Abstract: Energy-dispersive x-ray fluorescence is advantageous for trace analysis of soils present as thin films. A target thickness of about 2 mg cm-2 provides a compromise between optimal sensitivity and minimal absorption effect or optimal accuracy. Sample preparation involves only suspending the finely ground soil in water and drying this suspension on a thin mylar foil glued on a ring that fits into the x.r.f. spectrometer. The effective sample weight present in the exciting beam area is computed from the scatter peaks, a method that cancels out target heterogeneity problems. High accuracy is demonstrated for many elements in reference soil and rock materials; a precision around 5% and a detection limit around 10 ppm can be achieved. As an illustration, results for 16 trace elements and preliminary interpretation are given for a series of pedologically important soil samples from Brasil.

Abstract: A computer routine was developed for qualitative and quantitative analysis of photographically recorded spark-source mass spectra. Particular attention is given to the case of a graphite matrix. The program starts from the line intensities (expressed as Seidel values) and isotope masses calculated from the densitometer readings by a commercially available routine. From the intensities in the different exposures (typically 15 stages), it computes the parameters for the linear parts of the density curves for each ion. Taking into account mutual interferences of multivalent ions, isotope or C-clusters, oxide, carbide and dicarbide ions, the program automatically identifies and then quantifies the elements present. The precision of the results is around 5%. Reading and complete processing of one photoplate is achieved within 23 h.

Abstract: Non-destructive 14-MeV neutron activation analysis for silicon in steel has been applied with 56Mn as internal standard.56Mn is formed from the iron matrix via the 56Fe(n,p)56Mn reaction. Several methods of internal standardisation via56Mn are discussed. The 0.84-MeV photopeak of 56Mn is recommended if steel samples of about the same composition are to be analysed. Chemically analysed steel samples are used as silicon standards. A precision of 0.7% was obtained for an analysis plus standardisation time of 13 min. Special attention was paid to interferences produced by concentration changes of impurity elements. Several possible sources of errors were investigated.

Abstract: The precision of the 14-MeV neutron activation determination of oxygen in steel has been examined as a function of the oxygen content for a large number of steel and cast iron samples. The experimental and the statistically expected standard deviations have been compared. In the conditions used, 2.5 counts from 16N were registered for each p.p.m. of oxygen in the samples. The neutron flux was monitored by a simultaneously irradiated oxygen standard.

Abstract: A general standardization method is described for the determination of oxygen in solid samples via the 16O(n,p)16N reaction. Two systems of flux monitoring are considered: the sample versus standard comparator method and BF3 monitoring. The average flux in sample and standard, fast neutron shielding, fast neutron scattering, absorption of fast neutrons, absorption of 16N γ-rays and counting efficiency of sample and standard are considered. The influence of the target diameter on the obtained correction factors has also been studied. Total achievable accuracy is believed to be about 1%.

Abstract: Chromium and silicon are determined simultaneously in steel by 14-MeV neutron activation analysis. The activities of 52V(Eγ=1.43 MeV,TView the MathML source=3.76 min) from 52Cr(n,p)52V and 28Al (Eγ=1.78 MeV; TView the MathML source=2.24 min) from 28Si(n,p)28Al are evaluated by mixed γ-ray spectrometry. The influence of manganese and phosphorus, the main interfering elements, is negligible for most stainless steels. The count rate should be limited, to avoid 52V pulse pile-up effects interfering in the 28Al energy region. Precisions in the 2-10% range are reached, depending on the concentrations, for a 10-min analysis time. Results for a series of steel samples are compared with industrial analyses.

Abstract: The contamination of ground samples by a commercially available Lovibond McCrone Micronizing Mill is discussed. Tracer and weighing experiments showed that abrasion of corundum grinding elements was important, introducing 620 mg of abrasion products per minute of wet grinding. Agate grinding elements were abraded at ⩽6 mg min-1. The abrasion products and grinding elements were analyzed by x-ray fluorescence, spark-source mass spectrometry and neutron activation analysis. Contamination in trace element analysis of geological materials is likely to be negligible for agate grinding elements and, except for a few transition metals, also for corundum grinding elements. Contamination of typical biological samples is significant for a few elements even when agate elements are used, and is absolutely prohibitive for trace analysis when corundum elements are used.

Abstract: For multi-element analysis of human urine, 25-ml samples doped with yttrium as internal standard are evaporated gently and then ashed up to 460°C overnight. The residue is pelletized and analysed by energy-dispersive x-ray fluorescence. Acid addition to facilitate the digestion is not mandatory. Recoveries are nearly quantitative for traces of Fe, Ni, Cu, Zn and Sr, to a lesser extent for lead, but not for arsenic or selenium. The standard deviation per measurement is typically around 6%. The detection limits are such that some 10 elements can be determined simultaneously in normal urine, and possibly more in cases of importance to toxicology or industrial hygiene.

Abstract: All published procedures for multi-element preconcentration of trace elements, prior to x-ray fluorescence analysis of water, are reviewed and critically evaluated. Most preconcentration methods applied to the determination of single elements in water are also listed.

Abstract: Four decomposition procedures frequently used for biological material (dry ashing, open wet digestion, wet digestion in a teflon bomb and low-temperature ashing) are optimized for the conversion of biological samples to conducting electrodes suitable for multi-element trace determinations by spark-source mass spectrometry or emission spectrometry. The optimized procedures are evaluated with respect to contamination, retention and preconcentration of the trace elements, homogeneity of the electrodes and precision of the final results. Both dry-ashing methods are prone to losses by volatilization; simple dry ashing suffers from contamination problems during electrode preparation. Wet digestion gives better precision; digestion with nitric/sulfuric acids in an open flask is the method of choice for most elements being simpler and giving lower blanks than the bomb method.

Abstract: An instrumental neutron activation method for V, Mn and W in alloy steels with a 241 Am/Be isotopic neutron source is described. The samples were irradiated to induce the nuclear reactions 51V(n, γ) 52V, 55Mn(n, γ)56Mn, and 186W(n, γ)187W. The activities were measured with a NaI(TI) detector. Interferences on the measured photopeaks were shown to be negligible by measuring the half-lives of 62V, 56Mn and 187W.These thre elementes were determined in the range 1.512.9% in special steels; manganese in the range 0.51.6% was measured in cast irons. Calibration was done by comparison with results from wet chemistry and x-ray fluorescence spectrometry. The processing times for the vanadium, manganese and tungsten determinations were 11 min, 3 h and 26.3 h, respectively, but these were reduced greatly by intoruding a scheme wherein six samples were simultaneously irradiated and the 56Mn and 187W nuclides were measured sequentially for a series of 66 samples. The average processing time was reduced to 45 min for tungsten with a precision of 4.0% and accuracy of 3.4% and 22.8 min for manganese with a precision of 3.8% and accuracy of 3.1%.

Abstract: Ammonia is important in the atmosphere because it neutralizes acidic species. The relative importance of different inorganic ammonium compounds (chloride, nitrate and sulfate) in marine air chemistry was studied by single-particle characterization with the laser microprobe mass analyser. Standard aerosols were generated as a reference for compound identification, based on the fingerprint spectra obtained, and calculation of the relative sensitivity achieved for different ions in a marine aerosol matrix. The relative sensitivity for ammonium was low. Aerosol samples were collected in the Southern Bight of the North Sea under different meteorological conditions and examined for their ammonium compounds. Samples collected during an inversion period with continental influences showed a much higher content in all particles than samples collected under different meteorological conditions, where ammonium was mostly detected in the submicrometer particle-size range.

Abstract: Differential-pulse anodic stripping voltammetry is applied to determine cadmium, lead and copper in rain water acidified with nitric acid to pH 1.5, and zinc after partial neutralization to pH 4.5. Subsequently, cobalt and nickel are measured in the adsorptive mode after formation of their dimethylglyoximates. The effects of pH on the stripping peaks for Zn, Cd, Pb and Cu and of chloride on the stripping peak of copper are reported. Good agreement is found with d.p.s.v. determinations in hydrochloric acid medium and with a.a.s. measurements in most cases. Excellent accuracy is demonstrated; the average relative standard deviation per measurement appears to be between 12 and 22% for the overall analytical procedure for concentrations of 0.1550 μgl−1 of the various metals in the samples.