Showing papers on "Derivatization published in 1983"
TL;DR: In this article, the retention times of double-bond gibberellin isomers were determined using gradient or isocratic elution with methanol-acetic acid 1%.
118 citations
TL;DR: In this paper, a highly sensitive and moderately reactive derivatization reagents for hydroxysteroids have been developed, which are readily prepared from the corresponding anthracenecarboxylic acid in two steps.
95 citations
TL;DR: In this paper, the UV absorbance, corrected fluorescence spectra, quantum yields and lifetimes of 4-bromomethyl-6,7-dimethoxycoumarin derivatives of carboxylic acids as well as of a few fatty esters are presented.
95 citations
85 citations
TL;DR: In this article, the potential of 5-dimethylaminonaphthalene-1-sulphonylhydrazine (Dns-Hydrazine) as a precolumn fluorimetric labeling reagent for reducing sugars was examined in detail.
84 citations
TL;DR: A copper electrode has been used as an amperometric detector for amino acids in high-performance liquid chromatography, characterized by a high linear dynamic range, good reproducibility, the absence of electrode poisoning and a sensitivity comparable to that of UV absorption methods after derivatization of the amino acids.
75 citations
TL;DR: In this paper, the design of a post-column fluorescence derivatization system utilizing microbore columns is discussed theoretically and investigated experimentally, and it is shown that adequate mixing of two liquid streams can be achieved with a special 30-nl volume mixing chamber.
75 citations
60 citations
TL;DR: The derivatization method employing sodium naphthaquinone-4-sulphonate was found to be selective and sufficiently sensitive for the routine determination of amphetamine and methylamphetamine in urine and plasma samples at the ng/ml level.
58 citations
TL;DR: In this article, a simple and reproducible method for the simultaneous determination of dialkyltin compounds and their possible metabolites was developed, which can be used to detect the presence of any number of possible metabolites.
57 citations
TL;DR: In this paper, a trace analysis of aromatic amines is presented, which involves derivatization of the amines to the corresponding amides by reaction with a perfluorofatty acid anhydride.
TL;DR: In the HPLC system described extracts from citrus pulp are eluted after aflatoxin B1, and the use of post-column derivatization with iodine in water results in a 50-fold increase in sensitivity, permitting determinations at the microgram/kg level.
TL;DR: The regional distribution of CSA, CA, and other amino acids in the rat brain was studied using this new assay method that includes post-column derivatization of various amino acids with o-phthalaldehyde in the presence of 2-mercaptoethanol.
TL;DR: A comparative study of two post-column derivatization techniques for amino acid determination has been completed in this paper, using conventional high-performance liquid chromatography, amino acids were separated on either sodium- or lithium-form, polystyrene-based, strong cation exchangers, then derivatized with either ophthalaldehyde or ninhydrin.
TL;DR: In this article, a high-performance liquid chromatographic method was described for the simultaneous separation of nine guanidino compounds of biological importance using a reversed-phase column, μBondapak Phenyl, with linear gradient elution using aqueous methanol containing a Tris-hydrochloric acid buffer (pH 8.5).
TL;DR: In this paper, a method for the determination of formaldehyde and other aldehydes has been developed based on the reaction of the aldehyde species with 2-diphenylacetyl-1,3-indandione-1-hydrazone to form fluorescent azine derivatives.
Abstract: A sensitive, uncomplicated, and rapid method for the determination of formaldehyde and other aldehydes has been developed. The method is based on the reaction of the aldehyde species with 2-diphenylacetyl-1,3-indandione-1-hydrazone to form fluorescent azine derivatives. The fluorescence excitation and emission spectra have been obtained for several derivatives. The method developed eliminates the lengthy recovery steps required in other methods by performing the sample collection and derivatization directly in midget impingers containing an acetonitrile solution of the reagent. High performance liquid chromatography with fluorescence detection is used to separate and quantitate the individual aldehydes. The detection limits for formaldehyde, acetaldehyde, acrolein, and benzaldehyde are 6 ppb, 4.5 ppb, 0.6 pb, and 0.15 ppb, respectively, in the exhaust gas. The analysis time for the method is about 10 minutes if only one or two aldehydes are of interest. This technique has been used to measure ald...
TL;DR: The major advantages of the present device are that it produces thorough mixing of reagent and sample, so that a high and constant degree of derivatization occurs (thus producing high sensitivity; less than 0.1 pmol can be detected) and its low cost.
TL;DR: In this paper, a derivatization procedure with the use of o-phthalaldehyde (OPA) and various thiols was developed, and some structural assignments of the OPA-amino drug adducts were proposed and the electroactive properties of these substituted isoindolic products were investigated by voltamperometry.
TL;DR: In this paper, a method for the complete separation of the amino polycyclic aromatic hydrocarbons (amino-PAH) from complex coal-derived mixtures was described.
Abstract: A method is described for the complete separation of the amino polycyclic aromatic hydrocarbons (amino-PAH) from complex coal-derived mixtures. After pre-fractionation, the use of derivatisation with pentafluoropropionic anhydride of the amino-PAH-rich isolate of an SRC-II heavy distillate coal liquid enabled the complete separation of this chemical class to be achieved by gel permeation chromatography. The fluoroamide derivatives were converted back to the original amino functionality by catalytic hydrolysis on neutral aluminium oxide. Subsequent high-resolution separation of individual components was obtained by capillary column gas chromatography, and specific compounds were determined by gas chromatographic retention data and gas chromatography/mass spectrometry.
TL;DR: For the quantitative determination of traces of fatty acids in pore water, several gas and liquid chromatographic methods were tested and discussed and direct determination by gas-liquid chromatography with the use of formic acid-saturated carrier gas was found to be the least laborious method.
Abstract: For the quantitative determination of traces of fatty acids in pore water, several gas and liquid chromatographic methods were tested and discussed. Direct determination by gas-liquid chromatography with the use of formic acid-saturated carrier gas was found to be the least laborious method, but it is only recommended for the determination of volatile acids such as acetate and higher homologs. For the determination of lactate and formate, a derivatization procedure is necessary. The determination of these acids as phenacyl or benzyl esters was complicated by contaminants in the reagents. For this reason, a high-pressure liquid chromatography procedure with 4-bromomethyl-7-methoxycoumarin as a fluorescent labeling reagent is preferred. With this method, lactic, acetic, and formic acids could be demonstrated simultaneously at the nanogram level in 5-ml samples. Profiles of these acids in the sediment of Lake Vechten were measured, and they showed correlations with sulfate-reducing and methanogenic bacterial activities.
TL;DR: In this paper, the authors present an online type derivatization-separation-detection or separation-derivatizationdetection method for high performance liquid chromatography (HPLC) analytes.
Abstract: As in all other forms of chromatography, high performance liquid chromatography (HPLC) has come to rely quite heavily on derivatization of individual analytes for improved qualitative and quantitative identifications (1–13). Virtually all of this work has involved the use of homogeneous type derivatizations, wherein the sample solution to be injected, in the pre-column approach, or the HPLC effluent, in the post-column approach, are fully mixed with the derivatization reagents in solution. Clearly, homogeneous type derivatizations can be done off-line or on-line, in either the pre-or post-column modes, but in general, pre-column methods have been done offline, and post-column approaches have been done both on-line and off-line. Online type derivatizations, in either the pre-or post-column modes, appear to offer some very significant advantages. Major among these is the ability to perform derivatization-separation-detection or separation-derivatization-detection following injection of the sample m...
TL;DR: Optimal pH conditions of the aqueous medium were established which provide a quantitative yield of the formate derivative of primary and secondary catecholamines and these mixed derivatives appeared to be very suitable for quantitative determination of catechlamines and related compounds in biological fluids by gas chromatography-mass spectrometry.
TL;DR: This paper showed that most polymeric gel phases are in fact "monomeric" and showed that the clear distinction between monomeric and polymeric derivatised silica gel phases is not warranted.
TL;DR: As gas chromatography-mass spectrometry is the most conclusive confirmation technique available today for the detection of ppb levels of anabolics in the urine of cattle, the following procedure was used.
TL;DR: Sorbitan esters of several fatty acids have been analyzed by high pressure liquid chromatography (HPLC) using an RP-18 column as discussed by the authors, and they have been separated using isopropanol/water as the elution mixture.
Abstract: Sorbitan esters of several fatty acids have been analyzed by high pressure liquid chromatography (HPLC) using an RP-18 column. No derivatization was necessary. Mono-, di- and trisorbitan esters of palmitic, stearic, oleic, isostearic and sesquioleic acid have been separated using isopropanol/water as the elution mixture.
TL;DR: In this paper, a method for the quantitative determination of aliphatic carboxylic (fatty) acids in dilute aqueous solutions is presented, where acids are converted into pentafluorobenzyl esters by extractive alkylation and analyzed by means of capillary column gas chromatography with electron-capture detection.
TL;DR: In this paper, three N-substituted maleimides were tested as derivatizing reagents; N-(4-anilinophenyl) maleimide (APM) was the most favorable in terms of sensitivity and reactivity.
TL;DR: In this paper, the structures of the products formed between several n -aliphatic amines and o -phthalaldehyde (OPT) during routine post-column derivatization after high-performance liquid chromatographic (HPLC) elution, were determined by gas chromatography-mass spectrometry.