共查询到20条相似文献,搜索用时 34 毫秒
1.
Yan-Jun Zheng Yun-Tao Duan Yan-Fang Zhang Qiu-Hong Pan Jing-Ming Li Wei-Dong Huang 《Chromatographia》2009,217(6)
A new method for simultaneous determination of organic acids in red wine and must by liquid chromatography was studied. The
determination of organic acids in wines can be achieved in less than 13 min, preceded only by a simple sample dilution and
filtration step. With this method, the chromatographic separation of eight organic acids and interfering peaks present in
red wine, required only one reversed phase column (Waters Atlantis dC18 column, 4.6 × 150 mm ID, 5 μm). As mobile phase, isocratic
acetonitrile–0.01 mol L−1 KH2PO4 at pH 2.7 5:95 (v/v) at a flow rate of 0.8 mL min−1 was used. Detection wavelength was set at 210 nm except for ascorbic acid which was detected at 243 nm. Application to red
wine and must confirmed good repeatability and showed a wide variation range for concentrations of organic acids. 相似文献
2.
Reiter EV Cichna-Markl M Chung DH Shim WB Zentek J Razzazi-Fazeli E 《Analytical and bioanalytical chemistry》2011,400(8):2615-2622
The paper presents a new sample clean-up method based on immuno-ultrafiltration for the analysis of ochratoxin A in cereals.
In contrast to immunoaffinity chromatography, in immuno-ultrafiltration, the antibodies are used in non-immobilised form.
Ochratoxin A was extracted with ACN/water (60/40, v/v), and the extract was loaded onto the ultrafiltration device. After a washing step with phosphate-buffered saline, containing
0.05% Tween 20, ochratoxin A was eluted with MeOH/acetic acid (99/1, v/v). The detection of ochratoxin A was carried out with high-performance liquid chromatography and a fluorescence detector coupled
to an electrochemical cell (Coring cell). The electrochemical cell was used to eliminate matrix interferences by oxidising
matrix compounds. The method was validated by repeatedly analysing spiked barley and rye samples as well as a certified wheat
reference material. Recoveries and standard deviations (1 SD) were found to be 71 ± 9%, 77 ± 12% and 77 ± 8% in wheat, barley
and rye, respectively. The limit of detection (S/N = 3) and limit of quantitation (S/N = 10) were determined to be 0.4 μg kg-1 and 1 μg kg-1. The analysis of the certified reference material resulted in ochratoxin A concentrations which were in the range assigned
by the producer. Additionally, the effect of the electrochemical cell on other widely used clean-up techniques, namely the
immunoaffinity clean-up and multifunctional columns (Mycosep #229), was evaluated. In all clean-up methods, an improvement
of the chromatogram quality was registered. 相似文献
3.
Carola W. N. Damen Hilde Rosing Jan H. M. Schellens Jos H. Beijnen 《Analytical and bioanalytical chemistry》2009,394(4):1171-1182
A sensitive, specific and efficient high-performance liquid chromatography-tandem mass spectrometry assay for the simultaneous
determination of vincristine and actinomycin-D in human dried blood spots is presented. Dried blood spots were punched out
of a collection paper with a 0.25-in.-diameter punch. The analytes were extracted from the punched-out disc using sonication
during 15 min in a mixture of acetonitrile–methanol–water (1:1:1, v/v/v) containing the internal standard vinorelbine. Twenty-microlitre volumes were injected onto the HPLC system. Separation was
achieved on a 50 × 2.1 mm ID Xbridge C18 column using elution with 1 mM ammonium acetate–acetonitrile (70:30, v/v) adjusted to pH 10.5 with ammonia and run in a gradient with methanol at a flow rate of 0.4 mL/min. HPLC run time was 6 min.
The assay quantifies vincristine from 1 to 100 ng/mL and actinomycine-D from 2 to 250 ng/mL using a blood sample obtained
by a simple finger prick. Validation results demonstrate that vincristine and actinomycin-D can be accurately and precisely
quantified in human dried blood spots with the presented method. The assay can now be used to support clinical pharmacologic
studies with vincristine and actinomycin-D. 相似文献
4.
Hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, and dodecanoic acid are components of the trail pheromone of the ant species Lasius fuliginosus. The acids were extracted from the contents of the rectal ampullae and identified by the mass spectra and gas chromatographic retention times of the corresponding methyl esters. 相似文献
5.
Spyros Drivelos Marilena E. Dasenaki Nikolaos S. Thomaidis 《Analytical and bioanalytical chemistry》2010,397(6):2199-2210
A new hydrophilic interaction liquid chromatographic (HILIC) method for the simultaneous determination of isoascorbic (IAA)
and ascorbic acid (AA) was developed. The separation of IAA and AA was studied in various HILIC stationary phases and the
influence of the composition of the mobile phase, the ionic strength and the column temperature to the chromatographic characteristics
is presented. The final method used an aminopropyl column under isocratic elution with acetonitrile–100 mM ammonium acetate
solution (90:10, v/v) at a flow rate of 0.4 mL/min and a detection wavelength of 240 nm. This method was validated and the calibration curves
were found to be linear in the range of 1.0–65 μg/mL for both IAA and AA. The method limit of detection for IAA determination
in fish tissue was 2.3 μg/g. Inter-day precision (as %RSDR) was ranged between 0.56% and 8.3% at three concentration levels, whereas the respected recoveries ranged between 82% and
98%. This method was applied to the determination of IAA (as additive E315) in frozen redfish samples. The hyphenation of
the HILIC separation with a tandem mass spectrometer was also studied and the problems encountered with negative electrospray
ionization under HILIC separation conditions are discussed. 相似文献
6.
Liang Wang Jun Yue Bai Peng Fei Huang Hong Jing Wang Xiao Wei Wu Yu Qing Zhao 《Mikrochimica acta》2007,158(1-2):73-78
The electrochemical behaviors of uric acid (UA) at the penicillamine (Pen) self-assembled monolayers modified gold electrode
(Pen/Au) have been studied. The Pen/Au electrode is demonstrated to promote the electrochemical response of UA by cyclic voltammetry
(CV). The diffusion coefficient D of UA is 6.97 × 10−6 cm2 s−1. In differential pulse voltammetric (DPV) measurements, the Pen/Au electrode can separate the UA and ascorbic acid (AA) oxidation
potentials by about 120 mV and can be used for the selective determination of UA in the presence of AA. The detection limit
was 1 × 10−6 mol L−1. The modified electrode shows excellent sensitivity, good selectivity and antifouling properties. 相似文献
7.
Xiao-Li Liu Hong-Fang Zhang Guang-Jun Qiao Wei Cao Jian-Bin Zheng 《Chromatographia》2008,67(1-2):147-150
A rapid, sensitive, and specific method for quantification of olmesartan, the prodrug of olmesartan medoxomil, in human plasma,
using zidovudine as internal standard, is described. Sample preparation involved a simple solid-phase extraction procedure.
The extract was analyzed by high-performance liquid chromatography coupled to electrospray tandem mass spectrometry (LC–MS–MS).
Chromatography was performed isocratically on a 5 μm C18 analytical column (50 mm × 4.6 mm i.d.) with water–acetonitrile–formic acid 20:80:0.1 (v/v) as mobile phase. The response to olmesartan was a linear function of concentration over the range 4.82–1,928 ng mL−1. The lower limit of quantification in plasma was 4.82 ng mL−1. The method was successfully applied in a bioequivalence study of an olmesartan formulation after administration as a single
oral dose. 相似文献
8.
The solvation parameter model is used to elucidate the retention mechanism on a perfluorohexylpropylsiloxane-bonded (Fluophase
RP) and octadecylsiloxane-bonded (Betasil C18) stationary phases based on the same silica substrate with acetonitrile–water
and methanol–water mobile phase compositions. Dewetting affects the retention properties of Fluophase RP at mobile phase compositions
containing less than 20% (v/v) acetonitrile or 40% (v/v) methanol. It results in a loss of retention due to an unfavorable change in the phase ratio as well as changes in specific
intermolecular interactions. Steric repulsion reduces retention of bulky solutes on fully solvated Betasil C18 with methanol–water
(but not acetonitrile–water) mobile phase compositions but is not important for Fluophase RP. The retention of weak bases
is affected by ion-exchange interactions on Fluophase RP with acetonitrile–water, and to a lesser extent, methanol-water mobile
phases but these are weak at best for Betasil C18. The system constants of the solvation parameter model and retention factor
scatter plots are used to compare selectivity differences for Fluophase RP, Betasil C18 and a perfluorophenylpropylsiloxane-bonded
silica stationary phase Discovery HS F5 for conditions where incomplete solvation, steric repulsion and ion-exchange do not
significantly contribute to the retention mechanism. Lower retention on Fluophase RP results from weaker dispersion and/or
higher cohesion moderated to different extents by polar interactions since solvated Fluophase RP is a stronger hydrogen-bond
acid and more dipolar/polarizable than Betasil C18. Retention factors for acetonitrile–water mobile phases are highly correlated
for Fluophase RP and Betasil C18 except for compounds with a large excess molar refraction and weak hydrogen-bonding capability.
Selectivity differences are more significant for methanol–water mobile phases. Retention factors on Fluophase RP are strongly
correlated with those on Discovery HSF5 for acetonitrile–water mobile phases while methanol–water mobile phases retention
on Fluophase RP is a poor predictor of the retention order on Discovery HS F5. 相似文献
9.
Norbert Stoppacher Fritz Pittner Gerhard Sontag 《Monatshefte für Chemie / Chemical Monthly》2009,140(8):909-914
Abstract In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of 1-nitropyrene reduced at
a glassy carbon electrode between 0 and −0.8 V was investigated with respect to pH and solvent. Then polyclonal anti-1-nitropyrene
antibodies isolated from a rabbit antiserum were covalently bound to the surface of the glassy carbon electrode. This modified
electrode was immersed in standard solutions or sample extracts for 5–15 min. 1-Nitropyrene was bound by the antibodies, accumulated
and then analyzed at pH 6.5 in another supporting electrolyte by differential pulse voltammetry. Afterwards the immunosensor
could be regenerated for the next measurement by rinsing with acetonitrile–water (40:60, v/v). A linear response was found between 20 and 100 ng/cm3. The limit of detection was 10 ng/cm3 and the intraday reproducibility of three immunosensors assembled during two months was between 4.5 and 10%. This sensor
was applied to the analysis of 1-nitropyrene in air particulate matter and smoked tea.
Graphical abstract
相似文献
10.
Zhang ZX Gao PF Guo XF Wang H Zhang HS 《Analytical and bioanalytical chemistry》2011,401(6):1905-1914
1,3,5,7-Tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)difluoroboradiaza-s-indacene (TMBB-Su), a new BODIPY-based fluorescent probe, was designed and synthesized for the labeling of amino compounds.
It was used as a pre-column derivatizing reagent for determination of amino acid neurotransmitters by high-performance liquid
chromatography (HPLC). The fluorescence quantum yield in acetonitrile increased from 0.84 to 0.95 when it reacted with amino
acid neurotransmitters. Derivatization of TMBB-Su with seven amino acid neurotransmitters was completed within 30 min at 25 °C
in 24.0 mmol L−1 pH 7.8 boric acid buffer. The separation was performed on a C18 column with methanol–water–buffer 55:35:10 (v/v) as mobile phase (buffer: 0.10 mol L−1 H3Cit–0.10 mol L−1 NaOH). Interference from the other concomitant amino acids was eliminated successfully by means of pH gradient elution. With
fluorescence detection at 494 and 504 nm for excitation and emission, respectively, the limits of detection (signal-to-noise
ratio = 3) were from 2.1 to 12.0 nmol L−1. The proposed method has been used to determine amino acid neurotransmitters in the cerebral cortex of mice with cerebral
ischemia at the convalescence stage with satisfactory recoveries varying from 94.9 to 105.2%. 相似文献
11.
D.I. Sánchez-Machado J. López-Cervantes J. López-Hernández P. Paseiro-Losada J. Simal-Lozano 《Chromatographia》2003,58(3-4):159-163
Summary A reversed-phase high-performance liquid-chromatographic method has been used for analysis of the amino acids in edible seaweed. Sample proteins were hydrolysed with hydrochloric acid and the amino acids produced were derivatized with phenyl isothiocyanate. The resulting phenylthiocarbamyl amino acids were chromatographed on an ODS2 column with UV detection at 254 nm. The mobile phase was a mixture of 0.14 M ammonium acetate buffer, pH 6.4, containing 0.05% triethylamine (A) and 60:40 (v/v) acetonitrile–water (B), at a flow rate of 1.1 mL min–1; the elution gradient (min:A%) was: 0:90, 8:90, 10:70, 12:70, 18:52, 20:0, 25:0, 28:90, 35:90. Method precision for the different amino acids was between 1.33 and 3.88% (relative standard deviation); detection limits were between 6.9 and 14.3 ng mL–1. The amino acid content of the algae analysed ranged from 22.4 ± 1.9 to 138.0 ± 5.6 mg g–1 d.w. The amino acids present at highest concentrations were glutamic acid, alanine, and phenylalanine. 相似文献
12.
Macwan JS Ionita IA Dostalek M Akhlaghi F 《Analytical and bioanalytical chemistry》2011,400(2):423-433
The aim of the proposed work was to develop and validate a simple and sensitive assay for the analysis of atorvastatin (ATV)
acid, ortho- and para-hydroxy-ATV, ATV lactone, and ortho- and para-hydroxy-ATV lactone in human plasma using liquid chromatography-tandem mass spectrometry. All six analytes and corresponding
deuterium (d5)-labeled internal standards were extracted from 50 μL of human plasma by protein precipitation. The chromatographic
separation of analytes was achieved using a Zorbax-SB Phenyl column (2.1 mm × 100 mm, 3.5 μm). The mobile phase consisted
of a gradient mixture of 0.1% v/v glacial acetic acid in 10% v/v methanol in water (solvent A) and 40% v/v methanol in acetonitrile (solvent B). All analytes including ortho- and para-hydroxy metabolites were baseline-separated within 7.0 min using a flow rate of 0.35 mL/min. Mass spectrometry detection was
carried out in positive electrospray ionization mode, with multiple-reaction monitoring scan. The calibration curves for all
analytes were linear (R
2 ≥ 0.9975, n = 3) over the concentration range of 0.05–100 ng/mL and with lower limit of quantitation of 0.05 ng/mL. Mean extraction recoveries
ranged between 88.6–111%. Intra- and inter-run mean percent accuracy were between 85–115% and percent imprecision was ≤ 15%.
Stability studies revealed that ATV acid and lactone forms were stable in plasma during bench top (6 h on ice-water slurry),
at the end of three successive freeze and thaw cycles and at −80 °C for 3 months. The method was successfully applied in a
clinical study to determine concentrations of ATV and its metabolites over 12 h post-dose in patients receiving atorvastatin. 相似文献
13.
Shustak G Domb AJ Mandler D 《Langmuir : the ACS journal of surfaces and colloids》2004,20(18):7499-7506
The electrochemical formation and characterization of decanoic, myristic, palmitic, and stearic acid self-assembled monolayers on a native oxide surface of 316L stainless steel have been studied. This work describes a new approach to surface modification of stainless steel in which the self-assembly of n-alkanoic acids is facilitated by applying a potential to the stainless steel in an organic electrolyte solution. While decanoic acid forms a disorganized monolayer as a result of sweeping the potential in an acetonitrile solution containing 0.1 mM of the respective acid, longer acids, that is, myristic and palmitic acids, form highly ordered closed-packed monolayers. This electrochemical approach results in highly reproducible monolayers that are deposited within a shorter time than the traditional assembly process. The monolayers were characterized by cyclic voltammetry, double-layer capacity (ac voltammetry), contact angle measurements, X-ray photoelectron spectroscopy, and external reflection-absorption Fourier transform infrared spectroscopy. The utilization and implications of this modification technique are discussed. 相似文献
14.
A simple and sensitive assay was developed and validated for the simultaneous quantification of rosuvastatin acid (RST), rosuvastatin-5S-lactone (RST-LAC), and N-desmethyl rosuvastatin (DM-RST), in buffered human plasma using liquid chromatography–tandem mass spectrometry (LC-MS/MS).
All the three analytes and the corresponding deuterium-labeled (d6) internal standards were extracted from 50 μL of buffered
human plasma by protein precipitation. The analytes were chromatographically separated using a Zorbax-SB Phenyl column (2.1 mm × 100 mm,
3.5 μm). The mobile phase comprised of a gradient mixture of 0.1% v/v glacial acetic acid in 10% v/v methanol in water (solvent A) and 40% v/v methanol in acetonitrile (solvent B). The analytes were separated at baseline within 6.0 min using a flow rate of 0.35 mL/min.
Mass spectrometry detection was carried out in positive electrospray ionization mode. The calibration curves for all three
analytes were linear (R ≥ 0.9964, n = 3) over the concentration range of 0.1–100 ng/mL for RST and RST-LAC, and 0.5–100 ng/mL for DM-RST. Mean extraction recoveries
ranged within 88.0–106%. Intra- and inter-run mean percent accuracy were within 91.8–111% and percent imprecision was ≤15%.
Stability studies revealed that all the analytes were stable in matrix during bench-top (6 h on ice–water slurry), at the
end of three successive freeze and thaw cycles and at −80°C for 1 month. The method was successfully applied in a clinical
study to determine the concentrations of RST and the lactone metabolite over 12-h post-dose in patients who received a single
dose of rosuvastatin. 相似文献
15.
Shenghong Zhong 《Liquid crystals》2016,43(3):361-368
The pH-driven adsorption and desorption of fatty acid monolayers at the liquid crystal (LC)–water interface were studied. We doped fatty acids (stearic acid, palmitic acid, myristic acid, dodecanoic acid, and decanoic acid) into 4-cyano-4′-pentylbiphenyl (5CB), and employed sessile LC droplets as our experimental platform. Under a crossed polariser, the LC droplets displayed a bright flower bud-shaped texture at low pH, whereas at high pH, they exhibited a bright four-brush appearance due to desorption of the adsorbed fatty acids at the LC–water interface. Furthermore, we identified the critical transition pH of various concentrations of stearic acid and other fatty acids featuring distinct tail lengths. Based on the interfacial behaviour, we propose a new method to estimate the pKa of fatty acids, which opens up new possibilities for simple, precise, and reliable measurement of the pKa of other carboxylic acids. The findings presented herein will greatly facilitate the understanding of the interfacial behaviour of amphiphiles at the oil–water interface. 相似文献
16.
Jun Zhe Min Suguru Hatanaka Toshimasa Toyo’oka Shinsuke Inagaki Ruri Kikura-Hanajiri Yukihiro Goda 《Analytical and bioanalytical chemistry》2009,395(5):1411-1422
A simultaneous determination method based on ultra-performance liquid chromatography (UPLC) with fluorescence (FL) detection
and electrospray-ionization time-of-flight mass spectrometry (ESI-TOF-MS) was developed for 16 “designated substances” (Shitei-Yakubutsu)
controlled by the Pharmaceutical Affairs Law in Japan. These substances were first labeled with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole at 60 °C for 2 h in 0.1 M borax (pH 9.3). The resulting fluorophores
were well separated by reversed-phase chromatography using an Acquity UPLC™ BEH C18 column (1.7 μm, 100 mm × 2.1 mm i.d.) by isocratic elution with a mixture of water and acetonitrile–methanol (20:80) containing
0.1% formic acid. The separated derivatives were sensitively detected by both FL and TOF-MS. However, the determination of
several designated substances by FL detection showed interference from endogenous substances in biological samples. Therefore,
the determination in real samples was carried out by a combination of UPLC separation and ESI-TOF-MS detection. The structures
of the designated substances were identified from the protonated-molecular ions [M+H]+ obtained from the TOF-MS measurement. The calibration curves obtained from the peak area ratios of the internal standard
(I.S.), i.e., 3-phenyl-1-propylamine, and the designated substances versus the injection amounts showed good linearity. The
limits of detection
( \textS/N = 3 ) \left( {{\text{S/N}} = 3} \right) and the limits of quantification
( \textS/N = 10 ) \left( {{\text{S/N}} = 10} \right) in 0.1 mL of human plasma and urine for the present method were 0.30–150 pmol and 1.0–500 pmol, respectively. Good accuracy
and precision (according to intraday and interday assays) were also obtained with the present procedure. This method was applied
to analyses of human plasma, urine and real products.
相似文献
17.
T. D. Batueva A. V. Radushev V. Yu. Gusev 《Russian Journal of Applied Chemistry》2009,82(11):1997-2001
Dependence of physicochemical properties of N′,N′-dialkylhydrazides of aliphatic carboxylic acids (solubility in kerosene, acid-base properties) on the length of hydrocarbon
radicals in the functional group was studied. The extraction capacity for copper(II) salts in weakly acid and ammonia media
was examined in the range from pH 5–11 to a NH3 content of 2.7 M. The capacity of the organic phase for copper(II) and re-extraction conditions were determined for the example
of N′,N′-dibutylhydrazide of octanoic acid. 相似文献
18.
Danieli Cátia Ceni Laura Alegria Martins Andréa Garcia Pereira Pedro Eduardo Fr?ehlich Ana Maria Bergold 《Chromatographia》2009,69(Z2):189-194
A reversed-phase ion-pairing liquid chromatographic method was developed and validated for the assay of Fe(II) in ferrous
bisglycinate (Fe-bis-gly) capsules using 4-(2-pyridylazo) resorcinol reagent. The analysis was carried out using a Gemini
RP-18 (150 mm × 4.6 mm I.D., particle size 5 μm) analytical column; the mobile phase consisted of a mixture of acetonitrile–water
(28:72 v/v) containing 1 mM tetrabutylammonium hydrogensulfate and 1% phosphate buffer (pH 8.0). The flow rate was 1.0 mL min−1 and the detection was achieved with a photodiode array (PDA) detector at 706 nm. The specificity of the method was proved
using stress conditions and evaluated using a PDA detector. The data validation showed that the method is specific, fast,
accurate, and reproducible for the determination of Fe-bis-gly in dosage form. The response was linear over a range of 1.0–2.6 μg mL−1 (r = 0.9999). The accuracy of the method ranged from 98.02 to 102.75%. The RSD values for intra- and inter-day precision studies
were below 1.3 and 1.1%, respectively. There was no interference of the excipients on the determination of the active pharmaceutical
ingredient. 相似文献
19.
HPTLC-densitometric and HPLC–UV techniques were used for qualitative and quantitative determination of luteolin-7-O-glucuronide, lithospermic acid, rosmarinic acid and caffeic acid in several herbal drugs from the Lamiaceae family: Thymi herba, Serpylli herba, Majoranae herba and Menthae piperitae folium. Unmodified silica gel (HPTLC Si60) and silica gel chemically modified with aminopropyl groups (HPTLC NH2) were used during the investigation process. Among HPTLC methods the best resolution and selectivity was achieved with mobile
phases: diisopropyl ether–acetone–formic acid–water (50:30:10:10, v/v/v/v) and acetone–formic acid (85:15, v/v), respectively. Plates were densitometrically evaluated. Contents of analyzed compounds in the studied aqueous extracts prepared
from herbal drugs were established using both techniques. The results from the HPTLC-densitometric analysis have been compared
with those from HPLC–UV on a C18 column with acetonitrile–water–formic acid as a mobile phase. The chromatographic methods
were validated for linearity, LOD, LOQ, repeatability, intermediate precision and recovery. An analysis of variance showed
that the HPTLC-densitometric and HPLC–UV methods are equivalent and sufficiently precise for the estimation of polyphenolic
compounds mentioned above, in investigated herbal drugs. All of the suggested methods (HPTLC NH2, HPTLC Si60 and HPLC RP18) give results with good agreement. 相似文献
20.
Boroujerdi AF Lee PA DiTullio GR Janech MG Vied SB Bearden DW 《Analytical and bioanalytical chemistry》2012,403(3):777-784
In-line solid-phase extraction–capillary electrophoresis coupled with mass spectrometric detection (SPE–CE–MS) has been used
for determination of 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), codeine (COD), hydrocodeine (HCOD), and 6-acetylmorphine
(6AM) in urine. The preconcentration system consists of a small capillary filled with Oasis HLB sorbent and inserted into
the inlet section of the electrophoresis capillary. The SPE–CE–MS experimental conditions were optimized as follows: the sample
(adjusted to pH 6.0) was loaded at 930 mbar for 60 min, elution was performed with methanol at 50 mbar for 35 s, 60 mmol L−1 ammonium acetate at pH 3.8 was used as running buffer, the separation voltage was 30 kV, and the sheath liquid at a flow
rate of 5.0 μL min−1 was isopropanol–water 50:50 (v/v) containing 0.5% acetic acid. Analysis of urine samples spiked with the four drugs and diluted 1:1 (v/v) was studied in the linear range 0.08–10 ng mL−1. Detection limits (LODs) (S/N = 3) were between 0.013 and 0.210 ng mL−1. Repeatability (expressed as relative standard deviation) was below 7.2%. The method developed enables simple and effective
determination of these drugs of abuse in urine samples at the levels encountered in toxicology and doping. 相似文献