography-mass spectrometry (GC-MS) was developed
using headspace solid-phase microextraction
(SPME) and in-matrix derivatization. Amphetamines
were extracted from hair under alkaline conditions, and
were simultaneously derivatized to N-ethoxycarbonyl
amphetamines with ethylchloroformate in a vial. An
SPME fiber was then exposed to the headspace at 80°C
for 10min for extraction. The derivatives extracted into
the stationary phase of the fiber were desorbed by exposing
the fiber in an injection port of a GC-MS instrument.
The calibration curves showed linearity up to 10 ng/mg
in hair. The detection limits ranged from 0.01 to 0.5 ng/
mg according to the compound identity. No interferences
were found, and the time required for analysis was
about 30 min per sample. Furthermore, this proposed
method was applied to diagnosis of methamphetamine
intake in actual cases; methamphetamine and its metabolite
amphetamine were able to be detected in hair of
abuser patients admitted to a hospital.
Keywords Methamphetamine · Amphetamine ·
MDMA · MDA · Hair analysis · SPME
M. Yahata · A. Namera (*) · M. Nishida · M. Yashiki ·
K. Kimura
Department of Legal Medicine, Graduate School of Biomedical
Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku,
Hiroshima 734-8551, Japan
e-mail: namera@hiroshima-u.ac.jp
M. Yahata · T. Kuramoto
Scientific Investigation Laboratory, Hiroshima Prefectural Police
Headquarters, Hiroshima, Japan
Introduction
Amphetamine (AMP) and its related drugs (amphetamines)
are central nervous system stimulants like cocaine.
Recently, the abuse of amphetamines, especially
methylenedioxymethamphetamine (MDMA), by young
people to experience psychedelic and euphoric states has
become more common in many countries. The incidences
of acute intoxications and deaths following overdoses
of these drugs are increasing. Therefore, the
detection of these drugs from human specimens by mass
spectrometry (MS) is very important for detection of
drug abuse and diagnosis of cause of death. Verification
of abuse of these stimulants in forensic and clinical laboratories
is usually achieved by MS detection of amphetamines
and metabolites in urine samples obtained from
abusers. However, urine analysis has the following disadvantages:
(1) the period of detectability is short after
intake of amphetamines; and (2) the concentrations of
amphetamines in urine are affected by its pH. Recently,
hair analysis of abused and therapeutic drugs has been
used as a new tool in forensic and clinical toxicology,
because basic drugs remain in hair for several months or
even years, and hair analysis can verify a history of drug
abuse [1–5]. Some reviews have described chromatographic
methods for the detection of amphetamines in
hair [6–8]. These reported methods include complex procedures,
are costly and time consuming, and require
large volumes of organic solvents, causing environmental
problems.
In our previous studies [9,10], a fully automated
method by gas chromatography (GC)-MS for detection
of AMP and methamphetamine (MET) in urine was
developed using solid-phase microextraction (SPME)
after in-matrix derivatization. In this method, amphet-
13

52 Forensic Toxicol (2006) 24:51–57
amines were quickly converted to N-ethoxycarbonyl derivatives
using ethylchloroformate in urine and then the
derivatives were extracted from the headspace by SPME.
In the present study, we have extended this line of experiments
to human hair for optimization of the experimental
conditions.
Materials and methods
Materials
AMP hydrosulfate and pentadeuterated MET (MET-d 5,
internal standard, IS) hydrochloride were supplied by
Dr. Hara of Fukuoka University (Fukuoka, Japan).
MET hydrochloride was purchased from Dainippon
Pharmaceutical (Osaka, Japan); methylenedioxyamphetamine
(MDA) and MDMA were purchased from
Sigma (St. Louis, MO, USA). Other common reagents
and solvents used were of the highest quality commercially
available. Stock standard solutions of amphetamines
(1.0mg/ml) were dissolved in 0.01 M HCl and
stored at 4°C in a refrigerator.
An SPME autosampler holder and a fiber assembly
coated with polydimethylsiloxane (PDMS, 100µm) [11]
were purchased from Supelco (Tokyo, Japan). The fibers
were conditioned in a GC injection port at 250°C for 1 h
prior to use.
GC-MS conditions
The GC-MS instrument used was a GC-17A and QP-
5000 (Shimadzu, Kyoto, Japan), equipped with a 30 m ×
0.25 mm (i.d.) fused silica capillary column (Supelco,
PTE-5, film thickness 0.25 µm). The oven temperature
was programmed from 80° (3-min hold) to 220°C at
40°C/min and from 220° to 280°C (3-min hold) at 8°C/
min. The temperatures of the injection port and interface
were set at 250° and 230°C, respectively. Splitless injection
mode was used. Helium was used as a carrier gas at
a flow rate of 0.8 ml/min. Ions used for identification
were m/z 91, 116, and 207 for AMP, m/z 91, 102, 130,
and 221 for MET, m/z 116, 135, and 251 for MDA, and
m/z 102, 130, 135, and 265 for MDMA. Ions used for
quantitation in the selected ion monitoring (SIM) mode
were m/z 116 for AMP and MDA, m/z 130 for MET and
MDMA, and m/z 134 for MET-d 5 (IS).
Hair samples
Drug-free hair samples, collected from healthy men who
had not taken drugs, were used as blank hair or that to
be spiked with amphetamines. Hair samples of abusers
13
were cut at the surface of the scalp with their consent.
Drug-free hair and abusers’ hair samples collected
from clinical and medico-legal cases were kept at 4°C
until analyzed. Each hair was washed with sodium
dodecylsulfate (0.1%, three times), distilled water (three
times), methanol (once), and then dried at room temperature.
Each hair was cut into 1-mm lengths prior to
SPME.
A “control hair solution” was used to optimize analytical
conditions. The control hair solution was prepared
with a slight modification of the method described
by Koide et al. [12]. In brief, a 0.5-g of hair from healthy
men was dissolved in 50ml of 5M NaOH by heating at
75°C for 1h.
SPME procedure
A washed hair (10mg), NaOH solution (5 M, 1.0 ml),
ethylchloroformate (20 µl), and IS (1.0µg/ml, 30 µl) were
placed in a 10-ml vial and sealed rapidly with a silicone
septum cap. The vials were placed in a sample tray. The
following procedures (extraction and introduction to a
GC-MS instrument) were performed automatically using
Combi PAL (CTC Analytics, Zwingen, Switzerland).
The operator was not required to touch the sample until
the analysis was complete. The vial was rotated at
250 rpm and heated at 80°C for 10min to dissolve a hair
sample. The SPME needle was then inserted into the vial
and the extraction fiber was exposed at 80°C for 10 min
in the headspace. The vial was rotated at 250 rpm during
the SPME extraction. After extraction, the fiber was
pulled back into the needle and the needle was then
inserted into the injection port of the GC-MS instrument.
The fiber was exposed in the injection port to
desorb the analytes from the fiber for 3 min.
Results
Optimization of conditions
The dissolution of hair matrix was necessary prior to
extraction of amphetamines from hair. Three main
methods were used to dissolve the hair matrix with: (1)
strong alkali, (2) strong acid, and (3) enzyme hydrolysis.
A fourth method employed a methanol extraction without
dissolution of hair matrix. Higher extraction yield
was obtained at pH higher than 10, because of the high
acid dissociation constants of amphetamines (pK a 9.6–
10.1) [13]. When acid or enzyme hydrolysis was used, the
vial had to be opened to adjust the pH of the dissolved
sample before the SPME extraction. The addition of
excess methanol affected the SPME extraction badly.

Forensic Toxicol (2006) 24:51–57 53
Fig. 1 Effects of
ethylchloroformate
concentrations on the yields
of derivatives of amphetamines
using headspace solidphase
microextraction
(SPME) with in-matrix
derivatization. The
concentration of each drug
was 50 ng/ml in the presence
of 10 mg hair in a vial. AMP,
amphetamine; MET,
methamphetamine; MDA,
methylenedioxyamphetamine;
MDMA, methylenedioxymethamphetamine
Peak Area
800000
700000
600000
500000
400000
300000
200000
100000
The alkaline hydrolysis was advantageous for dissolving
the hair matrix, and extracting and derivatizing amphetamines
in hair in the same vial simultaneously. In this
study, therefore, alkaline hydrolysis was adopted to dissolve
hair.
The extraction yield is affected by the amounts of the
organic products formed after alkaline hydrolysis of
hair. To examine such effects, the extraction yields of
amphetamines spiked into the hair solution were tested
as a function of amounts of hair (1, 3, 7, 10, 20, and
40mg/vial) by heating at 80°C in 0.5 M NaOH solution.
The results showed yields of 90–100% in the presence of
1–10mg of hair in a vial. In the presence of more than
20mg of hair, the yields decreased to only 10–60%.
Therefore, 10 mg was adopted as the amount of hair for
each vial.
To minimize the damage to the fiber and maximize
the in-matrix derivatization, the amounts of
ethylchloroformate to be added were optimized. The
amounts of derivatives of amphetamines adsorbed to the
fiber were largest at 20 µl (Fig. 1). Therefore, 20 µl of
ethylchloroformate was adopted as the volume for routine
analysis. The effect of NaOH concentration in hair
solution on the yield of the derivatives was also tested by
heating at 80°C for 20 min. Although the yields increased
with higher concentrations of NaOH, the fiber coating
was more damaged as a result. Therefore, the concentration
of 5 M NaOH was selected.
To optimize the temperature and time for heating the
matrix mixture, the vials were heated at four different
temperatures (60°, 70°, 80°, and 90°C) for seven different
periods (3, 5, 10, 15, 20, 30, and 40min). The results are
shown in Fig. 2. Good equilibrium was reached at 80°C
for 10 min for AMP and MET. Equilibrium for MDA
0
AMP MET MDA MDMA
Compound
and MDMA was reached at around 90° or 100°C for
20 min. The yields of AMP and MET dramatically decreased
by changing temperature from 80°C to over
90°C. Therefore, the fiber was exposed in the headspace
of the vial at 80°C for 10 min in view of the best conditions
for AMP and MET rather than those of MDA and
MDMA.
Reliability of the method
Typical electron impact ionization (EI)-SIM chromatograms
extracted from the spiked hair are shown in Fig. 3.
The calibration curves showed linearity in the range of
0.02–5.0ng/mg for AMP, 0.01–10 ng/mg for MET, 0.05–
10 ng/mg for MDMA, and 0.5–10 ng/mg for MDA in
hair (Table 1). The correlation coefficients of the calibration
curves were 0.987 to 0.996. The limits of detection of
amphetamines in hair were 0.01 to 0.5 ng/mg; therapeutic
levels of amphetamines in hair can be measured by
this method. The intraday and interday coefficients of
variation for three different concentrations in hair were
2.90 to 11.4% and 1.54 to 12.8%, respectively (Table 2).
The recoveries of the amphetamines from the spiked hair
were 3.2 to 10.0%.
Application to actual cases
5µl
10µl
20µl
30µl
40µl
The present method was applied to an analysis of human
hair samples obtained from two abusers who ingested
MET. Sharp and symmetrical peaks of AMP and MET
were obtained without interference by endogenous impurities
(Fig. 4). The concentrations of MET and AMP
were 0.62 and 0.02 ng/mg, respectively, in case 1, and
0.26 and 0.05 ng/mg, respectively, in case 2.
13

54 Forensic Toxicol (2006) 24:51–57
Peak area
Peak area
1000000
800000
600000
400000
200000
150000
100000
50000
13
AMP MET
0
0
0 10 20 30 40 50 0 10 20 30 40 50
Adsorption time (min)
0
0 10 20 30 40 50
Adsorption time (min)
Peak area
Peak area
2000000
1500000
1000000
500000
700000
600000
500000
400000
300000
200000
100000
0
Adsorption time (min)
MDA MDMA
0 10 20 30 40 50
Adsorption time (min)
Fig. 2 Effects of temperature and time for heating the matrix mixture on the yields of derivatives of amphetamines. The composition of
the mixture was the same as specified in Fig. 1. Diamonds, 60°C; squares, 70°C; triangles, 80°C; crosses, 90°C
Table 1 Limit of detection and
linearity data for determination
of amphetamines in human
hair
LOD, limit of detection
Compound LOD Linearity range Equation Correlation
(ng/mg) (ng/mg) coefficient
AMP 0.02 0.02–5.0 y = 0.0189x − 0.0194 0.990
MET 0.01 0.01–10 y = 0.050x + 0.1112 0.996
MDA 0.50 0.50–10 y = 0.0010x − 0.0016 0.995
MDMA 0.05 0.05–10 y = 0.0076x − 0.0316 0.988
Table 2 Accuracy, intraday and interday precision for analysis of amphetamine-related drugs
Compounds Intraday a
Interday b
Compounds Intraday a
spiked (ng/mg)
Mean ± SD CV (%)
CV (%) spiked (ng/mg)
Mean ± SD CV (%)
AMP MDA
0.25 0.23 ± 0.01 3.70 8.31 0.50 0.52 ± 0.04 7.61 12.8
1.00 1.06 ± 0.04 3.79 5.58 2.00 2.11 ± 0.24 11.4 12.5
2.00 2.14 ± 0.11 5.10 9.02 4.00 4.33 ± 0.39 9.12 11.4
MET MDMA
0.50 0.49 ± 0.01 2.90 3.87 0.50 0.54 ± 0.04 8.09 8.34
2.00 1.97 ± 0.08 3.90 1.54 2.00 2.36 ± 0.21 8.72 9.80
4.00 4.06 ± 0.24 5.81 8.88 4.00 4.07 ± 0.39 9.64 10.1
Interday b
CV (%)
SD, standard deviation; CV, coefficient of variation; AMP, amphetamine; MDA, methylenedioxyamphetamine; MET, methamphetamine;
MDMA, methylenedioxymethamphetamine
a Intraday precision analysis was performed on a single day of analysis (n = 6)
b Interday precision analysis was performed over seven consecutive days (n = 7)

Forensic Toxicol (2006) 24:51–57 55
Fig. 3 Typical selected ion
monitoring (SIM)
chromatograms of the
derivatives of amphetamines
extracted from spiked and
blank hair. The composition
of the mixture was the same as
specified in Fig. 1, except that
30 ng of pentadeuterated MET
(IS) was added to the mixture
Discussion
Blank hair
Spiked hair
MET-d5
(IS)
AMP
MET-d5
(IS)
MET
SPME was developed as a new solventless extraction
technique by Pawliszyn’s group [11]. To date, more than
one hundred application studies on SPME have been
reported in clinical, forensic, environmental, and food
chemistry fields [14]. Although amphetamines in biological
materials were analyzed by GC or GC-MS in the
underivatized form in many applications [15–22], it was
difficult to obtain good accuracy and sensitivity, because
a free base was easily adsorbed to an injection port,
column, and surface of every gas route. Therefore, we
focused our studies on derivatization of these amines
to solve these problems and improved both sensitivity
and reproducibility [23–27]. Some years ago, unique
derivatization methods (on-fiber or headspace derivatization)
were reported for SPME analysis of
amphetamines [28–30]. However, some serious problems
regarding sensitivity, carryover, contamination, handling
of the procedure, and lifetime of fiber arose. In
particular, when the SPME fiber was dipped into or
MDA MDMA
exposed to a derivatization reagent, the property of
the fiber coating was changed and the lifetime was
shortened.
Application studies have also been reported for determination
of amphetamines in hair [12,31–34]. Koide et al.
[12] extracted AMP and MET by headspace SPME
and used a GC with a nitrogen-phosphorus detector
for analysis. Because this method did not employ
derivatization of the drugs, detection limits were markedly
enhanced. Liu et al. [32] extracted AMP and
MET from human hair by headspace SPME after
derivatization using heptafluoro-n-butyryl chloride. The
dynamic range of this method was narrow and it could
not be applied to an automated procedure, because the
vial had to be opened for addition of the derivatizing
reagent during the procedure. Recently, Musshoff et al.
[33] reported an automated GC-MS method using SPME
with on-fiber derivatization of amphetamines in hair;
they used the vapor of N-methyl-bis-(trifluoroacetamide)
(MBTFA). To our knowledge, MBTFA affects the next
analysis and damages the coating of the fiber.
13

56 Forensic Toxicol (2006) 24:51–57
Fig. 4 SIM chromatograms of
the derivatives of amphetamines
obtained from actual
cases
13
MET-d5
(IS)
AMP
MET-d5
(IS)
AMP
MET
MET
In the present study, we have established an automated
GC-MS method for analysis of amphetamines in
human hair using in-matrix derivatization and SPME.
This method appears to be superior to any method so far
reported for analysis of amphetamines in hair, because
damage to the SPME fiber is minimal, and the
derivatization is very simple and gives good shape peaks
of analytes with very high sensitivity. It is recommended
for routine forensic and clinical analysis of amphetamines
included in any type of biological samples.
Acknowledgments The authors thank Dr. K. Hara of Fukuoka
University for his supply of standard compounds; Dr. I. Tsukue of
Senogawa Hospital for collection of hair from the patients;
Shimadzu Co. for granting the use of the QP-5000 insrument; and
AMR Inc. and WINX Co. for granting the use of a Combi PAL.
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