Quantitative Determination Of Small Amounts Research Articles

Determination of small amounts of uranium by redox potentiometric titration

The redox titration of U in H3PO4 solution with an automatic titrator for determination of small amounts of U (0.1–0.2 mg) was studied. The choice of the oxidant appreciably affects the accuracy of the U determination, which decreases in the order KMnO4 > K2Cr2O7 > NH4VO3 > Ce(SO4)2. Irrespective of the oxidant used, the metrological characteristics of the method (repeatability r, laboratory precision R, and accuracy Δ) are significantly improved when the amount of U in the sample is increased from 0.1 to 0.2 mg, and high accuracy of the U determination is attained. The relationships obtained can be used in the development of a method for quantitative determination of small amounts of U in solutions.

Provision of accuracy for quantitative determination of small amounts of components: Principles of resolving the problem and their realization

Versions are suggested for resolving the problem of monitoring the accuracy of determining small amounts of components in samples of substances and materials.

Use of FTIR spectroscopy coupled with ATR for the determination of atmospheric compounds

Attenuated total reflection Fourier transformed infrared spectroscopy (ATR–FTIR) can be successfully used for the quantitative determination of small amounts of pollutants like the organic fraction of aerosols. The relation between sample concentration and reflectance is described by the Kubelka–Munk equation and was found to be linearly proportional to the absorption band of some functional group. Several parameters like the matter of solid matrix, the cleaning of the sampling support, the treatment of reflectance spectra and the base line correction considerably influenced the reflectance spectra and facilitated data interpretations. The feasibility of the ATR–FTIR was evaluated by the monitoring of specific organic group bands on filters collected in the French cities of Grenoble and Clermont-Ferrand. We have obtained for hydroxyl group a calibration curve by plotting the relative intensity of reflectance versus the concentration. The linearity was obtained for OH from 1 × 10 −1 to 1 × 10 0 mol L −1 with r 2 = 0.9959. We can consider that for a direct measurement of the intensity of reflectance, it is possible to perform quantitative ATR–FTIR organic group analysis.

Analysis of triethanolamine in trass cement pastes by voltammetric methods

Triethanolamine (TEA) in trass cement pastes has been analyzed by the Square Wave Voltammetric (SWV) technique. It has been observed that the adsorption effect of TEA on the trass cement increases with time and the adsorption is approximately complete at 12 h. The technique is sensitive for the quantitative determination of small amounts of TEA.

Use of diffuse reflectance spectrometry in spot test reactions for quantitative determination of cations in water

Diffuse reflectance spectroscopy can be successfully used for the quantitative determination of small amounts of pollutants like metals. The remission function was found to be linearly proportional to the concentration, when we applied the Kubelka–Munk equation. The color reactions of Cu(II), Co(II), and Ni(II) with dithiooxamide, were realised on filter paper. Reaction between Fe(III) and ammonium thiocyanate was realized on filter paper and gelatine matrix. All measurements were accomplished with a laboratory-constructed reflectometer. We have obtained a calibration curve by plotting the optical density of reflectance A R vs log of the mol l −1 concentration. Limits of detection at the 10 −4 M level were estimated for all the compounds. Linear dynamic range extend over one order of magnitude and shows the potential of device for the quantitative analysis of environmental pollutants.

Analysis of triethanolamine in white cement pastes by voltammetric methods

Triethanolamine (TEA) in cement paste has been analysed by square wave voltammetric technique. The technique is sensitive for the quantitative determination of small amounts of TEA. The percentage of the adsorbed TEA is very dependent upon the original TEA content of the cement sample. The adsorption reached a saturation level after 12 hours of hydration and remained almost invariant at longer times.

Quantitative measurements of ammonium, hydrogenophosphate and Cu(II) by diffuse reflectance spectrometry

Diffuse reflectance spectrometry is shown to be useful for the quantitative determination of small amounts of pollutants. The relation between sample concentration and reflectance is described by the Kubelka–Munk equation. The experiments were performed with a laboratory constructed diode array spectrophotometer. We can obtain the quantitative reflectance values of different precipitates like ammonium with Nessler’s reagent, hydrogenophosphate with silver nitrate and a complex such as Cu(II) with dithiooxamide ‘rubeanic acid’ by forming a spot colour on filter paper. We have obtained for each reagent a calibration curve by plotting the relative intensity of reflectance versus the log of the mol (dm 3) −1 concentration. The linearity was obtained for Cu(II) from 8×10 −4 to 2.5×10 −2 mol l −1 with r 2=0.9838 and from 10 −3 to 10 −1 mol l −1 for polyphosphate with r 2=0.9975 and from 5×10 −4 to 5×10 −2 mol l −1 for ammonium with r 2=0.9889. We can consider that for a direct measurement of the intensity of reflectance, it is possible to perform quantitative spot-test analysis.

A Quantitative Method of Determining Initial Amounts of DNA by Polymerase Chain Reaction Cycle Titration Using Digital Imaging and a Novel DNA Stain

A new nonradioactive method is described for quantitative determination of small amounts of DNA by PCR, examplified with mitochondrial DNA. The method represents a combination of serial dilution PCR and kinetic PCR and avoids the use of radioactivity by applying the fluorescent dye SYBR Green I, allowing visualization of PCR amplified bands on agarose gels in a broad exponential range of PCR cycles. After recording agarose gel images with a video camera in a computer, the band intensities are processed with the NIH image program and analyzed by a new graphical method. This nonradioactive method allows calculation of small original amounts of specific DNA in samples at high accuracy.

Time-resolved LIBS experiment for quantitative determination of pollutant concentrations in air

We propose a new time-resolved laser-induced breakdown spectroscopy (TRELIBS) system for quantitative determination of small amounts of pollutants in gas. Some experimental results showing the high resolution of the method are reported, and possible improvements of the system are discussed.

Quantitative Determination of Vinblastine in Tissue Cultures ofCatharanthus roseusby Radioimmunoassay

A radioimmunoassay has been developed for the quantitative determination of small amounts of vinblastine in tissue cultures of CATHARANTHUS ROSEUS (L.) G. Don. Antibody was obtained by the immunization of rabbits against a conjugate of vinblastine with bovine serum albumin. The antibody had a high affinity (Ka = 1.2 x 10 (9)l/mol) and specificity for vinblastine. The usable range of standard curve for assay was 0.5-10 ng/ml. Crude alkaloid extracts of tissue cultures could be assayed and many samples could be processed in one time. It was found that the vinblastine contents of multiple shoot cultures were lower than that of intact plants but much higher than that of callus cultures.

Photometrische Bestimmung aromatischer Kohlenwasserstoffe nach Reaktion mit Tetracyanoethylen

A rapid procedure for the quantitative determination of small amounts of aromatic hydrocarbons is described. After reaction with tetracyanoethylene in acetonitrile solution aromatics like benzene- and naphthaline-derivatives form stable and intensely coloured π-complexes, whose intensities can be determined by spectrophotometry. Optimum range for measurement is 50 to 600 μg in 10 ml solution.

A technique for the determination of protein concentration by neutron activation analysis of silver binding

A method for the quantitative determination of small amounts of protein samples was developed employing neutron activation analysis. Current methods of protein concentration determination are severely limited as a result of differences in the specific characteristics of each protein. Silver binding has been used as a sensitive colorimetric method to indicate the presence of protein. However, silver-protein complexes can have a variety of absorbance spectra unique to each protein, which complicate the analysis. Various amounts of specific proteins were equilibrated in an excess of silver nitrate prior to the reduction of the silver by the addition of NaBH4, HCHO, and NaOH. The protein-silver complex was rapidly separated from the unbound silver by centrifugation chromatography and the amount of bound silver was determined by INAA. The amount of silver was proportional to the amount of protein present in each sample. When the silver was not reduced prior to removal of the unbound silver by chromatography, only negligible amounts of silver remained bound to the protein. The stoichiometry of bound silver to protein on a molar basis showed relatively small differences for the proteins that were examined. This ratio was found to depend on the conditions of the binding and reduction of the silver. The results suggest that the binding of silver is not specific to any charged or polar groups on these proteins and may, therefore, provide a means of determination of the concentration of protein that has general application for all proteins.

Some Observations Upon the Distribution of Strontium in Four Species of Ophiuroids – Ophiocomina Nigra (Abildgaard), Ophiura Albida (Forbes), Ophiothrix Suensoni (Lütken) and Ophioderma Cinereum (Müller and Troschel)

Strontium was shown to occur in marine organisms in the early part of the nineteenth century (Moretti, 1813; Vogel, 1914). However, since early detection methods have relied upon chemical separation, accurate quantitative determination of small amounts of strontium, has presented many difficulties due to the chemical similarity of strontium and calcium. During the last 30 years a number of relatively sensitive methods have been developed (Smales, 1951; Thompson & Chow, 1955; Bowen, 1956; Hummel & Smales, 1956; Odum, 1957b; Sugawara & Kawasaki, 1958; Culkin & Cox, 1966; Riley & Segar, 1970; Gibbs & Bryan, 1972). Towards the beginning of this period, Vinogradov (1953) made an extensive review of the chemical data on the marine biota. Due to the limitations mentioned above there was relatively little information available on the occurrence of strontium.

Gas-liquid chromatographic analysis of dimedone derivatives of formaldehyde and other aliphatic aldehydes on capillary columns

The quantitative determination of small amounts of aliphatic aldehydes (formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde) in biological samples is difficult by the classical methods. The dimedone derivatives of these aldehydes were prepared and proved to be stable under the conditions of gas chromatography. The thermal properties of these derivatives were studied by thermal gravimetry, differential scanning calorimetry and thermal emission analysis, and the gas chromatographic peaks were identified by mass spectrometry. An analytical method was developed for the separation and determination of the dimedone adducts of aliphatic aldehydes by gas chromatography using capillary columns.

Quantitative Determination of Small Amounts of Toluene Diisocyanate Monomer in Urethane Adhesives by Gel Permeation Chromatography

Existing quantitative methods for determining isocyanate monomers are either too insensitive for small quantities, tedious, or give partially erroneous results due to sample reaction with moisture in the reagents or decomposition of sample where elevated temperatures are employed in the analysis. The objective was to develop a basic quantitative method which, with a minimum of modification, could be adapted to a variety of polyurethane products for quality control. Before chromatographing, the sample is treated with specially dried ethanol to convert the free monomer and any isocyanate groups on the prepolymer chain to the respective urethane derivatives. The sample is then diluted with tetrahydrofuran and chromatographed at room temperature on a 200, 200, 100, 100, 60 angstrom column series using a differential refractive index detector. Essentially, the basic procedure is not new or unique but its conversion to a quantitative reproducible method represents a breakthrough as far as a practical approach is concerned.

Purificatio of a specific d-apiitol dehydrogenase from a Micrococcus isolated from the surface of germinating parsley seeds

The branched-chain sugar d-apiose was oxidized to CO 2 by both Lemma minor and a bacterium which was isolated from the surface of germinating parsley seeds. An inducible dehydrogenase which catalyzed the interconvension of d-apiose and d-apiitol was detected in extracts of this microorganism. The enzyme which was purified about 200-fold was specific for d-apiose and d-apiitol. It oxidized myo- inositol and meso- erythritol slowly, but it was completely inactive with all of the other sugars and polyols tested. The enzyme was specific for NAD + and NADH as electron acceptor and donor, respectively. NADP +, NADPH, ascorbate, FAD, FADH 2, cytochrome c and ferricyanide were inactive. The K m for D-apiitol was 1.16·10 -2 M, d-apiose was 7.14 · 10 −2 M, NAD + was 3.5 · 10 -4 M and NADH was 1.5–15 -5 M. At high concentrations NADH inhibited the reaction. The molecular weight of the dehydrogenase determined by chromatography on Sephadex 200 and sucrose density centrifugal was 110 000. The products of the reaction were characterized by paper chromatography, periodate oxidation and gas chromatography of acetylated derivatives. A colorimetric method for the quantitative determination of small amounts of d-apiose was also developed during the course of this study.

Quantitative determination of 15-epi-PGF 2α in PGF 2α

High pressure liquid chromatography (HPLC) has been utilized successfully in the separation and analysis of prostaglandin isomers. An example involving the quantitative determination of small amounts of 15-epi-PGF 2α in PGF 2α is given in this report.

Determination of small amounts of hydrocarbon impurities in C 10-C 18n-paraffinic fractions

A method for the quantitative determination of small amounts of hydrocarbons contaminating n-paraffinic fractions of the range C 10-C 18 by using molecular sieve 5A has been developed. The determination is a two-stage analysis. First the sample with an intenal reference standard added is analysed in a separating column. The second stage is analogous, with the application of an additional pre-column, packed with molecular sieves which adsorb n-paraffinic hydrocarbons. By comparison of the results of this two-stage analysis, one obtains the contents of impurities in the sample being analysed. For fractions with the wide boiling range of the C 10-C 18 compounds, the impurities at a level of 0.4–10.0% w/w can be determined with satisfactory accuracy. In the case of narrow fractions or when the contamination of individual n-paraffins is to be determined, satisfactory accuracy of analysis was obtained even at low contents of impurities (down to 0.1% w/w).

The Synthesis of Isomers of d-Apiofuranosyl l-Phosphate

Abstract The α-d-apio-d-furanosyl 1-phosphate and α-d-apio-l-furanosyl 1-phosphate esters of d-apiose have been prepared from a mixture of the β-d-apiose tetraacetates in 20% yield. The β isomers of d-apiose tetraacetate were prepared from a dry syrup of the chromatographically pure sugar in almost quantitative yield. The tetraacetates of the two different ring forms were separated by paper and thin layer chromatography, and they were characterized by gas chromatography and analysis of their nuclear magnetic resonance spectrum. Reaction of the d-apiose tetraacetates with crystalline phosphoric acid resulted in the formation of four isomers of d-apiose monophosphate. The two monophosphate isomers described above and their 1,2-cyclic phosphodiester derivatives were separated by chromatography on Dowex 1-C1 columns. The products were further purified by paper chromatography in several solvent systems. Analytical data indicated the monophosphate esters were pure. The only sugar released on acid or enzymatic hydrolysis of these compounds was indistinguishable from d-apiose on paper chromatography with a wide range of solvent systems. Procedures for evaluating the stereochemical homogeneity of the d-apiose phosphate esters were developed. The configuration and position of the phosphate group was established by periodate oxidation and analysis of nuclear magnetic resonance spectrum. A colorimetric method for the quantitative determination of small amounts of d-apiose and microprocedures for studying the rate of phosphorylation of fully acetylated d-apiose-14C by crystalline phosphoric acid were also developed during the course of this study. The sugar phosphate esters were utilized to identify intermediates involved in the synthesis of the branched chain sugar which is present as a cell wall polysaccharide in Lemna minor and as a flavone glycoside in parsley.

A gas-chromatographic determination of tetra-aryl pyrophosphates and diaryl phosphorochloridates in triaryl phosphate

A gas-chromatographic method for the quantitative determination of small amounts of tetra-aryl pyrophosphates and diaryl phosphorochloridates in triaryl phosphate has been developed. The tetra-aryl pyrophosphates were converted by methanolysis into diaryl methyl phosphates, which were measured by gas-liquid chromatography with a flame-ionisation detector. The diaryl phosphorochloridates were converted with t-butyl alcohol into t-butyl chloride, which was measured in the same way.