Development of a procedure for the gas-chromatographic determination of vinyl chloride and 1,2-dichloroethane in blood with the use of headspace analysis

A procedure for the determination of the weight concentrations of vinyl chloride and 1,2-dichloroethane in blood over the range of 0.1–2.0 μg/cm³ was developed. The procedure is based on a static version of gas-chromatographic headspace analysis. The determination was performed on a column packed with a Chromaton N-AW-DMCS sorbent with 15 wt % Apiezon L using flame-ionization detection. The relative error of the procedure was no higher than 20%.     

Liquid Chromatographic Analysis of Ciprofloxacin and Ciprofloxacin Metabolites in Body Fluids

Abstract

An isocratic HPLC assay procedure for analysis of ciprofloxacin and three metabolites was developed. The procedure requires only dilution of bile, saliva, and urine samples prior to reverse-phase chromatography on a polystyrene-divinylbenzene (PSDVB) column; analysis of serum samples requires a cleanup step on a PSDVB cartridge prior to chromatography. The dependence of chromatographic efficiency on flow rate and temperature was investigated and the accuracy, precision, selectivity, and sensitivity of the procedure were evaluated. The developed procedure was also compared to a modified version of a published ciprofloxacin procedure that requires an octadecyl-silane (ODS) column for chromatographic separation. Similar efficiency, precision, and accuracy were observed with both procedures and both were used for analysis of clinical samples. However, the procedures were used for different purposes. The PSDVB procedure, because of more favorable column selectivity, was used to assay ciprofloxacin and its metabolites in bile, urine and saliva samples. The ODS procedure, because of a simpler serum preparation step, was used t o assay ciprofloxacin in serum samples.     

Determination of237Np in large volume samples of sea water by a radiochemical procedure

A radiochemical procedure followed by alpha spectrometry has been developed for the determination of²³⁷Np present at low activity concentrations in seawater. The analytical procedure is based on concentration of actinides from 1800 1 sea water samples by hydroxide precipitations. Neptunium is isolated by ion exchange, fluoride precipitation and extraction with TTA (thenoyltrifluoroacetone). As a radiochemical yield determinant²³⁹Np or²³⁵Np is used. Neptunium is electroplated onto stainless steel discs before alpha-spectrometry for about 10 days. The procedure allows for sequential separation of plutonium, americium, technetium and radiocaesium together with neptunium. The radiochemical yield for neptunium is only 20–50%, but the procedure has been applied with success on several samples contaminated with²³⁷Np at fallout or close to fallout levels.     

Group separation of rare earth elements by liquid-liquid extraction for the neutron activation analysis of silicate rocks

Rare earth elements are isolated as a group from neutron activated rock samples by a new radiochemical procedure based on extraction with thenoyltrifluoracetone/phenanthroline in CHCl₃. The procedure consists of three extraction steps, obviates the use of anactive carriers and gives practically quantitative chemical yields, thereby avoiding fractionation of the individual rare earths. Details of the dissolution, chemical separations and counting procedure are given togther with an analysis of BCR-1.     

Determination of Arsenic as the Oxidate by Ion Chromatography

Abstract

An ion chromatographic procedure is described for the analysis of arsenic as the oxo anion. The procedure involves oxidations of the arsenic to arsenate in an aqueous solution and injection onto an anion separator column, Comparison is made with a standard wet chemical procedure, and data is presented on reproducibility. In addition, there is a brief discussion of the applicability of this method to the determination of other oxo anions.     

Comparison of analytical methods for quality control of pharmaceutical formulations containing glutathione

Summary The aim of this investigation was the study and development of analytical procedures suitable for the assay of glutathione (GSH) in pharmaceutical formulations. Two are based on isocratic HPLC with a 250 mm×4.6 mm i.d., 5 μm C₁₈ column and UV detection. In the first procedure sample solutions were injected without pretreatment whereas in the second the samples were injected after derivatization with Ellman’s reagent which forms an easily detectable adduct with GSH. Good linearity was obtained over the range 0.12–6.00×10⁻⁴M for the direct procedure and 0.25–3.00×10⁻⁴M for the derivatization procedure. The precision and rapidity of analysis were also good for both methods. The third method is based on capillary zone electrophoresis (CZE) in a 27 cm×75 μm i.d untreated fused silica capillary containing pH 7 phosphate buffer. All results are in good agreement with a spectrophotometric procedure used as reference method.     

Potentiometric method for the determination of calcium in blood serum

A procedure for the determination of calcium in serum based on the complexation of calcium by a fixed amount of iminodiacetate at pH 9.6 with detection with a calcium-selective electrode is described. The effect of common concomitants was investigated; no interference was observed. When the procedure was tested on control sera, the bias was < 3% (6–8 replicate measurements); the relative standard deviation was < 5%.     

Speciation of waste water sediments

A sequential extraction procedure for waste water sediments was elaborated based on CO₂ and water extractants using supercritical fluid extraction instrumentation. The procedure gives information on water-soluble, carbonate-bound and mobile organic-bound trace metal fractions. The chemical interpretation of this procedure is comparable with the BCR recommended three-stage sequential extraction. The validation of the proposed procedure requires more detailed investigations.     

Determination of oxygen in bismuthate single crystals

An improved procedure for determining oxygen in single crystals was developed. The procedure was tested on samples prepared from stoichiometric BaBiO₃ by thermal treatment in a controlled medium. The error of the procedure is about 0.5 mol%.     

Partitioning of the orbital overlap matrix and the localization criteria

A new molecular orbital localization procedure is proposed. The approach is based on partitioning of the overlap matrix into atomic contributions in accordance with Bader's topological theory of atoms in molecules. The new procedure has several advantages over other schemes. It preserves the 6/7c-separability in planar systems and allows for a straightforward interpretation of the localized orbitals in terms of their localization indices and atomic occupancies. The new procedure is tested on the H2O, LiF, N2, CO, BH₃ · CO and Li₂ molecules.Research partially supported by US DOE.     

Identification of gasolines with hydrocarbon markers

A procedure for the identification of gasoline samples containing hidden chemical markers based on the results of fuel analysis by gas-liquid chromatography with sample preevaporation is proposed. Tetracosane (C₂₄H₅₀) in a concentration of 2.0 × 10⁻³ wt % was used as a marker. The procedure allowed us to detect the presence of the marker in gasoline samples subjected to uncontrollable evaporation in storage or on fire.     

Isolation of radioactive strontium from natural samples: A semi-automatic procedure

A procedure for semi-automatic isolation and determination of radioactive strontium from natural samples was developed. The method was tested by the determination of⁹⁰Sr in soil samples and the results obtained were compared to those obtained by the standard procedure. The procedure consists of leaching of strontium (and other cations as well) from soil samples with a water suspension of the cation exchanger Amberlite IR-20, the separation of strontium from other cations, e.g., potassium, calcium, sodium, barium by the anion exchangers Amberlite CG-400 or Dowex Ag 1×8 with 0.25M HNO₃ in ethanol-methanol mixture as eluent in the apparatus specially constructed for this purpose. Determination of⁹⁰Sr was done on the low-level gas-flow β-counter and by Cherenkow counting on the liquid-scintillation counter few hours after the separation. It was shown that this procedure might be successfully applied for rapid determination of⁹⁰Sr in soil samples and other natural samples in a timesaving manner.     

Gas-chromatographic determination of the impurity composition of permanent gases,methane, carbon monooxide,and carbon dioxide in high-purity monogermane

A procedure is developed for the gas-chromatographic determination of trace impurities of permanent gases (H₂, O₂/Ar, N₂), methane, and carbon mono- and dioxide in high-purity monogermane using a helium discharge detector and a heat-conductivity detector. The procedure is based on the principle of two-dimensional gas chromatography with a flowing injection system and allows the determination of the specified impurities in the concentration range from 2 × 10⁻⁵ to 10 vol %. The procedure is tested in the analysis of monogermane obtained by an electrochemical method.     

Speciation of butyltin compounds by on-line HPLC-ETAA of tropolone complexes in environmental samples

Tropolone (Trop) forms in solution stable complexes with monobutyltin (MBT Trop₂) and dibutyltin (DBT Trop). This property has been used to develop a separation procedure of butyltin compounds by liquid chromatography on cyanopropyl-bonded silica columns with a solution of tropolone in toluene as eluent. Tin-specific detection by on-line ETAA allowed the development of a simple procedure suitable for the determination of tributyltin and dibutyltin in water and sediment samples.     

Flow-injection photometric determination of trace copper in natural waters

A procedure for the flow-injection photometric determination of trace copper(II) in fresh natural waters is developed using a sorption preconcentration on the Diasorb-IDK-130 adsorbent with iminodiacetate groups. The procedure provides the determination of copper in the concentration range from 0.5 to 20 μg/L     

Procedures for a fast separation of berkelium from complex mixtures of reaction products

Two procedures are described for fast separations of berkelium from complex mixtures of reaction products arising from heavy ion reactions, such as¹⁸O+²⁴⁸Cm. The first procedure uses a combination of several extraction steps with a final separation on a cation exchanger, the second procedure starts with an anion exchange column which is followed by multiple extractions in different media. The elements separated in the different steps were analyzed and overall decontamination factors are given.     

The role of covariance in the analysis of gamma-ray spectra

When a gamma-ray spectrum contains a number of photopeaks originating from the same nuclide, the calculation of nuclide activity depends not only on the values of, and uncertainties in, the photopeak areas, photopeak efficiencies, gamma-ray emission probabilities and peak area correction factors, but also on the correlations that exist between these quantities. When photopeaks corresponding to a group of nuclides overlap or are unresolved, simultaneous estimation of the activities of all the nuclides present in the group is necessary if the information contained in the spectrum is to be used efficiently — a procedure which can prove important when the only prominent photopeak associated with a nuclide of interest overlaps with the photopeak of another nuclide. Two procedures for activity estimation are described: both procedures take correlations into account; one procedure deals with the special case of activity estimation for a single nuclide, where unresolved photopeaks are absent or neglected; the other procedure deals with simultaneous activity estimation using all the photopeaks associated with an interrelated group of nuclides.     

A green analytical procedure for sensitive and selective determination of iron in water samples by flow-injection solid-phase spectrophotometry

A greener analytical procedure based on flow-injection solid-phase spectrophotometry is proposed for iron determination. Iron(II) is reversibly retained on 1-(2-thiazolylazo)-2-naphthol immobilized on C18-bonded silica, yielding a brown complex. The metal ion is eluted as iron(II) with a small volume of a diluted acid solution without removing the immobilized reagent, which can be used for at least 100 determinations. Other chemicals (buffer and reducing agent) were carefully selected taking into account the analytical performance and toxicity. The developed procedure is 10-fold more sensitive in comparison to the analogous procedure based on measurements in solution, being suitable for the determination of iron in water samples with good accuracy and precision. The detection limit (99.7% confidence level), sampling rate and coefficient of variation (n = 10) were estimated as 15 μg L⁻¹, 25 measurements per hour and 4.0%, respectively. The proposed procedure involves a reduced effluent generation (3.6 mL per determination) and consumes micro amounts of reagents.