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1.
Huang KJ Zhang M Xie WZ Zhang HS Feng YQ Wang H 《Analytical and bioanalytical chemistry》2007,388(4):939-946
A simple, sensitive, selective, and low-cost method is proposed for rapidly determining nitric oxide (NO) in some rat tissues.
Polymer monolith microextraction (PMME) using a poly(methacrylic acid–ethylene glycol dimethacrylate) (MAA-EGDMA) monolithic
column was combined with derivatization of NO using 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacene (TMDABODIPY), and this was used to analyze the derivatives of NO by high-performance liquid chromatography (HPLC)
with fluorescence detection at λ
ex/λ
em = 498/507 nm. The baseline separation of TMDABODIPY and its NO derivative is performed under simple conditions in which a
C18 column is used and eluted with 50 mmol L−1 ethanolamine and methanol. The conditions for the extraction of NO derivatives were optimized. The limit of detection of
NO was 2 × 10−12 mol L−1 (S/N = 3). The linearity range of the method was 9 × 10−11−4.5 × 10−8 mol L−1. The interday and intraday relative standard deviations were less than 5%. The proposed method was successfully applied to
the determination of NO levels in some rat tissue samples including heart, kidney, and liver with recoveries varying from
87.1 to 95.2%. 相似文献
2.
Summary The indirect stereochemical resolution of the enantiomers of phenylalanine analogs was studied by high-performance liquid
chromatographic methods. The resolution was performed by applying pre-column derivatization with (S)-N-(4-nitrophenoxycarbonyl)phenylalanine methoxyethyl ester, (S)-NIFE, as a new chiral derivatizing agent. Its applicability is demonstrated by the derivatization and separation of a series
of ring-and α-methyl-substituted phenylalanines and phenylalanine amides, and especially by the derivatization of sterically
hindered, less reactive α-methyl-substituted phenylalanine analogs. The diastereomeric, derivatives produced were separated
by reversed-phase high-performance liquid, chromatography. The conditions of both derivatization and separation were optimized.
The method described offers good enantioselectivity for various chiral amino compounds derived from chemo-enzymatic processes. 相似文献
3.
Summary The reagentp-nitrobenzyloxycarbonyl chloride (PNZ-CI) was used for pre-column derivatization of biogenic amines (BAs) at ambient temperature
followed by reversed-phase, liquid-chromatographic separation of the derivatives. Optimized derivatization of samples was
achieved within 10 min in borate buffer by adding PNZ-Cl in acetonitrile (MeCN). Excess reagent was scavenged by subsequent
addition of glycine in water. For LC a Superspher? RP-18e column and gradient elution using a ternary gradient system containing sodium acetabe buffer (pH 6.1), sodium acetate
buffer (pH 4.3) and MeCN, were used. The PNZ-derivatives were quantified by their UV-absorption at 265 nm. Detection limits
of BAs were approximately 62–1000 μg L−1 (injected amounts: 53–850 pg) at a signal-to-noise ratio of 3:1. The coefficients of determination were 0.9906–0.9992. Diaminohexane
was used as internal standard. Recoveries of BAs ranged from 78–93% depending on the food matrix. This method was applied
to the quantitative determination of 2-phenylethylamine, tryptamine, serotonin, putrescine, histamine, cadaverine, tyramine,
spermidine, and spermine, in beer, wine, vinegars, and lactic fermented cabbage juice.
Parts of the results were presented at the 35th Congress of the “Deutsche Gesellschaft für Ern?hrung”, Kiel, 19th–20th March 1998, and the “Regionaltagung der Lebensmittelchemiker”, Giessen, 9th–10th March 1998 相似文献
4.
S. Tatar Ulu 《Chromatographia》2006,64(3-4):169-173
A new, simple, rapid and specific reversed-phase high-performance liquid chromatography (HPLC) method was developed and validated for the determination of fluvoxamine in pharmaceutical dosage forms. The HPLC separation was achieved on a C18 μ-Bondapack column (250 mm × 4.6 mm) using a mobile phase of acetonitrile–water (80:20, v/v) at a flow rate of 1 mL min−1. Proposed method is based on the derivatization of fluvoxamine with 1,2-naphthoquinone-4-sulphonic acid sodium salt (NQS) in borate buffer of pH 8.5 to yield a orange product. The HPLC method is based on measurement of the derivatized product using UV-visible absorbance detection at 450 nm. The method was validated for specificity, linearity, precision, accuracy, robustness. The degree of linearity of the calibration curves, the percent recoveries of fluvoxamine, the limit of detection and quantification, for the HPLC method were determined. The assay was linear over the concentration range of 45–145 ng mL−1 (r = 0.9999). Limit of detection and quantification for fluvoxamine were 15 and 50 ng mL−1, respectively. The results of the developed procedure (proposed method) for fluvoxamine content in tablets were compared with those by the official method. The method was found to be simple, specific, precise, accurate, reproducible and robust. 相似文献
5.
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
6.
Summary A simple method for quantitative determination of carbohydrates by reversed-phase, high-performance liquid chromatography
after pre-column derivatization and UV detection has been developed. Reducing sugars are condensed with 4-(3-methyl-5-oxo-2-pyrazolin-l-yl)
benzoic acid (PMPA) to yield UV adducts absorbing at 271 nm, which are resolved under typical reversed-phase conditions. After
derivatization, excess PMPA is easily removed from the reaction mixture by precipitation with mineral acids at pH<4. The influence
of experimental conditions on reaction yield, as well as chromatographic separation of derivatives, were investigated. The
quantitative performance was evaluated by means of a protocol comprising replicate measurements at several analyte levels.
The calibration curves obtained for 8 sugars showed excellent linearity over 10–5000 pmol. Limits of detection and quantification
for several monosaccharides were ca. 10 and 50 picomoles, respectively. Optimized conditions were successfully used for quantitative
determination of monosaccharides released after hydrolysis from fetuin, mucin, α1-acid glycoprotein, ovalbumin and transferrin. 相似文献
7.
You J Liu L Zhao W Zhao X Suo Y Wang H Li Y 《Analytical and bioanalytical chemistry》2007,387(8):2705-2718
A simple and sensitive method for evaluating the chemical compositions of protein amino acids, including cystine (Cys)2 and tryptophane (Try) has been developed, based on the use of a sensitive labeling reagent 2-(11H-benzo[α]-carbazol-11-yl) ethyl chloroformate (BCEC–Cl) along with fluorescence detection. The chromophore of the 1,2-benzo-3,4-dihydrocarbazole-ethyl
chloroformate (BCEOC-Cl) molecule was replaced with the 2-(11H-benzo[α]-carbazol-11-yl) ethyl functional group, yielding the sensitive fluorescence molecule BCEC–Cl. The new reagent BCEC–Cl
could then be substituted for labeling reagents commonly used in amino acid derivatization. The BCEC–amino acid derivatives
exhibited very high detection sensitivities, particularly in the cases of (Cys)2 and Try, which cannot be determined using traditional labeling reagents such as 9-fluorenyl methylchloroformate (FMOC-Cl)
and ortho-phthaldialdehyde (OPA). The fluorescence detection intensities for the BCEC derivatives were compared to those obtained when
using FMOC-Cl and BCEOC-Cl as labeling reagents. The ratios I
BCEC/I
BCEOC = 1.17–3.57, I
BCEC/I
FMOC = 1.13–8.21, and UVBCEC/UVBCEOC = 1.67–4.90 (where I is the fluorescence intensity and UV is the ultraviolet absorbance). Derivative separation was optimized on a Hypersil BDS
C18 column. The detection limits calculated from 1.0 pmol injections, at a signal-to-noise ratio of 3, ranged from 7.2 fmol for
Try to 8.4 fmol for (Cys)2. Excellent linear responses were observed, with coefficients of >0.9994. When coupled with high-performance liquid chromatography,
the method established here allowed the development of a highly sensitive and specific method for the quantitative analysis
of trace levels of amino acids including (Cys)2 and Try from bee-collected pollen (bee pollen) samples. 相似文献
8.
J. Auger F. Mellouki A. Vannereau J. Boscher L. Cosson N. Mandon 《Chromatographia》1993,36(1):347-350
Summary Two pre-column derivatization procedures coupled with reversed phase HPLC have been compared for the analysis ofS-Alk(en)yl0L-cysteine sulfoxides in variousAllium species. In order to establish external standards some (+/-) sulfoxides were synthesized, using a new method to enhance asymmetric synthesis of the diastereoisomers. The first derivatization method is the formation ofo-phthaldialdehyde/tert.-butylthiol derivatives which can be analyzed using UV detection. The second, presently used for amino acid analysis, is the Waters Pico-Tag method, which employs phenylisothiocyanate as derivatization reagent. As the Pico-Tag method was found to be the most efficient for determination ofS-alk(en)yl-L-cysteine sulfoxides it was used to determine the alliin content of various samples of garlic. 相似文献
9.
Summary 4:3-β-Naphthapyrone-4-acetic acidN-hydroxysuccinimidyl ester (NPA-OSu) is a highly sensitive and moderately reactive derivatizing reagent with a naphthapyrone
moiety as fluorophore and anN-hydroxysuccinimidyl active ester as reactive group toward amino compounds. It is readily prepared in two steps. The fluorescence
properties of NPA-OSu and its hydrolysis product have been studied in detail, and the conditions for derivatization and separation
of the NPA-OSu derivatives of some amino acids and oligopeptides have been investigated. Atλ
ex = 352 nm andλ
em = 422 nm the detection limits (signal-to-noise ratio=3) for amino acids and oligopeptides reached fmol levels, for injection
of 20 μL; this sensitivity was comparable with that obtained by use of 7-(diethylamino)coumarin-3-carboxylic acid succinimidyl
ester as derivatizing reagent in the analysis of amino acids by capillary electrophoresis with laser-induced-fluorescence
detection. 相似文献
10.
The conditions for the derivatization of hydrazine withp-dimethylaminobenzaldehyde and 4-chloro-5,7-dinitrobenzofurazan, extraction preconcentration of derivatives from natural water,
and HPLC determination of the toxicant with diode-array detection were studied. The 5,7-dinitrobenzofurazan derivative was
quantitatively extracted from water with isoamyl alcohol and a mixture of isoamyl alcohol with methylene chloride at pH 3–4.
A procedure was developed for the extraction-chromatographic determination of hydrazine in water with cmin = 0.05 Μg/L and the analytical range 0.12-60 Μg/L. The concentration of hydrazine in lake Kaban water was determined. 相似文献
11.
Godin JP Faure M Breuille D Hopfgartner G Fay LB 《Analytical and bioanalytical chemistry》2007,388(4):909-918
We describe a new method of assessing, in a single run, 13C isotopic enrichment of both Val and Thr by gas chromatography–combustion–isotope-ratio mass spectrometry (GC–C–IRMS). This
method characterised by a rapid one-step derivatisation procedure performed at room temperature to form the N(O,S)-ethoxycarbonyl ethyl ester derivatives, and a polar column for GC. The suitability of this method for Val and Thr in in-vivo
samples (mucosal hydrolysate) was demonstrated by studying protein metabolism with two tracers (13C-valine or 13C-threonine). The intra-day and inter-day repeatability were both assessed either with standards or with in-vivo samples at
natural abundance and at low 13C isotopic enrichment. For inter-day repeatability CVs were between 0.8 and 1.5% at natural abundance and lower than 5.5%
at 0.112 and 0.190 atom% enrichment for Val and Thr, respectively. Overall isotopic precision was studied for eleven standard
amino acid derivatives (those of Val, Ala, Leu, Iso, Gly, Pro, Asp, Thr, Ser, Met, and Phe) and was assessed at 0.32‰. The
13C isotopic measurement was then extended to the other amino acids (Ala, Val, Leu, Iso, Gly, Pro, Thr, and Phe) at natural
abundance for in-vivo samples. The isotopic precision was better than 0.002 atom% per amino acid (for n = 4 rats). This analytical method was finally applied to an animal study to measure Thr utilization in protein synthesis. 相似文献
12.
Nakamura S Wada M Crabtree BL Reeves PM Montgomery JH Byrd HJ Harada S Kuroda N Nakashima K 《Analytical and bioanalytical chemistry》2007,387(6):1983-1990
A sensitive semi-micro column HPLC method with peroxyoxalate chemiluminescence (POCL) detection and column switching has been
developed for simultaneous determination of 3,4-methylenedioxymethamphetamine (MDMA) and related compounds, for example 3,4-methylenedioxyamphetamine,
methamphetamine, and amphetamine, in hair. After digestion of the hair with 1 mol L−1 sodium hydroxide the compounds were extracted with n-heptane and derivatized with 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole. A mixture of hydrogen peroxide and bis(2,4,5-trichloro-6-carbopentoxyphenyl)oxalate
in acetonitrile was used as post-column CL reagent. Calibration plots showed linearity was good (r = 0.999); detection limits were 0.02–0.16 ng mg−1 hair at a signal-to-noise ratio of 3. The precision of the method, as RSD (n = 5), in intra-day and inter-day assays was better than 5.0 and 6.9%, respectively. The proposed method was sufficiently
sensitive to detect low ng mg−1 levels of MDMA and related compounds in hair, and could be used for quantification of the compounds in hair samples from
patients treated in a chemical dependency unit. 相似文献
13.
A microchip electrophoresis (MCE) method with LIF detection was presented for quantification of D ‐aspartic acid (D ‐Asp) and D ‐glutamate (D ‐Glu) in biological samples. D ‐Asp and D ‐Glu were determined after precolumn derivatization with FITC. The chiral separation was performed on a glass/PDMS hybrid microfluidic chip using γ‐CD as chiral selector in the running buffer. High sensitive detection was obtained by the LIF detection. The LODs (S/N = 3) for D ‐Asp and D ‐Glu were 6.0×10–8 and 4.0×10–8 M, respectively. Using this method, the levels of D ‐Asp and D ‐Glu in rat brain and human cerebrospinal fluid (CSF) were determined. 相似文献
14.
Summary The difect and indirect separation of enantiomers of secondary amino acids was studied by high-performance liquid chromatography.
Direct separation was by using a macrocyclic glycopeptide, teicoplanin or ristocetin A, as chiral stationary phase. Indirect
separation was via pre-column derivatization with (S)-N-(4-nitrophenoxycarbonyl)phenylalanine methoxyethyl ester [(S)-NIFE] as a new chiral derivatizing agent. Both direct and indirect separations were performed by means of reversed-phase
HPLC. Conditions for separations were optimized. The methods described offer good enantioselectivity for synthetic chiral
imino acids.
Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001 相似文献
15.
Jing Sun Guichen Chen Xianen Zhao Wenhua Xu Guoying Zhou Youji Han Jinmao You 《Chromatographia》2007,65(7-8):469-476
A simple and sensitive high-performance liquid chromatographic (HPLC) method with fluorescence detection and mass spectrometric
identification has been developed for analysis of 30 long-chain and short-chain free fatty acids (FFAs). The fatty acids were
derivatized to their esters with 1-[2-(p-toluenesulfonate)ethyl]-2-phenylimidazole-[4,5-f]-9,10-phenanthrene (TSPP) in N,N-dimethylformamide (DMF) at 90 °C with anhydrous K2CO3 as catalyst. A mixture of C1–C30 fatty acids was completely separated within 60 min by gradient elution on a reversed-phase C8 column. Qualitative identification of the acids was performed by atmospheric-pressure chemical ionization mass spectrometry
(APCI–MS) in positive-ion mode. The fluorescence excitation and emission wavelengths were 260 and 380 nm, respectively. Quantitative
determination of the 30 acids in two Tibetan medicines Gentiana straminea and G. dahurica was performed. The results indicated that the medicines contained many FFAs. Linear correlation coefficients for the FFA
derivatives were >0.9991. Relative standard deviations (RSDs, n = 6) for the fatty acid derivatives were <3%. Detection limits (at a signal-to-noise ratio of 3:1) were 3.1–38 fmol. When
the fatty acid derivatives were determined in the two real samples results were satisfactory and the sensitivity and reproducibility
of the method were good. 相似文献
16.
Yu. N. Belokon K. A. Kochetkov T. D. Churkina N. S. Ikonnikov A. A. Chesnokov O. V. Larionov H. V. Kagan 《Russian Chemical Bulletin》1999,48(5):917-923
It is shown that sodium alkoxides formed from (4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-bis(diphenylmethanol) ((R,R)-TADDOL) and some of its derivatives can be used as chiral catalysts for enantioselective alkylation of Schiff's bases derived
from alanine with reactive alkyl halides. Acid hydrolysis of the reaction products affords (R)-α-methylphenyl-alanine, (R)-α-allylalanine, and (R)-α-methylnaphthylalanine in 61–93% yields and withee 69–94%. When (S,S)-TADDOL is used, the (S)-amino acid is formed. A mechanism explaning the observed features of the reaction is proposed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 926–932, May, 1999. 相似文献
17.
Kristl J Veber M Krajnicic B Oresnik K Slekovec M 《Analytical and bioanalytical chemistry》2005,383(5):886-893
A new method is described for the determination of endogenous jasmonic acid (JA) in Lemna minor plant extracts using liquid chromatography (LC) with fluorescence detection. Plant tissues were extracted and derivatised
using 9-anthryldiazomethane (ADAM reagent) prepared in situ. Accuracy and precision were improved by using the internal standard
dihydrojasmonic acid (dh-JA) for the correction of JA losses during sample preparation steps. Liquid chromatography–mass spectrometry
(LC/MS) analysis of ADAM derivatives of JA and dh-JA confirmed that a single molecule of JA and dh-JA was coupled with one
molecule of reagent. Derivatives of JA and dh-JA were separated with gradient elution on a C18 reversed-phase column using acetonitrile/water as a mobile phase and detected by a fluorescence detector at excitation and
emission wavelengths of 254 and 412 nm, respectively. The detection limits of JA and dh-JA were 2.9 ng mL−1 and 3.7 ng mL−1 per 50-μL injection. The method is reproducible and selective and yields single peaks for each compound regardless of isomer.
The specificity and accuracy of the proposed LC/FD method was confirmed by liquid chromatography–TurboIon Spray tandem mass
spectrometric (LC/MS/MS) analysis of free JA in Lemna minor samples under multiple reaction monitoring conditions. 相似文献
18.
Chenxu Ding Xuejun Sun Xianen Zhao Wenchen Zhao Yulin Li Honglun Wang Yourui Suo Jinmao You 《Chromatographia》2008,67(3-4):245-251
A pre-column derivatization method for sensitive determination of oligopeptides, using the tagging reagent 2-(9-carbazole)ethyl
chloroformate (CEOC-Cl) followed by capillary electrophoresis (CE) with diode-array detection, has been developed. Maximum
yield close to 100% were observed when a three to fourfold molar excess of reagent was used at pH 9.0–10.0. Excess reagent
was extracted with n-hexane–ethyl acetate 9:1–10:1 (v/v); this enabled direct analysis using CE with no significant disturbance from the major fluorescent reagent degradation by-products.
The effects on the results of buffer pH and of SDS and organic modifier concentrations were examined. Good baseline resolution
in the separation of five CEOC-peptides was achieved with a 48.5-cm total length (effective length 40 cm) 50-μm inner diameter
capillary column. 相似文献
19.
Khalaj-Kondori M Sadeghizadeh M Khajeh K Naderi-Manesh H Ahadi AM Emamzadeh A 《Applied biochemistry and biotechnology》2007,142(2):200-208
Molecular phylogenetic analysis of a novel thermophilic eubacterium isolated from an Iranian hot spring using 16S rDNA sequence
showed that the new isolate belongs to genera Geobacillus. DNA pol I gene from this isolate was amplified, cloned, sequenced, and the three-dimensional (3D) structure of deduced amino
acid sequence was predicted. Sequence analysis revealed the gene is 2,631 bp long, encodes a protein of 876 amino acids with
a calculated molecular mass of 99 kDa, and belongs to family A DNA polymerases. Comparison of 3′–5′exonuclease domain of Klenow
fragment (KF) with corresponding region of newly identified DNA pol I (MF), the large fragment of Bacillus stearothermophilus DNA pol I (BF) and Klentaq1, revealed not only deletions in three regions compared to KF, but that three of the four critical
metal-binding residues in KF (Asp355, Glu357, Asp424, and Asp501) are altered in MF as well. Predicted 3D structure and sequence
alignments between MF and BF showed that all critical residues in the polymerase active site are conserved. 相似文献
20.
Conditions for silylation of benzidine (BZ) and 3,3′-dichlorobenzidine (DCBZ) have been optimized. Reactivity, repeatability,
and derivative stability were compared for the silylating reagents N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) and N-Methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBDMSTFA) and the catalysts 3% trimethylsilylimidazole (TMS-I) and 0.3% NH4-I–dithioerythritol. The results showed that derivatization with MTBDMSTFA/NH4-I containing 0.1 mg dithioerythritol was superior to other methods. The silylation conditions selected were reaction with
(MTBDMSTFA)–NH4I, 1000:3, with catalysis by dithioerythritol, at 80 °C for 80 min. The TBDMS derivatives of BZ and DCBZ had very good chromatographic
properties and very sensitive detection was achieved by gas chromatography with electron-impact ionization mass spectrometry
(GC-EIMS). Simultaneous determination of BZ and DCBZ in water was developed on the basis of the TBDMS derivatives. Deuterated
BZ (d8-BZ) was chosen as internal standard (IS) for analysis of water samples. BZ and DCBZ were extracted from water at pH
8.5 with dichloromethane and the extract was then dried and silylated. Recoveries of BZ and DCBZ were approximately 102 and
103% at a concentration of 2.0 ng mL−1. The coefficients of variation for BZ and DCBZ were less than 9 and 4% at concentrations of 0.2 and 0.5 ng mL−1, respectively. The method detection limits for 200 mL water were 0.004 ng mL−1 for BZ and 0.02 ng mL−1 for DCBZ. 相似文献