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1.
Determination of tetracycline residues in soil by pressurized liquid extraction and liquid chromatography tandem mass spectrometry 总被引:2,自引:0,他引:2
Vicente Andreu Pablo Vazquez-Roig Cristina Blasco Yolanda Picó 《Analytical and bioanalytical chemistry》2009,394(5):1329-1339
An optimized extraction and cleanup method for the analysis of chlortetracycline (CTC), doxycycline (DC), oxytetracycline
(OTC) and tetracycline (TC) in soil is presented. Soil extraction in a pressurized liquid extraction system, followed by extract
clean up using solid-phase extraction (SPE) and tetracycline determination by liquid chromatography tandem mass spectrometry
(LC-MS/MS) provided appropriate efficiency and reproducibility. Different dispersing agents and solvents for soil extraction
and several SPE cartridges for cleanup were compared. The best extraction results were obtained using ethylenediamine tetraacetic
acid-treated sand as dispersing agent, and water at 70 °C. The most effective cleanup was obtained using Strata-XTM sorbent in combination with a strong anion exchange cartridge. Recoveries ranged from 71% to 96% and precision, as indicated
by the relative standard deviations, was within the range of 8–15%. The limits of quantification (LOQs) by using LC-MS/MS,
based on signal-to-noise ratio (S/N) of 10, ranged from 1 μg kg−1 for TC to 5 μg kg−1 for CTC. These results pointed out that this technique is appropriate to determine tetracyclines in soils. Analysis of 100
samples taken in the Valencian Community revealed that, in soil, up to 5 μg kg−1 CTC, 15 μg kg−1 OTC, 18 μg kg−1 TC, and 12 μg kg−1 DC could be detected. Detection of the analytes in several samples, which typify great part of the Spanish agricultural soils,
should be outlined as most important result of this study.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
2.
Fumonisins B1 (FB1) and fumonisin B2 (FB2) are the main members of a family of mycotoxins produced by Fusarium verticillioides, Fusarium proliferatum, and other fungi species of the section Liseola. The present work shows the results of comparative studies using two different procedures for the analysis of fumonisins
in maize and maize-based samples. The studied analytical methods involve extraction with methanol/water, dilution with PBS,
and clean-up through immunoaffinity columns. Two reagents (o-phthaldialdehyde and naphthalene-2,3-dicarboxaldehyde) were studied for formation of fluorescent derivatives. The separation
and identification were carried out by high-performance liquid chromatography with fluorescence detection. The optimized method
for analysis of fumonisins in maize involved extraction with methanol/water (80:20), clean-up with an immunoaffinity column,
and derivatization with naphthalene-2,3-dicarboxaldehyde (NDA). The limit of detection was 20 μg kg−1 for FB1 and 15 μg kg−1 for FB2. Recoveries of FB1 and FB2 ranged from 79% to 99.6% for maize fortified at 150 μg kg−1 and 200 μg kg−1, respectively, with within-day RSDs of 3.0 and 2.7%. The proposed method was applied to 31 samples, and the presence of fumonisins
was found in 14 samples at concentrations ranging from 113 to 2,026 μg kg−1. The estimated daily intake of fumonisins was 0.14 μg kg−1 body weight per day. 相似文献
3.
A multiresidue method has been developed for the simultaneous determination of sulfadiazine, sulfathiazole, sulfapyridine,
sulfamerazine, sulfamethoxydiazine, sulfamethylthiazole, sulfamethazine, sulfamonomethoxine, sulfamethoxypyridazine, sulfisoxazole,
sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline in natural animal casings by HPLC after solid-phase extraction. The
sulfonamides were extracted with acetonitrile and the extract cleaned up with an Oasis MCX SPE cartridge prior to analysis.
Separation was on a ZOBAX Eclipse XDB-C8 column using gradient elution with acetonitrile/methanol/0.1% acetic acid. The effect of separation conditions on chromatographic
behavior and recovery has been studied. Calibration graphs were linear with very good correlation coefficients (r = 0.9983−0.9996) in the concentration range from 0.02 to 1 μg mL−1. The limits of quantitation (LOQ) for the 13 sulfonamides were in the range of 1.5–2.2 μg kg−1. Decision limits (CCα) and detection capabilities (CCβ) were in the range of 105.2–111.0 and 113.0–120.2 μg kg−1, respectively. The recovery for casings spiked with 1.5–100 μg kg−1 ranged from 65.2 to 85.9%. The relative standard deviations (RSDs) of the sulfonamides for six measurements at 100 μg kg−1 were from 2.2 to 7.7%. The applicability of the method to the analysis of salted swine casings, salted sheep casings and
dry casing samples was demonstrated. 相似文献
4.
This paper reports a novel approach for the detection, confirmation, and quantification of 15 selected pyrethroid pesticides,
including pyrethins, and two metabolites of dithiocarbamates in foods by ultra-performance liquid chromatography–tandem mass
spectrometry (UPLC–MS–MS). The proposed method makes use of a modified QuEChERS (quick, easy, cheap, effective, rugged, and
safe) procedure that combines isolation of the pesticides and sample cleanup in a single step. Analysis of pyrethroids and
dithiocarbamate metabolites was performed by UPLC–MS–MS operated with electrospray and atmospheric pressure chemical ionization,
respectively. Two specific precursor–product ion transitions were acquired per target compound in multiple reaction monitoring
(MRM) mode. Such acquisition achieved the minimum number of identification points according to European Commission (EC) document
no. SANCO/10684/2009, thus fulfilling the EC point system requirement for identification of contaminants in samples. The method
was validated with a variety of food samples. Calibration curves were linear and covered from 1 to 800 μg kg−1 in the sample for all target compounds. Average recoveries, measured at mass fractions of 10 and 100 μg kg−1 for pyrethroids and 5 and 50 μg kg−1 for dithiocarbamate metabolites, were in the range of 70–120% for all target compounds with relative standard deviations
below 20%. Method limits of quantification (MLOQ) were 10 μg kg−1 and 5 μg kg−1 for pyrethroids and dithiocarbamate metabolites, respectively. The method has been successfully applied to the analysis of
600 food samples in the course of the first Hong Kong total diet study with pyrethroids and metabolites of dithiocarbamates
being the pesticides determined. 相似文献
5.
C. Molins E. A. Hogendoorn H. A. G. Heusinkveld A. C. van Beuzekom P. van Zoonen R. A. Baumann 《Chromatographia》1998,48(5-6):450-456
Summary Recent work demonstrated that the combination of microwave assisted solvent extraction (MASE) and capillary gas chromatography
with selective nitrogen detection (GC-NPD) is a viable approach for the efficient determination of triazine herbicides in
soils. However, for soils with a high organic matter content or the injection of more concentrated extracts to obtain lower
LOD's the performance of gas chromatographic analysis of uncleaned extracts is hampered. This results in both a decrease of
the chromatographic response of analytes and a decrease in the life time of the column due to coextracted matrix substances.
The effect of various types of soils on the chromatographic analysis of triazine herbicides was studied. It appeared that
for the investigated samples with an organic matter content below 5% processing of uncleaned extracts is possible. Samples
with a higher organic matter content required a cleanup step. A rapid procedure on 100 mg silica cartridges has been developed
using solvents compatible with the MASE extracts and the instrumental analysis. Beside the testing with different standard
soils, about 120 samples of an ongoing monitoring program involving three different types of soil (organic matter content:
3–37%) were analysed. The selected compounds atrazine, desethylatrazine, desisopropyl-atrazine and simazine could be assayed
in the various soil types to a level of at least 2 μg kg−1. For soil samples with a high organic matter content (>5%), the rapid cleanup procedure allowed the trace analysis of the
triazines and considerably increased the life time of the capillary column. Recoveries at levels from 2 to 50 μg kg−1 ranged from 70 to 100% with RSDs ranging from 5.1 to 9.5%. Confirmation of positive samples was carried out by gas chromatography
mass spectrometry. 相似文献
6.
Capillary zone electrophoresis determination of oxytetracycline in pig tissue samples at maximum residue limits 总被引:2,自引:0,他引:2
Summary The determination of the antibiotic oxytetracycline (OTC), in pig tissues was investigated by capillary zone electrophoresis
(CZE) with a prior solid-phase extraction (SPE) using alkyl-bonded silica and polymeric cartridges. The methodology developed
allows determination of OTC in pig kidney, liver and muscle samples with detection limits below maximum residue limit values,
and the procedures to extract OTC and clean-up the matrix are simple and reliable. The limit of detection for OTC was 160,
120 and 85 μg kg−1 for kidney, liver and muscle samples, respectively. The average recoveries from spiked samples (200 μg kg−1 and 1600 μg kg−1) were in excess of 63% with coefficients of variation between 2.0 and 9.8%. This method would be useful for routine monitoring
of oxytetracycline residues in pig tissues. 相似文献
7.
Analytical methods used for the isotope dilution inductively coupled plasma mass spectrometric (ID-ICP-MS) measurement of
Cd at μg kg−1 and sub-μg kg−1 levels are described and applied to the certification of new dietary supplement, blood, and serum Standard Reference Materials
(SRMs). The materials are: SRM 3240 Ephedra sinica Stapf Aerial Parts, SRM 3241 Ephedra sinica Stapf Native Extract, SRM 3243 Ephedra-Containing Solid Oral Dosage Form, SRM 3244 Ephedra-Containing Protein Powder, SRM
966 Toxic Metals in Bovine Blood, Level 1 (L1) and Level 2 (L2), and SRM 1598a Animal Serum. The concentration of Cd in the
materials ranges from 120 μg kg−1 down to 0.03 μg kg−1. At these levels, the factors that most influence the accuracy of the ICP-MS data are the procedure blank and spectral and
nonspectral interferences. Nonspectral interference, caused by the high concentration of dissolved solids in the matrices
investigated, resulted in signal suppression. Matrix separation was used to enhance signal intensity and to reduce spectral
interference for the accurate determination of Cd in SRM 1598a and SRM 3244. Chromatographic separation procedures using Chelex
for SRM 1598a and anion exchange for SRM 3244 were optimized to achieve the desired separation characteristics without substantially
increasing the procedure blank. Sensitivity for the determination of Cd in serum was additionally enhanced through the use
of desolvation nebulization. We determined that separations were not required for the accurate ICP-MS determination of Cd
in SRM 3240, SRM 3241, SRM 3243, and SRM 966 L2 under optimized analysis conditions. These samples were diluted to a minimum
volume and introduced to the ICP-MS via low flow (40–100 μL/min) microconcentric nebulizers. SRM 966 L1 was also analyzed
directly, but results were highly variable. The ID-ICP-MS sample preparation and ratio measurement protocols described here
resulted in total expanded uncertainties of less than 1% for the determination of 90.85 μg kg−1 Cd in SRM 3240, and less than 10% total expanded uncertainty for the determination of 0.0468 μg kg−1 Cd in SRM 1598a. 相似文献
8.
A rapid and inexpensive method for simultaneous quantification of terbumeton (TER), and its major potential metabolites (TED;
terbumeton-desethyl, TOH; terbumeton-2-hydroxy and TID; terbumeton-deisopropyl) in soil bulk water (SBW) samples is proposed.
The analytical method involves extraction–concentration from SBW samples using a graphitized carbon black (GCB) cartridge
followed by their separation–detection by reversed-phase high-performance liquid chromatography analysis using a C18 column and a diode array detector. A mobile phase of acetonitrile−0.005 mol L−1 phosphate buffer (pH 7.0) (35:65, v/v) at a flow rate of 0.8 mL min−1 in isocratic elution mode has been used. After optimization of the extraction and separation conditions, this method can be
used for the simultaneous determination of investigated compounds in the range of the international limits of 0.1 μg L−1. For TER the detection limit was 0.009 μg L−1 and it was 0.100, 0.550, and 0.480 μg L−1 for TED, TOH, and TID, respectively. The recoveries of TER, TED, TOH, and TID from SBW samples, measured at three levels of
concentration range, were found to be between 48.0 and 102.0%. The intra-day precision measured by relative standard deviation
(RSD) was always lower than 9.0%. 相似文献
9.
Simultaneous determination of six major ergot alkaloids and their epimers in cereals and foodstuffs by LC–MS–MS 总被引:1,自引:0,他引:1
This paper describes a new and rapid method for accurate quantification of the six ergot alkaloids, ergometrine, ergotamine,
ergosine, ergocristine, ergocryptine, and ergocornine, by liquid chromatography–tandem mass spectrometry (LC–MS–MS). The six
ergot alkaloids studied have been defined by the European Food Safety Authority (EFSA) as among the most common and physiologically
active ones. In addition, the method enables the quantification of the corresponding six epimers (ergo-inines) of these ergot alkaloids. This is of considerable importance in terms of the differences in toxicity of the isomeric forms.
The method involves extraction under alkaline conditions using a mixture of acetonitrile and ammonium carbonate buffer followed
by a rapid clean-up using dispersive solid-phase extraction with PSA (primary secondary amine) and a short chromatographic
LC-run (21 min) with subsequent MS–MS detection. The method was developed and validated using ten different cereal and food
samples. The major strength of the new method compared with previously published techniques is the simplicity of the clean-up
procedure and the short analysis time. The limits of quantification were 0.17 to 2.78 μg kg−1 depending on the analyte and matrix. Recovery values for the 12 ergot alkaloids spiked into ten different matrices at levels
of 5, 50, and 100 μg kg−1 were between 69 and 105% for 85 of 90 recovery measurements made over six days. Measurement uncertainty values were highly
satisfactory. At a concentration level of 5 μg kg−1 the expanded measurement uncertainty ranged from ±0.56 to ±1.49 μg kg−1, at a concentration level of 100 μg kg−1 the expanded measurement uncertainty ranged from ±8.9 to ±20 μg kg−1. Both LOQs and measurement uncertainties were dependent on the analyte but almost independent of the matrix. The method performance
was satisfactory when tested in a mini-intercomparison study between three laboratories from three different countries.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
10.
There is an increasing need to assess the harmful effects of heavy-metal-ion pollution on the environment. The ability to
detect and measure toxic contaminants on site using simple, cost effective, and field-portable sensors is an important aspect
of environmental protection and facilitating rapid decision making. A screen-printed gold sensor in a three-electrode configuration
has been developed for analysis of lead(II) by square-wave stripping voltammetry (SWSV). The working electrode was fabricated
with gold ink deposited by use of thick-film technology. Conditions affecting the lead stripping response were characterised
and optimized. Experimental data indicated that chloride ions are important in lead deposition and subsequent analysis with
this type of sensor. A linear concentration range of 10–50 μg L−1 and 25–300 μg L−1 with detection limits of 2 μg L−1 and 5.8 μg L−1 were obtained for lead(II) for measurement times of four and two minutes, respectively. The electrodes can be reused up to
20 times after cleaning with 0.5 mol L−1 sulfuric acid. Interference of other metals with the response to lead were also examined to optimize the sensor response
for analysis of environmental samples. The analytical utility of the sensor was demonstrated by applying the system to a variety
of wastewater and soil sample extracts from polluted sites. The results are sufficient evidence of the feasibility of using
these screen-printed gold electrodes for the determination of lead(II) in wastewater and soil extracts. For comparison purposes
a mercury-film electrode and ICP–MS were used for validation. 相似文献
11.
Primal D’Cunha P. Sathyanarayana Bhat Y. Narayana 《Journal of Radioanalytical and Nuclear Chemistry》2011,290(1):171-174
The paper presents systematic studies on the vertical profiles of 210Po, an important decay product of 238U, in soils along coastal Kerala. Soil samples collected from different depth intervals 0–10, 10–20, 20–30 cm were analyzed
for 210Po activity concentration by radiochemical methods. The activity 210Po in soil samples were counted using a ZnS(Ag) alpha scintillation counting system. The mean values of activity concentrations
of 210Po in soil of various depths were found to be 8.66, 5.63 and 4.95 Bq kg−1 for depth intervals of 0–10, 10–20 and 20–30 cm, respectively. The overall activity concentration of 210Po in soil was found to vary from 2.26 ± 0.19 to 14.02 ± 0.12 Bq kg−1 with a mean value of 6.43 Bq kg−1. Maximum activity concentration was found in soil samples of Kollam region with the mean value of 10.08 ± 0.92 Bq kg−1. The activity of 210Po was found to be comparatively high in surface soil. The variation of 210Po activity concentration with organic matter contents was studied. 210Polonium activity concentration was found to increase with increasing organic matter content. 相似文献
12.
José Luis Martínez Vidal Antonia Garrido Frenich María de las Nieves Barco Bonilla Roberto Romero-González Juan Antonio Padilla Sánchez 《Analytical and bioanalytical chemistry》2009,395(5):1551-1562
A simple and rapid method based on pressurized liquid extraction has been validated for the simultaneous extraction of polychlorinated
biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) from agricultural soil samples. Effective extraction was carried
out in less than 17 min for all the studied compounds, and good recoveries were obtained for PAHs and PCBs, ranging from 70%
to 112%, when blank samples were spiked at 2.5 μg kg−1, except for naphthalene with recoveries close to 40%. The separation and determination were performed by gas chromatography
coupled to tandem mass spectrometry using a triple quadrupole mass analyzer. The target compounds were detected by electron
impact with selected reaction monitoring, and mass spectrometric conditions were optimized in order to increase selectivity
and sensitivity. The developed method was validated, and matrix-matched calibration was used for quantification purposes.
Repeatability and interday precision ranged from 0.9% to 16.8% and from 1.6% to 22.3%, respectively. Limits of quantification
ranged from 0.07 to 2.50 μg kg−1. The proposed method was applied to the analysis of agricultural soil samples collected from Almeria (Spain), and PAHs and
PCBs were detected in some samples at concentrations ranging from 0.1 to 210 μg kg−1. 相似文献
13.
A multi-component method focussing on thorough sample preparation has been developed for simultaneous analysis of swine manure
for three classes of antibiotic—tetracyclines, sulfonamides, and tylosin. Liquid manure was initially freeze-dried and homogenised
by pulverization before extraction by pressurised liquid extraction. The extraction was performed at 75°C and 2,500 psig in
three steps using two cycles with 0.2 mol L−1 citric acid buffer (pH 4.7) and one cycle with a mixture of 80% methanol with 0.2 mol L−1 citric acid (pH 3). After liquid–liquid extraction with heptane to remove lipids, the pH of the manure was adjusted to 3
with formic acid and the sample was vacuum-filtered through 0.6 μm glass-fibre filters. Finally the samples were pre-concentrated
by tandem SPE (SAX-HLB). Recoveries were determined for manure samples spiked at three concentrations (50–5,000 μg kg−1 dry matter); quantification was achieved by matrix-matched calibration. Recoveries were >70% except for oxytetracycline (42–54%),
sulfadiazine (59–73%), and tylosin (9–35%) and did not vary with concentration or from day-to-day. Limits of quantification
(LOQ) for all compounds, determined as a signal-to-noise ratio of 10, were in the range 10–100 μg kg−1 dry matter. The suitability of the method was assessed by analysis of swine manure samples from six different pig-production
sites, e.g. finishing pigs, sows, or mixed production. Residues of antibiotics were detected in all samples. The largest amounts
were found for tetracyclines (up to 30 mg kg−1 dry matter for the sum of CTC and ECTC). Sulfonamides were detected at concentrations up to 2 mg kg−1 dry matter (SDZ); tylosin was not detected in any samples.
相似文献
14.
Comparison of adsorbents for on-line solid-phase extraction of polycyclic aromatic hydrocarbons before liquid chromatography with UV detection 总被引:1,自引:0,他引:1
Summary On-line solid-phase extraction (SPE) coupled with reversed-phase liquid chromatography and UV detection at 254 nm has been
used for the determination of trace-level polycyclic aromatic hydrocarbons (PAH) in soil extracts. Five commercially available
adsorbents (C8, C18, PLRP-S, PRP-1, and Bond-Elut Env) were evaluated. Results showed that recovery of the PAH decreased with increasing molecular
weight, because of their poorer solubility. Recovery of high-molecular-weight PAH was significantly improved by addition of
10% (v/v) acetonitrile to the sample before loading of the SPE adsorbent. PAH recovery ranged from 64.0 to 108% when a 50
mL sample spiked with 1 μg L−1 was applied to these adsorbents. Determination of PAH was possible with detection limits below 0.05 μg L−1, which corresponds to 0.2 μg kg−1 soil. The method was successfully used to determine PAH in soil extracts. 相似文献
15.
To determine sulphamethazine (SMZ) residues in edible animal foods (pig muscle, chicken muscle, egg, fish, milk and liver),
a competitive direct enzyme-linked immunosorbent assay (ELISA) and a colloidal gold immunoassay were established. The limits
of detection of the ELISA and the colloidal gold immunoassay were 0.02 and 0.5 μg kg−1, respectively. The specificity of the ELISA developed to the SMZ was high according to the results of cross-reactivity testing
with 14 kinds of sulphonamides. To obtain a more sensitive immunoassay, buffer solution (30 mmol L−1 phosphate-buffered saline with 0.05% Tween 20, pH 8.5) was optimized through the whole test procedure. A simple and efficient
extraction method for the rapid detection of SMZ residues in foods was developed, with recoveries between 74 and 117.5%. Matrix
effects can be avoided by 1:10 dilution of pig muscle, chicken muscle, egg, fish, milk and liver with optimal buffer. The
detection limit of SMZ was 5 μg kg−1 in liver and 2 μg kg−1 in the other five samples. For the validation of the ELISA tests, sample extracts were analysed by ELISA and high-performance
liquid chromatography. The results obtained by these two methods showed a good correlation (r
2) which was greater than 0.9. The colloidal gold immunoassay presented in this assay was successfully applied to determine
SMZ in pig muscle, milk and fish below or equal to the maximum residue level (20 μg kg−1). 相似文献
16.
L. Giannetti F. Longo F. Buiarelli M. V. Russo B. Neri 《Analytical and bioanalytical chemistry》2010,398(2):1017-1023
A specific, sensitive and robust liquid chromatography tandem mass spectrometry method for determining oxytetracycline, tetracycline,
chlortetracycline and doxycycline in royal jelly and honey samples is presented. Extraction of drug residues was performed
by ammonium acetate buffer as extractant followed by a clean-up with metal chelate affinity chromatography and solid-phase
extraction. Tetracycline analysis was performed using liquid chromatography–electrospray ionisation–tandem mass spectrometry.
The presented method is the first validated for royal jelly and in accordance with the requirements set by Commission Decision
2002/657/EC. Recoveries of the methods, calculated spiking the samples at 5.0, 10.0, 20.0 and 30.0 μg kg−1, were 79% to 90% for honey and 77% to 90% for royal jelly. The intra-day precision (RSD) ranged between 8.1% and 15.0% for
honey and from 9.1% to 16.3% for royal jelly, while inter-day precision values were from 10.2% to 17.6% and from 10.6% to
18.4% respectively for honey and royal jelly. Linearity for the four analytes was calculated from 5.0 to 50.0 μg kg−1. The decision limits (CCα) ranged from 6.2 to 6.4 μg kg−1 and from 6.1 to 6.5 μg kg−1 for honey and royal jelly, respectively. Detection capabilities values (CCβ) ranged between 7.2 and 7.7 μg kg−1 and from 7.3 to 7.9 μg kg−1 respectively for honey and royal jelly. The developed method is currently in use for confirmation of the official control
analysis of honey and royal jelly samples. 相似文献
17.
Liu X Xu J Li Y Dong F Li J Song W Zheng Y 《Analytical and bioanalytical chemistry》2011,399(7):2539-2547
A sensitive and effective method for simultaneous determination of triazolopyrimidine sulfonamide herbicide residues in soil,
water, and wheat was developed using ultra-performance liquid chromatography coupled with tandem mass spectrometry. The four
herbicides (pyroxsulam, flumetsulam, metosulam, and diclosulam) were cleaned up with an off-line C18 SPE cartridge and detected
by tandem mass spectrometry using an electrospray ionization source in positive mode (ESI+). The determination of the target
compounds was achieved in <2.0 min. The limits of detection were below 1 μg kg−1, while the limits of quantification did not exceed 3 μg kg−1 in different matrices. Quantitation was determined from calibration curves of standards containing 0.05–100 μg L−1 with r
2 > 0.997. Recovery studies were conducted at three spiked levels (0.2, 1, and 5 μg kg−1 for water; 5, 10, and 100 μg kg−1 for soil and wheat). The overall average recoveries for this method in water, soil, wheat plants, and seeds at three levels
ranged from 75.4% to 106.0%, with relative standard deviations in the range of 2.1–12.5% (n = 5) for all analytes. 相似文献
18.
Dolores Barranco Martínez María Martínez Galera Piedad Parrilla Vázquez M. Dolores Gil García 《Chromatographia》2007,66(7-8):533-538
Liquid chromatography with electrospray mass spectrometry (LC–ESI-MS) instrumentation equipped with a single quadrupole mass
filter has been used to determine several benzoylphenylurea insecticides (diflubenzuron, triflumuron, hexaflumuron, lufenuron
and flufenoxuron). Chromatographic and MS parameters were optimised to obtain the best sensitivity and selectivity for all
pesticides. Solid-phase extraction (SPE) using C18 cartridges was applied for preconcentration of pesticide trace levels in river water samples. Recoveries of benzoylphenylurea
pesticides from spiked river water (0.01 and 0.025 μg L−1) were between 73 and 110% and detection limits were between 3.5 and 7.5 ng L−1. The applicability of the method to the determination of benzoylphenylurea insecticides in spiked cucumber, green beans,
tomatoes and aubergines was evaluated. Samples were extracted into dichloromethane without any clean-up step. The limits of
detection ranged from 1.0 to 3.2 ng mL−1 (0.68 and 2.13 μg kg−1 in the vegetable samples). Mean recoveries ranged from 79 to 114% at spiking levels of 0.01 and 0.03 mg kg−1. The method was applied to determine traces of benzoylphenylureas in both river water and vegetable samples with precision
values lower than 10%. Interferences due to the matrix effect were overcome using matrix-matched standards. 相似文献
19.
Summary The fluorogenic reagent 2-naphthyloxycarbonyl chloride (NOC-Cl) has been used for the automated precolumn derivatization of
biogenic amines (BAs) at ambient followed by liquid-chromatographic separation of the derivatives formed.
For optimized derivatization samples in 0.5 M borate buffer (pH 9.0) were derivatized with 5 mM NOC-Cl in acetonitrile (MeCN)
for 3 minutes. Excess of reagent was scavenged by addition of 20 mM glycine in water. For HPLC a Superspher? RP-18e column and gradient elution using 0.1 M sodium acetate buffer (pH 4.4) and MeCN were used. The NOC-derivatives were
detected by fluorescence at an emission wavelength of 335 nm at an excitation wavelength of 274 nm.
This method allows the detection of BAs (2-phenylethylamine, putrescine, histamine, cadaverine, tyramine, spermidine, spermine)
found in food and beverages (fruit juices, wines, various vinegars, fermented cabbage juice, and salmon).
Detection limit of BAs are approximately 49–113 μg kg−1 with the exception of histamine (747 μg kg−1) (injected amounts: 18–41 pg histamine 267 pg), at a signalto-noise ratio of 3:1. The limits of determination are approximately
82–189 μg kg−1 (histamine 1245 μg kg−1) at a signal-to-noise ratio of 5:1. The correlation coefficients of linearity are 0.9910–0.9976. Recoveries from different
matrices range from 65 to 109%, depending on the sample investigated.
Presented at the 21st ISC held in Stuttgart, Germany, 15th–20th September, 1996. 相似文献
20.
J. J. LaBrecque J. A. Alfonso P. R. Cordoves 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(2):405-411
As a result of routine soil sampling to determine the 137Cs background activities country-wide in Venezuela, it was decided to further investigate El Mirador (Lookout) area at the
base of the Sierra de Lema mountain range. In April 2003 (A), soil samples were collected at eight sites on and around the
edge of the diabase outcrop to confirm that this area had anomalously high 137Cs activities. In July 2003 (B), not only soil samples were collected again, but also black mat, palm tree leaves and trunks,
fruit bushes leaves and its fruit and fern leaves. The 137Cs content was measured by high resolution gamma-ray spectroscopy by a comparative method with reference materials. The 137Cs activity values range from 16.3 to 30.8 Bq·kg-1 in the soil samples collected in July 2003, 20.7–32.1 Bq·kg−1 for the black mat, 26.3–38.4 Bq·kg−1 for the palm leaves, 16.8–31.2 Bq·kg−1 for the palm trunks and 17.6–27.3 Bq·kg−1 for the fruit bush leaves, while, the 137Cs activity values for the whole fruit were between 23.4 and 30.7 Bq·kg−1; but, the value of the 137Cs activity in the center of the fruit (the edible part) was 51.6 Bq·kg−1, and the value of the 137Cs activity for the fern leaves was 51.8 Bq·kg−1. Thus, most of the 137Cs activity values determined in the soil, black mat and vegetation samples from El Mirador (Lookout) were considered anomalously
high with respect to those found near the equator and in other areas of Venezuela. Only the center of the fruit from the Clusia grandiflora bushes and the fern leaves had high activity ratios, about a factor of three and could be considered as biomonitors that
concentrate and retain the 137Cs. Finally, these anomalously high 137Cs activities have been attributed not only to the rich organic soils, as sinks, but also due to the affect of the cloud forests. 相似文献