Rapid Determination of Methylcyclopentadienyl Manganese Tricarbonyl in Gasoline by FAAS

ABSTRACT

A new method using microemulsified samples is presented. The method is suitable for the determination of manganese, present as methylcyclopentadienyl manganese tricarbonyl, in gasoline in the range 0～75μg ml^?1. The method has the advantage of simplicity, speed and the use of aqeous standards for calibration instead of organic standards. Coexistent elements do not disturb the determination. Results obtained by this method were better than those obtained by other methods for the same samples.     

Determination of Cd and Li in U3O8 Powder by AAS With Carbon Cup Atomization

Abstract

The flameless atomic absorption spectrometric technique has been applied for determination of Cd and Li in U₃O₈ by direct atomization of the powder samples in the carbon cups. Results obtained indicate that Cd and Li can be estimated in the ranges 0.05–2 ppm and 1–25 ppm respectively using 1 mg sample, Precision of the method for the two elements varies between 7–9%. Trace concentrations of transition elements do not affect their estimation.     

Special Report: Standard Practice of Liquid Size-Exclusion Chromatography - SEC (GEL Permeation Chromatography - GPC

Abstract

A reversed-phase ion-pair liquid chromatographic method was applied to the analysis of bambuterol hydrochloride chemical reference substance (CRS) and tablets. The purity evaluation of the reference substance was performed with amperometric, UV, diode array and mass spectrometric detection. The total amount of impurities found was less then 0.1%.

For the determination of bambuterol hydrochloride in tablets the method reproducibility was 0.9% and the recovery was in the range 99.8–100.7%. Detection limits for conceivable degradation products were about 1 ng. The suitability of different column packing materials was investigated.     

Determination of Gold and Palladium in Manganese and Nickel Compounds by Atomic Absorption Spectrometry After Separation by Use of Amberlite XAD-7 Resin

Abstract

A method for preconcentration and determination of traces of Au and Pd from manganese, nickel and their compounds is described. The trace elements are preconcentrated at a small column filled with Amberlite XAD-7 resin. After their eluation the elements are determined by flame AAS. The relative standard deviations (N=10) were found to be lower than 5%; the detection limit (3s, N=20) for Au and Pd in metal samples is 0.07 μg/g.     

Inductively Coupled Plasma Mass Spectrometry for Sequential Determination of Trace Metals in Rain and River Waters Using Electrothermal Vaporization

Abstract

The sequential determination of 14 trace metals, Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Mo, Cd, Sb and Pb, in rain and river water samples has been investigated using an inductively coupled plasma mass spectrometry (ICP-MS) with a graphite rod electrothermal vaporizer (ETV) in the presence of the mixed modifier of palladium nitrate and magnesium nitrate. The sensitivity enhancements due to the presence of the modifier were observed for all analyte elements. Detection limits as high as 0.52, 0.13, 0.89, 0.35, 1.76, 0.5, 0.9, 0.5, 0.04, 1.03, 0.28, 0.07, 0.1 and 3.78 pg, respectively, for Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Mo, Cd, Sb and Pb have been achieved. For the determination of trace metals in both rain and river water samples by this method, the repeatibility of sample solution were very good, i.e. from 1% to 7% (as a coefficient variation) and the recoveries of elements were good enough, i.e. from 81% to 106%, by using a standard addition method. There was no difference between the results obtained by nebulizer ICP-MS and those obtained by this method, except for zinc and arsenic.     

Determination of Penicillins and Cephalosporins N-Pyrrolylderivatives by HPLC

Abstract

An isocratic reversed-phase liquid chromatographic method for the determination of different types of penicillins and cephalosporins N-pyrrolylderivatives using UV detection at 254 nm is described. The mobile phases were aqueous methanolic (40–60%, v/v), 0.05M potassium phosphate buffer, pH 6.0.

The method is sufficiently sensitive and precise and is thus highly suited for use in the kinetic studies.     

Direct Determination of Some Trace Elements in Milk by Electrothermal Atomic Absorption Spectrometry

Abstract

A method for the determination of trace and ultra-trace elements (Fe, Cu, Mn, Co, Cr, Mo and Ni) in milk by electrothermal atomic absorption spectrometry is described. Milk samples are injected directly into the graphite tube. Optimal operating conditions have been established. The method appears to be accurate and reproducible. The relative standard deviation was, on average, 9%.     

Determination of Low-Molecular-Mass Aldehydes in Water Samples by Liquid Chromatography and Chemiluminescence Detection Using Continuous in situ Derivatization/Preconcentration with Dansylhydrazine

Abstract

A simple, expeditious, and sensitive method has been developed for the determination of low-molecular-mass aldehydes in water samples by liquid chromatography and peroxyoxalate–chemiluminescence detection. The method is based on continuous solid-phase extraction with in situ derivatization/preconcentration of the aldehydes using dansylhydrazine, which was first adsorbed on an RP–C₁₈ mini-column. For 10 mL of aqueous sample, the limits of detection (LOD) for C₁ to C₄ aldehydes were 20–30 ng L^?1, except for formaldehyde, which had an LOD of 400 ng L^?1. Application was illustrated by the determination of these aldehydes in water samples; the interday precision was always less than ca. 7%, and relative recoveries were more than 96%.     

The Stability of Precipitation Samples under Field Conditions

Abstract

Eight wet-only samplers. placed in one location were used to sample precipitation. Subsamples were taken from the sample bottles directly after the precipitation event and at regular intervals up to a period of 2100 hours and analysed, while the samples stayed in the samplers under field conditions.

Outliers were deleted by means of conventional statistical techniques. The resulting data base was tested by means of the F-test for consistency and for changes in the chemical composition of precipitation samples directly after sampling or after an extended stay under field conditions. Eighty-one percent of the samples showed consistent results and no clear indication of chemical changes was found.

Regression analysis indicated that the uncertainties for samples analysed after 1 week are less than 5% generally for the bulk elements and less than 14% for the trace elements. After a period of 400 hours the uncertainties for the buld elements increase to a level of 5–10% and 5–30% for the trace elements.

Contamination, as a result of handling the samples to obtain subsamples, seems the main cause for the increase of the concentrations which was observed.

Contamination during sample pretreatment and analysis in the laboratory is probably of minor importance.     

The Determination of a New Trifluorinated Quinolone,Fleroxacin, Its N-Demethyl,and N-Oxide Metabolites in Plasma and Urine by High Performance Liquid Chromatography with Fluorescence Detection

Abstract

A liquid chromatographic method is described for the determination of the new fluoroquinolone Ro 23–6240 and its N-demethyl and N-oxide metabolites in plasma and urine. The three substances were extracted from aqueous solution with dichloromethane/isopropanol containing sodium dodecyl sulphate. After evaporation and reconstitution, samples were analysed on a reversed-phase column using ion pair chromatography and fluorescence detection. The limit of quantification was 10–20 ng/ml (RSD 4%) using a 0.5 ml plasma sample, and the inter assay precision was 3–10% over the concentration range 50 ng/ml to 20 μg/ml. Recovery from plasma was 81% (RSD 10%) over the range 10 ng/ml to 5 μg/ml. The method has been applied successfully to the analysis of several thousand samples from human pharmacokinetic studies. Care has to be taken to avoid exposure of samples to direct sunlight, and the use of opaque vessels for sample storage and handling is recommended.     

Different Lubricating Oil Treatments for the Determination of Cu,Cr, Fe,Ni, Sb,Pb, and Zn by HR-CS FAAS

Abstract

Microwave-assisted acid decomposition, direct dilution in kerosene, and oil-in-water emulsion were evaluated as lubricating oil pretreatment procedures for Cu, Cr, Fe, Ni, Pb, Sb, and Zn determination by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS). For wet digestion, results were compared with those obtained by Flame Atomic Absorption Spectrometry (FAAS). The ultrasound probe used in emulsions sonication contaminated samples with Cr, although better results have been observed for the other six elements in this condition. In general, recovery percentages ranging from 81–106% (Cu), 80–107% (Cr), 85–114% (Fe), 82–116% (Ni), 86–117% (Pb), 85–115% (Sb), and 81–114% (Zn) were obtained. The HR-CS FAAS showed to be faster and more sensitive than FAAS.     

Determination of Triazine Herbicides in Aqueous Samples Using Solidification of a Floating Drop for Liquid-Phase Microextraction with Liquid Chromatography

Abstract

A rapid, simple, and efficient liquid-phase microextraction (LPME) method coupled with high-performance liquid chromatography and ultraviolet detection for the analysis of triazine herbicides was developed in this study. Under the optimum conditions, the enrichment factors and extraction recoveries were 33.0–72.6 and 11.2–23.2%, respectively. The detection limits (LODs) were in the range of 0.03–0.10 µg L^?1. The relative standard deviations for the determination of the triazine herbicides at μg L^?1 levels varied in the range 2.05–8.15%. The method was successfully applied in the determination of the triazine herbicides in aqueous samples with satisfactory results.     

Spektrochemische Bestimmung von Gallium -, Indium-Und Thalliumspuren unter Benutzung der Extraktionssysteme mit Drei Flussicen Phasen

Abstract

A new method for concentrating of microgram amounts of elements before their spectral determination is described. The method is based on the diantipyrilethanes property to divide the organic solvent into two phases, i. e., during the extraction of elements the three liquid phase system is formed. In one of the phases (the “third phase”) 93–98% of the extractable elements are concentrated. Owing to the small volume the third phase may be dropped onto electrodes avoiding evaporating, ashing of extracts and filling of electrodes before spectral determination. This twice of three times reduces the duration of analysis and increases the accuracy and sensibility of determinations. Based on the three liquid phase system the spectrochemical method of the microgram amounts determination Ga, In and Tl(II1) in Mg, Be, Al, Sc, Y, La, Ce, Zn, Cd, Pb has been developed. The use of such systems in analytical chemistry would be perspective.     

Slurry Sampling Electrothermal Vaporization Combined with ICP-AES for Direct Analysis of Environmental Samples

In this article, a polytetrafluoroethylene (PTFE) slurry was used as a chemical modifier for direct determination of trace elements in environmental samples by electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES) with slurry sampling. The vaporization behaviors of the analytes in slurry and solution were comparatively studied in the presence of PTFE. The main influence factors for this method were examined. Under the optimum operating conditions, the precision of this method was better than 7% with the detection limits varying from 1.7 ng mL^?1 (Cu) to 203 ng mL^?1 (Zn). The proposed method has been applied to the direct determination of the trace elements in camphor tree leaves and standard reference material (the combined sample of branch and leaf of shrub, GBW 07603) with satisfactory results.     

Direct Spectrographic Determination of In,La, Nb and Sr in Thorium Oxide

Abstract

A d.c. are emission spectrographic method is described for the determination of ppm levels of In, La, Nb and Sr in thorium oxide. The method permits determination of the above low and high volatile impurity elements in thoria using AgCl as carrier in an atmosphere of oxygen. The carrier-distillation technique reported makes possible the following range of estimations: In : 1–50 ppm; La, Nb : 10–500 ppm and Sr: 2–100 ppm. The method is simple and rapid and its precision ranges from 14% for In to 18% for Nb. Observations made on the choice of carrier and internal standard are presented.     

Determination of Pentachlorophenol (PCP) in Samples of the Environmental Specimen Bank Using Isotope Dilution

Abstract

Within the program of the Environmental Specimen Bank a quick and efficient method for determination of pentachlorophenol (PCP) in various environmental matrices has been developed. The method includes alkaline hydrolysis of bound PCP, acidification, simultaneous steam distillation and extraction in one glass apparatus. After clean-up and derivatization with acetic anhydride the samples were analyzed by gas chromatography/mass spectrometry. Concentrations were calculated using ¹³C-labeled PCP as the internal standard. Validation was carried out with various environmental samples (soil, fish, conifer needles, kale).

The method can be used for various biological samples without any modification. The extracts are free of matrix components (lipids, chloropyll, terpenes, etc.) and other contaminants, which results in clear chromatograms with few peaks; therefore, correct integration is facilitated. Although the recoveries of PCP are in the range of 50–90%, due to losses during the several method steps, these losses can be corrected with the ¹³C-labeled internal standard, resulting in high precision (1.5–2.2% standard deviation).     

Determination of Minocycline by Semi-Differential Cyclic Voltammetry at a Liquid/Liquid Interface

Abstract

The voltammetric behaviour of minocycline at a water/nitrobenzene interface has been studied by normal, semi-differential and semi-integral cyclic voltammetry. The semi-differential cyclic voltammetry can be used as a rapid, simple method for determination of the antibiotic minocycline in the range of 5–200 ug/ml and the relative standard deviation is within 3%. Drug samples were analyzed and satisfactory results were found as compared with US Pharmacopoeia method.     

Determination of Trace Elements in Aerosol Samples Collected on Polycarbonate Filters by Atomic Absorption Spectrometry

Abstract

The multi-element analysis of aerosol samples collected on polycarbonate filters and the wet digestion procedure in open vessel were investigated. The concentrations of Na, K, Ca, Mg and Zn were determined by flame atomic absorption spectrometry with a micro injection system while Cd, Pb, Cu, Ni and V were determined by graphite furnace atomic absorption spectrometry (AAS).

NIES N[ddot] 8 “Vehicle Exhaust Particulate” Certified Reference Material from the Japan Environment Agency was used to study the decomposition of the samples. Different treatments were applied in order to completely dissolve the aerosol samples. It was found that, from all the methods tested, attack with micro-quantities of HNO₃ and HCIO₄ in an air pressure digestion system was the best procedure for the determination of the elements by AAS.

The recommended method was appropriate for all elements and it was applied to real samples. Two nondestructive analytical techniques for the determination of Na, K, Ca, Mg, Zn and Pb have been compared with the proposed method: proton induced X-ray emission (PIXE) and neutron activation analysis (NAA). Results obtained by the application of these three techniques were similar.     

Atomic Absorption Spectrometry Analysis of Silicates by the Absorption Tube Technique

Abstract

By the combined use of the absorption tube technique and solvent extraction, determination of cadmium, cobalt, copper, iron, lead and nickel in silicate rocks was investigated.

Applicable concentration range was from 0.1 to 1.Oppm for all the elements except cadmium, for which the range was from 0.005 to 0.025ppm. The accuracy and recovery determined by the use of standard samples from the United States National Bureau of Standards and Geological Survey were satisfactory for practical purposes.     

Isomeric Transformation Of 4-Aminobiphenyl by U.V. Radiation and its Influence on the Determination by Flow Injection Analysis with Amperometric and Spectrophotometric Detection.

Abstract

Two flow-injection methods for the determination of 4-aminobiphenyl by amperometry (glassy carbon electrode) and spectrophotometry are proposed. A sample volume of 200 or 400 μl containing an analyte concentration of 0.1–1.0 μg ml^?1 or 0.8–24.0 μg ml^?1 for amperometric or spectrophotometric detection, respectively, is injected into a carrier stream containing 0.04 or 0.02 M Britton-Robinson buffer at pH 10.0 or 8.0, respectively.

The throughput thus achieved is 200 (amperometry) and 240 samples/h (spectrophotometry) and the relative standard deviation less than 2.5% and 4.2% respectively.

Both methods were applied to the determination of 4-aminobiphenyl in commercially available, legally permitted food colouring additive.