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1.
Li C Wen D Zhang J Chen Z Cong W Rao Z Liu H 《Analytical and bioanalytical chemistry》2006,386(7-8):1985-1993
Metabolism of four tobacco-specific N-nitrosamines (TSNAs), N′-nitrosonornicotine (NNN), N′-nitrosoanatabine (NAT), N′-nitrosoanabasine (NAB), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) has been studied by solid-phase extraction
(SPE) and liquid chromatography–tandem mass spectrometry (LC–MS–MS). 4-(Methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL)
was used as internal standard. SPE and LC–MS–MS was found to be a rapid, simple, sensitive, and selective method for analysis
of TSNAs in rabbit serum. The relative standard deviation (R.S.D., n = 6) for analysis of 5 ng mL−1 and 0.5 ng mL−1 standards and of serum sample spiked with 5 ng mL−1 standards of five TSNAs was 2.1–11% and recovery of 5 ng mL−1 standards from serum was 100.2–112.9%. A good linear relationship was obtained between peak area ratio and concentration
in the range of 0.2–100 ng mL−1 for NNAL and 0.5–100 ng mL−1 for other four TSNAs, with correlation coefficients (R
2) >0.99 (both linear and log–log regression). Detection limits for standards in solvent were between 0.04 and 0.10 ng mL−1. Doses of TSNAs administered to rabbits via the auricular vein were 4.67 μg kg−1 and 11.67 μg kg−1, in accordance with the different levels in cigarettes. Metabolic curves were obtained for the four TSNAs and for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol
(NNAL), a metabolite of NNK; on the basis of these curves we modeled metabolic kinetic equations for these TSNAs by nonlinear
curve fitting. 相似文献
2.
Summary A high-performance liquid chromatographic method with amperometric detection has been developed for the determination of levels
of clozapine (CLZ) and its active metabolite N-desmethylclozapine (DMC) in human plasma. The analysis was performed on a 5
μm C8 reversed phase column (150×4.6 mm i.d.), with acetonitrile-phosphate buffer (pH 3.5), as the mobile phase. The detection
voltage was +800 mV and the cell and column temperature were 50°C. Linear responses were obtained between 2 ng mL−1 and 100 ng mL−1. Absolute recovery for both clozapine and desmethylclozapine exceeded 88% and the detection limit was 1 ng mL−1. Repeatability, intermediate precision and accuracy were satisfactory. The method, which is rapid, sensitive and selective,
has been applied to therapeutic drug monitoring in schizophrenic patients following administration of Leponex? tablets. In 21 patients in steady state at a mean daily clozapine dosage of 358 mg (ranging from 150 to 500 mg day−1), clozapine levels averaged 379 ng mL−1 (ranging from 102 to 818 ng mL−1) and DMC levels averaged 233 ng mL−1 (ranging from 70 to 540 ng mL−1). The method requires only a very small amount of plasma (100 μL), and thus it is suitable for pharmacokinetic studies, as
well as for therapeutic drug monitoring. 相似文献
3.
Ródenas-Torralba E Morales-Rubio A de la Guardia M 《Analytical and bioanalytical chemistry》2005,383(1):138-144
An automated and greener spectrophotometric procedure has been developed for the determination of phenol in water at 700 nm.
The method uses the reaction between phenol, sodium nitroprusside, and hydroxylamine hydrochloride in a buffered medium at
pH 12.3. The flow manifold comprises four solenoid micro-pumps employed for sample and reagent introduction into the reaction
coil and to transport the colored product formed to the detector. The linear dynamic range was 50–3,500 ng mL−1 (R = 0.99997; n = 6) and the method provided a limit of detection (3σ) of 13 ng mL−1. The sampling throughput was estimated to be 65 measurements per hour and the coefficient of variation was 0.5% (n = 10) for a 1.0 μg mL−1 phenol concentration. Recoveries of 92–105% were obtained for phenol determination in spiked water samples at concentration
levels from 50 to 5,000 ng mL−1. The use of multicommutation reduced the reagent consumption 25-fold, the sample consumption 225-fold, and the waste generation
30-fold compared with the batch procedure. The proposed method is an environmentally friendly alternative to the official
4-aminoantipyrine method since it avoids the use of chloroform. 相似文献
4.
In this study, the determination of 4-Bromoaniline (4-BA) in green algae Chlamydomonas reinhardtii (C. reinhardtii) was investigated by applying continuous-flow microextraction (CFME) combined with high-performance liquid chromatography
(HPLC). Continuous-flow microextraction was conducted in a homemade glass chamber, i.e. the sample solution flowed through
a constant volume drop of solvent in the chamber at a constant flow rate. The effects of different factors on extraction efficiencies
were also investigated and these factors included the kind of extraction solvent, solvent drop volume, sample flow rate, extraction
time and addition amount of salt. Under the optimum extraction conditions (extraction solvent, carbon tetrachloride; solvent
drop volume, 3.5 μL; sample flow rate, 1.0 mL min−1; extraction time, 10 min; no addition of salt), the calibration plot was set up by plotting peak area against a series of
4-Bromoaniline concentrations (0.01–10 μg mL−1) in aqueous solution. The correlation coefficient (r) was 0.9990. The limit of detection (LOD) was 0.6 ng mL−1. The precision of this method was obtained by successive five time analyses of 100-ng mL−1 standard solution of 4-Bromoaniline, and the relative standard deviation (RSD) was 3.5%. The concentration factor was calculated
by the ratio of peak area of the analyte obtained after and before extraction and found to be 10.6. 4-Bromoaniline residues
in Chlamydomonas. reinhardtii cells and tap water samples were satisfactorily analyzed according to the method described above. 相似文献
5.
Dian-Lei Wang Yan Liang Lin Xie Tong Xie X. T. Wang Sen Yu Guang-Ji Wang Xiao-Dong Liu 《Chromatographia》2008,67(3-4):219-224
To evaluate the pharmacokinetics of a novel analogue of ginkgolide B, 10-O-dimethylaminoethylginkgolide B (XQ-1) in rat plasma in pre-clinical studies, a sensitive and specific liquid chromatographic
method with electrospray ionization mass spectrometry detection (LC–ESI–MS) was developed and validated. After a simple extraction
with ethyl acetate, XQ-1 was analyzed on a Shim-pack C18 column with a mobile phase of a mixture of 1 μmol L−1 ammonium acetate containing 0.02% formic acid and methanol (55:45, v/v) at a flowrate of 0.3 mL min−1. Detection was performed in selected ion monitoring (SIM) mode using target ions at [M + H]+
m/z 496.05 for XQ-1 and m/z 432.10 for the internal standard (lafutidine). Linearity was established for the concentration range from 2 to 1,000 ng mL−1 . The extraction recoveries ranged from 86.0 to 89.9% in plasma at concentrations of 5, 50, and 500 ng mL−1. The lower limit of quantification was 2 ng mL−1 with 100 μL plasma. The validated method was successfully applied to a pharmacokinetic study after intragastic administration
of XQ-1 mesylate in rats at a dose of 20 mg kg−1. 相似文献
6.
M. A. Campanero B. Calahorra E. García-Quetglás M. Escolar J. Honorato 《Chromatographia》1998,48(7-8):555-560
Summary A sensitive liquid chromatographic assay for the quantitative determination of the opioid analgesic tramadol and its active
metabolite is described. Fluconazole was used as internal standard. The assay involved a singletert-butyl methyl ether extraction and LC analysis with fluorescence detection. Chromatography was at 30°C pumping an isocratic
mobile phase of acetonitrile-water (19∶81, v/v) containing 0.06M NaH2PO4 and 0.05M triethylamine, adjusted to pH 7.90, at 1 mL min−1 through a reversed-phase, 250×4 mm base-stable column. The limit of quantitation of tramadol and its active metabolite was
1 ng mL−1, only 0.5 mL plasma sample was required for the determination. The calibration curve was linear from 1–1000 ng mL−1. Intra and inter-day precision (C.V.) did not exceed 10%. Mean recoveries of 96.38% for tramadol and 96.62% forO-demethyltramadol with CVs of 0.43% and 1.46% were obtained. Applicability of the method was demonstrated by a pharmacokinetic
study on normal volunteers who received 100 mg tramadol intravenously. 相似文献
7.
Determination of Aldehydes and Ketones in Fuel Ethanol by High-Performance Liquid Chromatography with Electrochemical Detection 总被引:1,自引:0,他引:1
A. A. Saczk L. L. Okumura M. F. de Oliveira M. V. B. Zanoni N. R. Stradiotto 《Chromatographia》2006,63(1-2):45-51
A new methodology was developed for analysis of aldehydes and ketones in fuel ethanol by high-performance liquid chromatography
(HPLC) coupled to electrochemical detection. The electrochemical oxidation of 5-hydroxymethylfurfural, 2-furfuraldehyde, butyraldehyde,
acetone and methyl ethyl ketone derivatized with 2,4-dinitrophenylhydrazine (DNPH) at glassy carbon electrode present a well
defined wave at +0.94 V; +0.99 V; +1.29 V; +1.15 V and +1.18 V, respectively which are the basis for its determination on
electrochemical detector. The carbonyl compounds derivatized were separated by a reverse-phase column under isocratic conditions
with a mobile phase containing a binary mixture of methanol / LiClO4(aq) at a concentration of 1.0 × 10−3 mol L−1 (80:20 v/v) and a flow-rate of 1.1mL min−1 . The optimum potential for the electrochemical detection of aldehydes-DNPH and ketones-DNPH was +1.0 V vs. Ag/AgCl. The
analytical curve of aldehydes-DNPH and ketones-DNPH presented linearity over the range 5.0 to 400.0 ng mL−1, with detection limits of 1.7 to 2.0 ng mL−1 and quantification limits from 5.0 to 6.2 ng mL−1, using injection volume of 20 μL. The proposed methodology was simple, low time-consuming (15 min/analysis) and presented
analytical recovery higher than 95%. 相似文献
8.
Summary Clenbuterol has been determined in urine by solidphase extraction on a C18 cartridge, diazotization of the eluate with nitrite, coupling of the diazonium ion with 1-(naphthyl)ethylenediamine, and
separation of the azo dye formed by HPLC with a C18 column and a micellar mobile phase containing 0.1 M sodium dodecyl sulphate, 12%n-butanol and 0.05 M citrate buffer, pH 3. Recoveries higher than 90% were obtained by mixing the samples with a 20% 0.2 M
NaOH before extraction. Limits of detection of 51 and 6.7 ng L−1 were obtained with spectrophotometric and thermal lens spectrometric detection, respectively; respective repeatabilities
were 3.1% (5 μg mL−1) and 5.6% (0.16 μg mL−1). 相似文献
9.
Guanidinoacetate methyltransferase deficiency is a recently discovered inborn defect of creatine biosynthesis which reduces
serum creatinine concentrations to as low as 0.58 μg mL−1 (or 0.00058 μg mL−1 after 1,000-fold dilution). To measure ultra trace levels of creatinine in diluted samples, molecularly imprinted solid-phase
extraction (MISPE) and molecularly imprinted polymer (MIP) sensor techniques have been found to be inadequate. A combination
of these techniques (i.e. MISPE hyphenated with use of an MIP-sensor), reported in this paper, has been found to be highly
suitable for direct assay of creatinine in highly diluted human blood serum without complicated pretreatment of the sample.
The proposed technique has the potential to enhance the sensitivity of creatinine measurement from μg mL−1 to ng mL−1 in highly dilute aqueous samples in which the concentrations of interfering constituents are reduced to negligible levels.
In this work the sensitivity to creatinine was found to be improved compared with that of the MIP-sensor method alone (limit
of detection, LOD, 0.00149 μg mL−1). After preconcentration by MISPE and use of the sensor the detection limit for creatinine was as low as 0.00003 μg mL−1 (RSD = 0.94%, S/N = 3; 50-fold preconcentration factor) in aqueous samples. 相似文献
10.
Schettgen T Tings A Brodowsky C Müller-Lux A Musiol A Kraus T 《Analytical and bioanalytical chemistry》2007,387(8):2783-2791
Analysis of biomarkers in exhaled breath condensate (EBC) is a non-invasive method for investigating the effects of different
diseases or exposures, on the lungs and airways. N
ɛ-carboxymethyllysine (CML) is an important biomarker of advanced glycation end products (AGEs). A method has been developed
for simultaneous determination of CML and its precursor, the amino acid lysine, in exhaled breath condensate (EBC). After
addition of labelled internal standards (d-4-CML; d-4-lysine), the EBC was concentrated by freeze-drying. Separation and detection
of the analytes were performed by hydrophilic-ion liquid chromatography coupled with tandem mass-spectrometric detection (HILIC–MS–MS).
The limits of quantification were 10 pg mL−1 EBC and 0.5 ng mL−1 EBC for CML and lysine, respectively. The relative standard deviation of the within-series precision was between 2.8 and
7.8% at spiked concentrations between 40 and 200 pg mL−1 for CML and between 6 and 20 ng mL−1 for lysine. Accuracy for the analytes ranged between 89.5 and 133%. The method was used for the analysis of EBC samples from
ten healthy persons from the general population and ten persons receiving dialysis. CML and lysine were detected in all EBC
samples with median values of 19 pg mL−1 CML and 11.9 ng mL−1 lysine in EBC of healthy persons and 25 pg mL−1 CML and 9.5 ng mL−1 lysine in EBC of dialysis patients. 相似文献
11.
Tetracycline antibiotics (TCs) such as doxycycline (DOTC), chlortetracycline (CTC), oxytetracycline (OTC), and tetracycline
(TC) react with Cu(II) in pH 3.5 BR buffer medium to form 1:1 cationic chelates, which further react with titan yellow to
form 2:1 ion association complexes. These result in great enhancement of resonance Rayleigh scattering (RRS) and the appearance
of new RRS spectra. The ion association complexes of DOTC, CTC, OTC, and TC have similar spectral characteristics and their
maximum RRS wavelengths are all located at 464 nm. The quantitative determination ranges and the detection limits (3σ) of the four TCs are 0.037–4.8 μg mL−1 and 11.2 ng mL−1 for DOTC, 0.041–5.2 μg mL−1 and 12.4 ng mL−1 for CTC, 0.050–4.8 μg mL−1 and 15.1 ng mL−1 for TC, and 0.088–5.0 μg mL−1 and 26.3 ng mL−1 for OTC, respectively. The optimum reaction conditions, the effects of foreign substances, the structure of ternary complexes,
and the reaction mechanism are discussed. A sensitive, rapid, and simple RRS method for the determination of DOTC has been
developed. 相似文献
12.
Summary A high-performance liquid chromatographic method, with 9-anthryldiazomethane as derivatizing agent, has been developed for
the simultaneous determination ofN-carbamoyl aspartate andl-dihydroorotate in serum. Sample preparation for 1 mL serum was by simple liquid-liquid extraction and then derivatization.
The compounds were separated on a Luna C18(2) column by use of a gradient prepared from acetonitrile and 10 mM sodium acetate
buffer, pH 6.0, and fluorimetric detection was performed at excitation and emission wavelengths of 365 nm and 412 nm, respectively.
The response was found to be linearly dependent on concentration between 0.8 and 60 μg mL−1 forl-dihydrooratate and between 0.9 and 90 μg mL−1 forN-carbamoyl aspartate; the mean recovery rates were 50 and 51%, respectively. The limits of detection and quantification were
0.33 μg mL−1 and 0.6 μg mL−1, respectively, forl-dihydroorotate and 0.4 μg mL−1 and 0.7 μg mL−1 forN-carbamoyl aspartate. This method can be used to assess accumulation ofN-carbamoyl aspartate andl-dihydroorotate in body fluids in situations where cellular pyrimidine de novo synthesis is impaired. 相似文献
13.
Xinfeng Zhao Weijin Zang Xin Zhao Shixiang Wang Xiaohui Zheng Jianbin Zheng 《Chromatographia》2007,65(3-4):149-153
A fast and validated assay was established for the pharmacokinetic study of amygdalin in Armeniacae Semen in rabbit. The method involved column switching (CS) enrichment, separation, post-column derivatization, and atmospheric pressure
chemical ionization (APCI) mass spectrometric detection. Plasma sample was enriched by CS using a MAYI-ODS as the first column.
Analytes of interest were isolated and analyzed on a second column of Zorbax SB-C18. To detect amygdalin in plasma samples, a T-piece was connected between the HPLC outlet and the APCI source to add a mixture
of dichloromethane and methanol to the eluent by an isocratic pump. Calibration graphs showed good linearity over a range
of 1.0–1,280 ng mL−1. The detection limit was 0.2 ng mL−1. The intra- and inter-day accuracies were within 3.9%. The method was successfully applied to a study of the pharmacokinetics
of amygdalin after an intravenous injection of amygdalin extracts to rabbits with a dose of 400 mg kg−1. The results indicate that amygdalin is a one-compartment open model with a first order absorption phase. 相似文献
14.
Haiyang Jiang Shuangyang Ding Fei Xu Sijun Zhao Jihong He Jinfeng Liu Xiaolin Hou Jianzhong Shen 《Chromatographia》2007,66(5-6):411-414
Eprinomectin is a novel and potent antiparasitic animal health drug. An analytical procedure for the determination of EPR
in bovine urine and feces has been developed. The urine sample was centrifuged and alkalized with ammonia following solid
phase extraction. The fecal sample was extracted with acetonitrile, defatted with hexane, cleaned-up using C18 cartridge.
All samples were analyzed by high performance liquid chromatography with fluorescence detection after derivatization with
N-methylimidazole. The limits of detection are 0.5 ng mL−1 and 0.5 ng g−1, respectively. Fortified at 2, 10, 50, and 100 ng mL−1(ng g−1), inter-assay recoveries of EPR in cattle urine and feces were in the range of 87.9–91.5% and 78.6–86.3%, with coefficients
of variation of 5.4–10.2% and 1.4–7.2%, respectively. Intra-assay mean recoveries of the analytes were 82.2–86.5% and 79.6–87.3%,
with coefficients of variation of 7.8–11.5% and 6.3–7.8%, respectively. The method was used to study the excretion of eprinomectin
in bovine urine and feces after subcutaneous administration at a dose of 0.5 mg kg−1. 相似文献
15.
Summary A reversed-phase ion-pair chromatographic (RPIPC) method withN,N,N′, N′-ethylenediaminetetrakis(methylenephosphonic acid) (EDTMP) as coordinating agent has been developed for simultaneous separation
and detection of Cu(II), Fe(III), and Pb(II) ions. Response is linearly dependent on amount of sample over the range 9.52–50.8
μg mL−1 for Cu(II), 8.31–41.8 μg mL−1 for Fe(III), and 37.3–51.8 μg mL−1 for Pb(II). The method has been applied successfully to an artificial mixed-ore sample. 相似文献
16.
Determination of rutin and forsythin in fruit ofForsythia suspensa(Thunb.) Vahl by capillary electrophoresis-electrochemical detection 总被引:1,自引:0,他引:1
Summary Capillary electrophoresis-amperometric detection is evaluated for simultaneous determination of rutin and forsythin. The cyclic
voltammogram, hydrodynamic voltammogram, effect of pH, buffer concentration and SDS, and percent organic modifier on separation
and detection were studied. Conditions were optimized as follows: 1.2 V detection potential; separation at 12 kV; 5 s at 15
kV for sample injection time and sample injection voltage; mobile phase 20 mM boric acid buffer; pH 8.4, containing 40 mM
SDS and 10% (v/v) acetontrile. The method gave low detection limit as 0.001 mg mL−1 and 0.0005 mg mL−1 (S/N=3), wide linear range 0.005–0.5 mg mL−1 for rutin and forsythin, respectively. The relative standard deviations of peak current and migration time for 8 consecutive
injections of the standard solution containing 0.1 mg mL−1 each compound were 4.78%, 3.63% and 6.40%, 2.95% for rutin and forsythin, respectively. In addition, levels of the two compounds
in traditional Chinese herbal drugs were easily determined. 相似文献
17.
Summary Capillary electrophoresis with amperometric detection has been evaluated for the simultaneous determination of rutin and quercetin.
The cyclic voltammogram, hydrodynamic voltammogram, and the effects of pH, concentration of buffer and sodium dodecyl sulfate
(SDS), and amount of organic modifier on the separation and the detection were studied. The optimized conditions were: detection
potential 1.2V, separation at 12 kV, 5 s at 15 kV for sample injection, running electrolyte 20 mmol L−1 borate buffer, pH 8.8, containing 40 mmol L−1 SDS and 10% acetonitrile. The detection limit of the method was low, 0.001 and 0.0005 mg mL−1, for rutin and quercetin, respectively; the linear ranges were wide −0.005–0.5 and 0.005–0.4 mg mL−1, respectively. The variations in peak current and migration time for eight consecutive injections of a standard solution
containing 0.1 mg mL−1 of each compound were 4.78 and 3.63%, and 6.50 and 2.59% for rutin and quercetin, respectively. The levels of the two compounds
in traditional Chinese herbal drugs were easily determined. 相似文献
18.
Determination of eight penicillins in serum from cattle and pigs by generic HPLC method 总被引:1,自引:0,他引:1
Summary An HPLC method was developed for determination of amoxicillin, penicillin G, penicillin V, ampicillin, oxacillin, cloxacillin,
nafcillin and dicloxacillin in serum from pigs and cattle. Serum was cleaned up by solid-phase extraction (SPE), ultra-filtered
and derivatised. The method was linear in the range tested up to 2000 ng mL−1 of individual penicillins in serum. Limits of detection were 11–14 ng mL−1. Mean recoveries were 90–103% in the range 20–2000 ng mL−1. The relative repeatability, standard deviation was <10% at 20 ng mL−1 level and <6% in the range 100–2000 ng mL−1. 相似文献
19.
Summary A rapid and simple liquid-chromatographic method has been developed for on-line quantification of amphetamine in biological
fluids. Untreated samples (20 μL) are injected directly into the chromatographic system and purified on a 20 mm×2.1 mm i.d.
pre-column packed with 30 μm Hypersil C18 stationary phase. After clean-up the analyte is transferred to the analytical column (125 mm×4 mm i.d., 5 μm LiChrospher
100 RP18) for derivatization and separation using a mixture of acetonitrile and the derivatization reagent (o-phthaldialdehyde andN-acetyl-L-cysteine) as the mobile phase. The experimental conditions for on-line derivatization and resolution of the amphetamine
have been optimized, and the results have been compared with those obtained by derivatizing the analyte in pre-column mode.
The method described has been applied to the determination of amphetamine in plasma and urine. Good linearity and reproducibility
were obtained in the 0.1–10.0 μg mL−1 concentration range, and limits of detection were 25 ng mL−1 and 10 ng mL−1 with UV and fluorescence detection, respectively. The procedure described is very simple and rapid, because no off-line manipulation
of the sample is required; the total analysis time is approximately 8 min. 相似文献
20.
C. Flores-Pérez H. Juárez-Olguín J. Flores-Pérez B. Ramírez-Mendiola J. Bobadilla Chávez 《Chromatographia》2005,62(7-8):373-377
The aim of the present study was to develop a simple method to measure plasma levels of propafenone by liquid chromatography
with a C18 reverse-phase column and fluorescence detection, without previous derivatization of the sample. Linearity was assessed
in the range from 50 to 1000 ng mL−1 and had a correlation coefficient of 0.999. The inter- and intra-day coefficients of variation were below 5%. The limits
of detection and quantification were 15 ng mL−1 and 50 ng mL−1, respectively. Drug levels were determined satisfactorily in two patients. A simple and reliable method was developed, especially
useful in children with heart failure under treatment with propafenone. 相似文献