共查询到20条相似文献,搜索用时 546 毫秒
1.
A convenient and sensitive ion chromatographic (IC) method for the analysis of ethylenediaminetetraacetic acid (EDTA) in water
samples was proposed. Using a fast reversible reaction of free EDTA and metal–EDTA complexes into Fe(III)–EDTA complex in
the presence of Fe(III) ions, sample solutions were applied to an ion-exchange column using a mobile phase (pH 2.3), which
was composed of 100 μM Fe(III) chloride and 5 mM methanesulfonic acid. The addition of Fe(III) solution (100 μL) containing
10 mM Fe(III) chloride and 0.5 M methanesulfonic acid to the sample solution (10 mL) permitted the injection of a large volume
(400 μL) of sample, which allowed for greater sensitivity. The proposed IC method gave a highly linear (r
2 > 0.999) calibration curve ranging 0.005–1.0 μM EDTA and had a limit of detection of 1.5 nM. High repeatability (RSD < 2.1%)
and recoveries (88–108%) were also obtained. With this method, total EDTA level in raw and drinking waters were analyzed successfully. 相似文献
2.
López-Blanco C Gómez-Alvarez S Rey-Garrote M Cancho-Grande B Simal-Gándara J 《Analytical and bioanalytical chemistry》2006,384(4):1002-1006
The European Union specificies that drinking water can contain pesticide residues at concentrations of up to 0.1 μg/L each
and 0.5 μg/L in total, and that 1–3 μg/L of pesticides can be present in surface water, but the general idea is to keep discharges,
emissions and losses of priority hazardous substances close to zero for synthetic substances. Therefore, in order to monitor
pesticide levels in water, analytical methods with low quantification limits are required. The method proposed here is based
on solid phase extraction (SPE) followed by gas chromatography with a nitrogen–phosphorous detector (GC-NPD). During method
development, six organophosphate pesticides (azinphos-ethyl, chlorfenvinphos, chlorpyriphos, ethoprophos, fenamiphos and malathion)
and two organonitrogen pesticides (alachlor and deltamethrin) were considered as target analytes. Elution conditions that
could influence the efficiency of the SPE were studied. The optimized methodology exhibited good linearity, with determination
coefficients of better than 0.996. The analytical recovery for the target analytes ranged from 70 to 100%, while the within-day
precision was 4.0–11.5 %. The data also showed that the nature of the aqueous matrice (ultrapure, surface or drinking water)
had no significant effect on the recovery. The quantification limits for the analytes were found to be 0.01–0.13 μg/L (except
for deltamethrin, which was 1.0 μg/L). The present methodology is easy, rapid and gives better sensitivity than solvent drop
microextraction for the determination of organonitrogen and organophosphate pesticides in drinking water at levels associated
with the legislation. 相似文献
3.
Summary The supercritical-fluid extraction of vitamins D2 and D3 with carbon dioxide is reported for the first time. The extraction recovery was enhanced by direct addition of diethyl ether
to sample contained in the extraction cell. Separation and detection of the analytes was performed off-line by reversed-phase
liquid chromatography with UV-detection. The quantification limit of the method is 4.1 μg for both analytes, with precision,
expressed as relative standard deviation, of 3.8 and 6.3% for vitamins D2 and D3, respectively (η=7). The proposed method has been applied to the determination of vitamin D in different pharmaceutical products;
recoveries were between 85 and 105%. 相似文献
4.
Fast multiresidue screening of 300 pesticides in water for human consumption by LC-MS/MS 总被引:1,自引:0,他引:1
The study tested the determination of 300 pesticides in mineral water at levels of 0.1 and 1.0 μg/L. Measurements were conducted
by direct sample injection into a liquid chromatograph coupled to a tandem mass spectrometer without any sample enrichment
and/or cleanup. Two separate injections enabled the recording of two transitions per analyte (600 selected reaction monitoring
transitions in total). For 285 analytes the sensitivity of direct sample injection (100 μL) was sufficient to quantify residues
at 0.1 μg/L. All remaining pesticides were detected at 1.0 μg/L. Calibration functions were linear for more than 80% of analytes.
Signal suppression or enhancement compared with signals in high-performance liquid chromatography water was equal to or smaller
than 20% for 240 analytes. Even the largest matrix-induced suppression did not result in the disappearance of peaks. Combining
the results of seven mineral waters, the relative standard deviation of “recovery” was 20% or less for 87% of the substances.
A second transition for confirmatory purposes was often available. Consequently, the proposed direct injection of samples
without any sample enrichment and/or cleanup is suitable for screening of many pesticides in mineral and drinking water. 相似文献
5.
J. A. Salonia R. G. Wuilloud J. A. Gásquez R. A. Olsina L. D. Martinez 《Analytical and bioanalytical chemistry》2000,367(7):653-657
An on-line zinc preconcentration and determination system implemented with inductively coupled plasma atomic emission spectrometry
(ICP-AES) associated with flow injection (FI) was studied. The zinc was retained as zinc-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol
(Zn-(5-Br-PADAP)) complex at pH 9.2. The zinc complex was removed from the knotted reactor (KR) with 30% v/v nitric acid.
An enrichment factor of 42 was obtained for the KR system with respect to ICP-AES using pneumatic nebulization. The detection
limit for the preconcentration of 10 mL of aqueous solution was 0.09 μg/L. The precision for 10 replicate determinations
at the 5 μg/L Zn level was 2.3% relative standard deviation (RSD), calculated with the peak heights obtained. The calibration
graph using the preconcentration system for zinc was linear with a correlation coefficient of 0.9997 at levels near the detection
limits up to at least 100 μg/L. The method was succesfully applied to the determination of zinc in river water samples.
Received: 27 December 1999 / Revised: 14 March 2000 / Accepted: 15 March 2000 相似文献
6.
G. A. Shabir 《Journal of Analytical Chemistry》2011,66(10):963-968
A new and simple isocratic high-performance liquid chromatographic method with ultraviolet detection is described for simultaneous
determination of active guaiphenesin and preservative sodium benzoate in Liqufruta garlic cough medicine formulation. The
chromatographic separation was achieved using a Zorbax CN; 150 mm × 4.6 mm and 5 μm particle size column employing acetonitrile
and water (20: 80, v/v) containing 0.1% formic acid (pH 3.5 ± 0.05) as the mobile phase. The method was validated with respect
to linearity, range, precision, accuracy, specificity, limit of detection and limit of quantitation. The both analytes were
detected by UV-Vis detector at 245 nm. The method was linear over the concentration range of 0.2–0.8 mg/mL and 0.02–0.06 mg/mL
for guaiphenesin and sodium benzoate, respectively. The limit of detection was found to be 0.14 μg/mL for GP and 0.06 μg/mL
for SB and the quantification limit was 0.54 μg/mL for GP and 0.22 for SB. Accuracy, evaluated as recovery, was in the range
of 97.8–100.0%. Intra-day precision and intermediate precision showed relative standard deviation <1% in each case. 相似文献
7.
The first method for quantifying cannabinoids and cannabinoid glucuronides in whole blood by liquid chromatography–tandem
mass spectrometry (LC–MS/MS) was developed and validated. Solid-phase extraction followed protein precipitation with acetonitrile.
High-performance liquid chromatography separation was achieved in 16 min via gradient elution. Electrospray ionization was
utilized for cannabinoid detection; both positive (Δ9-tetrahydrocannabinol [THC] and cannabinol [CBN]) and negative (11-hydroxy-THC [11-OH-THC], 11-nor-9-carboxy-THC [THCCOOH],
cannabidiol [CBD], THC-glucuronide, and THCCOOH-glucuronide) polarity were employed with multiple reaction monitoring. Calibration
by linear regression analysis utilized deuterium-labeled internal standards and a 1/x
2 weighting factor, yielding R
2 values >0.997 for all analytes. Linearity ranged from 0.5 to 50 μg/L (THC-glucuronide), 1.0–100 μg/L (THC, 11-OH-THC, THCCOOH,
CBD, and CBN), and 5.0–250 μg/L (THCCOOH-glucuronide). Imprecision was <10.5% CV, recovery was >50.5%, and bias within ±13.1%
of target for all analytes at three concentrations across the linear range. No carryover and endogenous or exogenous interferences
were observed. This new analytical method should be useful for quantifying cannabinoids in whole blood and further investigating
cannabinoid glucuronides as markers of recent cannabis intake. 相似文献
8.
Burhenne J Halama B Maurer M Riedel KD Hohmann N Mikus G Haefeli WE 《Analytical and bioanalytical chemistry》2012,402(7):2439-2450
The benzodiazepine midazolam is a probe drug used to phenotype cytochrome P450 3A activity. In this situation, effective sedative
concentrations are neither needed nor desired, and in fact the use of very low doses is advantageous. We therefore developed
and validated an assay for the femtomolar quantification of midazolam and 1′-hydroxymidazolam in human plasma. Plasma (0.25 mL)
and 96-well-based solid-phase extraction were used for sample preparation. Extraction recoveries ranged between 75 and 92%
for both analytes. Extracts were chromatographed within 2 min on a Waters BEH C18 1.7 μm UPLC? column with a fast gradient
consisting of formic acid, ammonia, and acetonitrile. Midazolam and 1′-hydroxymidazolam were quantified using deuterium- and
13C-labeled internal standards and positive electrospray tandem mass spectrometry in the multiple reaction monitoring mode,
which yielded lower limits of quantification of 50 fg/mL (154 fmol/L) and 250 fg/mL (733 fmol/L) and a corresponding precision
of <20%. The calibrated concentration ranges were linear for midazolam (0.05–250 pg/mL) and 1′-hydroxymidazolam (0.25–125 pg/mL),
with correlation coefficients of >0.99. Within-batch and batch-to-batch precision in the calibrated ranges for both analytes
were <14% and <12%. No ion suppression was detectable, and plasma matrix effects were minimized to <15% (<25%) for midazolam
(1′-hydroxymidazolam). The assay was successfully applied to assess the kinetics of midazolam in two human volunteers after
the administration of single oral microgram doses (1–100 μg). This ultrasensitive assay allowed us to quantify the kinetics
of midazolam and 1′-hydroxymidazolam for at least 10 h, even after the administration of only 1 μg of midazolam. 相似文献
9.
Summary Elevated plasma homocysteine is, a known risk factor in arteriosclerotic vascular disease. To measure homocysteine in a large
number of samples, we have developed a rapid, simple, robust and inexpensive reversed-phase HPLC method for routine analysis.
Mercaptopro-pionylglycine was used as the internal standard and an external calibration in plasma was performed. Improvement
was achieved by the use of gradient elution (using a sodium acetate buffer and methanol) resulting in a higher number of samples
analyzed per day. Plasma samples were reduced with tributylphosphine and the proteins were precipitated with perchloric acid
before addition of internal standard. The analytes were derivatized by use of 7-fluorobenzofurazone-4-sulfonic acid ammonium
salt. For calibration human plasma was spiked with nine different concentrations of homocysteine (range 2–50 μmol L−1). The inter-assay precision of replicate (n=29) analysis of the concentration of homocysteine in a sample of pooled plasma was 3.0%. The limit of detection, defined
as three times the signal-to-noise ratio, was 0.25 μmol L−1. The linearity of the assay was confirmed for a plasma concentration range of 2–2000 μmol L−1. The variation of duplicate analyses of 842 plasma samples was 2.6±1.7%. 相似文献
10.
Summary A new method for the simultaneous identification and quantification of base/neutral and acidic pesticides at a low nanogram
per liter concentration level in natural waters is presented. The method includes enrichment of the compounds by solid phase
extraction on graphitized carbon black, followed by sequential elution of the base/neutral and acidic pesticides. Identification
and quantification of the compounds is performed with HPLC-ESI-MS. This procedure involves passing 1 L of ground water and
2 L of drinking water samples through a 0.5 g graphitized carbon black (GCB) extraction cartridge. A conventional 4.6-mm-i.d.
reversed phase LC C-18 operating with a 1 mL min−1 flow of the mobile phase was used to chromatograph the analytes. A flow of 100 μL min−1 of the column effluent was diverted to the ESI source. The ESI source was operated in positive ion mode for base/neutral
pesticides and in negative-ion mode for acid pesticides. For the analyte considered, the response of the mass detector was
linearly related to the amount of the analytes injected between 5 and 250 ng. In all cases, recoveries of the analytes were
better than 90%. The limit of detection (signal-to-noise ratio=3) of the method for the pesticides considered in drinking
water samples was estimated to be about 3–10 ng L−1. 相似文献
11.
Summary A method for detection, quantification, and confirmation of 30 multi-class pesticide residues in fresh vegetables by gas chromatography-tandem
mass spectrometry (GC-MS-MS) has been developed. The optimum ionization mode, electron impact (El-MS-MS) or chemical ionization
(Cl-MS-MS), was used for different groups of pesticides in a single run. The residues were previously extracted from vegetables
with dichloromethane. A 10μL aliquot of the extract can be injected in routine analysis without a clean up step when the glass
liner is used with Carbofrit. Recovery efficiencies ranged 70–119% at the two different fortification levels studied and the
relative standard deviation was <16.9% for all compounds. The limit of detection of each compound was 30 ng Kg−1−6 μg Kg−1. The proposed method was applied to the routine analysis of pesticides in vegetables grown in an important greenhouses area
located in El Ejido (Almería, Spain). 相似文献
12.
Summary Two procedures, based on large-volume injection with a programmed-temperature vaporizer (PTV), have been developed for the
determination of several triazine and organophosphorus pesticides. The use of PTV for injection in gas chromatography (GC)
has enabled the introduction of up to 200 μL sample extract into the GC, thus increasing the sensitivity of the method. PTV
injection has been combined off-line with two different microextraction procedures—liquid-liquid partition and solid-phase
extraction.
A simple and rapid off-line liquid-liquid microextraction procedure (5 mL water/1 mL methyltert-butyl ether) was applied to surface water samples spiked at levels between 0.01 and 5μg L−1. Recoveries of the overall procedure were >80% and the precision was better than 15%. Detection limits were <30 ngL−1 from 200-μL injections in GC-NPD analysis of triazines and GC-FPD analysis of organophosphorus pesticides. Off-line automated
solid-phase extraction with C18 cartridges has been applied to water samples (50 mL) spiked at 0.01, 0.1 and 1 μg L−1. The overall procedure was satisfactory (recoveries >80% and coefficients of variation <12%) and the limits of detection
ranged from 1 to 9 ng L−1.
Finally, several surface water samples were anlysed, and triazine herbicides were detected at concentrations of approx. 0.1–0.2
μg L−1. The results were similar to those obtained by conventional solvent extraction then GC-MSD after splitless injection of 2
μL. 相似文献
13.
Fu SC Tzing SH Chen HC Wang YC Ding WH 《Analytical and bioanalytical chemistry》2012,402(6):2209-2216
A simple sample pretreatment technique, dispersive micro-solid phase extraction, was applied for the extraction of N-nitrosodimethylamine (NDMA) and other four N-nitrosamines (NAs) from samples of swimming pool water. The parameters affecting the extraction efficiency were systematically
investigated. The best extraction conditions involved immersing 75 mg of carbon molecular sieve, Carboxen™ 1003 (as an adsorbent),
in a 50-mL water sample (pH 7.0) containing 5% sodium chloride in a sample tube. After 20 min of extraction by vigorous shaking,
the adsorbent was collected on a filter and the NAs desorbed by treatment with 150 μL of dichloromethane. A 10-μL aliquot
was then directly determined by large-volume injection gas chromatography with chemical ionization mass spectrometry using
the selected ion storage mode. The limits of quantitation were <0.9 ng/L. The precision for these analytes, as indicated by
relative standard deviations, were <8% for both intra- and inter-day analyses. Accuracy, expressed as the mean extraction
recovery, was between 62% and 109%. A preliminary analysis of swimming pool water samples revealed that NDMA was present in
the highest concentration, in the range from n.d. to 100 ng/L. 相似文献
14.
A simple, rapid, sensitive and reliable high-performance liquid chromatographic method for the simultaneous determination
of eight sulfonamides (SAs) in bovine milk was developed (sulfadiazine, sulfathiazole, sulfamethazine, sulfamethoxypyridazine,
sufamonomethoxine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline) in bovine milk was developed. Samples were prepared
by extraction with ethyl acetate and cleaning-up with an anion solid-phase extraction (SPE) column. Analytical separation
was performed on an Inertsil ODS-3 column with photodiode-array detection at 270 nm under gradient condition. The whole procedure
was evaluated according to the European Commission Decision 2002/657/EC. Specificity, decision limit (CCα), detection capacity
(CCβ), trueness and precision were determined during the validation process. It was found that the analytes were isolated
from spiked samples with good recoveries between 70.5 and 89.0%. The used analytical conditions allow to successively separating
all the tested sulfonamides with good limit of detection between 0.8 and 1.5 μg L−1. 相似文献
15.
M. Freney H. Irth H. Lindberg U. Alkner L. Greiff C. G. A. Persson M. Andersson G. Marko-Varga 《Chromatographia》2001,54(7-8):439-445
Summary Fucose (6-deoxygalactose) is a constituent of airway mucous glycoproteins. In this paper we describe a high-throughput method
for screening nasal lavage fluid samples and induced sputum samples for fucose. Fucose was released by hydrolysis with 0.5m sulfuric acid at 100°C for 4 h. After pH adjustment remaining proteins were removed by on-line dialysis. Chromatography was
performed with two 300 mm×7.8 mm i.d. Bio-Rad Aminex HPX-87H columns arranged in a box-car configuration. Post-column derivatization
was performed with benzamidine under alkaline conditions. Fluorescence was monitored at an excitation wavelength of 360 nm,
using an optical cut-off filter of 420 nm. The limit of quantitation for fucose was 40 μm (S/N=3) in 300μL nasal lavage medium, with use of a 20-μL injection loop. Relative standard deviation (RSD) values for intra and inter assay data were below 15% and 20%, respectively, at spike levels of 635 μm l-fucose. The method was used to monitor the fucose content of human airway secretions.
Presented at: 23rd International Symposium on Chromatography, London, UK, October 1–5, 2000 相似文献
16.
M. A. Raggi R. Mandrioli G. Casamenti V. Volterra C. Desiderio S. Fanali 《Chromatographia》1999,50(7-8):423-427
Summary An HPLC method with fluorescence detection has been developed for the determination of fluoxetine and its main metabolite
norfluoxetine in human plasma. Pretreatment of the biological samples by liquid-liquid extraction was used to improve the
sensitivity of a previously published SPE procedure. The method uses 200 μL plasma and recovery is good for both analytes.
On a C8 column with a mixture of perchlorate buffer and acetonitrile as mobile phase fluoxetine, norfluoxetine and the internal standard
(paroxetine) were eluted in less than 9 min, without interference from the biological matrix. Response for both analytes was
linearly dependent on concentration over the range 2.5–500 ng mL−1, and repeatability (RSD%) was <4%. The limit of detection was 1 ng mL−1 for both fluoxetines. Application to plasma samples from depressed patients treated with fluoxetine gave good results. There
was no interference from other common CNS drugs. This method seems to be a useful tool for clinical monitoring, because it
requires small plasma samples and is highly sensitive and highly selective. 相似文献
17.
Summary An HS-SPME method was developed and applied for the isolation of volatile organic compounds from plants native or acclimatized
to Brazil. Method optimization was performed using typical analytes from the target samples; fibers coated with 100 μm PDMS
and 75 μm Carboxen/PDMS were tested. Using PDMS 100 μm fibers and GC-MS for separation and identification, up to 99.9% of
the peak area in the chromatograms from plants were identified. The method was also applied to quantify the major volatile
components of one of the samples (Aloysia gratissima) with results comparable to those from the conventional steam distillation method. 相似文献
18.
Summary A rapid and simple method has been developed for determination of imidazolinone (IMI) residues in soil.
Extraction of the analytes from the soil matrix was performed with a pressurized-liquid-extraction apparatus built in this
laboratory. Four different types of soil sample (clay, clay loam, sandy clay loam, and silty loam) were fortified with target
compounds at levels of 10 and 50 ng g−1 by a procedure which can mimic weathered soils. The samples were then dried and packed in a 25 cm×4.6 mm i. d. stainless
steel column; this was placed inside a GC oven and extracted by passing an aqueous solution of KCl (0.1m, 20 mL) through the column at 90°C.
Quantification of the analytes in the final extract (50-μL injection) was performed by reversed-phase liquid chromatography-mass
spectrometry with a TurbolonSpray interface. Recoveries of the analytes were greater than 83% andRSD less than 7%. The method detection limit was in the 1–2.5ng g−1 range in analysis by time-scheduled selected-ion monitoring (SIM). 相似文献
19.
Summary This paper describes a study of the potential of large-volume on-column injection for the determination of triazine herbicides
in clean water samples (ground-water). The sensitivity of chromatographic determination has been increased by two orders of
magnitude by injection of up to 200 μL of pesticide solutions and nitrogen-phosphorus detection. Analytical characteristics
expressed as precision, linear range and limit of detection have been determined, the results indicating adequate analytical
performance and the ruggedness of the injection technique. As an application, gas chromatography with large-volume on-column
injection and nitrogen-phosphorus detection was combined with off-line liquid-liquid micro-extraction with hexane (1 mL water/1
mL hexane). The procedure was applied to spiked groundwater samples at two concentration levels (1 and 10 μg L−1) with good recoveries (between 81 and 103%, except for deethylatrazine) and repeatability (better than 15% at the 1 μg L−1 level). Limits of detection of the triazine herbicides studied ranged from 0.08 to 0.16 μgL−1. 相似文献
20.
A successful flow-through system was developed for trace analysis of copper using DPASV with a glassy-carbon electrode. Periodical
chemical regeneration of the electrode with a 1 mol/L NaOH solution increased sensitivity and precision. The method was shown
to be applicable with a detection limit of 0.56 μg/L, with a determination time of less than 7 min per measurement (without
deaeration time). The drawback of the system is the 10 min deaeration time. The system gave an accuracy of 0.090±0.005% for
a certified reference material of low alloy steel containing 0.090±0.004% Cu. Applicability to various fresh water samples
with a Cu content between 1.57 and 13.11 μg/L with an RSD<2.36% is illustrated.
Received: 11 March 1996/Revised: 1 July 1996/Accepted: 4 July 1996 相似文献