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1.
A very fast chromatographic separation of isoflavonoids genistein, daidzein, formononetin and biochanin A was developed on a C18 high-speed column under isocratic conditions. The method was validated in terms of detection limits, quantitation limits (LOQs), linearity and precision. LOQs in 0.04-0.2 microg/g range were calculated, making feasible the determination of these compounds of nutritional concern at trace levels. Good linearity was demonstrated over three concentration orders of magnitude for each analyte (r2 0.990-1.000). The intra-day and inter-day repeatability was evaluated in terms of relative standard deviation (RSD%) at two concentration levels for each analyte (RSD% <9%). An optimization strategy was adopted to find the best conditions for the extraction of isoflavonoid aglycones from yellow soybeans using microwave-assisted extraction. The most relevant parameters resulted to be the microwave power, the extraction time and the acid concentration, optimal values being 600 W, 1 min and 12 M, respectively. When performing sample treatment on a fortified soybean sample, high recovery percentage was obtained for both compounds (94+/-8% for daidzein and 97+/-5% (n = 4) for genistein). The concentration level at which daidzein and genistein were found in the soybean sample were 1.21+/-0.15 mg/g and 2.38+/-0.09 mg/g (n=4), respectively. 相似文献
2.
Graziele P. Ramos Paula M. B. Dias Cláudia B. Morais Pedro E. Fröehlich Miguel Dall’Agnol José A. S. Zuanazzi 《Chromatographia》2008,67(1-2):125-129
Red clover (Trifolium pratense L.) is an important forage plant that contains the isoflavones daidzein, genistein, formononetin, and biochanin A. These
compounds have been studied lately due to their human health benefits. The aim of this study was to develop and validate an
HPLC method with simplified sample preparation to quantify daidzein, genistein, formononetin and biochanin A simultaneously
in red clover leaves. The validation showed that the method is specific, accurate, precise and robust, not to mention that
the sample preparation is easier and faster than those described earlier. The response was linear over a range of 0.01–0.2 μg mL−1 for daidzein, 0.05–0.5 μg mL−1 for genistein, 4–40 μg mL−1 for formononetin and 2–20 μg mL−1 for biochanin A. The range of recoveries was 85.6–101.0%. The RSD for intra- and inter-day precision were <2.54 and <7.22%,
respectively. Five populations of red clover, from the National Plant Germplasm System-USDA were analyzed and the content
of daidzein, genistein, formononetin and biochanin A ranged from 7.87–91.31, 51.60–131.30, 6568.33–23461.82, to 2499.55–10337.33 μg g−1 of dried material, respectively. 相似文献
3.
A rapid, ultra high-performance liquid chromatographic (UHPLC) method has been developed and validated for simultaneous identification
and analysis of the isoflavones genistein, daidzein, glycitin, puerarin, and biochanin A, and the flavonoids (±)-catechin,
(−)-epicatechin, rutin, hesperidin, neohesperidin, quercitrin, and hesperetin in human urine. Urine samples were incubated
with β-glucuronidase/sulfatase. UHPLC was performed with a Hypersil Gold (50 × 2.1 mm, 1.9 μm) analytical column. Elution
was with a gradient prepared from aqueous trifluoroacetic acid (0.05%) and acetonitrile. UV detection was performed at 254
and 280 nm. The calibration curves were indicative of good linearity (r
2 ≥ 0.9992) in the range of interest for each analyte. LODs ranged between 15.4 and 107.0 ng mL−1 and 3.9 and 20.4 ng mL−1 for flavonoids and isoflavones, respectively. Intra-day and inter-day precision (C.V., %) was less than 3.9% and 3.8%, respectively,
and accuracy was between 0.03% and 5.0%. Recovery was 70.35–96.58%. The method is very rapid, simple, and reliable, and suitable
for pharmacokinetic analysis. It can be routinely used for simultaneous determination of these five isoflavones and seven
flavonoids in human urine. The method can also be applied to studies after administration of pharmaceutical preparations containing
isoflavones and flavonoids to humans. 相似文献
4.
We present here a high-performance liquid chromatography−tandem mass spectrometry (LC-MS/MS) method for quantifying phytoestrogenic
isoflavones (daidzein, equol, genistein, and O-desmethylangolensin) and lignans (enterodiol and enterolactone) in urine without the use of extraction or the preconcentration
techniques inherent in existing methods. The development of this concept was made possible by use of atmospheric pressure
photoionization (APPI); an ionization technique that we found to improve analyte sensitivity relative to electrospray ionization
and atmospheric pressure chemical ionization for this particular group of compounds. The analytical performance of this method
was equal to or exceeded that of comparable methods. Between-run coefficients of variation (CVs) across three quality control
(QC) pool levels analyzed in duplicate over 20 days were 3.1–5.8% CV; within-run CVs were 2.3–6.0%. Accuracy, as determined
by average spike recovery in QC pools, was generally within ±10% of being quantitative (100%). Relative limits of detection
were 0.04–0.4 ng/mL urine, with absolute detection limits as low as 0.1 pg. This method was applied to the analysis of >2,500
urine specimens for the 2005–2006 Centers for Disease Control and Prevention’s National Health and Nutrition Examination Survey
(NHANES). The method was capable of quantifying these compounds in 95–100% of study samples. This work is the first ever report
of using APPI for the LC-MS/MS determination of these compounds in urine. It is also the first method of its kind to do so
without any need for analyte extraction or preconcentration prior to analysis. 相似文献
5.
Summary A rapid and simple liquid-chromatographic method has been developed for on-line quantification of amphetamine in biological
fluids. Untreated samples (20 μL) are injected directly into the chromatographic system and purified on a 20 mm×2.1 mm i.d.
pre-column packed with 30 μm Hypersil C18 stationary phase. After clean-up the analyte is transferred to the analytical column (125 mm×4 mm i.d., 5 μm LiChrospher
100 RP18) for derivatization and separation using a mixture of acetonitrile and the derivatization reagent (o-phthaldialdehyde andN-acetyl-L-cysteine) as the mobile phase. The experimental conditions for on-line derivatization and resolution of the amphetamine
have been optimized, and the results have been compared with those obtained by derivatizing the analyte in pre-column mode.
The method described has been applied to the determination of amphetamine in plasma and urine. Good linearity and reproducibility
were obtained in the 0.1–10.0 μg mL−1 concentration range, and limits of detection were 25 ng mL−1 and 10 ng mL−1 with UV and fluorescence detection, respectively. The procedure described is very simple and rapid, because no off-line manipulation
of the sample is required; the total analysis time is approximately 8 min. 相似文献
6.
The feasibility of circulating cooling-solid phase microextraction (CC-SPME) combined with gas chromatography-nitrogen phosphorous
detector (GC-NPD) for the determination of five organophosphorous pesticides (OPPs) in tomato samples is evaluated. By heating
the sample while cooling the fiber coating, the developed method provides better performance in terms of sensitivity, linearity
and recovery than that of traditional headspace-solid phase microextraction (HS-SPME). The extraction capacities of activated
carbon fiber (ACF) and three commercially available fibers were compared. ACF is found to be the most suitable fiber for the
analysis of OPPs in tomatoes. The main factors affecting the CC-SPME process such as adsorption time, adsorption temperature
and ionic strength were investigated and optimized. The matrix effect was evaluated, and concluded that addition of water
is required to reduce the matrix effect. Good linearity (R
2 > 0.992) is observed in the 1–200 ng g−1 concentration range with satisfactory RSD (%) values of 5.6–8.5%. The limits of detection obtained using the proposed method
range from 0.2 to 0.5 ng g−1, and the recoveries for CC-SPME are in the range of 82.5–90.0% with RSDs lower than 8.7%. Experimental results confirm the
usefulness of the proposed method for the analysis of OPPs in tomato samples. 相似文献
7.
Summary A method has been developed for separation and quantitation of midecamycin A1 and related impurities by high-performance liquid chromatography with evaporative light-scattering detection (ELSD). Chromatographic
conditions included use of a Diamonsil C18 column; the mobile phase was 52:48 acetonitrile −0.2 mol L−1 ammonium formate solution (adjusted to pH 7.3 with triethylamine) at a flow rate of 1 mL min−1. The column temperature was 35°C, the shift tube temperature of the ELSD was 105°C, and the gas flow rate of the ELSD was
3.0 L min−1. The response factors of midecamycins in HPLC-ELSD were the same; the linear equation wasy=599292.44x+2868618.04,r=0.9979, the linear range was 5–80 μg,RSD=0.21–1.54%, and theLOD andLOQ were 0.36 and 1.2 μg, respectively. The method was simple, quick, and precise and could be used to determine midecamycin
and its related impurities directly. 相似文献
8.
A novel HPLC method has been developed and validated for the determination of Raloxifene in rat plasma. Samples were prepared
based on a simple protein precipitation. Separation of Raloxifene in plasma was performed on a C18 column, with a mobile phase
of acetonitrile–ammonium acetate. Good linearity was demonstrated in the range of 0.2–75.0 μg mL−1 (r = 0.9931). The method was used to measure the concentration and pharmacokinetics of Raloxifene in rat plasma after a single
oral dose, and a linear pharmacokinetic profile of Raloxifene was found. 相似文献
9.
A high performance liquid chromatographic method was developed and validated for the quantitative determination of carbamazepine
in intravenous nanoemulsions. The method validation yielded good results with respect to linearity, specificity, precision
and accuracy. The method was carried out on a RP-18 column with a mobile phase composed of methanol–water (70:30 v/v) subjected to a gradient of acetonitrile after drug elution, and detection at 286 nm. The linearity in the range of 10.0–50.0 μg mL−1 presented a determination coefficient (r
2) of 0.9996, calculated by least-squares regression; the RSD values for intra-day and inter-day precision for % recovered
were <0.44 and <1.21%, respectively; and the recovery of carbamazepine from the sample matrix ranged from 94.3 to 104.9%. 相似文献
10.
A method was described for simultaneous determination of nine organic heterocyclic pesticide residues by gas chromatography-mass
spectrometry-selected ion monitoring. Atrazine, vinclozolin, procymidone, triflumizole, imazalil, buprofezin, propiconazole,
fenarimol, and pyridaben were clearly separated from each other, extracted with acetone—hexane mixture, purified with graphitized
carbon black cartridge and neutral Al2O3 cartridge, eluted with acetone—hexane mixture, simultaneously determined by GC-MS, and then quantified with an external standard
method. Recoveries of pesticides ranged from 73 % to 116 % at the spiked level of 0.01–30 mg kg−1, while the relative standard deviation was between 3 % and 27 %. In addition, the limits of determination (0.01 mg kg−1 to 5.0 mg kg−1) and linearity (0.02–40 μg mL−1) revealed that simultaneous determination of multi-residues in Chinese teas (like Oolong tea, green tea, red tea, etc.) was possible. Furthermore, an interlaboratory study among 5 labs was conducted to further validate the method, and the results
were satisfactory. 相似文献
11.
A reverse phase HPLC method was developed and validated for the simultaneous determination of 2-hydroxy-4-methoxybenzaldehyde
and 2-hydroxy-4-methoxybenzoic acid in the root extracts of Hemidesmus indicus. A comprehensive validation of the method including sensitivity, linearity, reproducibility, accuracy, limit of detection
(LOD) and limit of quantification (LOQ) was conducted using the optimized chromatographic conditions. The method was found
to be linear (r > 0.998) in the range of 5–350 μg mL−1 for 2-hydroxy-4-methoxybenzaldehyde and for 2-hydroxy-4-methoxybenzoic acid (r > 0.999) in the range 10–300 μg mL−1. The method was found to be precise with inter-day precision values (% RSD) in the ranges of 0.61–1.76% for 2-hydroxy-4-methoxybenzaldehyde
and 1.3–2.8% for 2-hydroxy-4-ethoxybenzoic acid while intra-day precisions (% RSD) of two analytes were in the range of 0.41–1.07
and 0.95–2.5%. The limits of detection (LODs) for 2-hydroxy-4-methoxybenzaldehyde and 2-hydroxy-4-methoxybenzoic acid were
0.84 and 2.34 μg mL−1. The described method was fast, sensitive and reproducible, and thus well suited for routine analysis of these two compounds
from root extracts of H. indicus and other plants. 相似文献
12.
Summary A chiral capillary electrochromatographic (CEC) method for determination of the enantiomeric purity of either enantiomer of
metoprolol has been validated. High resolution and efficiency separations (R
s
=2.5 and 80000 plates m−1, respectively) were achieved by use of a teicoplanin chiral stationary phase in the polar organic mode. Method validation
showed that detection linearity, robustness, accuracy, and repeatability were adequate. The method was also shown to be sufficiently
sensitive for the determination of a minor enantiomer; the limit of quantitation (LOQ) was determined to be 0.09% of the peak area of the enantiomer under investigation. A similar commercial column was subsequently
evaluated by use of the validated method and found to yield results for metoprolol comparable with those obtained on the homepacked
columns. Acceptable separations on this commercial column were also obtained for other β-blocking drugs; those for alprenolol
were particularly noteworthy (R
S
=3.8 and 265000 plates m−1). 相似文献
13.
Summary Capillary electrophoresis has been used to separate inorganic (Hg2+) and organic (methyl-, ethyl-, and phenylmercury) mercury compounds as their cysteine complexes. The optimized electrophoretic
separation was performed in fused-silica capillary tubing at 25 kV with 25mm sodium borate buffer (pH 9.3). Identification and quantification of the mercury species at mg L−1 levels was achieved by use of UV detection at 200 nm. The relative standard deviation (n=10) ranged from 0.38 to 0.51% for migration times and from 0.43 to 2.94% for corrected peak areas. Good recovery (>90%) was
obtained for all four mercury species in surface waters, and for inorganic mercury and methylmercury in five- to tenfold diluted
biofluids (urine, saliva, and cerebrospinal fluid). TheLOQ values obtained were too high to be useful for determination of mercury species in real samples.
Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001 相似文献
14.
Summary Solid-phase extraction (SPE) was coupled at-line to capillary electrophoresis (CE) for the determination of a series of basic
test compounds (i. e. tricyclic antidepressants). The analysis was performed using a non-aqueous CE buffer, which resulted
in baseline separation of all test compounds. This is in marked contrast with CE using aqueous buffers where hardly any separation
was obtained either with or without micelles. The SPE procedure was used to remove simultaneously most of the water from the
sample, because no direct analysis of aqueous samples is possible when a non-aqueous CE buffer is used. With the present method
the antidepressants can be determined in both urine and serum. Analyte detectability is increased up to 10-fold due to trace
enrichment during the extraction process; the limits of detection (LODs; UV 214 nm) are 30–300 ng mL−1 in urine and 300–1000 ng mL−1 in serum. TheRSD values (n=5) of the within-day and between-day precision are below 9% and 11% respectively. Therefore, the present procedure can be
used for drug monitoring. 相似文献
15.
Conde FJ Afonso AM González V Ayala JH 《Analytical and bioanalytical chemistry》2006,385(7):1162-1171
A sampling and analysis method for the determination of 21 phenolic compounds in smoke samples from biomass combustion has
been developed. The smoke is used to make smoked foods, following an artisanal procedure used in some parts of the Canary
Islands. The sampling system consists of a Bravo H air sampler, two impingers, each one containing an aqueous solution of
sodium hydroxide 0.1 mol L−1, followed by a silica gel trap. The variables optimized to reach the best sampling conditions were volume of absorbent solution
and sampling flow. Under the optimum conditions, 100 mL of absorbent solution of NaOH 0.10 mol L−1 and 2 L min−1 for the sampling flow, sampling efficiencies are higher than 80%. Analysis of phenolic compounds was carried out by headspace
solid-phase microextraction (HS-SPME) coupled to gas chromatography–mass spectrometry (GC-MS). Five different fiber coatings
were employed in this study. By means of a central composite design, extraction time, salt concentration, and pH of the solution
were optimized: 65-μm carbowax–divinylbenzene, extraction time 90 min, concentration in NaCl of 35% (m/v), and pH 2 yielded
the highest response. Detection limits of phenol and their alkyl derivatives, guaiacol and eugenol, are between 1.13 and 4.60 ng mL−1. 3-Methoxyphenol, 2,6-dimethoxyphenol, and vanillin have detection limits considerably higher. Good linearity (R
2≥0.98) was observed for all calibration curves in the established ranges. The reproducibility of the method (RSD, relative
standard deviation) was found to oscillate between 7 and 18% (generally close or lower than 10%). 相似文献
16.
Zhao RS Diao CP Wang X Jiang T Yuan JP 《Analytical and bioanalytical chemistry》2008,391(8):2915-2921
This paper describes a novel, simple and environmentally friendly method for rapid determination of the amide herbicides metoalchlor,
acetochlor, and butachlor. It is based on dispersive liquid-liquid microextraction and gas chromatography–mass spectrometry.
Factors that may influence the enrichment efficiency, such as type and volume of extraction solvent, type and volume of dispersive
solvent, extraction time, and content of NaCl, were investigated and optimized in detail. Under the optimum conditions, the
limits of detection of metoalchlor, acetochlor, and butachlor were 0.02, 0.04, and 0.003 μg L−1, respectively. The experimental results indicated that there was linearity over the range 0.1–50 μg L−1 and good reproducibility with relative standard deviations over the range 1.6–3.0% (n = 5). The proposed method has been applied for the analysis of real-world water samples, and satisfactory results were achieved.
Average recoveries of spiked herbicides were in the range 80.3–108.8%. All of these indicated that the developed method would
be an efficient method for simultaneous determination of the three herbicides in environmental water samples. 相似文献
17.
Lozano A Martínez-Uroz MA Gómez-Ramos MJ Gómez-Ramos MM Mezcua M Fernández-Alba AR 《Analytical and bioanalytical chemistry》2012,402(2):935-943
Due to the basic properties of nicotine, it is not easily integrated into commonly used multiresidue methods. The present
work investigates the application of two commonly employed multiresidue methods—the QuEChERS method and the ethyl acetate
method—for determining nicotine in mushrooms. Both methods are employed in a modified form and an unmodified form: the former
to address the special properties of nicotine and the latter, combined with the use of isotopically labelled nicotine, to
compensate for poor recoveries. The QuEChERS-based methods were followed by liquid chromatography–time-of-flight mass spectrometry
and those based on ethyl acetate extraction were followed by gas chromatography–triple quadrupole-mass spectrometry. All methods
were validated according to European guidelines (document no. SANCO/10684/2009). Recovery studies performed on mushroom spiked
at 10 and 100 μg kg−1 yielded average recoveries in the range 80–110% with relative standard deviation (RSD) values below 9%. The linearity of
the response over two orders of magnitude was demonstrated (r
2 > 0.995) for all of the determination techniques employed. The limits of detection and quantification obtained were in the
0.7 and 10 μg kg−1 range, depending on the technique, and thus below the maximum residue level established for this toxic alkaloid by current
EU legislation. Good repeatability and reproducibility were obtained in terms of the RSD of the analytical methods (0.4–13.2%).
The modified QuEChERS method was tested in a proficiency test on nicotine in dried mushrooms obtaining good results. The methods
were successfully applied to 20 real samples. 相似文献
18.
Medina CM Pitarch E López FJ Vázquez C Hernández F 《Analytical and bioanalytical chemistry》2008,390(5):1343-1354
The potential of gas chromatography/tandem mass spectrometry with a triple quadrupole analyzer for determination of 12 polybrominated
diphenyl ethers in human breast tissues has been investigated. After extraction with hexane, two purification procedures-automated
normal-phase high-performance liquid chromatography and solid-phase extraction-were assayed. Both electron impact ionization,
in selected reaction monitoring mode, and negative chemical ionization, in selected ion recording mode, were tested for the
optimum determination of analytes. Isotopically labeled standards were added before extraction as surrogates: [13C]BDE47, [13C]BDE99 and [13C]BDE153 for electron impact ionization, and p,p′-DDE-d
8 for negative chemical ionization. The method was validated in terms of accuracy, precision, limits of detection and limits
of quantification, using human breast tissue spiked at three levels in the range 1–50 ng/g (5–250 ng/g for BDE209). The analytical
approach using solid-phase extraction cleanup followed by gas chromatography/mass spectrometry (negative chemical ionization
) led to lower detection limits (0.006–2 ng/g) and allowed the determination of the most problematic congener, BDE209, whose
poor sensitivity made difficult its determination at low residue levels. Special attention was given to the confirmation of
the compounds detected in samples in order to avoid reporting false positives. Two tandem mass spectrometry transitions or
three m/z ions were selected for each analyte when using electron impact ionization or negative chemical ionization modes, respectively.
In both cases, the transition to ion intensity ratio was used as a confirmation parameter. The method developed was applied
to the analysis of real human samples. Several brominated diphenyl ethers (congeners 47, 100, 99, 154, 153, 183 and 209) were
detected in the range 0.08–0.23 ng/g. 相似文献
19.
《Journal of separation science》2018,41(16):3250-3257
A valine carbamate prodrug of daidzein was synthesized to improve its bioavailability because of the poor solubility and low permeability of daidzein. To evaluate the pharmacokinetic behavior of the prodrug, a sensitive and high‐throughput method was developed and validated for the simultaneous determination of daidzein and its prodrug in rat plasma. The samples were extracted by ethyl acetate and then analyzed by a supercritical fluid chromatography with electrospray ionization tandem mass spectrometry method. The separation was achieved by an ACQUITY UPC2™ BEH 2‐EP column maintained at 40°C using carbon dioxide (≥99.99%) and methanol within 3.0 min by gradient elution. The mass transition ion pairs were m/z 254.8→136.7, 398.0→254.9, and 271.0→91.07 for daidzein, the prodrug, and genistein, respectively. The calibration curves were linear over the concentration ranges of 2–500 (r > 0.997) and 10.0–5000.0 ng/mL (r > 0.996) with lower limits of quantification of 2 and 10 ng/mL for daidzein and the prodrug, respectively. The intra‐ and interday accuracy and precision were within ±15% for all quality control samples. This developed method enabled high specificity, low cost, low solvent consumption, and a brief analysis time and was successfully applied to a bioavailability evaluation of daidzein and its carbamate prodrug. 相似文献
20.
Summary A simple and rapid capillary zone electrophoretic method with UV detection has been developed for determination of tosufloxacin
and trovafloxacin. The separation was performed in fused-silica capillaries (57 cm length × 75μm i.d.); the running buffer
was 35mm borate + 35mm phosphate buffer solution, pH 8.6, containing 6% (v/v) acetonitrile. The applied potential was 15 kV, the temperature 30°C, and detection was at 262 nm. Piromidic acid was used
as the internal standard. Response was linearly dependent on concentration in the range 1.0–120.0 μg mL−1 and the detection limit was 0.2 μg mL−1 for both compounds. The analysis was highly reproducible (RSD between 3.41 and 1.25%). The method was applied to the determination of tosufloxacin and trovafloxacin in human and rat urine.
The method was validated by using HPLC as a reference method. Recovery was between 96.8 and 102%. 相似文献