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1.
Guillamont EM Lino CM Baeta ML Pena AS Silveira MI Vinuesa JM 《Analytical and bioanalytical chemistry》2005,383(4):570-575
Ochratoxin A (OTA) is a secondary fungal metabolite produced by several moulds, mainly by Aspergillus ochraceus and by Penicillium verrucosum, that occurs in meat products. The aim of this work was to optimize an efficient extraction procedure for the determination
of OTA in muscle tissue in order to assess its occurrence in meat samples. Three different apparatus, a Waring blender, a
switching apparatus, and an ultrasonic processor, were evaluated to verify the efficiency of extraction. The analytical methods
proposed involve the extraction with chloroform-orthophosphoric acid, cleanup through an immunoaffinity column, high-performance
liquid chromatography/fluorescence detection for separation and identification of OTA, and confirmation with liquid chromatography/FD
after methylation of OTA in muscle tissue. The limit of quantification of the proposed method was 0.04 μg kg−1. Recoveries of OTA, using switching apparatus, ranged from 90.3 to 103.2% for chicken muscle spiked at 2.4 and 0.48 μg kg−1, respectively, with a within-day relative standard deviation of 17 and 15.3%. The proposed method was applied to 38 chicken,
swine, and turkey muscle samples and the presence of OTA was confirmed in five samples. Finally, the estimated daily intake
of OTA in this study was between 23 pg kg−1 body weight per day for swine samples and 18 pg kg−1 body weight per day for turkey samples. 相似文献
2.
Arsenic-speciation analysis in marine samples was performed by high-pressure liquid chromatography (HPLC) with ICP–MS detection.
Separation of eight arsenic species—AsIII, MMA, DMA, AsV, AB, TMAO, AC and TeMAs+—was achieved on a C18 column with isocratic elution (pH 3.0), under which conditions AsIII and MMA co-eluted. The entire separation was accomplished in 15 min. The HPLC–ICP–MS detection limits for the eight arsenic
species were in the range 0.03–0.23 μg L−1 based on 3σ for the blank response (n=5). The precision was calculated to be 2.4–8.0% (RSD) for the eight species. The method was successfully applied to several
marine samples, e.g. oysters, fish, shrimps, and marine algae. Low-power microwave digestion was employed for extraction of
arsenic from seafood products; ultrasonic extraction was employed for the extraction of arsenic from seaweeds. Separation
of arsenosugars was achieved on an anion-exchange column. Concentrations of arsenosugars 2, 3, and 4 in marine algae were
in the range 0.18–9.59 μg g−1.
This paper was presented at the European Winter Conference 2005 相似文献
3.
Inagaki K Takatsu A Watanabe T Aoyagi Y Yarita T Okamoto K Chiba K 《Analytical and bioanalytical chemistry》2007,387(7):2325-2334
A new marine sediment certified reference material, NMIJ CRM 7306-a, for butyltin and phenyltin analysis has been prepared
and certified by the National Metrological Institute of Japan at the National Institute of Advanced Industrial Science and
Technology (NMIJ/AIST). Candidate sediment material was collected at a bay near industrial activity in Japan. After air-drying,
sieving, and mixing the material was sterilized with γ-ray irradiation. The material was re-mixed and packaged into 250 glass
bottles (15 g each) and these were stored in a freezer at −30 °C. Certification was performed by use of three different types
of species-specific isotope-dilution mass spectrometry (SSID–MS)—SSID–GC–ICP–MS, SSID–GC–MS, and SSID–LC–ICP–MS, with 118Sn-enriched organotin compounds synthesized from 118Sn-enriched metal used as a spike. The 118Sn-enriched mono-butyltin (MBT), dibutyltin (DBT), and tributyltin (TBT) were synthesized as a mixture whereas the 118Sn-enriched di-phenyltin (DPhT) and triphenyltin (TPhT) were synthesized individually. Four different extraction methods,
mechanical shaking, ultrasonic, microwave-assisted, and pressurized liquid extraction, were adopted to avoid possible analytical
bias caused by non-quantitative extraction and degradation or inter-conversion of analytes in sample preparations. Tropolone
was used as chelating agent in all the extraction methods. Certified values are given for TBT 44±3 μg kg−1 as Sn, DBT 51 ± 2 μg kg−1 as Sn, MBT 67 ± 3 μg kg−1 as Sn, TPhT 6.9 ± 1.2 μg kg−1 as Sn, and DPhT 3.4 ± 1.2 μg kg−1 as Sn. These levels are lower than in other sediment CRMs currently available for analysis of organotin compounds. 相似文献
4.
A simple reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination
of the antiepileptic drugs (AEDs) zonisamide (ZNS), primidone (PRI), lamotrigine (LTG), phenobarbital (PB), phenytoin (PHT),
oxcarbazepine (OXC), and carbamazepine (CBZ) and two of their active metabolites, monohydroxycarbamazepine (MHD) and carbamazepine
10,11-epoxide (CBZE) in human plasma. Plasma (100 μL) was pretreated by deproteinization with 300 μL methanol containing 20 μg mL−1 propranolol hydrochloride as internal standard. HPLC was performed on a C8 column (4.6 mm × 250 mm; particle size 5 μm) with methanol–acetonitrile–0.1% trifluoroacetic acid, 235:120:645 (v/v), as mobile phase at a flow rate of 1.5 mL min−1. ZNS, OXC, and CBZ were monitored by UV detection at 235 nm, and PRI, LTG, MHD, PB, PHT, and CBZE by UV detection at 215 nm.
Relationships between response and concentration were linear over the concentration ranges 1–80 μg mL−1 for ZNS, 5–50 μg mL−1 for PRI, 1–25 μg mL−1 for LTG, 1–50 μg mL−1 for MHD, 5–100 μg mL−1 for PB, 1–10 μg mL−1 for CBZE, 0.5–25 μg mL−1 for OXC, 1–50 μg mL−1 for PHT, and 1–25 μg mL−1 for CBZ. Intra-day and inter-day reproducibility were adequate (coefficients of variation were ≤11.6%) and absolute recovery
ranged from 95.2 ± 6.13 to 107.7 ± 7.76% for all the analytes; for the IS recovery was 98.69 ± 1.12%. The method was proved
to be accurate, reproducible, convenient, and suitable for therapeutic monitoring of the nine analytes. 相似文献
5.
Fábio A. Silva Cilene C. F. Padilha Gustavo Rocha de Castro Paulo dos Santos Roldan Ana R. de Araujo Nogueira Paula M. Moraes Pedro M. Padilha 《Central European Journal of Chemistry》2011,9(1):119-125
This paper proposes a method to determine selenium in samples of fish muscle and liver tissue using ultrasound assisted extraction
process, and analysed by graphite furnace atomic absorption spectrometry (GFAAS). The selenium content was extracted by 0.10
M HCl at the optimal extraction conditions which were established as follows: sample mass of 100 mg; granulometry of the sample
<60 μm; sonication time of five 40 s cycles; and sonication power of 136 W. The selenium determinations were performed by
GFAAS, at a drying temperature of 120°C/250°C, pyrolysis temperature of 1300°C, atomization temperature of 2300°C, and cleaning
temperature of 2800°C. Palladium nitrate was used as a chemical modifier coinjected with the samples, and tungsten as a permanent
modifier. The concentration of selenium determined in the pool of fish muscle and liver tissue were 280.4±4.2 e 592.3±6.7
μg kg−1, respectively. The accuracy and precision of the proposed extraction method were evaluated using certified standard Bovine
Muscle — NIST 8414. The results obtained by the ultrasonic extraction method were equivalent to those obtained by the method
of acid mineralization of samples in a microwave oven 相似文献
6.
GC determination of nicotine in subcutaneous adipose tissue obtained by minimal trauma tissue biopsy
Summary Nicotine has been analyzed by gas chromatography nitrogen-phosphorus detection in tissue samples obtained by repeated minimal
trauma tissue biopsies from human subcutaneous adipose tissue. For sample preparation, a single extraction step of the tissue
samples with chloroform was performed at 30–45°C. Calibration curves generated with spiked porcine subcutaneous adipose tissue
were linear over a concentration range from 0.20 to 100 μg g−1, therefore, the limit of quantification was fixed at 0.20 μg g−1. The limit of detection was found to be 0.05 μg g−1 adipose tissue. The recovery of nicotinespiked porcine subcutaneous adipose tissue by chloroform extraction was 100±8%. The
performance of the assay was not affected by the complex lipid matrix. The method was employed for analysis in a clinical
study on nicotine penetration from a transdermal delivery system through the skin of moderate smokers.
Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999. 相似文献
7.
González-Martínez MA Penalva J Rodríguez-Urbis JC Brunet E Maquieira A Puchades R 《Analytical and bioanalytical chemistry》2006,384(7-8):1540-1547
A comparative study of enzymatic and non-enzymatic labels combined with luminescence detection, developed for immunosensing of pesticide residues (carbaryl, 1-naphthol, irgarol 1051) in organic media, is presented. Peroxidase and alkaline phosphatase enzymes with fluorogenic (3-p-hydroxyphenylpropanoic acid) and luminogenic (AMPPD derivative) substrates, respectively, were assessed as enzymatic markers. As an alternative, terbium(III) chelate, with time-resolved fluorescence detection, was evaluated as a non-enzymatic label. The best sensitivity was achieved by use of alkaline phosphatase in an immunocomplex capture assay format (I
50 values 0.06, 0.27, and 7.45 μg L−1 in buffer, 1:1 methanol–buffer, and methanol, respectively). Results were also good (I
50 1.00 and 6.30 μg L−1 for water and aqueous–organic mixture, respectively) for Tb(III) chelate in an immobilized conjugate assay format. Use of alkaline phosphatase label to measure carbaryl (100 ng L−1) in different spiked river water samples, after solid-phase extraction and analyte elution with an ethyl acetate–methanol mixture, resulted in recoveries ranging from 81 to 98%, with acceptable precision (CV 4–14%, n=4). 相似文献
8.
Sánchez-Rodas D Oliveira V Sarmiento AM Gómez-Ariza JL Nieto JM 《Analytical and bioanalytical chemistry》2006,384(7-8):1594-1599
A preservation study has been performed for arsenic speciation in surface freshwaters affected by acid mine drainage (AMD), a pollution source characterized by low pH and high metallic content. Two sample preservation procedures described in the literature were attempted using opaque glass containers and refrigeration: i) addition of 0.25 mol L−1 EDTA to the samples, which maintained the stability of the arsenic species for 3 h; and ii) in situ sample clean-up with a cationic exchange resin, in order to reduce the metallic load, which resulted in a partial co-adsorption of arsenic onto Fe precipitates. A new proposed method was also tried: sample acidification with 6 mol L−1 HCl followed by in situ clean-up with a cationic exchange resin, which allowed a longer preservation time of at least 48 h. The proposed method was successfully applied to water samples with high arsenic content, taken from the Aguas Agrias Stream (Odiel River Basin, SW Spain), which is severely affected by AMD that originates at the nearby polymetallic sulfide mine of Tharsis. The speciation results obtained by liquid chromatography–hydride generation–atomic fluorescence spectrometry (HPLC-HG-AFS) indicated that during the summer the main arsenic species was As(V) at the hundred μg L−1 level, followed by DMA (dimethyl arsenic) and As(III) below the ten μg L−1 level. In winter, As(V) and As(III) increased at least fivefold, whereas the DMA was not detected. 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.
Lei Zhang Liang Xu Xiao-Jie Tan Qiong-Feng Liao Wei Guo Xiao-Hui Chen Kai-Shun Bi 《Chromatographia》2007,66(1-2):115-120
A sensitive and reliable ion-paired high-performance liquid chromatographic method has been established for the simultaneous
quantification of six major active ingredients, namely baicalin, baicalein, wogonin, oxysophocarpine, oxymatrine and matrine
in the Chinese herbal preparation, Sanwu-Huangqin-Tang. HPLC analyses were performed on a Phenomenex luna C18 column with mobile phase of methanol–acetonitrile–aqueous phosphoric acid at a flow rate of 0.9 mL min−1. The complete separation was achieved within 35 min for the six target constituents. A good linear regression relationship
between peak-areas and concentrations was obtained over the range of 12.10–242.0 μg*mL−1 for baicalin, 5.05–101.0 μg*mL−1 for baicalein, 0.95–19.0 μg*mL−1 for wogonin, 2.75–55.0 μg*mL−1 for oxysophocarpin, 2.75–55.0 μg*mL−1 for oxymatrine and 4.90–98.0 μg*mL−1 for matrine, respectively. The repeatability was evaluated by intra- and inter-day assays with relative standard deviation
(RSD) being less than 5.1%. The recoveries, measured at three concentration levels, varied from 93.8 to 102.1%. The assay
was successfully applied for determination of six bioactive compounds in Sanwu-Huangqin-Tang. The interaction of chemical
constituents was observed when the herbs were used in compatibility. The results indicated that the developed assay method
was rapid, accurate and could be readily utilized as a quality control method for Sanwu-Huangqin-Tang. 相似文献
11.
R. Rahnama Kozani Y. Assadi F. Shemirani M. R. Milani Hosseini M. R. Jamali 《Chromatographia》2007,66(1-2):81-86
Dispersive liquid–liquid microextraction (DLLME) has been used for preconcentration of trihalomethanes (THMs) in drinking
water. In DLLME an appropriate mixture of an extraction solvent (20.0 μL carbon disulfide) and a disperser solvent (0.50 mL
acetone) was used to form a cloudy solution from a 5.00-mL aqueous sample containing the analytes. After phase separation
by centrifugation the enriched analytes in the settled phase (6.5 ± 0.3 μL) were determined by gas chromatography with electron-capture
detection (GC–ECD). Different experimental conditions, for example type and volume of extraction solvent, type and volume
of disperser solvent, extraction time, and use of salt, were investigated. After optimization of the conditions the enrichment
factor ranged from 116 to 355 and the limit of detection from 0.005 to 0.040 μg L−1. The linear range was 0.01–50 μg L−1 (more than three orders of magnitude). Relative standard deviations (RSDs) for 2.00 μg L−1 THMs in water, with internal standard, were in the range 1.3–5.9% (n = 5); without internal standard they were in the range 3.7–8.6% (n = 5). The method was successfully used for extraction and determination of THMs in drinking water. The results showed that
total concentrations of THMs in drinking water from two areas of Tehran, Iran, were approximately 10.9 and 14.1 μg L−1. Relative recoveries from samples of drinking water spiked at levels of 2.00 and 5.00 μg L−1 were 95.0–107.8 and 92.2–100.9%, respectively. Comparison of this method with other methods indicates DLLME is a very simple
and rapid (less than 2 min) method which requires a small volume of sample (5 mL). 相似文献
12.
Summary A clean method without use of organic solvents has been developed for isolation and high-performance liquid chromatographic
(HPLC) determination of oxytetracycline (OTC) and sulphadimidine (SDD) in cow's milk. Isolation is rapid and simple—homogenization
with an inorganic acid solution by means of a handy ultrasonic homogenizer, which is easy-to-use and portable, followed by
centrifugation. Reversed-phase HPLC was performed on a C4 column, with 1.25 mmol L−1 succinic acid solution as mobile phase, and identification was by means of a photodiode-array detector. Separation of the
analytes was achieved in less than 8 min. Significant linearity was established over the concentration range of 0.1–1.0 μg
mL−1 for both target compounds (r>0.99,P<0.01). Average recoveries of OTC and SDD (each spiked at 0.1–1.0 μg mL−1) were ≥88.8, and inter- and intra-assay variability was ≤2.8%. The total time required for analysis of one sample was <20
min. The limits of quantitation of the method (μg mL−1 in milk) were 0.044 for OTC and 0.023 for SDD. No organic solvent was used at any stage of the analysis. 相似文献
13.
Amereih S Meisel T Kahr E Wegscheider W 《Analytical and bioanalytical chemistry》2005,383(7-8):1052-1059
Speciation analysis of Sb(III) and Sb(V) in a soil sample was performed through extraction and on-line isotope dilution concentration
determination after a chromatographic separation. The total Sb concentration found in a through traffic contaminated soil
sample was (4.17 μg g−1, 0.3 μg g−1 SD, n=6). It was determined using ICP-MS after soil digestion using the sodium peroxide sintering method. The optimized extraction
procedure for speciation analysis was carried out using 100 mmol L−1 citric acid at pH 2.08 by applying an ultrasonic bath for 45 min at room temperature. The effects of citric acid concentration
(0–500 mmol L−1), pH (1–6), and temperature (30–60°C) on inorganic antimony species distribution in the examined sample were studied and
optimized. The separation of Sb(III) and Sb(V) was achieved using an anion exchange column (PRP-X100) and 10 mmol L−1 EDTA and 1 mmol L−1 phthalic acid at pH 4.5 as a mobile phase. The eluent from the HPLC was mixed with an enriched (94.2%) 123Sb spike solution that was pumped by a peristaltic pump with a constant flow rate (0.5 mL min−1) in a three-way valve. The blend passed directly to the Conikal nebulizer of the ICP-MS. By using the above extraction procedure
and methodology, 43.2% Sb(V) (2.9% RSD, n=3) and 6.0% Sb(III) (1.3% RSD, n=3) of total Sb found in the sample could be detected. The detection limits achieved by the proposed method were 20 ng L−1 and 65 ng L−1 for Sb(V) and Sb(III), respectively. The precision, evaluated by using RSD with 100 ng L−1 calibration solutions, was 2.7% and 3.2% (n=6) for Sb(V) and Sb(III), respectively, in aqueous solutions. 相似文献
14.
The profile distribution of arsenic(III) and arsenic(V) species in soil and groundwater was investigated in the samples collected
in 2005 from a hand-drilled well, in the Bozanta area, Baia Mare region, Romania. The total content of arsenic in the soil
was in the range of 525–672 mg kg−1 exceeding 21–27 times the action trigger level for sensitive soil. 0.9–11.3 % of the total content was soluble in water,
83.0–92.6 % in 10 mol dm−3 HCl and 2.6–13.3 % was the residual fraction. Arsenic(V) was the dominant arsenic species in the soil in the range of 405–580
mg kg−1. The distribution and mobility of arsenic species was governed by soil pH and contents of Al, Fe, and Mn. The mobility of
arsenic(V) decreased with depth, while that of arsenic(III) was high at the surface and in the proximity of groundwater. The
total concentration of arsenic in groundwater was (43.40 ± 1.70) μg dm−3, which exceeded the maximum contaminant level of 10 μg dm−3.
Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May
2006. 相似文献
15.
Cantú MD Toso DR Lacerda CA Lanças FM Carrilho E Queiroz ME 《Analytical and bioanalytical chemistry》2006,386(2):256-263
Simple, sensitive, and reproducible off-line solid-phase microextraction and liquid chromatography (SPME/LC) methods are described
for the determination of seven anticonvulsants and tricyclic antidepressants in human plasma. Factorial design and simplex
methodology were applied in the optimization of the SPME procedure for tricyclic antidepressants analyses. Important factors
in the SPME efficiency are discussed, such as the fiber coatings (both lab-made and commercial), extraction time, pH, ionic
strength, influence of plasma proteins, and desorption conditions. The development of the lab-made fiber coatings, namely,
octadecylsilane, aminosilane, and polyurethane, are further described and applied to anticonvulsants analyses. The investigated
plasmatic range for the evaluated anticonvulsants, using CW-TPR fiber, were the following: phenylethylmalonamide (3.00–40.0 μg
mL−1), phenobarbital (5.00–40.0 μg mL−1), primidone (3.00–40.0 μg mL−1), carbamazepine and carbamazepine-epoxide (2.00–24.0 μg mL−1), phenytoin (2.00–40.0 μg mL−1), and lamotrigine (0.50–12.0 μg mL−1). The antidepressants’ linear plasmatic concentration ranged from 75.0 to 500 ng mL−1 for imipramine, amitriptyline, and desipramine, and from 50.0 to 500 ng mL−1 for nortriptyline, being in all cases, the limit of quantification represented by the lowest value. The precision (interassays)
for all investigated drugs in plasma sample spiked with different concentrations of each analyte and submitted to the described
procedures were lower than 15%. The off-line SPME/LC methodologies developed allow anticonvulsants and antidepressants analyses
from therapeutic to toxic levels for therapeutic drug monitoring. 相似文献
16.
A simple, rapid and reproducible HPLC method was developed and validated for the simultaneous determination of olmesartan
(OLM) medoxomil and hydrochlorothiazide (HCT) in combined tablets. Chromatography was carried out on a 4.6 mm I.D × 200 mm,
5 μm cyano column with methanol–10 mM phosphoric acid containing 0.1% triethylamine (pH 2.5, 50:50 v/v) at a flow rate of 1.0 mL min−1 and UV detector was set at 260 nm. Valsartan (VAL) was used as internal standard (IS). A linear response was observed in the
range of 0.2–6 μg mL−1 (r
2 = 0.9998) for OLM and 0.1–4 μg mL−1 (r
2 = 0.9999) for HCT, respectively. The method showed good recoveries (99.56% for OLM and 99.48% for HCT) and the relative standard
deviation (RSD) values for intra- and inter-day precision were 0.70–1.59 and 0.80–2.00% for OLM and 1.20–1.37 and 1.63–1.93%
for HCT, respectively. The developed method was applied successfully for quality control assay of OLM and HCT in combined
tablets and in vitro dissolution studies. 相似文献
17.
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
18.
Lué-Merú Marcó Parra 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):479-484
The onion (Allium cepa L.) is one of the most important cultivars in the world and its production level occupies the second place in Venezuela.
It becomes important to develop analytical procedures for arsenic determination and to study the effect of this element on
the cultures, as well the absorption, transport and translocation processes. A TXRF method for As determination in onions
was developed. Two treatments were applied to the onion plants, As contaminated and control. The contaminant was added to
the plants to an amount of 100 μg, in a single time 3 weeks after the transplant of plantlets. The green leaves bulbs, and
roots together with the stems were separated 45 days after transplant and analyzed by TXRF and HG-AAS for total Arsenic determination.
A good agreement was found between these two techniques, demonstrating the accuracy of the TXRF procedure. It was found that
the highest concentration corresponded to the root and stems (37 ± 31 μg g−1), followed by the bulbs (11 ± 7 μg g−1), being the smallest level found in the green leaves (4 ± 3 μg g−1). At low As contamination levels of 0.25 μg g−1, a risk for translocation of the toxic element to the edible parts of the onion plants exists. At this level the normal development
of the plant is not affected, being the only exception the root length, which is significantly higher in the contaminated
treatment. 相似文献
19.
A rapid and simple procedure for the determination of antioxidants and preservatives in cosmetics has been developed utilizing
solid-phase microextraction combined with GC–MS. A silica fiber coated with polyacrylate provided the highest extraction efficiency.
Detection limits in the range from 0.4 to 8.5 ng mL−1 were obtained. Linearity is over a wide range from 1 to 2,000 ng mL−1 with a relative standard deviation under 16%. Cosmetic from a local supermarket were analysed for antioxidants and preservatives
to demonstrate the effectiveness of the proposed method. The concentration of antioxidants and preservatives determined was
20–1,218 μg g−1 for methylparaben and 5–3,779 μg g−1 for propylparaben. 相似文献
20.
A highly sensitive high-performance liquid chromatographic method with fluorescence detection has been developed for determination
of vitamin B1. Vitamin B1 was converted into a fluorescent compound by treatment with hydrogen peroxide–horseradish peroxidase and the derivative was
subsequently analyzed by HPLC on a Waters Spherisorb ODS2 column (250 mm×4.6 mm ID, 5 μm) with 40:60 methanol–pH 8.5 acetate
buffer solution as mobile phase and fluorescence detection at 440 nm (with excitation at 375 nm). The calibration graph was
linear from 5.00×10−10 mol L−1 to 5.00×10−7 mol L−1 for vitamin B1 with a correlation coefficient of 0.9991 (n=9). The detection limit was 1.0×10−10 mol L−1. The method was successfully used for determination of vitamin B1 at pg mL−1 levels in microalgal fermentation media and seawater after solid-phase extraction. Recovery was from 89 to 110% and the relative
standard deviation was in the range 1.1 to 4.3%. 相似文献