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1.
Vanesa Guillén-Casla María Eugenia León-González Luis Vicente Pérez-Arribas Luis María Polo-Díez 《Analytical and bioanalytical chemistry》2010,397(1):63-75
Changes in free amino acids content and its potential racemization in ready-to-eat foods treated with E-beam irradiation between
1 and 8 kGy for sanitation purposes were studied. A simple heart cut two-dimensional high performance liquid chromatographic
method (LC–LC) for the simultaneous enantiomeric determination of three pairs of amino acids used as markers (tyrosine, phenylalanine,
and tryptophan) is presented. The proposed method involves the use of two chromatographs in an LC–LC achiral–chiral coupling.
Amino acids and their decomposition products were firstly separated in a primary column (C18) using a mixture of ammonium acetate buffer (20 mM, pH 6) (94%) and methanol (6%) as the mobile phase. Then, a portion of
each peak was transferred by heart cutting through a switching valve to a teicoplanin-chiral column. Methanol (90%)/water
(10%) was used as the mobile phase. Ultraviolet detection was at 260 nm. Detection limits were between 0.16 and 3 mg L−1 for each enantiomer. Recoveries were in the range 79–98%. The LC–LC method combined with the proposed sample extraction procedure
is suitable for complex samples; it involves an online cleanup, and it prevents degradation of protein, racemization of L-enantiomers,
and degradation of tryptophan. Under these conditions, D-amino acids were not found in any of the analyzed samples at detection
levels of the proposed method. 相似文献
2.
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
3.
Jason W Costin 《Analytica chimica acta》2003,480(1):67-77
The determination of the amino acids proline, histidine, tyrosine, arginine, phenylalanine and tryptophan using flow injection analysis (FIA) with chemiluminescence detection is described. Proline was the only amino acid to exhibit chemiluminescence with the tris(2,2-bipyridyl)ruthenium(III) reaction at pH 10. While, histidine was found to selectively enhance the reaction of luminol with Mn(II) salts in a basic medium. Acidic potassium permanganate chemiluminescence was able to selectively determine tyrosine at pH 6.75. Low pressure separations using a C18 guard column allowed the simultaneous determination of tyrosine and tryptophan or phenylalanine and tryptophan with acidic potassium permanganate and copper(II)-amino acid-hydrogen peroxide chemiluminescence, respectively. Precision for each method was less than 3.9% (R.S.D.) for five replicates of a standard (1×10−5 M) and the detection limits ranged between 4×10−9 and 7×10−6 M. Preliminary investigations revealed that the methodology developed was able to selectively determine the individual amino acids in an equimolar mixture of the 20 naturally occurring amino acids. 相似文献
4.
Zhang ZX Gao PF Guo XF Wang H Zhang HS 《Analytical and bioanalytical chemistry》2011,401(6):1905-1914
1,3,5,7-Tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)difluoroboradiaza-s-indacene (TMBB-Su), a new BODIPY-based fluorescent probe, was designed and synthesized for the labeling of amino compounds.
It was used as a pre-column derivatizing reagent for determination of amino acid neurotransmitters by high-performance liquid
chromatography (HPLC). The fluorescence quantum yield in acetonitrile increased from 0.84 to 0.95 when it reacted with amino
acid neurotransmitters. Derivatization of TMBB-Su with seven amino acid neurotransmitters was completed within 30 min at 25 °C
in 24.0 mmol L−1 pH 7.8 boric acid buffer. The separation was performed on a C18 column with methanol–water–buffer 55:35:10 (v/v) as mobile phase (buffer: 0.10 mol L−1 H3Cit–0.10 mol L−1 NaOH). Interference from the other concomitant amino acids was eliminated successfully by means of pH gradient elution. With
fluorescence detection at 494 and 504 nm for excitation and emission, respectively, the limits of detection (signal-to-noise
ratio = 3) were from 2.1 to 12.0 nmol L−1. The proposed method has been used to determine amino acid neurotransmitters in the cerebral cortex of mice with cerebral
ischemia at the convalescence stage with satisfactory recoveries varying from 94.9 to 105.2%. 相似文献
5.
The inhibiting effect of heavy metal ions, organic nitrogen-containing heterocyclic compounds, and amino acids on the catalytic
activity of yeast alcohol dehydrogenase (ADH) in the reaction of ethanol oxidation by nicotinamide adenine dinucleotide was
detected. Sensitive procedures were developed for the determination of the most effective ADH inhibitors [mercury (II), silver(I),
zinc(II), copper(II), 1,10-phenanthroline, 2,2′-dipyridyl, 8-hydroxyquinoline, quinoline, 3,4-dimethylimidazole, benzimidazole,
1,2,3-benzotriazole, histidine, tryptophan, proline, and histamine] with cL = 5x 10-10-1 x 10-4M (RSD = 1–12%). 相似文献
6.
Apparent molar volumes of a homologous series of amino acids in aqueous proline solutions have been obtained from densities
at 298.15 K, measured with a vibrating-tube digital densimeter. These data have been used to deduce the partial molar volumes
of transfer from water to aqueous proline solutions; these partial molar volumes of transfer are found to be positive for
glycine, alanine, α-amino-n-butyric acid and valine, whereas they are negative for leucine. The number of water molecules hydrated to the amino acids
was estimated from the partial molar volume data. In order to supplement this information, enthalpies of transfer of aqueous
amino acids from water to 0.1, 2.25 and 1 mol⋅dm−3 aqueous proline have been determined at 298.15 K using a VP-ITC titration calorimeter. The data on the partial molar volumes
and enthalpies of transfer are discussed in terms of various interactions operating in the ternary mixtures of amino acids,
water and proline. 相似文献
7.
Abderrahim A?t Adoubel Christophe J. Morin Nadine Mofaddel Georges Dupas Paul-Louis Desbène 《Analytical and bioanalytical chemistry》2009,394(2):597-608
Enantiomer separations of underivatised amino acids were carried out by using ligand exchange capillary electrophoresis (LECE).
Chiral discrimination is based on the formation of ternary complexes between copper(II), a chiral selector (L-proline or trans-4-hydroxy-L-proline) and an amino acid. All amino acids containing aromatic moieties or not were detected at 214 nm because
of their interactions with copper(II). In order to reduce copper(II) adsorption onto capillary walls, we used hexadimethrine
bromide to reverse the electroosmotic flow. Using this original strategy, the studied enantiomers migrated in the opposite
direction of the anodic electroosmosis. After optimising the analytical conditions taking into account the chiral resolution
and the detection sensitivity, we performed very satisfactory enantioseparations not only of aromatic amino acids (tryptophan,
tyrosine, phenylalanine and histidine) but also of aliphatic amino acids (threonine, serine, isoleucine and valine). These
enantioseparations were performed in a short analysis time at 35 °C. In order to rationalise the obtained results, we evaluated
the complexation constants corresponding to the formed ternary complexes by capillary electrophoresis and we used molecular
mechanics modelling. 相似文献
8.
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
9.
Sevillano Cabeza A Moliner Martinez Y Molins Legua C Campíns Falcó P 《Analytical and bioanalytical chemistry》2003,376(6):918-922
Bond Elut C18 solid-phase extraction cartridges were used for pre-concentration followed by derivatization with o-phthaldialdehyde-N-acetylcysteine (OPA-NAC) of primary amines in water. Optimal conditions were: conditioning the cartridges with borate buffer pH 10.4, retention of the primary amines, addition of the OPA-NAC(3.7 mmol L–1) 1:1 molar ratio and borate buffer pH 8, elution of the isoindol with MeOH-borate buffer (9:1) pH 10.2 and fluorescence measurement. The equations of the calibration graphs for methylamine, ethylamine, propylamine, butylamine, pentylamine, and -phenylethylamine at excitation=330 nm and emission=440 nm, in the optimal conditions are presented. The solid-phase extraction procedure improved ten times the detection limits of the solution derivatization. Those values are in the 0.01–0.06 mg L–1 interval in function of the amine. Also, it is possible to estimate the total primary aliphatic amine concentration in water, expressed as molar concentration of –NH2 group or –NH2-N mg L–1. On the basis of these studies, the method was applied for the determination of primary amino groups in tap, ground, factory and source water samples. 相似文献
10.
The feasibility of a microcolumn electrophoresis technique was investigated with a 100 mm length, 2 mm I.D. fused-silica microcolumn packed with uniform quartz microncrystals prepared by hydrothermal synthesis. To evaluate the separation technique, tryptophan, phenylalanine and tyrosine were primarily separated by the microcolumn electrophoresis and detected at 216 nm without derivatization by an ordinary spectrophotometer. The separation conditions of the amino acids were optimized. With 1.5 mmol/L disodium phosphate buffer solution (pH 11.5) containing 25% (v/v) methanol and 10% (v/v) acetonitrile, the three amino acids were separated and the separation efficiency of tryptophan was 4.5 × 104 plates/m. The limits of detection were 0.035, 0.22 and 0.20 μmol/L, respectively. The sample capacity of the electrophoretic microcolumn achieved 35 μL. The proposed method was used to determine these amino acids in compound amino acid injection samples without derivatization. For the simplicity and portability of the microcolumn electrophoresis, it is studied as one of the high-performance separation techniques for an in situ and real-time electrokinetic flow analysis system. For its high detection sensitivity and large sample capacity, it can be developed for preparative electrophoresis. 相似文献
11.
A new method was developed for the simultaneous determination of lidocaine, proline and lomefloxacin in human urine by capillary
electrophoresis-electrochemiluminescence detection with Ru(bpy)3
2+. Conditions of the separation and detection were investigated and optimized. It was proved that 20 mM phosphate buffer at
pH 6.7 could achieve the most favorable resolution, and the high sensitivity of detection was obtained by using the detection
potential at 1.15 V and 5 mM Ru(bpy)3
2+–60 mM phosphate buffer at pH 7.6 in the detection reservoir. The detection limits were 0.02 μg mL−1 for lidocaine, 0.03 μg mL−1 for proline and 0.06 μg mL−1 for lomefloxacin. Relative standard deviations of the ECL intensity and the migration time were 3.5 and 1.1% for 6 μg mL−1 lidocaine, 3.2 and 1.0% for 6 μg mL−1 proline and 3.7 and 1.2% for 6 μg mL−1 lomefloxacin, respectively. A baseline separation for lidocaine, proline and lomefloxacin was achieved within 360 s. The
developed method was successfully applied to determine the amounts of lidocaine, proline and lomefloxacin in human urine.
The recovery and RSD were in the range of 93.3–97.2 and 3.8–4.9%, respectively. 相似文献
12.
A. D. Smolenkov A. V. Chernobrovkina R. S. Smirnov O. A. Shpigun 《Journal of Analytical Chemistry》2012,67(4):360-363
A method is proposed for the quantification of hydrazine by reversed-phase chromatography after its derivatization with naphthalene-2,3-dialdehyde.
The conditions of derivatization and the chromatography separation on a Zorbax Eclipse XDB-C8 column in the gradient mode
are optimized. The derivatization and chromatography analysis take 1 and 16 min, respectively. If fluorimetry detection (λex = 273 nm, λem = 500 nm) is used and the injection volume is 100 μL, the detection limit is 0.05 μg/L. The procedure is applicable to the
quantification of hydrazine in natural waters and soil extracts. A simple and rapid procedure is elaborated for the determination
of 0.1–50 μg/L hydrazine in natural waters, RSD = 12% (n = 3). 相似文献
13.
Francesco Dallavalle Giuseppina Folesani Rosangela Marchelli Gianni Galaverna 《Helvetica chimica acta》1994,77(6):1623-1630
Formation constants of ternary complexes of CuII with (S)-amino-acid amides (phenylalaninamide, prolinamide, and tryptophanamide) and (R)- or (S)-amino acids (valine, phenylalanine, proline, and tryptophan) were determined potentiometrically at 25° and I = 0.1M (KC1). Significant stereoselectivity was found for the systems (S)-tryptophanamide/proline, (S)-prolinamide/tryptophan, and (S)-phenylalaninamide/proline, the diastereoisomeric complexes with ‘homochiral’ (SS) being more stable than with ‘heterochiral’ (SR) ligands. The stereoselectivity observed may be explained on the basis of repulsive interactions between the ligand side-chain residues. The present data on the stability of mixed complexes in solution allow to draw some conclusions on the mechanism of chiral discrimination of amino acids in HPLC (reversed-phase) using CuII complexes of (S)-amino-acid amides as selectors for ligand-exchange chromatography (LEC). 相似文献
14.
Summary A method is presented that enables the fully automated precolumn derivatization of mixtures of DL-amino acids (DL-AA) witho-phthaldialdehyde together withN-isobutyryl-L(orD)-cysteine. HPLC on a 250 mm×4 mm i.d. column packed with Shandon Hypersil ODS, 5 μm, and a linear gradient
formed from 23 mM sodium acetate (pH 6.0) and methanol/acetonitrile (600 ml+50 ml) separates completely an AA standard composed
of 17 pairs of DL-AA (including Asn and Gln), Gly and the internal standard L-homo-Arg, within 75 min at a flow rate at 1 ml/min. Applications are shown of the determination of free D-AA isolated from an
orange juice concentrate and from soy sauce, and the detection of D-AA in a gelatine total hydrolysate. In the case of these
foodstuffs fluorescence detection (excitation at 230 nm, emission at 445 nm) allows the routine detection of 5–10 pmol per
AA; and approx. 0.2–1% D-AA, in an excess of L-AA, are quantifiable.
Presented in part at the “International Symposium on Separation of Peptides, Proteins and Polynucleotides”, October 29–31,
1990, Wiesbaden (abstract 620), ANAKON '91, April 22–24, Baden-Baden (abstract C 5), and at the “15th International Symposium
on Column Liquid Chromatography”, June 3–7, 1991, Basel (abstract P26/2). 相似文献
15.
The analytical potencies of ligand-exchange capillary electrophoresis (LECE) in regard to the determination of bioactive substances are discussed. As it is shown, complexation with copper(II) in the
electrophoretic determination with UV detection makes possible the determination of amino acids, amines, and sugars, which
do not absorb in the UV region, with the limits of detection 5–10 mg/L, and reduce the detection limits of the absorbing analytes,
such as tryptophane, tyrosine, and histamine by 2–3 times. Prospects for using online preconcentration for the reduction of
c
min are shown on an example of aliphatic amino acids, i.e., thirtyfold preconcentration is attained. LECE is shown to be applicable
to the simultaneous determination of glucose, Na(+), and K(+) in human blood serum. Also versions of ligand-exchange capillary electrophoresis with direct UV detection and capillary
zone electrophoresis with indirect one are compared in terms of efficiency, time of analysis, and limit of detection. The
potencies of the LECE method are compared with those of ligand-exchange chromatography. 相似文献
16.
A supramolecular catalytic kinetic spectrofluorimetric method was developed for the determination of platinum(IV) and the
possible mechanism of catalytic reaction was discussed. The method was based on the fluorescence-enhancing reaction of salicylaldehyde
furfuralhydrazone (SAFH) with potassium bromate, which was catalysed by platinum(IV) in a water–ethanol medium. β–Cyclodextrin (β-CD) obviously sensitized the determination at pH 5.20 and 25°C. Under optimum conditions, the β-CD–platinum–KBrO3–SAFH supramolecular kinetic catalytic reaction system had excitation and emission maxima at 372 and 461 nm, respectively.
The linear range of this method was 0.60–180 ng ml−1 with a relative standard deviation of 1.2%, and the detection limit was 0.18 ng ml−1. Investigation of the mechanism and the effects of interferences is presented. The proposed method was applied successfully
to determine trace platinum(IV) in the chemotherapeutic drug cisplatin and serum from patients with satisfactory results.
相似文献
17.
O. A. Snytnikova P. S. Sherin L. V. Kopylova Yu. P. Tsentalovich 《Russian Chemical Bulletin》2007,56(4):732-738
Photochemical reactions involving kynurenines, viz., molecules present in the eye lens, can result in modifications of the lens proteins and cause a development of a cataract.
The rate constants of the reactions of photoexcited kynurenine with several amino acids and antioxidants contained in the
lens were measured. The most efficient quenchers of triplet kynurenine are amino acids tryptophan and tyrosine, as well as
antioxidant ascorbate. In all cases, the quenching reaction proceeds by the electron transfer mechanism, except for the reaction
with oxygen where transfer of the triplet energy to the oxygen molecule occurs.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 704–710, April, 2007. 相似文献
18.
Ferreira JA Dias E Rocha SM Coimbra MA 《Analytical and bioanalytical chemistry》2011,401(6):1889-1898
Helicobacter pylori diagnosis is fundamental in the management of gastrointestinal pathologies, whose current clinical guidelines support a non-invasive
‘test-and-treat’ strategy. As such, the present work reports the basis of a new, low-cost, specific breath test based on the
detection of volatile carboxylic acids resulting from the hydrolysis of short-chain aliphatic amides by H. pylori amidases. Propionamide and butyramide, which are metabolized by amidases to propionic and butyric acids, were elected for
this study. Conditions for the extraction of these acids from a vapour phase were optimized concerning the use of solid-phase
microextraction (SPME) followed by gas chromatography–quadrupole mass spectrometry (GC–qMS) analysis. SPME–GC–qMS was then
used to detect the acids released into a vapour phase upon incubation of a H. pylori reference strain J99 or a clinical specimen with the amides. These experiments have demonstrated that the administration
of less than 9 mg of propionamide and/or butyramide to H. pylori cultures, in loads recognized to cause infection (106–109 cells), resulted in the formation of detectable and/or quantifiable amounts of propionic and/or butyric acids after 30 min
incubation. As such, propionic and butyric acids can be used as biomarkers for H. pylori upon incubation with the corresponding amides. SPME–GC–qMS was also used to verify the hepatic stability of the acids. These
experiments were conducted in mouse liver cells and revealed no signs of metabolization that could compromise their bioavailability
in future in vivo assays. Moreover, SPME–GC–qMS permitted the detection of both acids in amounts as low as 0.8 μg in systems
mimicking exhaled breath, demonstrating the sensitivity of the method for these compounds. 相似文献
19.
The enthalpies of dissolution of glycine (Gly) and L-α-alanine (Ala) in water at 288.15–318.15 K were measured. The results were compared with the earlier obtained data for L-α-phenylalanine (Phe) and L-α-histidine (His). The standard enthalpies of dissolution (Δsoln
H
0) and differences (ΔC
p
0
) between the limiting partial molar heat capacity of the amino acids in solution and the heat capacity of the amino acids
in the crystalline state
were calculated in the temperature interval 273–373 K. Changes in the entropy of dissolution (ΔΔsoln
S
0) and reduced Gibbs energy [Δ (Δsoln
G
0/T)] in the temperature interval from 273 to 373 K were determined from the known thermodynamic relationships. The ΔC
p
0
value is negative for hydrophilic glycine and positive for other amino acids. The ΔΔsoln
S
0 values increase with an increase in the hydrophobicity of the amino acids. The Δ(Δsoln
G
0/T) values become more negative in the order Ala, Phe, Gly, His.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 711–714, April, 2007. 相似文献
20.
Summary A new chiral derivatizing agent (CDA), (1S,2S)-1,3-diacetoxy-1-(4-nitrophenyl)-2-propylisothiocyanate, (S,S)-DANI, was applied to the separation of the enantiomers of unusual amino acids containing two chiral centers. Different β-methyl-α-amino
acids (β-MePhe, β-MeTyr and β-MeTrp) and β-amino acids with cycloalkane skeletons (2-aminocyclopentanecarboxylic acid and
2-aminocyclohexanecarboxylic acid) were derivatized and the thiourea derivatives produced were separated by reversed-phase
high-performance liquid chromatography. The applicability of this new CDA in the separation of unusual amino acids is demonstrated.
The four stereoisomers of the investigated amino acids (except β-MePhe) could be separated in one chromatographic run.
Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999 相似文献