Showing papers on "Derivatization published in 1993"
TL;DR: A highly reactive amine derivatizing reagent, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, has been synthesized in a rapid, one-step procedure to form stable unsymmetric urea derivatives which are readily amenable to analysis by reversed phase HPLC.
988 citations
TL;DR: A rapid fully automated method for the determination of amino acids is described based on high-performance liquid chromatography and pre-column o-phthaldialdehyde derivatization and the coefficient of variation for the peak areas measured was below 3%, both in aqueous standards and in plasma.
275 citations
TL;DR: An HPLC method using a normal-phase silica column and a gradient of dichloromethane-methanol-formic acid water mixtures as the eluent was developed to separate procyanidins on a molecular mass basis, without derivatization.
183 citations
TL;DR: A simple technique for the rapid determination of methylmercury in fish tissue using standard reference materials demonstrates the accuracy, precision, and reproducibility of the analytical method.
Abstract: A simple technique is described for the rapid determination of methylmercury in fish tissue. Following simple dissolution in methanolic KOH solution, aqueous phase ethylation by derivatization with NaB(C2H5)4, cryogenic trapping on a packed chromatographic column, and GC separation, volatile mercury species are detected by atomic absorption spectrometry. Absolute detection limits are 4 pg of Hg for CH3Hg+ and 75 pg of Hg for labile Hg2+. Concentration detection limits for this optimized procedure are 4 ng of Hg for CH3Hg+ and 75 ng of Hg for labile Hg2+ per gram of pulverized dried fish tissue. Analysis of standard reference materials demonstrates the accuracy, precision, and reproducibility of the analytical method.
136 citations
TL;DR: In this article, a multiresidue method for the analysis of 30 pesticides and various transformation products (TPs) has been developed using 10 Empore 4.6-mm extraction disks containing C-18 and/or styrenedivinylbenzene.
Abstract: A multiresidue method for the analysis of 30 pesticides and various transformation products (TPs) has been developed. On-line solid-phase extraction (SPE) using 10 Empore 4.6-mm extraction disks containing C-18 and/ or styrenedivinylbenzene were placed in a disk holder and were used coupled on-line with liquid chromatography (LC) with either UV or postcolumn fluorescence derivatization (EPA method 531.1). The on-line SPE method, using 150 and 10 mL of water for LC-UV and postcolumn fluorescence derivatization, respectively, has been compared with the liquid-liquid extraction (LLE) method involving dichloromethane (NPS method 4) and 1 L of water
133 citations
TL;DR: In this paper, a 12-vertex closo-carborane CB 11 H 12 was derived with the ultimate goal of making it more versatile, more chemically inert, less coordinating, less nucleophilic, and more soluble in low dielectricsolvents.
Abstract: Of all the known classes of weakly coordinating anions (oxy anions, fluoro anions, tetraarylborates, carbanions, polyoxometalates, and carboranes), it is the carboranes that are perhaps most suited to further derivatization. With the ultimate goal of making the 12-vertex closo-carborane CB 11 H 12 - larger, more versatile, more chemically inert, less coordinating, less nucleophilic, and more soluble in low dielectricsolvents, 13 new derivatives have been synthesized.
128 citations
TL;DR: The new method, which uses C6 (3-microns particle) column material and an isocratic acetonitrile-water eluent, separates nearly to baseline 12 of the physiologically most abundant long-chain fatty acids in serum in < 20 min with a detection limit of approximately 2 pmol, making it suitable for routine analysis even with basic HPLC equipment.
Abstract: We developed a method for determining individual free fatty acids in serum by using a modified one-step Dole extraction, derivatization, and a new high-performance liquid chromatographic (HPLC) separation. Sample handling is minimized to a single transfer of the fatty acids (upper layer of the Dole extract), which are readily derivatized at 85 degrees C with p-bromophenacyl bromide without significant hydrolysis of esterified fatty acids. The derivatization mixture is directly injected into the HPLC apparatus. The new method, which uses C6 (3-microns particle) column material and an isocratic acetonitrile-water eluent, separates nearly to baseline 12 of the physiologically most abundant long-chain fatty acids (C12-C22) in < 20 min with a detection limit of approximately 2 pmol. It is therefore suitable for routine analysis even with basic HPLC equipment and can easily analyze a series of 10-20 samples in about 2 h including extraction until first results are available. The method is also applicable to other matrices than serum, e.g., for determination of precursor fatty acids such as arachidonic acid in platelets or of fatty acid patterns liberated by lipases or phospholipases A1/A2 in test systems.
125 citations
TL;DR: A new derivatizing reagent, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC), has been used successfully for chromatographic enantioseparation of 31 amino acids on cyclodextrin bonded stationary phases.
108 citations
TL;DR: In this paper, an approach using derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydrorylamine hydrochloride (PFBHA) followed by gas chromatography/mass spectrometry (GC/MS) analysis for the identification of unknown carbonyl compounds is presented.
Abstract: Carbonyl compounds play an important role in many environmenfl oxidation processes, but the identification of unknown carbonyl compounds can be difficult using existing techniques. We have developed an approach using derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydrorylamine hydrochloride (PFBHA) followed by gas chromatography/mass spectrometry (GC/MS) analysis for the identification of unknown carbonyl compounds. Electron ionization, electron-capture negative chemical ionization, and positive chemical ionization mass spectrometry have all been examined using model compounds. Methods for identifying molecular weight the described, as well as methods for differentiating between different types of carbonyl compounds
102 citations
TL;DR: When similar hydrolytic conditions were used in preparing protein hydrolysates, amino acid results obtained with the PITC derivatization method were generally in close agreement with those obtained by IEC; there is, however, room for improvement in the HPLC analysis of amino acids in physiological samples.
95 citations
TL;DR: Derivatization of amino acids by using ethyl chloroformate-ethanol-pyridine provides volatile products, N-ethoxycarbonyl amino acid ethyl esters (ECEEs), which are easily amenable to GC or GC-MS analysis.
TL;DR: A sensitive gas chromatographic method is presented that enables the uptake of cyclophosphamide during occupational activities, such as the preparation and administration of antineoplastic agents in hospitals, to be measured.
TL;DR: A simple and sensitive high-performance liquid chromatographic (HPLC) method that uses fluorescence as a detector for quantifying serum phenol and p-cresol in uremic patients on hemodialysis that will be useful for monitoring serum phenols in dialyzed patients as an index of he modialysis adequacy.
Abstract: We developed a simple and sensitive high-performance liquid chromatographic (HPLC) method that uses fluorescence as a detector for quantifying serum phenol and p-cresol in uremic patients on hemodialysis. Identification of phenol and p-cresol was confirmed by liquid chromatography/mass spectrometry. Because the HPLC method requires only simple extraction by ethyl acetate and does not require further steps such as derivatization, it is simple and rapid compared with gas chromatography or gas chromatography/mass spectrometry. Concentrations of phenol and p-cresol in uremic serum were significantly (p < 0.01) higher than those in normal serum. Reduction rates of phenol and p-cresol by hemodialysis were lower than those of urea and creatinine, suggesting a protein-binding property of phenol and p-cresol. This method will be useful for monitoring serum phenols in dialyzed patients as an index of hemodialysis adequacy.
TL;DR: In this paper, the extraction of chlorophenoxy acid herbicides from soil samples with supercritical carbon dioxide as extractant and tetrabutylammonium hydroxide and methyl iodide as derivatization agents was investigated.
Abstract: Extraction of chlorophenoxy acid herbicides from soil samples with supercritical carbon dioxide as extractant and tetrabutylammonium hydroxide and methyl iodide as derivatization agents was investigated. The extraction was carried out at 400 atm and 80 o C for 15 min static, followed by 15 min dynamic, at a carbon dioxide flow rate of approximately 1.5 mL/min (as liquid). The me of other derivatization agents (trimethylphenylammonium hydroxide, benzyltrimethylammonium chloride, and benzyltriethylammonium chloride) provided to be less effective than the tetrabutylammonium hydroxide/ methyl iodide combination
TL;DR: In this article, the derivatization of hydrazine with 2,3-naphthalene dicarboxaldehyde (NDA) followed by fluorescence detection is shown to be an effective method for the selective determination of extremely low concentrations of HZ in solution.
Book•
1 Jan 1993
TL;DR: The theory of chromatographic separations with reference to gas chromatography has been discussed in this article, where the development, technology and utilization of capillary columns for gas chromation are discussed.
Abstract: Introduction to the theory of chromatographic separations with reference to gas chromatography Gas chromatography instrumentation, operation, and experimental considerations The development, technology and utilization of capillary columns for gas chromatography Applications of packed and capillary GC Chemical derivatization in gas chromatography Gas chromatography in analytical toxicology - Principles and practice Gas chromatography in clinical chemistry Chrial separations by gas chromatography Environmental analysis using gas chromatography The role of gas chromatography in petroleum exploration Combined instrumental techniques using gas chromatography. Appendices.
TL;DR: A new, sensitive, and stable method has been developed for the analysis of fumonisin B 1 in rodent feed through gradient elution HPLC using precolmun derivatization with FMOC and fluorescence detection.
Abstract: A new, sensitive, and stable method has been developed for the analysis of fumonisin B 1 in rodent feed. Fumonisin B 1 , which is the major fumonisin metabolite produced by the fungus Fusarium moniliforme, has been implicated in human and animal diseases. Fumonisin B 1 was extracted from spiked rodent feed with acetonitrile/water (50/50) and then cleaned up with tandem C 18 Sep-Pak Vac and strong anion-exchange (SAX) columns. Fumonisin B 1 was eluted off the SAX colmun with 1% acetic acid in methanol and quantitated via gradient elution HPLC using precolmun derivatization with FMOC and fluorescence detection
TL;DR: In this paper, a microwave induced plasma atomic emission detector (MIP AED) was used to detect butyl and phenyltin compounds in water samples down to the level of 0.1 ng/l.
Abstract: A rapid, simple and sensitive method has been developed for the simultaneous determination of butyl- and phenyltin species in environmental waters. The ionic organotin compounds are ethylated in the aqueous phase using sodium tetraethylborate (NaBEt4) and extracted with hexane. A 25 μl aliquot of the extract is injected at a low temperature into a Tenax filled liner. After solvent venting the analytes are transferred onto the capillary column using programmed temperature vaporization (PTV) injection. Detection is done by means of a microwave induced plasma atomic emission detector (MIP AED). The method allows the determination of butyl- and phenyltin compounds in water samples down to the level of 0.1 ng/l (as Sn) while 50 ml of sample is sufficient for analysis. The accuracy of the method was confirmed by GC-AAS after chelation and Grignard derivatization.
TL;DR: In this article, an optimized method for the determination of substances occurring in auxin metabolism and l -tryptophan (TRP) catabolism was developed based on solid-phase extraction (SPE), two isocratic reversed-phase high-performance liquid chromatographic (HPLC) separations at different liquid phase conditions and simultaneous detection of fluorescence and UV absorbance at different wavelengths.
TL;DR: The method was linear for the studied amine carbamates up to 250 mg/l and found no artifact formation of either choline or trimethylamine (dietary amine compounds) or of dimethylethylamine or triethylamines (catalyst amines in the industrial setting).
TL;DR: A capillary gas chromatographic method with 63Ni electron-capture detection is reported for the determination of fluoxetine (Prozac) and its metabolite norfluoxetines in human plasma, showing stability studies show that fluoxettine and norfluxetine are stable inhuman plasma for up to 96 h at room temperature and up to one year at -20 degrees C.
TL;DR: Urinary recoveries following oral administration of these sugars to control dogs were determined as a baseline for the investigation of intestinal damage in this species and comparison of chromatograms illustrated enhanced permeability in dogs with gluten-sensitive enteropathy.
TL;DR: In this article, high-resolution X.p.s. analysis of TFAA-derivatized poly(vinyl alcohol) and plasma-polymerized poly (allyl alcohol) reveals significant chemical shifts in the carbon atoms attached to the −OC(O)CF3 group and carbon atoms in the β position relative to this group.
TL;DR: The ozonation products of cholesterol, which are of interest as possible biomarkers of O3 exposure, were studied by derivatization with 2,4-dinitrophenylhydrazine and a possible mechanism involving an enamine functionality is proposed.
TL;DR: The new fluorescent derivatization reagent with a lophine skeleton, 2-(4-hydrazinocarbonylphenyl)-4,5-diphenylimidazole (HCPI), has been synthesized and applied to the assay of saturated free fatty acids and could be successfully applied to four saturated fatty acids in normal human serum.
TL;DR: Using HPLC, this derivatization of vitamin D3 metabolites has been shown to increase the UV detectability of 25-hydroxyvitamin D3 by about 5-fold and the use of on-line capillary LC has been found to decrease the detection limits to the low picogram level.
TL;DR: The chapter describes the application of AQC to the analysis of protein and peptide hydrolyzate samples, with an emphasis on the accuracy and reproducibility of the compositional data.
Abstract: Publisher Summary This chapter discusses compositional protein analysis using 6-aminoquinolyl- N -hydroxysuccinimidyl carbamate (AQC)—a novel derivatization reagent. Today many standard protein chemistry protocols—such as Edman degradation and peptide mapping—can be accomplished with low or even subpicomole sample amounts through the use of modem liquid chromatography. Amino acid analysis has been assisted in this drive for higher sensitivity by the use of an array of precolumn derivatization reagents that yield easily detected labels. The synthesis of a novel activated carbamate, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC), forms the basis for a precolumn derivatization method and provides very accurate amino acid analysis of hydrolyzed peptides and proteins. A rapid reaction with amino acids forms highly stable asymmetric urea compounds with good fluorescence characteristics. A dramatic shift in fluorescence emission maximum for the amino acid adducts compared to the major reagent peak allows the direct injection of the sample reaction mixture with no interference from excess reagent. The chapter describes the application of AQC to the analysis of protein and peptide hydrolyzate samples, with an emphasis on the accuracy and reproducibility of the compositional data.
TL;DR: In this article, several red-absorbing labels containing a single succinimidyl ester functionality were synthesized and used for the derivatization of primary and secondary amines.
Abstract: To fully exploit the attractive visible diode laser-induced fluorescence (LIF) detection technique in column liquid chromatography (LC), covalent labeling procedures need to be developed which are compatible with near-infrared fluorescence. For this purpose, several red-absorbing labels containing a single succinimidyl ester functionality were synthesized and used for the derivatization of primary and secondary amines. Oxazines/thiazines, squaraines, and dicarbocyanines were examined as redabsorbing fluorophores. The quality of the LC-diode LIF system for the analytes concerned is illustrated by the concentration detection limit of the labeled n-octylamine (a test compound), which was as low as 2×10 -12 M. As expected in view of the limited reactivity of the succinimidyl ester group, the analyte concentrations required to obtain quantitative reaction with the label were equal to or higher than 2×10 -8 M. To show the applicability of the method to biological samples, urine was spiked with 5×10 -7 M 1-adamantanamine, extracted, derivatized with a dicarbocyanine-based label, and analyzed by LC-diode LIF
TL;DR: In this paper, the techniques for chiral recognition in NMR are reviewed with reference to applications primarily in the life sciences, including derivatization methods, lanthanide shift reagents, the use of cyclodextrins as chiral shifters, and the chiral auxiliaries.
Abstract: The techniques for chiral recognition in NMR are reviewed with reference to applications primarily in the life sciences A number of strategies for chiral discrimination are discussed in detail, including derivatization methods, lanthanide shift reagents, the use of cyclodextrins as chiral shift reagents and the use of chiral auxiliaries