共查询到20条相似文献,搜索用时 31 毫秒
1.
Lina Kantiani Marinella Farré Josep Manuel Grases i Freixiedas Damià Barceló 《Analytical and bioanalytical chemistry》2010,398(3):1195-1205
A fully automated method has been developed for analysis of eighteen antibacterial compounds, including penicillins, cephalosporins
and sulfonamides, in animal feed with limits of quantification in the range 0.25–5.79 μg kg−1. The method is based on pressurized liquid extraction of 3 g homogenized feed with water and online clean-up of 500 μL of
the extract with C18HD cartridges. The purified sample was directly analysed by liquid chromatography–electrospray tandem mass spectrometry (SPE–LC–ESI-MS–MS).
Chromatographic separation was achieved within 10 min by use of a C12 Phenomenex Hydro-RP reversed-phase analytical column and a mobile phase gradient (water + 0.1% formic acid–methanol + 0.1%
formic acid). The method was validated, revealing capability for detection of concentrations as low as 0.09 μg kg−1, decision limits (CCα) and detection capabilities (CCβ) in the range 10–174 μg kg−1 and 22–182 μg kg−1, respectively, and inter-day precision ranging from 0.7 to 8.3%. Recovery, with internal standard correction, was in the
range 93–134% for all analytes. The method was then applied to analysis of fifteen feed samples, nine of which contained at
least one antimicrobial at concentrations between 0.006 and 1.526 mg kg−1. The performance data and results from the method were compared with those from a previous method developed by our group,
using offline SPE, by analyzing the same set of samples by both methods. The online SPE approach resulted in slightly improved
sensitivity, with LODs of 0.09–2.12 μg kg−1 compared with 0.12–3.94 μg kg−1 by the offline approach. In general, better recovery was achieved by use of online purification (for 72% of the analytes)
and the correlation between the two methods was good. The main advantages of the new online method are rapid and automated
sample pre-treatment, and reduction of sample manipulation, enabling high-throughput analysis and highly accurate results.
Because of all these characteristics, the proposed method is applicable and could be deemed necessary within the field of
food control and safety. 相似文献
2.
Misako Tagiri-Endo Shigeru Suzuki Tomoyuki Nakamura Takashi Hatakeyama Kazuo Kawamukai 《Analytical and bioanalytical chemistry》2009,393(4):1367-1375
A simple and quick online solid-phase extraction (SPE) coupled to liquid chromatography (LC)/tandem mass spectrometry (MS/MS)
for the determination of the five antibiotics (florfenicol, FF; lincomycin, LCM; oxytetracyclin, OTC; tylosin, TS; valnemulin,
VLM) in swine wastewater has been developed. After filtration, aliquots (100 μl) of wastewater samples were directly injected
to a column-switching LC system. Some matrix interference was removed by washing up SPE column with 0.2% formic acid solution
and acetonitrile. Antibiotics eluted from SPE column were separated on analytical column by converting switching valve and
were detected by MS/MS. Calibration curves using the method of standard addition had very good correlation coefficients (r > 0.99) in the range of 0.1 to 2 ng/ml. The intra-day precision of the method was less than 12% and the inter-day precision
was between 6 to 17%. The detection limits were 0.01–0.1 ng/ml. When this method was applied to wastewater samples in swine
facilities, four compounds (LCM, OTC, TS, and VLM) were detected. 相似文献
3.
Minakata K Nozawa H Gonmori K Yamagishi I Suzuki M Hasegawa K Watanabe K Suzuki O 《Analytical and bioanalytical chemistry》2011,400(7):1945-1951
An electrospray ionization tandem mass spectrometric (ESI-MS-MS) method has been developed for the determination of cyanide
(CN–) in blood. Five microliters of blood was hemolyzed with 50 μL of water, then 5 μL of 1 M tetramethylammonium hydroxide solution
was added to raise the pH of the hemolysate and to liberate CN– from methemoglobin. CN– was then reacted with NaAuCl4 to produce dicyanogold, Au(CN)2–, that was extracted with 75 μL of methyl isobutyl ketone. Ten microliters of the extract was injected directly into an ESI-MS-MS
instrument and quantification of CN– was performed by selected reaction monitoring of the product ion CN– at m/z 26, derived from the precursor ion Au(CN)2– at m/z 249. CN– could be measured in the quantification range of 2.60 to 260 μg/L with the limit of detection at 0.56 μg/L in blood. This
method was applied to the analysis of clinical samples and the concentrations of CN– in the blood were as follows: 7.13 ± 2.41 μg/L for six healthy non-smokers, 3.08 ± 1.12 μg/L for six CO gas victims, 730 ± 867 μg
for 21 house fire victims, and 3,030 ± 97 μg/L for a victim who ingested NaCN. The increase of CN– in the blood of a victim who ingested NaN3 was confirmed using MS-MS for the first time, and the concentrations of CN– in the blood, gastric content and urine were 78.5 ± 5.5, 11.8 ± 0.5, and 11.4 ± 0.8 μg/L, respectively. 相似文献
4.
Martínez-Uroz MA Mezcua M Belmonte Valles N Fernández-Alba AR 《Analytical and bioanalytical chemistry》2012,402(3):1365-1372
A gas chromatography–mass spectrometry method in negative chemical ionization mode has been developed incorporating simultaneous
detection using a micro-electron capture detector (μ-ECD) for the determination of pesticides in fruits and vegetables. This
instrument configuration uses a three-way splitter device which divides the effluent from the analytical column between the
two detectors with the split ratio 1:0.1 (MSD/μ-ECD) in each run. The μ-ECD was used for confirmation purposes. Validation
of the method was performed on three matrices: tomato, apple, and orange. The ethyl acetate method was assayed; recovery studies
were performed at 10 and 100 μg/kg. Recoveries between 70% and 120% were achieved and relative standard deviations lower than
20% (n = 5) were obtained for all pesticides and matrices studied. Limits of quantification lower than 10 μg/kg were obtained for
100% of pesticides in all of the matrices. Limits of quantification lower than 2.5 μg/kg were achieved for 77.8% of pesticides
in the tomato and apple matrices, and for 72.2% of pesticides in the orange matrix. The method showed linear response in the
concentration range tested (2.5–500 μg/kg) with correlation coefficients >0.99. Good repeatability and reproducibility results
were obtained in all cases, with relative standard deviations lower than 16.7% and 20%, respectively. Finally, 20 incurred
samples were analyzed using the proposed method. The simultaneous use of the two detectors was satisfactory for the analysis
of these real samples. The total number of pesticides identified was 25. The number of samples which contained at least one
pesticide was 15—this represented 75% of the total number of samples studied. 相似文献
5.
An ultra-performance liquid chromatography-tandem mass spectrometry method was developed, optimised and validated for the
quantification of synthetic folic acid (FA), also called pteroyl-l-glutamic acid or vitamin B9 and naturally occurring 5-methyltetrahydrofolate (5-MTHF) found in folate-fortified breads. Optimised
sample preparation prior to analysis involved addition of 13C5 labelled internal standards, treatments with α-amylase and rat serum, solid-phase extraction using aromatic-selective cartridges
and ultra-filtration. Analytes were separated on a Waters ACQUITY HSS T3 column during a 6-min run and analysed by positive
ion electrospray selected reaction monitoring MS/MS. Standard calibration curves for the two analytes were linear over the
range of 0.018–14 μg FA/g of fresh bread (r
2 = 0.997) and 9.3–900 ng 5-MTHF/g of fresh bread (r
2 = 0.999). The absolute recoveries were 90% and 76% for FA and 5-MTHF, respectively. Intra-day coefficients of variation were
3% for FA and 18% for 5-MTHF. The limit of detection was 9.0 ng/g for FA and 4.3 ng/g for 5-MTHF, determined using pre-extracted
tapioca starch as the blank matrix. The assay is rugged, fast, accurate and sensitive, applicable to a variety of food matrices
and is capable of the detection and quantification of the naturally occurring low levels of 5-MTHF in wheat breads. The findings
of this study revealed that the FA range in Australian fortified breads was 79–110 μg/100 g of fresh bread and suggest that
the flour may not have the mandated FA fortification level (200–300 μg/100 g of flour), though this cannot be determined conclusively
from experimental bread data alone, as variable baking losses have been documented by other authors. 相似文献
6.
M. Reska E. Ochsmann T. Kraus T. Schettgen 《Analytical and bioanalytical chemistry》2010,397(8):3563-3574
Styrene is one of the most important industrial chemicals, with an enormously high production volume worldwide. The urinary
mercapturic acids of its metabolite styrene-7,8-oxide, namely N-acetyl-S-(2-hydroxy-1-phenylethyl)-l-cysteine (PHEMA 1) and N-acetyl-S-(2-hydroxy-2-phenylethyl)-l-cysteine (PHEMA 2), are specific biomarkers for the determination of individual internal exposure to this highly reactive
intermediate of styrene. We have developed and validated a fast, specific and very sensitive method for the accurate determination
of the sum of phenylhydroxyethyl mercapturic acids (PHEMAs) in human urine with an automated multidimensional liquid chromatography–tandem
mass spectrometry method using 13C6-labelled PHEMAs as internal standards. Analytes were stripped from the urinary matrix by online extraction on a restricted
access material, transferred to the analytical column and subsequently determined by tandem mass spectrometry. The limit of
quantification (LOQ) for the sum of PHEMAs was 0.3 μg/L urine and allowed us to quantify the background exposure of the (smoking)
general population. Precision within series and between series ranged from 1.5 to 6.8% at three concentrations ranging from
3 to 30 μg/L urine; the mean accuracy was between 104 and 110%. We applied the method to spot urine samples from 40 subjects
of the general population with no known occupational exposure to styrene. The median levels (range) for the sum of PHEMAs
in urine of non-smokers (n = 22) were less than 0.3 μg/L (less than 0.3 to 1.1 μg/L), whereas in urine of smokers (n = 18), the median levels were 0.46 μg/L (less than 0.3 to 2.8 μg/L). Smokers showed a significantly higher excretion of the
sum of PHEMAs (p = 0.02). Owing to its automation and high sensitivity, our method is well suited for application in occupational or environmental
studies. 相似文献
7.
The opioid tilidine is a prodrug which is hepatically metabolized to active nortilidine and bisnortilidine. Due to the increasing
abuse of tilidine by drug users and the lack of a specific immunoassay, we developed an analytical method for the quantification
of tilidine, nortilidine, and bisnortilidine in urine suitable for screening. In a following step, this method was used to
establish data on excretion kinetics of the substances in order to evaluate the time window of detection after a single oral
dose of tilidine/naloxone and also was applied to authentic urine samples from correctional facilities. Urine samples were
mixed with internal standard solution and extracted on a weak cation exchanger at pH 6 using a Symbiosis Pico system. The
chromatographic separation was achieved within a 3.5-min run time on a Phenylhexyl column (50 × 2.0 mm, 5 μm) via gradient
elution (methanol and 0.2% formic acid) at a flow rate of 0.50 mL/min. The ESI-MS/MS was performed on a QTrap 3,200 in positive
multiple reaction monitoring mode using two mass transitions per analyte. Validating the method resulted in a lower limit
of quantification of 1.0 μg/L followed by a linear calibration range to 100 μg/L for each analyte (r
2 > 0.99). The analytical method allowed the detection of a single dose of a commercially available tilidine solution up to
7 days after administration. Using this highly sensitive method, 55 of 3,665 urine samples were tested positive. 相似文献
8.
A simple HPLC-MS/MS method for simultaneous determination of loureirin A and loureirin B in rat urine, feces, and bile after
oral administration of 10.6 g/kg of longxuejie (one rare traditional Chinese medicinal herb) was developed for the first time.
The analytes and buspirone (internal standard) were separated on a C5 column with acetonitrile–water (containing 0.1% formic acid) as mobile phase at a flow rate of 0.4 min/mL. The detector was
a Q-trap™ mass spectrometer with an electrospray ionization interface operating in the multiple reaction monitoring mode.
Calibration curves of loureirin A in rat urine, feces, and bile were linear over the concentration range of 1.00–5,000 ng/mL.
Loureirin B in rat urine, feces, and bile ranged between 0.08 and 20, 0.20 and 20, and 0.10 and 500 ng/mL, respectively. Validation
revealed that the method was specific, accurate, and precise. The fully validated method was applied to the excretion study
of loureirin A and loureirin B in rats. After oral administration of 10.6 g/kg longxuejie, cumulative excretion amount of
loureirin A and loureirin B in rat urine were 2.94 ± 0.81 and 0.36 ± 0.16 μg at 72 h, respectively. Of the total dose, 5.35%
of loureirin A and 5.46% of loureirin B were excreted from feces at 60 h. The cumulative amounts of loureirin A and loureirin
B in rat bile reached 4.49 ± 0.98 and 5.11 ± 0.83 μg, respectively, at 36 h after dosing, accounting for 0.054% and 0.056%
of the total dose. 相似文献
9.
Hua Wei Jun Wen Rui Xie Houwen Lin Guorong Fan Yutian Wu 《Analytical and bioanalytical chemistry》2009,395(5):1461-1469
A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, followed by a 96-well protein precipitation,
has been developed and fully validated for the determination of Phakellistatin 13 (PK13), a new cyclic heptapeptide isolated
from the sponge Phakellia fusca Thiele, in rat plasma. After protein precipitation of the plasma samples (50 μL) in a 96-well plate by methanol (200 μL)
containing the internal standard Pseudostellarin B (20 ng/mL), the plate was vortex mixed for 3 min. Following filtration
for 5 min, the filtrate was directly injected into the LC-MS/MS system. The analytes were separated on an XB-C18 analytical
column (5 μm, 50 mm × 4.6 mm i.d.) using an eluent of methanol–water (85:15, v/v) and detected by electrospray ionization mass spectrometry in the negative multiple reaction monitoring mode with a chromatographic
run time of 5.0 min. The method was sensitive with a lower limit of quantification (LLOQ) of 0.1 ng/mL, with good linearity
(r > 0.999) over the quantitation range of 0.1–5 ng/mL. The validation results demonstrated that this method was significantly
specific, accurate, precise, and was successfully applied in measuring levels of PK13 in rat plasma following intravenous
administration of 20, 50, and 100 μg/kg of peptide in rats, respectively, which was suitable for the preclinical pharmacokinetic
studies on PK13. 相似文献
10.
Davis C Gordon N Murphy S Singh I Kavanagh K Carberry S Doyle S 《Analytical and bioanalytical chemistry》2011,401(8):2519-2529
Gliotoxin is produced by non-ribosomal peptide synthesis and secreted from certain fungi, including Aspergillus fumigatus. It is an epipolythiodioxopiperazine that contains an intact disulphide bridge and is the focus of intense research as a
consequence of its negative immunomodulatory properties. Gliotoxin detection is generally enabled by reversed-phase–high-performance
liquid chromatography (RP-HPLC), with absorbance detection (220–280 nm), or liquid chromatography-mass spectrometry, yet detection
is not readily achievable by matrix-assisted laser desorption ionisation–time-of-flight mass spectrometry (MALDI-ToF MS).
We have developed a single-pot derivatisation strategy which uses sodium borohydride-mediated reduction of gliotoxin followed
by immediate alkylation of exposed thiols by 5′-iodoacetamidofluorescein to yield a stable product, diacetamidofluorescein-gliotoxin
(GT-(AF)2), of molecular mass 1103.931 Da ((M + H)+). This product is readily detectable by RP-HPLC and exhibits a 6.8-fold increase
in molar absorptivity compared with gliotoxin, which results in a higher sensitivity of detection (40 ng; 125 pmoL). GT-(AF)2 also fluoresces (excitation/emission, 492:518 nm). Unlike free gliotoxin, the product (>800 fmol) is detectable by MALDI-ToF
MS. Sporidesmin A can also be detected by RP-HPLC and MALDI-ToF MS (>530 fmol) using this strategy. We also demonstrate that
the strategy facilitates detection of gliotoxin (mean ± SD = 3.55 ± 0.07 μg 100 μL−1; n = 2) produced by A. fumigatus, without the requirement for organic extraction of culture supernatants and associated solvent removal. GT-(AF)2 is also detectable (150 ng; 460 pmol) by thin-layer chromatography. 相似文献
11.
Delhomme O Raeppel C Teigné D Briand O Millet M 《Analytical and bioanalytical chemistry》2011,399(3):1325-1334
To measure dermal exposure of a non-agricultural occupationally exposed population to pesticides, a new method has been developed
for analysis of 13 pesticides from different classes (fungicides, herbicides, insecticides) on dermal patches. The method
includes extraction of the patches and analysis of the pesticides by GC–MS and/or HPLC–fluorescence. Water-soluble pesticides
(glyphosate and glufosinate) on patches were ultrasonically extracted twice with ultra-pure water for 10 min and analysed
by HPLC–fluorescence after derivatisation with FMOC. Organic-soluble pesticides (bifenthrin, cyprodinil, difufenicanil, fludioxonil,
oxadiazon, pyriproxyfen, clopyralid, 2,4-D, fluroxypyr, 2,4-MCPA, and triclopyr) were extracted ultrasonically twice for 10 min
with 70:30 dichloromethane–acetonitrile and analysed by GC–MS directly or after derivatisation with N-methyl-N-tert-butyldimethylsilyltrifluoroacetamide. Detection limits varied between 3 and 4 μg L−1 for water-soluble pesticides and between 1 and 10 μg L−1 for organic-soluble pesticides. 相似文献
12.
Byrdwell WC 《Analytical and bioanalytical chemistry》2011,401(10):3317-3334
A method is demonstrated for analysis of vitamin D fortified dietary supplements that eliminates virtually all chemical pretreatment
prior to analysis, which is referred to as a “dilute-and-shoot” method. Three mass spectrometers, in parallel, plus a UV detector,
an evaporative light-scattering detector (ELSD), and a corona charged aerosol detector (CAD) were used to allow a comparison
of six detectors simultaneously. Ultraviolet data were analyzed using internal standard, external standard, and response factor
approaches. The contents of gelcaps that contained 2,000 IU (50 μg) vitamin D3 in rice bran oil, diluted to 100 mL, were analyzed without the need for lengthy saponification and extraction. Vitamin D3 was analyzed using UV detection, extracted ion chromatograms, selected ion monitoring (SIM) atmospheric pressure chemical
ionization mass spectrometry (APCI-MS), and two transitions of multiple reaction monitoring (MRM) APCI-MS. The internal standard,
external standard, and response factor methods gave values of 0.5870 ± 0.0045, 0.5893 ± 0.0041, and 0.5889 ± 0.0045 μg/mL,
respectively, by UV detection. The values obtained by MS were 0.6117 ± 0.0140, 0.6018 ± 0.0244, and 0.5848 ± 0.0146 μg/mL
by SIM and two transitions of MRM, respectively. The triacylglycerols in the oils were analyzed using full-scan APCI-MS, electrospray
ionization (ESI) MS, up to MS4, an ELSD, and a CAD. The method proved to be very sensitive for vitamin D3, as well as triacylglycerols (TAGs), allowing identification of intact TAGs containing fatty acids up to 28 carbons in length.
LC-ESI-MS of glycerin polymers is also demonstrated. 相似文献
13.
A novel method combining matrix solid phase dispersion (MSPD) with Soxhlet simultaneous extraction clean-up (SSEC) was developed.
Being a single-step extraction and clean-up procedure, it could be used instead of multistep solvent extraction and Florisol
column clean-up. It not only reduces sample contamination during the procedure, but it also decreases the amount of organic
solvent needed. The retention times of standards were used to qualitatively assess the method, and the external standard method
was used to quantitatively assess it. Residues of organochlorine pesticides (OCP) in tobaccos were determined by gas chromatography–electron
capture detection (GC–ECD), and their identities were confirmed by the standard addition method (SAM). The performance of
the method was evaluated and validated: the detection limit was 0.01–0.02 μg g−1, relative standard deviations were 5–26%, and recoveries were 72–99% at fortification levels of 0.10, 1.00 and 10.0 μg g−1. The analytical characteristics of MSPD–SSEC compared very favorably with the results from the classical multistep solvent
extraction and Florisol column clean-up method. 相似文献
14.
Chen F Chen L Wang Q Zhou J Xue X Zhao J 《Analytical and bioanalytical chemistry》2009,393(3):1073-1079
A rapid and reliable method was developed and applied for the simultaneous determination of 17 organochlorine pesticides (OCPs)
in propolis. After extraction with hexane and acetone (1:1, v/v), four sorbents (florisil, silica, graphitized carbon, and
tandem graphitized carbon plus florisil) were assayed for the clean-up step. The elution solvents hexane and ethyl acetate
(1:1, v/v), hexane and dichloromethane (3:7, v/v), and ethyl acetate and hexane (2:8, v/v) were studied. The results showed
that the combination of the tandem graphitized carbon and florisil cartridge with the elution solvent of 6mL of ethyl acetate
and hexane (2:8, v/v), which was capable of eliminating matrix interference and providing colorless eluates, was the most
efficient clean-up procedure for propolis extracts when testing for OCPs. The analytical technique employed was gas chromatography
with electron capture detection (GC–ECD). The correlation coefficients from linear regression for the analyzed concentrations
(5∼100 μg/kg) were >0.9961. The limits of detection (LODs) varied between 0.8 μg/kg for 4,4′-DDE and 11.4 μg/kg for endosulfan
II, and the limits of quantitation (LOQs) ranged from 2.6 to 38.1 μg/kg. The average recoveries varied between 62.6 and 109.6%.
Relative standard deviations (RSD%) ranged from 0.8 to 9.4%. Sample analysis indicated that 4,4′-DDE was detected more often
in propolis than other pesticides, such as β-HCH, δ-HCH and heptachlor.
Figure GC-ECD chromatogram of a standard solution with 0.1 mg/L of OCPs 相似文献
15.
Repizo LM Martinez LD Olsina RA Cerutti S Raba J 《Analytical and bioanalytical chemistry》2012,402(2):965-973
A novel, simple, and rapid reversed-phase liquid chromatography–tandem mass spectrometric methodology was developed for the
analysis of natamycin in wine samples. Natamycin was protonated to form singly charged ions in an electrospray positive ion
mode. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM) of three fragment ion transitions
(666.3 → 648.2, 666.3 → 503.3, and 666.3 → 485.2) to provide a high degree of sensitivity and specificity. Chromatographic
separation was performed on a rapid resolution column using a mobile phase consisting of an acetonitrile/water mixture with
a total run time of 5.0 min. After only filtration as pretreatment, the sample was injected into the chromatographic system.
The proposed method was validated in terms of selectivity, trueness, precision, decision limit (CCα), and detection capability (CCβ) according to 2002/657/EC Commission decision. The values for trueness, reported as bias (%), agreed with those established
by the aforementioned document. Repeatability (intraday variability) values were 12.37% at a concentration of 1.0 μg L−1 and 8.99–4.19% at concentrations between 2.5 and 10 μg L−1. The overall within-laboratory (interday variability) reproducibility was 15.47% at a concentration of 1.0 μg L−1, which was significantly lower than the indicative value reported in the EU decision. The results indicated that the proposed
approach is a sensitive, fast, reproducible, and robust methodology suitable for the analysis of natamycin levels in wine
samples. 相似文献
16.
Berthet A Bouchard M Schüpfer P Vernez D Danuser B Huynh CK 《Analytical and bioanalytical chemistry》2011,399(6):2243-2255
Captan and folpet are fungicides largely used in agriculture. They have similar chemical structures, except that folpet has
an aromatic ring unlike captan. Their half-lives in blood are very short, given that they are readily broken down to tetrahydrophthalimide
(THPI) and phthalimide (PI), respectively. Few authors measured these biomarkers in plasma or urine, and analysis was conducted
either by gas chromatography coupled to mass spectrometry or liquid chromatography with UV detection. The objective of this
study was thus to develop simple, sensitive and specific liquid chromatography–atmospheric pressure chemical ionization-tandem
mass spectrometry (LC/APCI-MS/MS) methods to quantify both THPI and PI in human plasma and urine. Briefly, deuterated THPI
was added as an internal standard and purification was performed by solid-phase extraction followed by LC/APCI-MS/MS analysis
in negative ion mode for both compounds. Validation of the methods was conducted using spiked blank plasma and urine samples
at concentrations ranging from 1 to 250 μg/L and 1 to 50 μg/L, respectively, along with samples of volunteers and workers
exposed to captan or folpet. The methods showed a good linearity (R
2 > 0.99), recovery (on average 90% for THPI and 75% for PI), intra- and inter-day precision (RSD, <15%) and accuracy (<20%),
and stability. The limit of detection was 0.58 μg/L in urine and 1.47 μg/L in plasma for THPI and 1.14 and 2.17 μg/L, respectively,
for PI. The described methods proved to be accurate and suitable to determine the toxicokinetics of both metabolites in human
plasma and urine. 相似文献
17.
D. García-Rodríguez A. M. Carro R. Cela R. A. Lorenzo 《Analytical and bioanalytical chemistry》2010,398(2):1005-1016
A microwave-assisted extraction method followed by clean-up with solid-phase extraction (SPE) combined with large-volume injection
gas chromatography–tandem mass spectrometry (LVI-GC-MS/MS) for the analysis of 17 pesticides in wild and aquaculture edible
seaweeds has been developed. An experimental central composite design was employed to evaluate the effects of the main variables
potentially affecting the extraction (temperature, time, and solvent volume) and to optimize the process. The most effective
microwave extraction conditions were achieved at 125 °C and 12 min with 24 mL of hexane/ethyl acetate (80:20). SPE clean-up
of the extracts with graphitized carbon and Florisil, optimized by means of the experimental design, proved to be efficient
in the removal of matrix interferences. The analytical recoveries were close to 100% for all the analytes, with relative standard
deviations lower than 13%. The limits of detection ranged from 0.3 to 23.1 pg g−1 and the limits of quantification were between 2.3 and 76.9 pg g−1, far below the maximum residue levels established by the European Union for pesticides in seaweed. The results obtained prove
the suitability of the microwave-assisted extraction for the routine analysis of pesticides in aquaculture and wild seaweed
samples. 相似文献
18.
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
19.
A method involving simultaneous extraction and sample clean-up procedure: hollow fiber sorptive microextraction, coupled with
gas chromatography–mass spectrometric detection for quantification of seven organochlorine pesticides in Radix et Rhizoma
Rhei is described. SiO2 hollow fiber with porous structure was synthesized for the first time. The internal diameter of SiO2 hollow fiber is 380 μm and average wall thickness is 100 μm. Aggregated SiO2 particles deposited on the surface of the hollow fiber in a regular array lead to porous structure. SiO2 hollow fiber was applied to the determination of organochlorine pesticides in Radix et Rhizoma Rhei to avoid sample clean-up
and minimize the matrix effects. Extraction solvent, extraction temperature and equilibration time were optimized. Fiber to
fiber repeatability over the concentration ranges were less than 10%. Recoveries were satisfactory (between 63% and 115%)
for most of organochlorine pesticides at spiking levels. Furthermore, the proposed method was also applied to determine seven
organochlorine pesticides in 43 commercial Radix et Rhizoma Rhei samples, in which the selected pesticides were found in eight
samples. The results have been further confirmed by solvent extraction methods according to China Pharmacopoeia (2005). 相似文献
20.
A new adsorbent is proposed for the solid-phase extraction of phenol and 1-naphthol from polluted water. The adsorbent (TX-SiO2) is an organosilica composite made from a bifunctional immobilized layer comprising a major fraction (91%) of hydrophilic
diol groups and minor fraction (9%) of the amphiphilic long-chain nonionic surfactant Triton X-100 (polyoxyethylated isooctylphenol)
(TX). Under static conditions phenol was quantitatively extracted onto TX-SiO2 in the form of a 4-nitrophenylazophenolate ion associate with cetyltrimethylammonium bromide. The capacity of TX-SiO2 for phenol is 2.4 mg g−1 with distribution coefficients up to 3.4 × 104 mL g−1; corresponding data for 1-naphthol are 1.5 mg g−1 and 3 × 103 mL g−1. The distribution coefficient does not change significantly for solution volumes of 0.025–0.5 L and adsorbent mass less than
0.03 g; 1–90 μg analyte can be easily eluted by 1–3 mL acetonitrile with an overall recovery of 98.2% and 78.3% for phenol
and 1-naphthol, respectively. Linear correlation between acetonitrile solution absorbance (A
540) and phenol concentration (C) in water was found according to the equation A
540 = (6 ± 1) × 10−2 + (0.9 ± 0.1)C (μmol L−1) with a detection range from 1 × 10−8 mol L−1 (0.9 μL g−1) to 2 × 10−7 mol L−1 (19 μL g−1), a limit of quantification of 1 μL g−1 (preconcentration factor 125), correlation coefficient of 0.936, and relative standard deviation of 2.5%. A solid-phase colorimetric
method was developed for quantitative determination of 1-naphthol on adsorbent phase using scanner technology and RGB numerical
analysis. The detection limit of 1-naphthol with this method is 6 μL g−1 while the quantification limit is 20 μL g−1. A test system was developed for naked eye monitoring of 1-naphthol impurities in water. The proposed test kit allows one
to observe changes in the adsorbent color when 1-naphthol concentration in water is 0.08–3.2 mL g−1. 相似文献