High-performance liquid chromatographic method for the quantitative analysis of a synthetic copolymer with antitumor activity (copovithane) and methylamine in human blood plasma and urine

A method for the determination of a synthetic polymeric compound with antitumor activity (copovithane) and methylamine in blood plasma and urine is described. Copovithane is prepared by radical polymerisation of a diurethane with N-vinylpyrrolidone. The method is based on high-performance liquid chromatography of the methylamine hydrochloride which arises during the hydrochloric acid hydrolysis of the parent substance. The methylamine hydrochloride is converted to the trinitrobenzenesulphonyl derivative for the purpose of chromatographic detection. The limit of determination for copovithane in blood plasma is 1.2 mg/l and in urine 1.5 mg/day. The determination limit for methylamine in blood plasma is 0.2 mg/l and in urine 0.3 mg/day. The imprecision is dependent on the sample, and amounts to +/- 6.8% for blood plasma and +/- 6.4% for urine.     

A general method for coulometric titration of alkylanilines with bromine

A general method is described for the coulometric titration of alkylanilines with anodically generated bromine. The reaction is carried out in water-acetic acid medium and the reactivity is governed by varying the water content and the concentration of bromide ion and by the addition of pyridine. In this way most types of alkylanilines can be titrated quantitatively. Unlike the case for alkylphenols, the bromine consumption is not always higher in the pyridine-containing media than in the pyridine-free. The bromine consumption is also more dependent on the bromide content of the medium than it is for alkylphenols. The mean relative error, for the best medium for each compound, is +/-0.9% for primary alkylanilines, +/-0.9% for secondary and +/-1.2% for tertiary.     

Prediction of Retention in Liquid-Solid Chromatography with Ternary Mobile Phases

The method for the prediction of capacity factors in ternary mobile phases is presented. The adsorption mechanism of retention is considered. The simple theoretical equations are proposed for mobile phases for which the ratio of mole fractions of the weaker solvents remains fixed. The relations between parameters characterizing retention in ternary and binary mobile phases are discussed. The theoretical model is verified for numerous solutes and different mobile phases.     

Determination of formaldehyde in frozen fish with formaldehyde dehydrogenase using a flow injection system with an incorporated gel-filtration chromatography column

A flow injection analysis (FIA) system for determination of formaldehyde in frozen fish products is described. The system provides a rapid and selective determination of formaldehyde in aqueous fish extracts by the combination of a deproteinization procedure and a stopped-flow enzymatic approach in a FIA system. The FIA system is furnished with a gel-filtration chromatography column for on-line removal of the proteins from the extract before the enzymatic analysis is performed. Compared with the standard methods for determination of formaldehyde in fish products the present method is much faster and less affected by interferences. The limit of detection for the proposed method is 2.5 mg/l of formaldehyde. The sampling frequency is about 10 determinations per hour.     

Determination of cadmium in urine by extraction and flameless atomic-absorption spectrophotometry Comparison of urine from smokers and non-smokers of different sex and age

A method is presented for determining cadmium in urine by nameless atomic-absorption spectrophotometry after extraction. The sample is dried, ashed in the presence of nitric acid, and then the residue is dissolved in hydrochloric acid. Cadmium is extracted as its tetrahexylammonium iodide complex into methyl isobutyl ketone. The organic phase is analysed for cadmium by atomic-absorption spectrophotometry with electrothermal atomization. The median urinary excretion of cadmium for smokers aged 50-64 has been found to be 0.7 and 0.75 mug l . for males and females respectively, the values for non-smokers being 0.25 and 0.4mug l .     

Polarographic determination of methyl methacrylate

The permanganate oxidation of methyl methacrylate in weakly acidic solution yields methyl pyruvate. Hydroxylamine hydrochloride is used for destroying the excess of permanganate. At the same time it is consumed for oximation of the pyruvate, and the resulting oxime is determined polarographically. The reaction scheme of permanganate oxidation of methyl methacrylate is suggested and optimum working conditions are found both for permanganate oxidation and for polarographic determination. The method is used for the determination of vapours of methyl methacrylate in the air, for industrial hygiene purposes.     

A reproducible method for determination of nitrocellulose in soil

A reproducible analytical method for determination of nitrocellulose in soil is described. The new method provides the precision and accuracy needed for quantitation of nitrocellulose in soils to enable worker safety on contaminated sites. The method utilizes water and ethanol washes to remove co-contaminants, acetone extraction of nitrocellulose, and base hydrolysis of the extract to reduce nitrate groups. The hydrolysate is then neutralized and analyzed by ion chromatography for determination of free nitrate and nitrite. A variety of bases for hydrolysis and acids for neutralization were evaluated, with 5N sodium hydroxide and carbon dioxide giving the most complete hydrolysis and interference-free neutralization, respectively. The concentration of nitrocellulose in the soil is calculated from the concentrations of nitrate and nitrite and the weight percentage of nitrogen content in nitrocellulose. The laboratory detection limit for the analysis is 10mg/kg. The method acceptance range for recovery of nitrocellulose from control samples is 78-105%.     

The method of moments for multiplet deconvolution in gamma-ray spectrometry

The method of moments is described for deconvolution of a mixture of identical distributions; it is not necessary to know the type of the individual peak distribution. The algorithm for computing the positions and contributions of the peaks forming the multiplet is presented. The real shape of the peak is used. The computational stability of the method of moments for the deconvolution of various types of convolved triple peaks is shown to be satisfactory. The algorithm is used for deconvolution of some double peaks obtained in neutron activation analysis of rock standards. The program is fast and suitable for microcomputers.     

Atomic absorption determination of traces of cadmium in urine after electrodeposition onto a tungsten wire

A three-coil tungsten wire is used as electrode for the preconcentration of cadmium, which is then placed in a graphite tube for atomization and atomic absorption measurement. The heating parameters of the graphite furnace are optimized using the Modified and Weighted Centroid Simplex Method (MWCS), and computer program for automatic calculation. Sulphuric acid is selected as the supporting electrolyte for electrodeposition. The linear range of the calibration graph is 0.00-0.55 ng/ml. The detection limit is 0.01 ng/ml. For 0.1 ng/ml cadmium the coefficient of variation is 3.35% for ten parallel determinations. No interference occurs in the presence of more than 20 coexisting ions. Traces of cadmium in urine of normal people and in river water and the recoveries for cadmium are determined. The results are satisfactory.     

Theoretical analysis of resonant raman scattering: Simulations of lineshapes and excitation profiles

The steady-state response of a three-level system in the presence of a strong laser field is described with the density operator formalism, in order to derive an analytical expression for the intensity of resonance Raman scattering. The Liouville equation for the density operator is written in quantum form for both the molecular system and the radiation field, making use of the dipole and rotating-wave approximations for the matter-radiation interaction, and of the Markov approximation for the molecular decays. The equation is solved exactly for the laser field, and in perturbative way for the generated field. The results account for power broadening of the generated line. Rabi intensity-dip of the generated signal, and for the excitation profiles in the Franck-Condom approximation.     

Laser-induced breakdown spectroscopy applied on low-alloyed zinc samples

The use of laser-induced breakdown spectroscopy for chemical analysis in the single-shot regime has been investigated for low-alloyed zinc samples. Several parameters that are important for plasma formation has been investigated and their importance for accurate and precise single-shot measurements are discussed. The standard deviation is compared for measurements performed on a day-to-day basis during four days and for a measurement series consisting of five measurements in one day. It was found that the spread is not larger for a measurement series performed on a single day compared to day-to-day basis. The influence of local spatial inhomogeneities of the alloy elements in the sample concentrations is discussed in this context and the reference samples have been investigated with a scanning electron microscopy and light optical microscopy to verify this. It is found that the relative standard deviation of the signal depends to large extent on the sample homogeneity at low concentrations. The importance of spatial averaging for LIBS when doing calibrations is established in this case. The relative error for single-shot measurements will depend on the slope of the analytical curve and increase at lower concentrations.     

Statistical mechanical theory for steady state systems. II. Reciprocal relations and the second entropy

The concept of second entropy is introduced for the dynamic transitions between macrostates. It is used to develop a theory for fluctuations in velocity, and is exemplified by deriving Onsager reciprocal relations for Brownian motion. The cases of free, driven, and pinned Brownian particles are treated in turn, and Stokes' law is derived. The second entropy analysis is applied to the general case of thermodynamic fluctuations, and the Onsager reciprocal relations for these are derived using the method. The Green-Kubo formulas for the transport coefficients emerge from the analysis, as do Langevin dynamics.     

Activation analysis of bromine in rock samples

A simple method for the radiochemical neutron activation analysis of bromine in rock samples is described. The irradiated samples are ignited in an induction furnace in a flow of air for four minutes. The bromine expelled is collected onto activated charcoal which is measured using a Ge(Li) detector. The yield of the chemical separation is 85–100% and the detection limit is 7 ppb. The method is discussed and results for the analysis of 14 USGS standard rock samples are presented.     

Mathematical modeling of cyclic voltammetry for EC<Subscript>2</Subscript> reaction

The non-steady-state concentration for an EC reaction at planar electrode is derived. The analytical expression for the concentration for EC reaction is reported for small and large value of reaction rate. The asymptotic expression for the non-steady-state current for EC reaction is also derived. The analytical solutions for normalized current response were formulated using the method of Laplace transformation. The concentration and current are compared with available limiting case results, and are found to be in good agreement.     

Information and classical thermodynamic transformations

The relation between information and classical thermodynamic transformations is investigated. A probabilistic facet of reversible transforms is first illustrated. A method for quantifying the information associated with heating, cooling, expansion, and compression is then presented. Several applications are illustrated for a single-component van der Waals fluid. The significance is discussed in terms of dimension and measurement resolution properties, critical point behavior, and the algorithms designed for heat engines. The uncertainty in the state point position due to fluctuations is well-established for equilibrium systems. What is examined here is the uncertainty surrounding an extended locus of points. The Shannon information serves as a useful tool for quantifying this uncertainty.     

Conducting polymer ion sensor electrodes-III. Potentiometric sulfide ion selective electrode

A new potentiometric sensor electrode for sulfide based on conducting polymer films is introduced. The electrode is formed by electrochemically depositing a film of poly(3-methylthiophene) and poly(dibenzo-18-crown-6) onto an alloy substrate. Different methods were used for the electrode preparations. The alloy used has a low melting point, which allowed its use for manufacturing a microsize version of this electrode. The electrode response is stable for 3 days. The working temperature range for this electrode is between 10 and 40 degrees C. The linear dynamic range is 1.0x10(-7)-1.0x10(-2) M and measures total sulfide concentration over a range of pH from 1 to 13. The polymer electrode showed high selectivity for sulfide in the presence of many common interfering anions. The electrode is useful for the measurement of total sulfide in biological environments and can be manufactured in the micron scale. Therefore, it will be useful for the measurement within biofilms.     

A model calculation of protonic mobility in ice

The protonic conductivity in ice crystals is considered within the framework of strong coupling developed earlier by the present authors for semiconductors with narrow bands and strong coupling of electrons with phonons. The generalization for a two-band model is developed. The model used is the one described by Gosar and Pintar, the principal feature of which is the concept of the protonic conduction bands. The analytical expression for the protonic mobility is given. The results of the theory are in qualitative agreement with the experimental data.     

The evaluation and use of properties of individual ions in slution

A critical examination is given of extra-thermodynamic methods for evaluation of properties of individual ions in solution. The ways in which such data may be applied, or are required in various problems concerning specific properties of electrolyte solutions and in the fields of kinetics, electrochemistry, colloid and interfacial chemistry, are outlined. Special attention is given to the problem of evaluation of individual ionic thermodynamic functions for the hydration of ions but, in some cases, corresponding data for nonaqueous solutions are available for discussion and are of interest in a comparative way. The reliability of the various methods is assessed and estimates of numerical values for various individual ionic functions are tabulated. The question of scales of individual ionic radii, on which some of the derived data depend, is also examined. The dependence of various properties for anions and for cations on ionic radius is discussed and data are plotted comparatively. It is shown that for most, but not all, properties, the values for anions are more sensitive to increasing ionic radius than are the values for cations. This behavior, as well as the exceptions, is of theoretical interest. The significance of ion-specific behavior at interfaces is considered and the importance of interactions between ions of like sign of charge is indicated.Presented at the Symposium on Electrolytes, University of Reading, September 13, 1977.     

Liquid chromatographic determination of fenbendazole residues in pig tissues after treatment with medicated feed.

Fenbendazole (FBZ) is an anthelmintic widely used in farm animals to treat parasitic infestations. In pigs, it is administered in the food. The aim of this study was to validate an analytical method for the determination of FBZ and its metabolites in pig tissues. This method is based on oxidation of FBZ and its sulfoxide metabolite to the sulfone metabolite (FBZSO2). The limit of quantitation for this method is 20 ng FBZSO2/g for all tissues. The maximum residue limits (MRLs) established for FBZ and its metabolites in pig tissues are 50 ng/g for muscle, fat, and kidney and 500 ng/g for liver. This method is based on a liquid-liquid extraction followed by an oxidation with peracetic acid and a cleanup procedure based on 2 liquid-liquid extractions. Determination is achieved by high-performance liquid chromatography with ultraviolet detection. The present method is adjusted to the MRL established for FBZ and its metabolite residues. The analysis of the residues shows that after 72 h posttreatment, no FBZSO2 was detected in muscle, fat, and kidney and that liver levels were below the MRL.