Showing papers on "Derivatization published in 1978"
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1 Jan 1978
TL;DR: In this paper, Blau et al. present an approach for the esterification of Esterification (K. Blau and A. Darbre), which is based on the derivatization for fast atom/Ion bombardment Mass Spectrometry (R. Evershed).
Abstract: Partial table of contents: Esterification (K. Blau & A. Darbre). Advances in Silylation (R. Evershed). Derivative Formation by Ketone-Base Condensation (R. Brandenberger & H. Brandenberger). Colored and UV-Absorbing Derivatives (F. Li & C. Lim). Derivatization for Chromatographic Resolution of Optically Active Compounds (M. Skidmore). Derivatization for Fast Atom/Ion Bombardment Mass Spectrometry (R. Spreen). Derivatives for Gas Chromatography-Mass Spectrometry (J. Halket). Practical Considerations (K. Blau). Index.
875 citations
TL;DR: The accuracy of amino acid analysis by enantiomer labelling is equal or superior to that of hitherto known methods.
210 citations
TL;DR: It is shown that a solid-phase immune adsorbent can be prepared from rabbit antiserum by isolating the IgG fraction with the A protein of Staphylococcus aureus associated covalently with a Sepharose matrix using the cross-linking agent dimethylsuberimidate.
152 citations
TL;DR: Application of the high-performance liquid-chromatographic method for measuring histamine, norepinephrine, octopamine, normetanephrine, dopamine, serotonin, and tyramine in plasma, brain, or urine to urine from normal persons and a patient with a brain tumor is demonstrated.
Abstract: We describe a high-performance liquid-chromatographic method for measuring histamine, norepinephrine, octopamine, normetanephrine, dopamine, serotonin, and tyramine in plasma (2 ml), brain (0.2 g), or urine. These amines are modifed by pre-column derivatization with o-phthalaldehyde, which stabilizes the molecules, facilitates extraction, and improves detection of nanogram amounts. Before separation, samples were neutralized with KOH and immediately derivatized and extracted into ethyl acetate, in which derivatives were stable for longer than 24 h. Interfering amino acids were removed from ethyl acetate by partitioning twice with Na2HPO4 buffer (pH 10.0). Separation was complete in about 90 min on a "mu Bondapak/phenyl" column, with which a stepwise gradient of methanol/phosphate buffer (pH 5.1) was used. A variable-wavelength fluorometer was used (exciting wavelength, 340 nm; emission wavelength, 480 nm). Amount and response were linearly related from 1 to 200 pmol. Precision (CV) for retention times was 1%, for derivatization and injection 2.5%. Analytical recoveries of the seven amines from 2 ml of plasma fortified with 200 pmol averaged 65% (CV approximately 8%). Data on rat-brain tissue samples are compared with results by the trihydroxyindole method. Application of the method to urine from normal persons and a patient with a brain tumor is demonstrated.
121 citations
TL;DR: A method for the fluorescence labeling of fatty acids with 4-bromomethyl-7-methoxycoumarin using 18-crown-6 as a catalyst is described in this paper.
109 citations
TL;DR: In this paper, a new derivatization procedure was developed for converting enantiomeric amines into diastereomers for resolution by high-performance liquid chromatography, and two chiral reagents, (−)- a -methoxy- a -methyl-1-naphthaleneacetic acid and (−)- methoxy -a -mthyl-1naphthynaphthalenesacetic acetic acid, were prepared and optically resolved by fractional crystallization of their (+)- a-methylbenzylamine salts.
79 citations
TL;DR: Fluorescent esters of the prostaglandins D2, E2, F2alpha, and 6-keto-F1alpha and of thromboxane B2 have been prepared using the reagent 4-bromomethyl-7-methoxycoumarin using a high-performance liquid chromatography method.
74 citations
TL;DR: In this article, high pressure liquid chromatography was used to separate the flourescent adducts formed from the reaction of o-phthalaldehyde with primary biogenic amines, which can be detected and quantified with fluorometry in the low picogram range.
Abstract: High-pressure liquid chromatography was used to separate the flourescent adducts formed from the reaction of o-phthalaldehyde with primary biogenic amines. Using precolumn derivatization and isocratic elution techniques fluorescent o-phthalaldehyde adducts can be detected and quantified with fluorometry in the low picogram range. The relative retention values of the o-phthalaldehyde adducts strongly depend on the pH of the eluent and percent organic solvent in the mobile phase. The method was applied to the analysis of free norepinephrine in pooled urine samples and in small-volume (2-h) urine collections obtained from thermally stressed subjects. Samples were treated with alumina, and the catecholamines, including internal standard 3,4-dihydroxy-benzylamine, eluted from it were reacted with o-phthalaldehyde prior to injection onto a reverse-phase column (octadecyl-silica stationary phase) with methanol/0.08 mol/liter acetic acid (50/50 by vol) as the mobile phase. Assay of pooled urine specimens...
57 citations
TL;DR: In this paper, a high pressure liquid chromatomagraphic method was developed for separation of anthocyanins from fruits and their products on a μBondapak c 18 analytical column, which enables a relatively fast separation and identification of twenty anthocyains in one run without prior treatment of the plant extract, or derivatization of the piments.
57 citations
TL;DR: In this paper, an analytical procedure was described that permits the determination of phenol and substituted phenols, which do not possess inherent electron-capture sensitivity, at concentrations ⩾10 ng/ml in aqueous media by gas chromatographic analysis of the heptafluorobutyryl derivatives.
55 citations
TL;DR: In this article, a new derivatization procedure was developed for converting enantiomeric amino acids into diastereomers for resolution by high-pressure liquid chromatography, and two chiral reagents, (−)-1,7-dimethyl-7-norbornyl isothiocyanate and (+)-neomenthyl amines, were synthesized from corresponding amines.
TL;DR: A fast and sensitive method for the separation of serum and urinary creatinine is described, designed for incorporation into a definitive assay and the ease and speed of analysis makes is very attractive for routine clinical use.
TL;DR: A gas-liquid chromatographic method is presented for the rapid analysis of gentamicin, tobramycin, netilmicin, and amikacin from human serum, which may have application to all aminoglycoside drugs.
TL;DR: A novel technique of on-line photochemical derivatization is described which can enhance considerably both the sensitivity and specificity of detection in high-performance liquid chromatography (HPLC) which will extend the use of HPLC to many substances that cannot be satisfactory detected at present.
TL;DR: The importance of unavoidable phosphorus-oxygen bond cleavage reactins during trimethylsilyl (TMS) derivatization of condensed polyphosphates is demonstrated in this paper.
TL;DR: In this article, a rapid and reproducible high-pressure liquid chromatographic determination of gentamicin has been developed using a combination of paired-ion chromatography, post-column derivatization and fluorescence detection.
TL;DR: Application of the method to urine samples of patients with various endocrine disorders is included and preliminary results are given on the reproducibility of the derivatization procedure (formation of methoxime-trimethylsilyl (MO-TMS) ethers), the gas chromatographic analysis and the whole method.
TL;DR: In this article, the electron impact mass spectrum showed the typical peaks of a chloroindolyl-3-acetic acid methyl ester: the molecular ion cluster at m/e 223, 225 and the characteristic indole fragment ions atm/e 164, 166 (M-COOCH3)+.
Abstract: Immature green peas were harvested from plants grown in water culture on Johnson's nutrient solution with radioactive chloride. Twenty five g of lyophilized peas were extracted with butanol, the extract chromatographed, first on Sephadex LH 20 and then on silica gel. The radioactive hormone was followed by scintillation counting without the use of any scintillant. The radioactive fractions were taken up in a few μl of chloroform and injected into a gas chromatograph interfaced with a mass spectrometer. Derivatization was not necessary. The electron impact mass spectrum showed the typical peaks of a chloroindolyl-3-acetic acid methyl ester: the molecular ion cluster at m/e 223, 225 and the characteristic indole fragment ions at m/e 164, 166 (M-COOCH3)+. The chlorine atom was assigned to the 4 position of the indole ring after thin layer chromatography of radioactive extract and standards of four different chlorinated indolyl-3-acetic acid methyl esters.
TL;DR: A new column packing, SP-2510 DA (Supelco, Inc., Bellefonte, Pa), is an excellent stationary phase for the determination of a wide variety of anticonvulsant drugs by gas--liquid chromatography without derivatization, but when uncomplicated extraction procedures are used, serum cholesterol interferes with thedetermination of primidone.
Abstract: A new column packing, SP-2510 DA (Supelco, Inc., Bellefonte, Pa. 16823), is an excellent stationary phase for the determination of a wide variety of anticonvulsant drugs by gas--liquid chromatography without derivatization. However, when uncomplicated extraction procedures are used, serum cholesterol interferes with the determination of primidone. By the simple expedient of adding a short "pre-column" containing another phase (SP-2250 DA) the problem is overcome.
TL;DR: In this article, a derivatization method for the high-sensitive gas chromatographic determination of primary amines with teh alkali flame-ionization detector is presented Amino-containing compounds easily react with dimethylthiophosphinic chloride in the presence of triethylamine between −20 and +20°.
TL;DR: HPLC has not only helped to elucidate the complex metabolic pathways of polycyclic hydrocarbons, but has also enabled study of the covalent interaction of the reactive metabolites with cellular macromolecules, there contributing to the elucidation of the mechanism of action of these hydrocarbon carcinogens.
Abstract: Summary In conclusion, HPLC has proved to be a mild, convenient, and highly efficient method of analysis of polycyclic aromatic hydrocarbons and their oxygenated metabolites. Since some of the metabolites of polycyclic hydrocarbons are highly labile compounds, they are not amenable to the conventional gas chromatographic—mass spectrometric analysis. The HLPC analysis can be performed at ambient temperatures and practically in an anaerobic environment. Moreover, in reverse-phase chromatography, the metabolites are in chemically inert and highly lipophilic medium. HPLC offers a powerful complement to gas chromatography in that polar, and thermally labile metabolites that would have to be derivatized can be handled directly. Additionally, compounds which differ widely in polarity can be directly quantified in a single reverse-phase analysis without derivatization. HPLC has not only helped to elucidate the complex metabolic pathways of polycyclic hydrocarbons, but has also enabled study of the covalent interaction of the reactive metabolites with cellular macromolecules, there contributing to the elucidation of the mechanism of action of these hydrocarbon carcinogens.
TL;DR: A specific and sensitive quantitative assay for salicylate in serum or plasma that is faster, more specific, and more sensitive than existing fluorometric methods.
Abstract: We report a specific and sensitive quantitative assay for salicylate in serum or plasma. As little as 3 microliter of sample can be analyzed by an external standard procedure and larger volumes by diluting with the internal standard (o-methoxybenzoic acid). No extraction or derivatization is necessary and salicylic acid and the internal standard elute in 6 and 3.75 min, respectively. Peak-height ratios are linearly related to concentrations between 10 and 500 mg/liter. By comparison with an existing fluorometric method, our procedure is faster, more specific, and more sensitive.
TL;DR: In this paper, a method for the determination of picomole quantities of carboxylic acids by gas chromatography in combination with electron capture detection is presented, where the acids are extracted from aqueous media into dichloromethane by ion-pair extraction with tetrapentylammonium ions, and derivatized as their pentafluorobenzyl esters.
TL;DR: Carbofuran, and non-conjugated 3-hydroxycarbofuran and 3-ketocarbofuran were extracted from carrots, corn and potatoes with acetone and partitioned into hexane-methylene chloride, and Absolute recoveries for all three compounds were between 50 and 65% for spiked samples by the extraction method used.
TL;DR: The chief advantage of this new procedure is its sensitivity, requiring smaller amounts of sample to detect and quantitate estrogens in biological materials, and within-run precision was better than 5% for the full extraction and derivatization procedure for estriol from pregnancy urine samples.
TL;DR: This assay shows that in plasma of normal adult subjects there is a vitamin D3 concentration of 5 to 11 ng/ml, lower than those values reported for biological and competitive protein binding assays.
TL;DR: In this paper, the degradation of pentafluorobenzyl bromide has been studied with methylene chloride as the organic phase and aqueous phases with different pH values, buffer systems and quaternary ammonium ions.
TL;DR: In this article, a 10 min and sensitive determination of 3,4-dihydroxyphenyl-L-alanine (L-dopa), noradrenalin and doparmine has been developed.
TL;DR: In this paper, a procedure for the gas chromatographic (GC) determination of trace amounts of inorganic mercury is described, where Hg2+ is converted into diphenylmercury (DPM) with tetraphenylborate and the DPM is extracted with toluene.