Determination of palladium in gasoline by neutron activation analysis and automated column extraction

^? Palladium in gasoline was determined by means of neutron activation analysis (NAA) and selective sorbent extraction. Unleaded gasoline consistent with DIN EN 228, RON 95 was irradiated at a thermal neutron flux of Φ_th = 1.68 · 10¹³s^–1cm^–2 and an epithermal neutron flux of 3.32 · 10¹¹s^–1cm^–2 for t_irr = 12 h. The irradiated gasoline was digested with nitric acid and palladium was then separated as N,N-diethyl-N’-benzoylthiourea complex by an automated column pre-concentration procedure. The eluate of 50 μL was dried on a filter paper and the 88.03 keV photons resulting from the decay of ¹⁰⁹Pd were detected in a low level HPGe spectrometer with an efficiency of 35.5%. Severe interferences with other matrix constituents, especially ⁸²Br could be overcome and the detection limit for palladium was improved to 3.4 ng/L at a confidence level of 90%. Although the analytical procedure applied yielded the lowest detection limit for palladium obtained in gasoline up to now, no indications for the presence of palladium were found.     

Determination of trace impurities in palladium by neutron activation analysis

Trace amounts of Ir, Au, Ag, Pt, Zn, Mn, and Cu were determined in high purity palladium by destructive and instrumental neutron activation analysis (NAA). The latter version of NAA was employed for the determination of Ir, Au and Ag. Special attention was paid to a new non-destructive method for the determination of silver traces in palladium. The results obtained by both versions of NAA are critically discussed and compared.     

Determination of palladium in alloys and ores by substoichiometric thermal neutron activation analysis

A rapid, selective and simple method have been developed for the determination of palladium in alloys and ores by thermal neutron activation analysis, incorporating substoichiometric solvent extraction of Pd/II/ with 1,2,3-benzotriazole /1,2,3-BT/ into methyl iso-butyl ketone /MIBK/. Two samples and a standard can be processed and counted within two hours.     

Substoichiometric determination of palladium by neutron activation analysis

A method is described for the substoichiometric determination of traces of palladium by neutron activation analysis involving the extraction of palladium with isonitrosoacetophenone. The sensitivity of the method is 0.005 μg of Pd. With 200 mg of silver alloy containing 0.0005% palladium, the average of three determinations of Pd is 0.98 μg, which varies between 1.07 μg and 0.91 μg at 95% confidence limit. The time required for radiochemical purification and counting of the sample does not exceed 12 minutes. Part of this work was presented at the International Conference on Modern Trends Activation Analysis, held in Gaithersburg, Maryland, USA, October 7–11, 1968.     

Determination of palladium by chemical neutron activation analysis using low energy photon spectrometry

A chemical neutron activation analysis method to determine trace amounts of palladium present in the uranium ores has been developed. Palladium was concentrated on an anionic exchanger to purify from large amounts of uranium, iron and copper that were present in the ore. The resin in which Pd was adsorbed was neutron irradiated and the activation product¹⁰⁹Pd was assayed through its daughter^109mAg by low energy photon spectrometry to estimate palladium. Both the 88 keV gamma-line and the 22 keV X-ray line (arising out of the internal transition of^109mAg) were used to arrive at the concentration values by a standard comparison technique. A thin window Si(Li) detector and an HPGe detector were used for the radioactive assay. Detection limits and the advantage of using the X-ray line of Ag over that of the gamma-line were discussed. An absolute detection limit of 0.12·10⁻⁹ g could be arrived at by the use of the 22.10 keV X-ray line in an interference-free condition.     

An automated facility for neutron activation analysis

A fully automated neutron activation analysis (NAA) facility has been constructed at the Whiteshell Nuclear Research Establishment. This high-capacity facility has been designed for use with a wide variety of neutron sources, including Canada's SLOWPOKE II and MAPLE research reactors. Its pneumatic transfer system is driven by a Square-D Model 500 programmable controller, linked in turn to a Nuclear Data ND6700 computer/spectrometer. Custom software for data entry and system control has been combined with Nuclear Data software for gamma-spectrum acquisition and processing to create a flexible, easy-to-use facility for NAA. Its design and performance are discussed.     

Determination of fluorine in zinc ores using an isotope neutron source based automated neutron activation analysis system

A method has been developed for routine determination of fluorine in zinc sulfide ores by activation with fast neutrons from a 6.6 Ci²²⁷Ac−Be isotope source and counting of the 4.5 to 7 MeV gamma-rays of the product nuclide¹⁶N. Samples and standards consist of pellets pressed from a mixture of powdered material with wax or graphite. Samples and standards alternate in a sequence of 20 seconds irradiation, 4 seconds decay and 20 seconds counting. This analysis sequence, including the computation of the analysis results from the counting data automated by means of a LSI-11 Microprocessor with 12K×16 bit memory. The zinc ores, containing 0.3 to 0.7% fluorine have been analysed with a precision ranging from 1.56 to 1.33% relative. As a test for the reliability of the method, three standard reference materials were analysed in the same way as the zinc ore samples.     

Determination of mercury in air by neutron activation analysis

A sensitive method for the determination of mercury in sea and surface waters is presented. A distinction is made between inorganic, organic and particulate mercury. In the determination of inorganic mercury, the element is isolated by reduction and volatilization, followed by absorption on a charcoal column. The total mercury content of the water with and without suspended solids is determined by absorption from the solution onto a column of charcoal. In all cases, the mercury on the absorber is determined by thermal neutron activation analysis. The limit of detection is l ng 1^-1.     

Determination of lithium in graphite by neutron activation analysis

Trace impurities of lithium in graphite is one of the sources of tritium in high-temperature reactors. To determine contents of less then 1ng/g a procedure based on the (n,)-reaction of⁶Li was developed. The samples are irradiated in a reactor and then ignited in a Wickbold apparatus. Thereby the tritium produced by the (n,)-reaction is completely converted in HTO, which can be easily purified by distillation and, if necessary, by a scavenger precipitation step. Several types of graphite have been investigated and the lowest content measured was 0.2 ng/g.     

Determination of mercury in bismuth by neutron activation analysis

A method has been developed for the determination of traces of mercury in bismuth by neutron activation analysis. After sample irradiation at a flux of 7 · 10¹³ n cm^-2 s^-1 for 20 min, mercury was separated from bismuth by addition of ammonium sulfide and re-dissolution of bismuth (matrix) sulfide with nitric acid, and filtration of sulfur containing mercury on a membrane filter. The activity of the 68- or 68–77-keV region, counted with a Ge(Li) or NaI(Tl) detector, was used for quantitative measurements. The method was applied to bismuth samples containing 0.1–100 p.p.m. of mercury.     

Determination of rhenium in molybdenites by neutron activation analysis

A thermal neutron activation method for the determination of rhenium in molybdenites is described. The rhenium is separated from the matrix after irradiation by pyridine extraction from 4 N sodium hydroxide solution; γ- and β-spectrometry are applicable. For a neutron flux of 4 · 10¹¹ n/cm².sec, an irradiation of 2 h and a sample of ca. 50 mg, β-counting allows determinations in the p.p.b. range.     

Determination of lithium by instrumental neutron activation analysis

The fast transfer system in the DR 2 reactor for irradiation at a thermal neutron flux density of 10¹³ n·cm⁻²·sec⁻¹ was used for the determination of lithium by the⁷Li(n, γ)⁸Li reaction. β-counting with a large perspex Cerenkov detector begun at 0.3 s after the end of irradiation, and multi-scaler data was accumulated in 300 channels at 0.1 s per channel. With a suitable choice of discrimination level only¹⁶N and background interfere, and the 0.84 s half-life of⁸Li was resolved by the method of weighted least squares. Results are presented for 36 international geochemical reference materials, and for a few biological samples, including BOWEN's kale and the NBS Standard Reference Material 1571 Orchard Leaves.     

Determination of gunshot residues by neutron activation analysis

Systematic investigations of gunshot residues, deposited around the bullet hole, have been carried out. The traces were produced by firing on filter papers from distances of 5 to 200 cm using one rifle and three pistols as arms. Antimony, lead and barium were quantitatively determined after irradiating the samples in the nuclear reactor TRIGA Mainz by measurement of gamma-lines of^122mSb,¹²²Sb,^207mPo and¹³⁹Ba. The determinations were made purely instrumentally and-where the half lives were long enough-also after chemical separation of the nuclides. The amount of the elements were determined in dependence of the firing distance and of the area around the bullet hole.     

Determination of chromium in blood by neutron activation analysis

A procedure for the determination of chromium in blood has been developed with a sensitivity of 5×10⁻³ μg Cr. Dried blood was irradiated with a neutron flux of 10¹² n·cm⁻²·sec⁻¹ in the VVRS reactor for 4 weeks, then the sample was mineralized and the chromium isolated by extraction as perchromic acid. The determination of the chromium content was accomplished by measuring the 0.32 MeV gamma energy of⁵¹Cr. In order to make correction for the interfering reaction⁵⁴Fe(n,α)⁵¹Cr, the formation of chromium from high-purity iron was investigated. The chromium content of the blood samples was between 1.03×10⁻² and 5.2×10⁻² ppm Cr.     

Determination of gold in platinum by neutron activation analysis

The determination of gold in platinum by neutron activation analysis is described. The possibility of screening out the influence of the nuclear reactions on the final result of the determination was studied. In the case of microamounts of gold in platinum, gold was separated previously by extraction chromatography with dithizone as organic stationary phase. Gold fixed on the column was irradiated and determined gamma-spectrometrically.     

Determination of bismuth in lead by neutron activation analysis

Neutron activation analysis for bismuth in lead was performed through the separation and measurement of²¹⁰Po, using two different extraction procedures. The reproducibility of the results was good for lead containing bismuth in higher concentrations. For high purity lead, variations in the bismuth content have been found by different analyses of the same sample, owing to inhomogeneity in the distribution of the Bi metal traces. An independent analysis of the same lead samples gave comparable Bi concentrations.     

Determination of iron isotopes by neutron activation analysis

Instrumental neutron activation analysis has been applied to the determination of Fe isotopic abundances in iron materials with the experimental accuracy of 5%. The proposed method can be considered as a quite simple and fast quality check system on the iron isotope enriched oxides used as standard in Mössbauer spectroscopy.     

Determination of arsenic and antimony in biological materials by solvent extraction and neutron activation

Arsenic and antimony in digested biological samples can be extracted with pyrrolidinecarbodithioate at pH 1 into chloroform and stripped with nitric acid for neutron-activation analysis (NAA). The extraction method eliminates interferences from matrix species, including Br and Na, making the accurate determination of low levels of As and Sb in biological materials feasible. The detection limits under the experimental conditions used are 0.005 and 0.006 mug/g for arsenic and antimony, respectively. A comparison of the results obtained for As and Sb in NBS biological standards by this method and by non-destructive instrumental neutron-activation analysis (INAA) is also given.     

Determination of trace impurities in tin by neutron activation analysis

Arsenic, selenium and antimony were determined in four different tin samples. After distillation from HBr?H₂SO₄ medium arsenic and selenium were precipitated with thioacetamide, and antimony was subsequently separated by deposition on iron powder. The separated samples were counted on a high-resolution Ge(Li) γ-spectrometer. The sensitivity of the method is highly satisfactory.     

Determination of indium in standard rocks by neutron activation analysis

A rapid neutron activation method for the determination of indium in rocks, based on 54 min (116m)In, is described. The method has been applied to a series of geochemical standards including granite G-1 and diabase W-1. The precision is better than +/- 5% for samples containing more than 5 x 10(-10)g indium. Good agreement with previously published values for G-1 and W-1 has been obtained.