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1.
Petropoulou SS Tsarbopoulos A Siskos PA 《Analytical and bioanalytical chemistry》2006,385(8):1444-1456
A gas chromatography–tandem mass spectrometric (GC-MS/MS) method has been developed for the determination of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl
methylcarbamate), carbaryl (1-naphthyl-N-methylcarbamate) and their main metabolites in human blood plasma. Optimization of
the isolation of the compounds from plasma matrix included the precipitation, denaturation and digestion of plasma proteins.
Derivatization was achieved by the use of trifluoroacetic acid anhydride and was optimized for temperature, time and volume
of derivatization agent. In the proposed method, a mild precipitation technique was applied using β-mercaptoethanol and ascorbic
acid in combination with solid-phase extraction technique using Oasis HLB (Hydrophobic Lipophilic Balance) cartridges for
further clean up of samples. Carbamate linkage was not hydrolyzed to its phenol product, but both carbamate phenol and ketones
were transformed into trifluoroacetyl derivatives in order to become volatile compounds and were determined using tandem mass
spectrometry. The linearity of the method was shown for nine concentrations in the range of 0.50–250 ng mL−1 in fortified plasma aliquots. Limits of detection (LODs) for all compounds ranged from 0.015–0.151 ng mL−1. Inter-day and intra-day assays (RSD) for all compounds, at three concentration levels of 2.5, 25 and 100 ng mL−1 (n=3) in fortified plasma samples were less than 18%. Accuracy (%E
r) was calculated at three concentration levels, 8, 80 and 160 ng mL−1 (n=3), and ranged from −12.0 to 15.0%. Matrix effect was evaluated so mean recoveries were calculated for all compounds and
ranged from 81–107%. Specificity for the use of this method to biological monitoring studies was achieved including four main
metabolites of CF, 1-naphthol and 2-naphthol from the naphthalene metabolism pathways, and both the parent compound of carbofuran
and carbaryl. The proposed method was applied to plasma samples of pesticide users. 相似文献
2.
A simple, sensitive and accurate spectrophotometric method for the determination of sulphonamides (sulphamethoxazole (SMZ),
sulphaguanidine (SGD), sulphaquinoxaline sodium (SQX), sulphametrole (SMR), and sulphadimidine sodium (SDD)) has been developed.
The charge-transfer reactions between sulphonamides as n-electron donors and 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), and 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone
(chloranilic acid, p-CLA) as π-acceptors resulting in highly coloured complexes were studied. Experimental conditions for these CT reactions were carefully
optimised. Beer’s law is valid over the concentration ranges from 4–280 μg mL−1, 4–260 μg mL−1, 4–200 μg mL−1, and 4–200 μg mL−1 of SMZ, SGD, SQX, and SDD using DDQ reagent, respectively. While the calibration curves are linear in the concentration ranges
from 4–180 μg mL−1, 4–80 μg mL−1, 4–60 μg mL−1, 4–180 μg mL−1, and 4–60 μg mL−1 of SMZ, SGD, SQX, SMR, and SDD, respectively, using TCNQ reagent and from 4–380 μg mL−1 and 4–300 μg mL−1 of SQX and SDD, respectively, using p-CLA reagent, respectively. Different analytical parameters, namely molar absorptivity
(ε), standard deviation, relative standard deviation, correlation coefficient, limit of detection, and limit of quantification,
were calculated. The results obtained by the proposed methods are in good agreement with those obtained by the official method
as indicated by the percent recovery values. 相似文献
3.
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
4.
Capitán-Vallvey LF Valencia MC Arana Nicolás E García-Jiménez JF 《Analytical and bioanalytical chemistry》2006,385(2):385-391
An integrated solid-phase spectrophotometry–FIA method is proposed for simultaneous determination of the mixture of saccharin
(1,2-benzisothiazol-3(2H)-one-1,1-dioxide; E-954) (SA) and aspartame (N-l-α-aspartyl-l-phenylalanine-1-methyl ester; E-951) (AS). The procedure is based on on-line preconcentration of AS on a C18 silica gel minicolumn and separation from SA, followed by measurement, at λ=210 nm, of the absorbance of SA which is transiently retained on the adsorbent Sephadex G-25 placed in the flow-through cell
of a monochannel FIA setup using pH 3.0 orthophosphoric acid–dihydrogen phosphate buffer, 3.75×10–3 mol L−1, as carrier. Subsequent desorption of AS with methanol enables its determination at λ=205 nm. With a sampling frequency of 10 h−1, the applicable concentration range, the detection limit, and the relative standard deviation were from 1.0 to 200.0 μg mL−1, 0.30 μg mL−1, and 1.0% (80 μg mL−1, n=10), respectively, for SA and from 10.0 to 200.0 μg mL−1, 1.4 μg mL−1, and 1.6% (100 μg mL−1, n=10) for AS. The method was used to determine the amounts of aspartame and saccharin in sweets and drinks. Recovery was always
between 99 and 101%. The method enabled satisfactory determination of blends of SA and AS in low-calorie and dietary products
and the results were compared with those from an HPLC reference method. 相似文献
5.
Protein can greatly enhance the fluorescence of curcumin (CU) in the presence of sodium dodecyl benzene sulfonate (SDBS).
Experiments indicate that under the optimum conditions, the enhanced intensity of fluorescence is proportional to the concentration
of proteins in the range of 0.0050–20.0 μg mL−1 for bovine serum albumin (BSA), 0.080–20.0 μg mL−1 for human serum albumin (HSA), and 0.040–28.0 μg mL−1 for egg albumin (EA). Their detection limits (S/N=3) are 1.4 ng mL−1, 20 ng mL−1, and 16 ng mL−1, respectively. The method has been satisfactorily used for the determination of proteins in actual samples. In comparison
with most of fluorimetric methods, this method is quick and simple, has high sensitivity and good stability. The interaction
mechanism is also studied. 相似文献
6.
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
7.
Study of a toxin–alkaline phosphatase conjugate for the development of an immunosensor for tetrodotoxin determination 总被引:2,自引:0,他引:2
This paper describes a direct competitive immunoenzymatic spectrophotometric assay (ELISA) for tetrodotoxin (TTX) determination
and the adaptation of this method for use in an electrochemical assay format. The novelty of this work involves the use of
the antigen labelled with alkaline phosphatase (AP); this conjugate was prepared in our laboratory as there is no commercially
available conjugate of any kind for TTX. The new conjugate was characterized in terms of its affinity for the specific antibody
as well as the residual concentration and the residual activity of the enzyme (AP) incorporated as label. The proposed method
based on the new conjugate showed satisfactory results for TTX determination: for the spectrophotometric method the dynamic
range was 4–15 ng mL−1 with a limit of detection (LOD) of 2 ng mL−1 (R=0.9247), whereas for the electrochemical protocol the dynamic range was 2–50 ng mL−1 and the LOD was1 ng mL−1. 相似文献
8.
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
9.
A new chemiluminescence (CL) method combined with flow injection technique is described for the determination of Cr(III) and
total Cr. It is found that a strong CL signal is generated from the reaction of Cr(III), lucigenin and KIO4 in alkaline condition. The determination of total Cr is performed by pre-reduction of Cr(VI) to Cr(III) by using H2SO3. The CL intensity is linearly related to the concentration of Cr in the range 4.0 × 10−10–1.0 × 10−6 g mL−1. The detection limit (3s
b) is 1 × 10−10 g mL−1 Cr and the relative standard deviation is 1.9% (5.0 × 10−8 g mL−1 of Cr(III) solution, n = 11). The method was applied to the determination of Cr(III) and total Cr in water samples and compared satisfactorily with
the official method. 相似文献
10.
A new method is described for simultaneous determination of 3-methylindole (3MI) and indole in porcine adipose tissue. Sample preparation included liquid–liquid extraction with n-hexane and 75% aqueous acetonitrile. The acetonitrile extracts were analysed by liquid chromatography–mass spectrometry (LC–MS) using atmospheric pressure chemical ionization (APCI) with selective ion monitoring of protonated ions [M + H]+. This method showed excellent linearity over the concentration range tested (from 2 to 500 ng mL−1 for 3MI and from 1 to 500 ng mL−1 for indole) and good accuracy (recovery of 92 ± 10% for 3MI and 91 ± 10% for indole). This new LC–MS method was compared with traditional colorimetric method for 3MI equivalent. Additionally, the correlation between 3MI concentrations in adipose tissue and plasma was studied. The described LC–MS method can be used to quantify 3MI and indole in porcine adipose tissue in various endocrinological or meat science studies. 相似文献
11.
Pilar Viñas Carmen López-Erroz Francisco Joseé Cerdán Natalia Campillo Manuel Hernández-Córdoba 《Mikrochimica acta》2000,134(1-2):83-87
A new fluorimetric procedure for the determination of thiamine using flow injection analysis is proposed. The method is based
on the derivatization reaction of the primary amine group with o-phthalaldehyde in the presence of 2-mercaptoethanol using fluorimetric detection. The calibration graph based on peak area
was linear in the range 0.2–6 ng mL−1. The detection limit was close to 0.1 ng mL−1. The method was applied to the determination of the vitamin in commercial pharmaceutical preparations.
Received March 31, 1999. Revision October 15, 1999. 相似文献
12.
Summary A reliable and sensitive high-performance liquid chromatographic method for the determination of the recent antidepressant
citalopram and two metabolites in human plasma has been developed. Fluorescence detection at 300 nm was used, exciting at
238 nm. Separation was obtained using a reversed-phase column (C18, 250 × 3.0 mm i.d., 5 μm) and a mobile phase. 40% acetonitrile:
60% aqueous tetramethylammonium perchlorate (pH 1.9). Calibration curves were linear over a working range: 5–300 ng mL−1 for citalopram, 2.5–150.0 ng mL−1 for desmethylcitalopram and 2.5–50.0 ng mL−1 for didesmethylcitalopram. The limits of quantitation (LOQ) were 1.5 ng mL−1 for citalopram and desmethylcitalopram and 2.0 ng mL−1 for didesmethylcitalopram. Precision data, as well as accuracy, were satisfactory and no interference from different psychotropic
drugs was found. The method was therefore suitable for therapeutic drug monitoring of citalopram and its active metabolites
in plasma of depressed patients. 相似文献
13.
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
14.
Summary Solid-phase extraction (SPE) was coupled at-line to capillary electrophoresis (CE) for the determination of a series of basic
test compounds (i. e. tricyclic antidepressants). The analysis was performed using a non-aqueous CE buffer, which resulted
in baseline separation of all test compounds. This is in marked contrast with CE using aqueous buffers where hardly any separation
was obtained either with or without micelles. The SPE procedure was used to remove simultaneously most of the water from the
sample, because no direct analysis of aqueous samples is possible when a non-aqueous CE buffer is used. With the present method
the antidepressants can be determined in both urine and serum. Analyte detectability is increased up to 10-fold due to trace
enrichment during the extraction process; the limits of detection (LODs; UV 214 nm) are 30–300 ng mL−1 in urine and 300–1000 ng mL−1 in serum. TheRSD values (n=5) of the within-day and between-day precision are below 9% and 11% respectively. Therefore, the present procedure can be
used for drug monitoring. 相似文献
15.
This paper describes a simple, rapid and sensitive method for the determination of triasulfuron and bensulfuron-methyl using
a multi-walled carbon nanotube-packed cartridge as the preconcentration step prior to analysis by high-performance liquid
chromatography. The experimental results indicate an excellent linear correlation between the peak area and the concentration
for triasulfuron and bensulfuron-methyl over the concentration range of 0.08–80 and 0.04–40 ng · mL−1, and the correlation coefficients are 99.93 and 99.38%, respectively. The detection limits are 22.4 and 2.9 ng · L−1 based on the signal being three times the baseline noise (S/N = 3). The precision of the method is satisfactory at a very
low level, and the relative standard deviations (RSD) are 2.6 and 4.8% (n = 6), respectively. Satisfactory recoveries were achieved with spiked real water samples, inferring that the established
method can be applied to real sample analysis. 相似文献
16.
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
17.
Silica gel was prepared by the sol–gel method, modified with nanometer-sized zirconium oxide, and this material was characterized
by X-ray diffraction. A micro-column packed with silica gel modified with nanometer zirconium oxide as sorbent has been developed
for the quantitative separation and preconcentration of trace amounts of chromium(III) prior to their determination by electrothermal
atomic absorption spectrometry. Total chromium was determined after the reduction of chromium(VI) to chromium(III) by 10%
(m/v) of aqueous ascorbic acid as reducing reagent. The adsorption capacity for chromium(III) was found to be 2.36 mg g−1. The detection limit for chromium(III) was 15 ng L−1 with an enrichment factor of 100. The relative standard deviation was 3.2% (n = 7, c = 2.0 ng mL−1). 相似文献
18.
Neng Zhou Yi-Zeng Liang Ben-Mei Chen Ping Wang Xian Chen Feng-Ping Liu 《Chromatographia》2007,66(7-8):481-486
A rapid, simple and specific liquid chromatography-electrospray ionization mass spectrometry method has been developed and
validated for the determination of hydroxyzine hydrochloride in human plasma. Samples were separated using a Thermo Hypersil-HyPURITYC18
reversed-phase column (150 mm × 2.1 mm i.d., 5 μm). The mobile phase consisted of 50 mM ammonium acetate (pH 4.0)–methanol–acetonitrile
(45:36:19, v/v). Hydroxyzine and its internal standard were measured by electrospray ion source in positive selective ion monitoring mode.
The method was validated with a linear range of 1.56–200.0 ng mL−1 and the lowest limit of quantification was 1.56 ng mL−1 for hydroxyzine hydrochloride (r
2= 0.9991). The extraction efficiencies were about 70% and recoveries of the method were in the range of 93.5–104.4%. The intra-day
relative standard deviation (RSD) was less than 8.0% and inter-day RSD was within 7.4%. QC samples were stable when kept at
ambient temperature for 12 h at −20 °C for 30 days and after four freeze–thaw cycles. The method has been successfully applied
to the evaluation of pharmacokinetics and bioequivalence of two hydroxyzine hydrochloride formulations in 12 healthy Chinese
volunteers after an oral dose of 25 mg. 相似文献
19.
Summary A method for the determination of 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP) and 2-hydroxy-N-methylsuccinimide (2-HMSI) in
plasma was developed. 5-HNMP and 2-HMSI are metabolites to the widely used organic solvent N-methyl-2pyrrolidone (NMP). The
5-HNMP and 2-HMSI were purified from plasma by C8 solid phase extraction, derivatised by bistrimethylsilyl trifluoroacetamid,
and analysed by gas chromatography with mass spectrometric detection. For 5-HNMP, the precision was 2–7 % (120 and 780 ng
mL−1) and the detection limit was 6 ng mL−1 (m/z 98). For 2-HMSI, the precision was 2–9 % (160 and 1000 ng mL−1) and the detection limit was 4 ng mL−1 (m/z 144). The method is applicable for analysis of plasma samples from workers exposed to NMP. 相似文献
20.
A simple, rapid, and highly sensitive spectrofluorimetric method for the determination of acitretin was developed based on
the strong green fluorescence of acitretin. Influence of organic solvents on the fluorescence spectra of acitretin was studied.
Effects of pH, standing time, and foreign ions on the determination of acitretin were also examined. Under the optimum conditions,
linear relationship between the relative fluorescence intensity and the concentration of acitretin in the range of 30.0–1100
ng mL−1 was obtained. Detection limit of this method is 9.56 ng mL−1 for acitretin. Relative standard deviation for the determination of 480 ng mL−1 of acitretin was 1.70 %. This method was used for the determination of acitretin in pharmaceuticals and the results were
compared with those obtained by the HPLC method. 相似文献