Showing papers on "Derivatization published in 1994"
TL;DR: In this article, primary and secondary amines are rapidly labelled by 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate to form highly fluorescent asymmetric urea derivatives which are readily amenable to analysis by liquid chromatography.
216 citations
TL;DR: The simple sample preparation and short analysis time make the HPLC method particularly suitable for routine analysis of large series of samples, and it can be used for determining primary amino acids in plasma and cerebrospinal fluid.
Abstract: We present an HPLC method for the determination of amino acids in plasma. The method is based on automated precolumn derivatization of amino acids with o-phthalaldehyde, separation of the derivatives by reversed-phase chromatography, and quantification by fluorescence detection. Complete separation was achieved within 12 min. Total analysis time, including derivatization, chromatography, and reequilibration of the column, was 17 min. The assay was linear from 5 to 800 mumol/L for all amino acids. Recovery of amino acids added to plasma samples was 96-106%, except for tryptophan (89%). Within-run precision (CV) was 1.8-6.4%, and between-run precision was 2.1-7.2%. The method can be used for determining primary amino acids in plasma and cerebrospinal fluid. The simple sample preparation and short analysis time make the method particularly suitable for routine analysis of large series of samples.
208 citations
TL;DR: In this paper, derivatization reagents for thiols are reviewed with respect to their reactivity, selectivity, spectroscopic characteristics and their applicability especially to high-performance liquid chromatography.
166 citations
TL;DR: The applicability of the method to various fields of biosciences is demonstrated with the detection and determination of d -amino acids in bacteria, microfungi, higher plants, invertebrates and vertebrates, including man, and in the amino acid-containing Murchison meteorite.
155 citations
TL;DR: In this article, the use of Cu electrodes has been shown to provide an attractive method for detection and quantification of amino acids and peptides after separation by capillary electrophoresis (CE).
Abstract: Electrooxidation of amino acids and peptides at Cu electrodes has been shown to provide an attractive method for detection and quantitation of these compounds after separation by capillary electrophoresis (CE). As has been previously seen in analogous liquid chromatography applications, the use of Cu electrodes permitted the direct detection of amino acid species in CE at constant applied potential and without derivatization. Strongly alkaline media, typically 50-100 mM NaOH, were required for the electrode process to proceed optimally; but such media were found to be suitable for useful CE separations
146 citations
TL;DR: Derivatization reactions aimed at creating the basis for the chromatographic resolution of biologically and pharmaceutically important enantiomers are reviewed, with emphasis on the literature published in the last 10 years.
111 citations
TL;DR: Capillary electrophoresis combined with electrochemical detection at copper electrodes has been shown to provide a simple and sensitive method for the direct analysis of samples containing a wide range of carbohydrate compounds including simple sugars, sugar acids and alditols as mentioned in this paper.
110 citations
106 citations
TL;DR: A method for characterizing flavan-3-ols and procyanidins by HPLC separation in connection with on-line UV detection and chemical reaction detection is described in this paper.
105 citations
TL;DR: The procedure allowed the determination of neutral lipid classes without derivatization of mono- and diglycerides, and the main triglycerides identified were PPO, POS, POO, POL and OOO.
104 citations
TL;DR: A number of recent studies have detected gamma-aminobutyric acid in brain microdialysates by measuring an electroactive o-phthaldialdehyde (OPA)-alkylthiol derivative using HPLC with electrochemical detection, but a particular problem of this approach is the stench of the thiol reagents involved, and the poor stability of the electroactive GABA derivative.
TL;DR: Various derivatization methods for the fluorometric detection of aflatoxins after separation by HPLC are reviewed and the methods are compared with respect to experimental convenience, selectivity, reproducibility and suitability for automation.
TL;DR: In this article, a supercritical fluid extraction (SFE) procedure for simultaneous determination of butyltin and phenylltin compounds in sediment samples was developed, followed by hexyl derivatization onto the sediment with hexylinagnesium bromide, which took place in situ within the extraction cell.
Abstract: A supercritical fluid extraction (SFE) procedure for the simultaneous determination of butyltin and phenyltin compounds in sediment samples was developed. Following a hexyl derivatization onto the sediment with hexylinagnesium bromide, which took place in situ within the extraction cell SFE was performed in mild thermal conditions (T=40 o C, P=350 atm). The recovered SFE extracts were analyzed by gas chromatography with flame photometric detection without any additional cleanup step. This procedure minimizes the sample handling steps, saves analysis time, and reduces the usage of solvent. Analysis of tributyltin in standard reference materials demonstrates the validity of this method
TL;DR: A precolumn derivatization method for the determination of amino acids using 6-aminoquinolyl-N-hyroxy-succinimidyl carbamate (AQC) followed by high-performance liquid chromatography is described in this paper.
TL;DR: In this article, neutral polycyclic aromatic hydrocarbons (PAHs), a heteroaromatic, a substituted aromatic, and the highly conjugated molecule buckminsterfullerene (C 60 ) are ionized (i.e., derivatized) in solution via reaction with the chemical electron-transfer reagents trifluoroacetic acid (TFA), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), or antimony pentafluoride and
Abstract: Analytes are typically detectable by electrospray ionization mass spectrometry (ES-MS) only if they are ionic in solution. Neutral nonpolar analytes are not generally amenable to the technique. In this paper, neutral polycyclic aromatic hydrocarbons (PAHs), a heteroaromatic, a substituted aromatic, and the highly conjugated molecule buckminsterfullerene (C 60 ) are ionized (i.e., derivatized) in solution via reaction with the chemical electron-transfer reagents trifluoroacetic acid (TFA), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), or antimony pentafluoride and then detected in the gas phase as their respective radical cations by ES-MS. The nature of these electron-transfer reactions dictates selectivity for analytes of this type, i.e., analytes that are easy to oxidize
TL;DR: A method has been developed for the determination of fumonisin B1 (FB1) in the faeces of non-human primates (vervet monkeys) and showed that the radioactivity extracted corresponded mainly to FB1 and a new metabolite with chromatographic properties similar to those of the mycotoxin.
TL;DR: Various chiral stationary phases were investigated in sub- and supercritical fluid chromatography for the separation, without derivatization, of basic (beta-blockers, benzodiazepines) and acidic (nonsteroidal anti-inflammatory drugs, beta-agonists) pharmaca.
Abstract: Various chiral stationary phases were investigated in sub- and supercritical fluid chromatography for the separation, without derivatization, of basic (beta-blockers, benzodiazepines) and acidic (nonsteroidal anti-inflammatory drugs, beta-agonists) pharmaca. For all racemates, baseline separation was achieved within short analysis times. For several solutes, the high resolution obtained allowed injection of milligram amounts and semipreparative collection of the enantiomers. The parameters affecting enantioselectivity (column efficiency, influence of modifiers and basic or acidic additives, and temperature) have been studied. Enantiomerization of 3-OH-benzodiazepines could be suppressed by working at low temperatures or by using acetonitrile as a comodifier. Serial coupling of different chiral stationary phase columns resulted in a column triplet (Chiralpak AD, an amylose derivative; Chiralcel OD, a cellulose derivative; and Chirex 3022, a Brush-type with pi-donor characteristics) on which all solutes investigated could be baseline separated.
TL;DR: Among the different reagents investigated, isobutyl chloroformate derivatized amino acids were found to provide more sensitivity for analyses by GC-flame ionization detection and GC-MS relative to derivatives prepared by other alkyl chloroforms.
TL;DR: In this article, two simple sample preparation methods for the speciation analysis of triphenyltin and butyltin compounds in marine biotissues, using tetramethylammonium hydroxide (TMAH) solubilization and enzymic hydrolysis, have been developed and compared with conventional acid digestion.
Abstract: Two simple sample preparation methods for the speciation analysis of triphenyltin and butyltin compounds in marine biotissues, using tetramethylammonium hydroxide (TMAH) solubilization and enzymic hydrolysis, have been developed and compared with conventional acid digestion. Derivatization was carried out in situ using sodium tetraethylborate (NaBEt4) without prior separation of the analytes from the tissue matrix. Separation and detection was performed using capillary gas chromatography (GC) coupled to microwave-induced plasma atomic emission spectrometry (MIP AE) allowing detection limits of 2 ng g−1 (as tin) to be reached. The accuracy of the presented methods was demonstrated by the analysis of a fish reference material (NIES No. 11). the necessity for sample clean-up is discussed and examples of the analysis of mussel tissue are shown.
TL;DR: D-alanine, D-arginine and D-aspartate were the most abundant and widely distributed D-amino acids found in the crustacean nervous tissues and eyes.
TL;DR: The relative amounts of free D-amino acids (D-AA) in the urine of seven healthy volunteers were determined using chiral phase (Chirasil-L-Val) capillary gas chromatography in conjunction with selected ion monitoring mass spectrometry.
Abstract: The relative amounts of free D-amino acids (D-AA) in the urine of seven healthy volunteers (age 27 to 49 years) were determined using chiral phase (Chirasil-L-Val) capillary gas chromatography in conjunction with selected ion monitoring mass spectrometry. The absolute amounts of free D-AA were determined by pre-column derivatization of the amino acids witho-phthaldialdehyde andN-isobutyryl-L-cysteine followed by high-performance liquid chromatographic separation and fluorescence detection of the isoindol derivatives formed. The following most abundant D-AA were found (highest and lowest absolute and relative amounts): D-Ser (379.8 - 30.1µMol/L; 56.5 - 19.0%), D-Ala (53.8 - 7.6µMol/L; 19.6 - 5.7%), D-Thr (5.8 - 0.25µMol/L; 3.4 - 1.0%), D-Val (3.7 - 0µMol/L; 4.2 - 0%), and D-Phe (3.5 - 0.35µMol/L; 4.8 - 1.4%).
TL;DR: A new and specific precolumn derivatization reaction for acidic monosaccharides was introduced and evaluated in the separation and sensitive detection of carbohydrates by capillary electrophoresis.
Abstract: A new and specific precolumn derivatization reaction for acidic monosaccharides was introduced and evaluated in the separation and sensitive detection of carbohydrates by capillary electrophoresis. The derivatization reaction involved the attachment of sulfanilic acid (a UV absorbing tag) or 7-amino-naphthalene-1,3-disulfonic acid (a UV absorbing and fluorescing tag) via a condensation reaction between the amino group of the derivatizing agent and the carboxyl group of the sugar in the presence of a water-soluble carbodiimide. The derivatization reaction replaced the weak carboxylic acid of the sugar by a strong sulfonic acid, which is fully ionized at all pH. This allowed the electrophoresis of the sugar derivatives over a wide pH range and permitted the determination of acidic carbohydrates at very low femtomole levels by UV and fluorescence detection.
TL;DR: The results of the method are in good agreement with those obtained with the standard amino acid autoanalyzer method and was applied to the determination of amino acids in animal feed and powdered milks.
TL;DR: In this article, a linear relationship was found between cellulose crystallinity and the rate of hydroxyl labeling in a range of celluloses using X-ray diffraction and infrared spectroscopy.
TL;DR: In this paper, mixed amino-alkylamide chemically bonded phases have been prepared via two-step reaction which involved the initial modification of silica with aminopropyldimethylsilyl groups under environmentally sealed conditions followed by a secondary derivatization with different acid chlorides (i.e., acetyl, hexanoyl and stearoyl chlorides).
TL;DR: In this article, a method suitable for the determination of 19 biogenic amines in wine has been developed, which involves derivatization of amines by treatment with dansyl chloride and solid-phase extraction of the derivatives.
Abstract: A method suitable for the determination of 19 biogenic amines in wine has been developed. The method involves derivatization of amines by treatment with dansyl chloride and solid-phase extraction of the derivatives. Prior to the derivatization procedure, clean-up of the wine sample with polyvinylpyrrolidone is carried out. Reversed-phase gradient elution HPLC with UV detection at 250 nm was used to determine these compounds. Some consideration was given to the effect of temperature on the separation process. Linearity of derivatization was obtained for amounts of all the biogenic amines ranging from 500 μg·L−1 to 20 mg·L−1. Limits of detection (signal-to-noise ratio=3) of the amines were similar for all the dansylderivatives (between 50 and 150 μg·L−1). Addition of standard amines was used for the determination of amine recoveries. These were better than 85% for ethanolamine, tryptamine, phenetylamine, putrescine, cadaverine and histamine. The overall process was succesfully applied to identify and quantify biogenic amines in white and red wines.
TL;DR: Different approaches apply for small versus large analyte molecules, different advantages and disadvantages are visualized with pre- and post-column arrangements and particular interest is focused upon solid-phase derivatization reagents.
TL;DR: A post-column derivatization method has been developed and used to evaluate the plasma concentration of cisplatin and its monohydrated form in a patient.
TL;DR: A rapid and fully automated pre-column derivatization method for the determination of primary and secondary biogenic amines and amino acids is described in this article, using 9-fluorenylmethyl chloroformate and heptylamine for removing the excess of reagent.
TL;DR: In this article, a new approoch to the analysis of free amino acids from infant foods is described, based on reaction of the free amino acid with phenylisothiocyanate to form stable derivatives which are subsequently separated by liquid chromatography.
Abstract: A new approoch to the analysis of free amino acids from infant foods is described. The method is based on reaction of the free amino acids with phenylisothiocyanate to form stable derivatives which are subsequently separated by liquid chromatography. Sample preparation procedures are described. Separation of all amino acids using this method was completed in 20 min. This method was much faster than the traditional Ion-exchange methods (2–3 h). Variability of the method (expressed as coefficients of variation) for the determination (including preparation of samples, derivatization and liquid chromatography) of all amino acid was less than 10%.