Showing papers in "Analytical Letters in 1976"
TL;DR: A radioimmunoassay for a prostaglandin endoperoxide metabolite, thromboxane B2, was developed and the antibodies were very specific for this compound, and the method had a sensitivity of 10 pg.
Abstract: A radioimmunoassay for a prostaglandin endoperoxide metabolite, thromboxane B2, was developed. The antibodies were very specific for this compound, and the method had a sensitivity of 10 pg. Platelets from a human subject were aggregated by addition of collagen and the synthesis of prostaglandin endoperoxides with time was monitored by parallel assay of prostaglandin E2, F2α and thromboxane B2.
190 citations
TL;DR: The first successful application of ion chromatography (IC) to the analysis of total water soluble sulfate and nitrate in ambient aerosols was described in this article, where conditions and data on sensitivity, selectivity, accuracy and repeatability were described.
Abstract: Ion exchange has been known to provide excellent separation of ions since 1850, and ion exchange chromatography has been in use since 1940. However, ion exchange chromatography has not been widely used for the automated analysis of eluted ions because of the background produced by the electrolyte used for elution. H. Small, T. S. Stevens, and W. C. Bauman, (Anal. Chem., 47, 1801 (1975)) recently developed a technique whereby the background is reduced to a minimum with eluant suppression. Eluant suppression allows the use of ion exchange chromatography with conductimetric detection as a sensitive and selective means for the analysis of practically all ionic species. This communication describes the first successful application of ion chromatography (IC) to the analysis of total water soluble sulfate and nitrate in ambient aerosols. Analytical conditions and data on sensitivity, selectivity, accuracy and repeatability are described. The application of this technique to the analysis of atniospheric ...
108 citations
TL;DR: In this article, the performances of several sorbents as collection media for the quantitative concentration and analysis of volatile, hazardous, vapor-phase compounds from ambient atmospheres were evaluated under a variety of conditions relevant to field sampling.
Abstract: The performances of several sorbents as collection media for the quantitative concentration and analysis of volatile, hazardous, vapor-phase compounds from ambient atmospheres were evaluated under a variety of conditions relevant to field sampling. Tenax GC was found to be superior to other sorbents in most cases. The effects of humidity, background air pollution, repeated re-use of sorbent, and transportation and storage of collected samples were investigated.
99 citations
TL;DR: In this paper, a scheme was proposed which permits the quantitative assay of seven different heavy metal species in natural waters using anodic stripping voltammetry of labile and total metal.
Abstract: A scheme is proposed which permits the quantitative assay of seven different heavy metal species in natural waters. The concentration of each species is calculated from measurements using anodic stripping voltammetry of labile and total metal in samples which were (a) untreated, (b) u.v. irradiated, (c) passed through a chelating resin column, and (d) u.v. irradiated then passed through a chelating resin column. The scheme was applied to the analysis of Cd, Pb and Cu in seawater.
94 citations
TL;DR: In this paper, a special enzyme thermistor device with a probe and a reference thermistor was described, and linear relationships between the temperature changes, At, measured with this device and the concentration of substrates applied were obtained.
Abstract: A special enzyme thermistor device with a probe and a reference thermistor is described. Linear relationships between the temperature changes, At, measured with this device and the concentration of substrates applied were obtained. The substrates tested were cholesterol, glucose, lactose and uric acid in standard solutions as well as in biological samples.
67 citations
TL;DR: The split-flow system described in this paper is comprised of two identical micro-columns, one containing an immobilized enzyme preparation, the other an inert support material, and the heat produced in each column on introduction of a sample is measured with thermistors placed in these columns.
Abstract: The split-flow system is comprised of two identical micro-columns, one of which contains an immobilized enzyme preparation, the other an inert support material. The heat produced in each column on introduction of a sample is measured with thermistors placed in these columns. The use of a reference column virtually eliminates the influence on the measurements of artifactual signals as unspecific heat, i.e., heat not produced by the enzymic reaction. The performance of the split-flow enzyme thermistor at a variety of pH's, ionic strengths or viscosities associated with the sample has been investigated and compared with previously described alternative enzyme thermistor arrangements. In this comparative study glucose at a concentration of 5 · 10−4 M was used throughout. On passage through the imnobilized glucose oxidase preparation this solution gave rise to a heat change At of about 0.01°C. The insensitivity of the system described herein towards such variations makes it particularly suitable for t...
45 citations
TL;DR: In this article, an enzyme thermistor was used to measure the heat produced when urea is passed through a small column containing immobilized urease, and the stability and sensitivity as well as the performance with clinical serum samples were evaluated.
Abstract: The application of an enzyme thermistor device in a simple and accurate procedure for the determination of serum urea is described. The enzyme thermistor measures the heat produced when urea is passed through a small column containing immobilized urease. The stability and sensitivity as well as the performance with clinical serum samples of the system is evaluated. Advantages are the simplicity, the low enzyme cost and the insensitivity to the optical properties of the sample and interfering substances, which may affect the commonly used assay procedures.
41 citations
TL;DR: In this article, a model for axial light attenuation of a coated waveguide (collector/sensor) whose polymer coating has been sensitized to ammonia was proposed.
Abstract: A model is proposed which addresses the factors involved in the axial light attenuation of a coated waveguide (collector/sensor) whose polymer coating has been sensitized to ammonia. The experimental results appear to corroborate the model predictions of high sensitivity (ppb) and independence of sample flow on the collector/sensor. Concentration and relative humidity both determine the slopes of the transmission curves, the latter factor of which can be reduced to a second order effect by controlling the relative humidity in the sample holder.
39 citations
TL;DR: Two different enzyme electrodes for the specific assay of phosphate ion are described, using the enzymes phosphorylase-a, phosphoglucomutase and glucose-6-phosphate dehydrogenase and hexokinase for amperometric monitoring of the NADH or NADPH formed in the reaction.
Abstract: Two different enzyme electrodes for the specific assay of phosphate ion are described. One system utilizes the enzymes phosphorylase-a, phosphoglucomutase and glucose-6-phosphate dehydrogenase, the second glyceraldehyde-phosphate dehydrogenase, phosphoglycerate kinase and hexokinase. In both cases the assay is effected by amperometric monitoring of the NADH or NADPH formed in the reaction at an applied potential of +0. 65 V.
31 citations
TL;DR: In this article, a quantitative analytical method for catechols in tobacco smoke using catechol-14C as internal standard was developed, and the concentrate of the dihydroxybenzenes was analyzed by GLC/MS.
Abstract: A quantitative analytical method has been developed for catechols in tobacco smoke using catechol-14C as internal standard. Main and sidestream smoke particulates are collected in cold traps, the acidic portion of the particulate matter is neutralized and the catechols are enriched by complexing with boric acid. The concentrate of the dihydroxybenzenes is analyzed by GLC/MS.
30 citations
TL;DR: In this article, selective adsorption of trace arsenite and arsenate anions in an aqueous solution by ferric hydroxyde supported on silica gel particles was investigated.
Abstract: Selective adsorption of trace arsenite- and arsenate anions in an aqueous solution by ferric hydroxyde supported on silica gel particles was investigated. Silica gel particles were loaded with ferric hydroxide of the range of 1 – 3 wt. % in terms of Fe based on the dry gel, and the extent of adsorption of arsenite or arsenate ion measured by batch- and column processes, being the highest at pH 6 in the presence of diverse foreign ions. With the use of silica gel containing 3.3 wt. % Fe, as much as 0.07 m mol of arsenic per gram of dry gel was adsorbed.
TL;DR: A fluorometric enzyme inhibition detector has been developed for the detection of carbamate pesticides after separation using high speed liquid chromatography as discussed by the authors, which was found to have the greatest sensitivity toward the carbamates, together with horse plasma and bovine erythrocyte cholinesterases.
Abstract: A fluorometric enzyme inhibition detector has been developed for the detection of carbamate pesticides after separation using high speed liquid chromatography. Housefly head cholinesterase was found to have the greatest sensitivity toward the carbamates, together with horse plasma and bovine erythrocyte cholinesterases. The substrate N-methyl indoxyl acetate is used for monitoring of enzyme activity.
TL;DR: In this article, the authors present the technique of coating application, the sensitivity relative to the amount of coating applied, a comparison of totally coated crystals to center coated ones, and a comparison with the new coating relative to triethanolamine.
Abstract: A considerable number of compounds have been shown to be sensitive to sulfur dioxide sorption using quartz crystals. To utilize the technique for the continuous measurement of SO2, coating loss has been shown to be a major limitation. For such a continuously flowing system a previous coating, triethanolamine, was found to evaporate at undesirable rates when used at high enough temperatures and flow rates for an adequate response time. Methods of remedying this problem have led to a new SO2 sensitive coating, ethylenedinitrilotetraethanol. This work presents the technique of coating application, the sensitivity relative to the amount of coating applied, a comparison of totally coated crystals to center coated ones, and a comparison of the new coating relative to the previously used triethanolamine.
TL;DR: In this article, an atomic absorption spectrometer has been used as a detector to monitor the effluents from a high-pressure liquid chromatograph for lead alkyl analysis.
Abstract: A routine atomic absorption spectrometer has been used as a detector to monitor the effluents from a high-pressure liquid chromatograph. This rapid, plug-in combination allows the selective, high-sensitivity determination of the individual inorganic and metallorganic compounds of the element of interest, resolved by the chromatographic column. The application to the analysis of lead alkyls, both in synthetic mixtures and in commercial gasoline, is illustrated.
TL;DR: In this paper, a rapid fluorometric method was developed for the determination of 0.01 − 0.5 mg 1−1 of boron in aqueous medium, which involved mixing aliquots of the sample and chromotmpic acid solutions plus acetate buffer at pH 6.7.
Abstract: A rapid fluorometric method was developed for the determination of 0.01–0.5 mg 1−1 of boron in aqueous medium. The procedure involved mixing aliquots of the sample and chromotmpic acid solutions plus acetate buffer at pH 6.7. Excitation and emission wavelengths were 313 nm and 380 mm, respectively. Interference could be eliminated by incorporating EDTA and DCTA an metal complexants in the buffer reagents.
Abstract: The utility of cyclic boronate derivatives for the combined gas chromatography-mass spectrometry of 1,2- and 1,3- diols has been further extended by the application of chemical ionisation techniques. Abundant quasi-molecular ions (M+1) in the isobutane chemical ionisation spectra of the examples studied (which include the methaneboronates of monoglycerides, monoalkyl glyceryl ethers, a steroid, dihydrosphingosine and a ceramide) are frequently accompanied by intense and informative fragment ions.
TL;DR: In this article, N-Nitrosodimethylamine (DMN) levels in ambient air were determined for an area surrounding an industrial site in Baltimore, MD using a Tenax GC cartridge for concentrating DMN and glass capillary gas-liquid chromatography/mass spectrometry with specific ion (m/e 74) monitoring.
Abstract: N-Nitrosodimethylamine (DMN) levels in ambient air were determined for an area surrounding an industrial site in Baltimore, MD. Using a Tenax GC cartridge for concentrating DMN and glass capillary gas-liquid chromatography/mass spectrometry with specific ion (m/e 74) monitoring, DMN was quantified. The limit of detection was ca. 0.3 ppt at 25°C. On the industrial site DMN levels reached 32,000 ng/m3 (10.67 ppb) of ambient air.
TL;DR: In this article, the titration curve permits simultaneous determination of octylsulfate and di-2-ethylhexglsulfosuccinate with an accuracy of 1.0%.
Abstract: Mixtures of sodium octylsulfate with sodium dodecyl-benzenesulfonate or sodium di-2-ethylhexglsulfosuccinate (Aerosol OT) were determined potentiometrically. The titration curve permits the simultaneous determination of both components with en accuracy of 1.0%.
TL;DR: It is concluded that, in most instances, enzymatic regeneration techniques are superior to chemical regeneration techniques and cofactor regeneration and reuse is most efficient when processing enzymes as well as cofactor regenerating enzymes are contained in the same reactor.
Abstract: The use of cofactor requiring enzymes in practical processes is dependent on regeneration and multiple reuse of the cofactor. Various methods currently available for the accomplishment of this goal are evaluated. We conclude that, in most instances, enzymatic regeneration techniques are superior to chemical regeneration techniques. We also conclude that, except in very unusual cases, cofactor regeneration and reuse is most efficient when processing enzymes as well as cofactor regenerating enzymes are contained in the same reactor. A cofactor classification based on regeneration requirements is proposed. Methods for the retention of both modified (for example, macro molecular) and native cofactors within the process reactor are discussed, as well as various cofactor recovery techniques. Finally, a prototype enzyme reactor employing native cofactor without retention, and allowing high substrate to product conversion with an extremely high number of cofactor cycles, is proposed. Utilizing this react...
TL;DR: In this article, a dedicated instrument for the quantitative determination of urea in blood serum or plasma has been developed, which uses urease immobilized on a porous alumina support and a gas-detecting electrode to measure ammonia resulting from hydrolysis.
Abstract: A dedicated instrument for the quantitative determination of urea in blood serum or plasma has been developed. The instrument uses urease immobilized on a porous alumina support and a gas-detecting electrode to measure ammonia resulting from hydrolysis of urea. Reproducibility and recovery studies show a high degree of accuracy, sensitivity, and specificity. Comparison of patient samples (plasma and serum) show no statistical difference when compared to the diacetyl monoxime, Auto Analyzer method.
TL;DR: A mass spectrometric method for compound identification in a mass-analyzed ion kinetic energy spectrometer (MIKES) is described in this paper, where the daughter ions arising from unimolecular and/or collision-induced dissociations are identified.
Abstract: A mass spectrometric method in which separation and compound identification are accomplished in a mass-analyzed ion kinetic energy spectrometer (MIKES) is described This procedure is possible in a reversed sector (source-magnet-energy analyzer-detector) mass spectrometer when ions characteristic of each mixture component are caused to fragment after mass analysis For each mass-selected ion, a scan of the ion kinetic energy spectrum identifies the daughter ions arising from unimolecular and/or collision-induced dissociations Straightforward application of this method to isomeric C5H100 ketone mixtures allows separation, identification, and quantitative analysis which is easy, rapid, and unambiguous
TL;DR: In this article, a method for the determination of 1-arginine and 1-lysine using decarboxylase enzymes and a carbonate ion selective membrane electrode is described.
Abstract: Manual and automated flow methods for the determination of 1-arginine and 1-lysine using decarboxylase enzymes and a carbonate ion selective membrane electrode are described. Excellent results are obtained in the millimolar concentration range for aqueous samples having physiological saline levels. The method could be utilized for the simple determination of specific amino acids in biological samples.
TL;DR: In this paper, the proton transfer of nineteen buffer moieties have been determined by adiabatic titration calorimetry in dilute aqueous solutions, and corresponding ionization constants covering a pK range between 6 and 11 were evaluated potentiometrically.
Abstract: Heats of proton transfer of nineteen buffer moieties have been determined by adiabatic titration calorimetry in dilute aqueous solutions. Corresponding ionization constants covering a pK range between 6 and 11 were evaluated potentiometrically. Relevant entropies of ionization were computer yielding a comprehensive tabulation of fifty-seven δH°, pK and δ° assignments, encompassing a wide variety of primary, secondary, and tertiary amine and amino acid systems. The majority of the systems included display suitable buffering capacity in the physiological pH range and are expected to be of utility in thermochemical studies of enzymatic processes.
TL;DR: A radioimnunoassay (RIA) has been developed to measure nanogram amounts of drug-related materials in human serum, after oral administration of 1.0 mg glyburide, G, Micronase®, (Micronase® is the registered trademark of The Upjohn Company for 1-[[p-[5-chloro-o-anisamido)ethyl]phenyl]-sulfonyl] 3-cyclohexylurea).
Abstract: A radioimnunoassay (RIA) has been developed to measure nanogram amounts of drug-related materials in human serum, after oral administration of 1.25, 2.5, 3.75 or 5.0 mg glyburide, G, Micronase®, (Micronase® is the registered trademark of The Upjohn Company for 1-[[p-[2-(5-chloro-o-anisamido)ethyl]phenyl]-sulfonyl] 3-cyclohexylurea). Of the compounds tested, only the known hydroxy metabolites of G cross-reacted significantly. Using 20 μl specimens, containing 25.6 ng G/ml serum, the within-day and between-day coefficients of variation for the assay were 3.47% and 3.18%, respectively. Recoveries were quantitative (100.6%). In normal human volunteers, peak serum drug concentrations were observed at 4.3 ± 1.4 hrs (S.D., M = 32). After single oral doses
TL;DR: In this paper, complete deuteriated alkanes are completely separated from the corresponding unlabeled alkanes and serve as suitable internal standards for the quantitation of environmental alkanes by gas chromatography alone.
Abstract: Quantitation by gas chromatography requires the use of suitable internal standards. Deuteriated analogs are superior, but usually require a mass spectrometer as the gas chromatographic detector to distinguish them from the compounds being measured. Completely deuteriated alkanes are, however, completely separated from the corresponding unlabelled alkanes and serve as suitable internal standards for the quantitation of environmental alkanes by gas chromatography alone.
TL;DR: In this paper, a simple semimicro carbon paste electrode is described for use in several electrochemical cells designed to accommodate between 1 and 300 μ1 of sample solution, which can be used to study the electrochemical properties of phenolic compounds.
Abstract: A simple semimicro carbon paste electrode is described for use in several electrochemical cells designed to accommodate between 1 and 300 μ1 of sample solution. Using this apparatus it is possible to study the electrochemical properties of phenolic compounds when the total sample available is on the microgram level or below. Quantitative work is possible for samples eluted from paper or thin-layer chromatograms. A semiautomatic device for serial assay of over 60 samples/hour is described.
Abstract: A general approach to the chromatographic analysis of quaternary ammonium compounds on silica gel thin layers is described The quaternary cations migrate as ion pairs with bromide or iodide as counter ions Methanol or chloroform-methanol mixtures serve as developing solvents, in which excess amounts of NaBr or NaI are dissolved If the solvent cannot dissolve sufficient quantities of halide salts, the latter can be sprayed onto the plate as a methanol solution prior to development The separation patterns of the quaternary ammonium compounds can be influenced by the choice of counter ion and by the choice of the organic solvent components
TL;DR: In this paper, the authors demonstrated the chemiluminescent detection of Ni(CO)4 in air using a reaction with O2/O3 and purified CO. The detection limit on their prototype detector is 0.01 ppb, with linear response into the ppm range.
Abstract: We have demonstrated the chemiluminescent detection of Ni(CO)4 in air using a reaction with O2/O3 and purified CO. The detection limit on our prototype detector is 0.01 ppb, with linear response into the ppm range. Decay of Ni(CO)4 in air has been studied in the ppb range and is approximately first order with a half life of about 30 minutes.
TL;DR: In this paper, the collector-surfactant-inert gas system consisting of lead sulfide, stearyl amine, and nitrogen was used to preconcentrate silver from spiked seawater samples.
Abstract: ACF was used to preconcentrate silver from spiked seawater samples by a collector-surfactant-inert gas system consisting of lead sulfide, stearyl amine, and nitrogen. Analysis was conducted in MIBK following complexation of the silver with TOTP and in an aqueous matrix with an atomic absorption unit. Replicate samples in the MIBK matrix yielded a mean recovery of 73.5% with a relative standard deviation of 18.4%; those conducted in an aqueous matrix and a mean recovery of 91.8% and a relative standard deviation of 8.1%. Silver in a seawater sample can be filtered, preconcentrated, and analyzed in approximately one hour.
TL;DR: In this paper, the qualitative and quantitative analysis of methyl cholanates using a ¼″ by 1′ μPorasil column, various mixtures of hexane and ethyl acetate and a refractive index detector is presented.
Abstract: Methods have been developed for the qualitative and quantitative analysis of hydroxy and keto derivatives of methyl cholanates utilizing a ¼″ by 1′ μPorasil column, various mixtures of hexane and ethyl acetate and a refractive index detector. The system has been calibrated for some of the methyl dihydroxycholanates using 3α;,7α-dihydroxy-12-oxocholanate as an internal standard and applied to the analysis of the mixtures of diols resulting from the reduction of methyl 3,12-dioxocholanate with NaBH4 and with Raney nickel.