Direct and sensitive analysis of methamphetamine, ketamine, morphine and codeine in human urine by c

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Direct and sensitive analysis of methamphetamine,
ketamine, morphine and codeine in human urine by
cation-selective exhaustive injection and
sweeping micellar electrokinetic chromatography
Yi-Hui Lin1, Shou-Mei Wu1,2,3
1. Graduate Institute of Pharmaceutical Science,
College of Pharmacy, Kaohsiung Medical
University, Kaohsiung, Taiwan2. Faculty of
Fragrance and Cosmetics, College of Pharmacy,
Kaohsiung Medical University, Kaohsiung,
Taiwan3. Faculty of Pharmacy, College of
Pharmacy, Kaohsiung Medical University, Kaohsiung
807, Taiwan
Abstract Cation-selective exhaustive
injection and sweeping micellar electrokinetic
chromatography (CSEI-Sweep-MEKC) was directly
used to test some abuse drugs in human urine,
including morphine (M), codeine (C), ketamine (K)
and methamphetamine (MA). First, phosphate buffer
(50 mM , pH 2.5) containing 30 methanol was
filled into uncoated fused silica capillary (40
cm, 50 µm I.D.), then high conductivity buffer
(100 mM phosphate, 6.9 kPa for 99.9 s) was
followed. Electrokinetic injection (10 kV, 500 s)
was used to load samples and to enhance
sensitivity. The stacking step and separation
were performed at -20 kV and 200 nm using
phosphate buffer (25 mM, pH 2.5) containing 20
methanol and 100 mM sodium dodecyl sulfate. Using
CSEI-Sweep-MEKC, the analytes could be
simultaneously analyzed and have a detection
limit down to ppb level. It was unnecessary to
have sample pretreatments. During method
validation, calibration plots were linear (r
0.9982) over a range of 150 3000 ng/mL for M
and C, 250 - 5000 ng/mL for MA, and 50 - 1000
ng/mL for K. The limits of detection were 15
ng/mL for M and C, and 5 ng/mL for MA and K (S/N
3, sampling 500 s at 10 kV). Comparing with
capillary zone electrophoresis, the results
indicated that this stacking method could
increase 6000-fold sensitivity for analysis of
MA. Our method was applied for analysis of 28
real urine samples. The results showed good
coincidence with immunoassay and GC-MS. This
method was feasible for application to detect
trace levels of abused drugs in forensic
analysis.
Figure 2. Scheme of CSEI-Sweep-MEKC mode
Results
Figure 3. Electropherograms of the standard
mixture and three real samples obtained under
optimized conditions.
Table 1. Precision and accuracy for the
determination of MA, K, C and M in urine.
Table 2. Data of urine samples from 28 addicts
tested by CE, FPIA and GC-MS.
ND, not done. FPIA fluorescence
polarization immunoassay
Conclusion
The present work provided a potential
CSEI-Sweep-MEKC method which could be
successfully applied to the direct analysis of
urine samples of MA, K, M and C addicts.
Figure 1. Structures of MA, K, M and C.
RE ( relative error) (conc. found conc.
known) x 100/ (conc. known)