Neutron activation analysis of palladium,platinum and rhodium in lead foam

The determination of palladium, platinum and rhodium in industrial concentrates such as lead foam and raw lead by neutron activation analysis is described. The noble elements are separated from the matrix by spontaneous deposition on amalgamated copper powder prior to activation. After the determination of palladium and platinum, rhodium is coprecipitated on iron hydroxide, and the precipitate irradiated for the determination of rhodium. The results are compared with those obtained by fire assay. Research Associate of I.I.K.W., Belgium.     

Radiochemical separation and determination of platinum,gold and palladium in complex matrices employing substoichiometric thermal neutron activation analysis

A radiochemical separation method has been developed for the separation of platinum, gold and palladium from various matrices by thermal neutron activation analysis and employing substoichiometric extractions of Pt and Au with 2-mercaptobenzothiazole and Pd with isonitrosobenzoylacetone. Decontamination factors for the individual elements after separation was also studied and was found to be greater than 10⁵ for most of the elements.     

The determination of barium,platinum and ruthenium in experimental catalysts by neutron activation analysis

The determination of platinum and ruthenium in the presence of barium by instrumental neutron activation analysis is hampered by interference from barium isotopes. This difficulty is surmounted by utilizing gold and rhodium isotopes produced from the β-decay of platinum and ruthenium isotopes.     

Neutron activation analysis of noble metals in vegetation

Detection limits are presented for the platinum metals in vegetation for different neutron activation analysis conditions, namely, short irradiation, cyclic and long irradiations both thermally and epithermally. These detection limits for instrumental neutron activation analysis are compared with those using preconcentration technique—dry ashing and fire assay and post irradiation separation of the platinum metals using Srafion NMRR in exchange resin. The results are evaluated for plant material and it is concluded that dry ashing followed by cyclic, epithermal irradiation for rhodium and palladium and long, thermal irradiations for osmium, platinum, iridium and ruthenium enable these elements to be detected in plants at background levels.     

Extraction of gold, palladium and platinum from chloride, bromide and iodide solution with di-n-octyl sulphide (DOS) in cyclohexane

The extraction of gold, palladium and platinum from hydrochloric acid, hydrobromic acid and iodide media by solutions of di-n-octyl sulphide in cyclohexane was examined. From distribution data it was concluded that the monosolvates AuX(3).DOS and disolvates PdX(2).2DOS are extracted. Extraction of platinum was efficient only from iodide solutions; a disolvate PtI(4).2DOS was formed. The possibility of separation of gold and palladium from platinum by extraction from bromide or chloride solutions and simultaneous extraction of palladium and platinum from an iodide medium was demonstrated.     

火试金减杂-电感耦合等离子体原子发射光谱法（ICP-AES）法测定高冰镍的金、银、铂、钯含量

建立了火试金减杂-电感耦合等离子体原子发射光谱法（ICP-AES）测定高冰镍中金、银、铂、钯含量的分析方法。实验采用火试金富集、熔融、灰吹得到合粒,通过减杂法得到银含量,通过ICP-AES法测定得到金、铂、钯含量。金、银、铂、钯的加标回收率在99.53%-101.83%之间,相对标准偏差小于3%。此方法快速、简洁,准确度高、精密度好,能够满足高冰镍的测定需求。     

A fire-assay and wet chemical method for the determination of palladium, platinum, gold, and silver in ores and concentrates

A method is presented for the determination of palladium, platinum, gold and silver in ores and concentrates by a fire-assay and wet chemical technique. After parting of the lead assay button with dilute nitric acid, and separation of the solution from the residue, the palladium and platinum in the solution are precipitated by the addition of stannous chloride, with tellurium as collector. The resulting precipitate is combined with the gold residue and dissolved in aqua regia, then the solution is analysed for palladium, platinum and gold by atomic-absorption spectrophotometry (AAS). Silver is determined in the original solution by AAS before the reduction step.     

Simultaneous determination of palladium, platinum, rhodium and gold by on-line solid phase extraction and high performance liquid chromatography with 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine as pre-column derivatization regents

In this paper, 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine (HNATR) was synthesized. A new method for the simultaneous determination of palladium, platinum, rhodium and gold ions as metal-HNATR chelates was developed using a rapid analysis column high performance liquid chromatography equipped with on-line solid phase extraction technique. The samples (Water, human urine, geological samples and soil) were digested by microwave acid-digestion. The palladium, platinum, rhodium and gold ions in the digested samples were pre-column derivatized with HNATR to form colored chelates. The Pd-HNATR, Pt-HNATR, Rh-HNATR and Au-HNATR chelates can be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] with a buffer solution of 0.05 mol L(-1) phosphoric acid as mobile phase. After the enrichment had finished, by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and travelling towards the analytical column. These chelates separation on the analytical column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] was satisfactory with 72% acetonitrile (containing 0.05 mol L(-1) of phosphoric acid and 0.1% of Triton X-100) as mobile phase. The palladium, platinum, rhodium and gold chelates were separated completely within 2.5 min. Compared to the routine chromatographic method, more then 80% of separation time was shortened. By on-line solid phase extraction system, a large volume of sample (10 mL) can be injected, and the sensitivity of the method was greatly improved. The detection limits (S/N=3, the sample injection volume is 10 mL) of palladium, platinum, rhodium and gold in the original samples reaches 1.4, 1.8, 2.0 and 1.2 ng L(-1), respectively. The relative standard deviations for five replicate samples were 2.4-3.6%. The standard recoveries were 88-95%. This method was applied to the determination of palladium, platinum, rhodium and gold in human urine, water and geological samples with good results.     

Radiotracer study of the reduction of noble metals by amalgamated copper powder

A systematic study has been made on the reducing power of amalgamated copper powder in hydrochloric acid solution for palladium, platinum, rhodium, iridium, gold and silver. In order to apply this method to the activation analysis of palladium, platinum and rhodium in industrial concentrates which contain a large amount of ‘base elements’, the behaviour of palladium, platinum and rhodium in the presence of the ‘base elements’ has also to be considered. Research associate of I.I.K.W., Belgium     

Determination of total mercury in coal fly ash by gold amalgamation cold vapour atomic absorption spectrometry

A method for the determination of total mercury in coal fly ash by gold amalgamation cold vapour atomic absorption spectrometry (CV-AAS) was optimized. Most of the experiments were performed on NBS SRM 1633a Coal Fly Ash with a certified value of 160 ± 10 ng Hg g^?1. The main attention was focused on the decomposition of the sample. The efficacy of pressure decompositions in closed silica and sealed Pyrex tubes using various combinations of acids (HNO₃, HCl, HClO₄) was compared with oxidative combustion of the coal fly ash. Notwithstanding the incomplete mineralization of the sample in sealed tubes, the results obtained showed good agreement with the certified value and results obtained by neutron activation analysis (NAA), which suggests that mercury is quantitatively released from the sample into solution. Lower results were obtained using decomposition in closed (but not hermetically sealed) silica tubes owing to losses of mercury by volatilization during decomposition. Interferences from some metal ions (nickel, lead, copper, silver, palladium, zinc and antimony) were also examined. The results showed a serious depression of the mercury signal only when gold, palladium and platinum were present at higher concentrations, which never or very seldom occur in fly ash matrices, and therefore do not represent a limitation of the method.     

Some noble metals and copper content of italian meteorites as determined by destructive neutron activation analysis

Copper, iridium, platinum and gold content was determined in 15 italian chondritic meteorites by destructive neutron activation analysis. The chemical procedure involves few steps: sample dissolution, group separation of noble metals on inorganic adsorbers and gamma-ray spectrometry. Element content and atomic abundances (Si=10⁶ atoms) are presented and discussed. Precision and accuracy of the analytical method are given as well. Copper, platinum and gold content is within the reported ranges for ordinary chondrites, whereas the iridium content is located on the low side of reported values.     

The separation of platinum, palladium and gold from silicate rocks by the anion exchange separation of chloro complexes after a sodium peroxide fusion: an investigation of low recoveries

A series of experiments was undertaken to measure the recovery efficiency of platinum, palladium and gold from silicate rocks using a sodium peroxide fusion followed by anion exchange separation of the analytes as chloro complexes. Results obtained by graphite furnace atomic absorption spectrometric analysis of standard solutions prepared in dilute HCl or HCl-acidified sodium peroxide solution showed that recoveries were near quantitative. However, when standard solutions were added to an alkaline sodium peroxide solution, which was then acidified, low results were obtained for platinum and gold (46% and 76% respectively). Low and variable results were also obtained when standard solutions were added to a peridotite sample that had been dissolved by the state procedure, and in the analysis of the South African Bureau of Standards certified reference material, SARM 7. Various experiments were undertaken to investigate these low recoveries, but the reason proposed here is the formation of hydroxychloro compounds in alkaline solution which are not, on acidification with HCl, converted quantitatively to the chloro complex necessary for quantitative anion exchange separation. It is concluded that a sodium peroxide fusion followed by an anion-exchange separation does not appear to form the basis of a successful technique for the determination of platinum, palladium and gold in silicate rocks.     

Radiochemical fire-assay for determination of the platinum group elements

The radioactive study of Ni–NiS bead fire-assay followed by neutron activation analysis showed nearly quantitative collection of the platinum group elements and gold in the bead. However, there was clearly some loss of gold and ruthenium at the dissolution and filtration stage. A preliminary study of the radiochemical fire-assay method indicates that the technique could overcome the problem of losses. Chemical carrier behaves in the same way as platinum metal concentrate during the analytical procedure and could be used to evaluate yields during each determination. When applied to rock samples, the radiochemical fire-assay gives good sensitivity and could be applied to the determination of nanogram concentrations of the platinum group elements without the problem of high blank values from reagents.     

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.     

Studies on the extraction of platinum metals with tri-iso-octylamine from hydrochloric and hydrobromic acid: separation and determination of gold, palladium and platinum

The extraction of Pd(II), Rh(III), Ir(III), Au(III) and Pt(IV) from hydrochloric and hydrobromic acid with 5% tri-iso-octylamine solution in carbon tetrachloride has been studied. The gold extract from hydrochloric acid is yellow and absorbs at 325 nm, the palladium compound is red and absorbs at 290 nm and 467 nm, and the platinum compound is blood-red and shows absorption at 268 nm. The gold, palladium and platinum extracts from hydrobromic acid are crimson. reddish brown and blood-red, with maximum absorption at 260, 345 and 300 nm respectively. Methods have been devised for the separation of gold from platinum and for its determination and also for the simultaneous determination of palladium and platinum.     

Modified microelectrodes and multivariate calibration for flow injection amperometric simultaneous determination of ascorbic acid, dopamine, epinephrine and dipyrone

Flow injection amperometric quantification of ascorbic acid (AA), dopamine (DA), epinephrine (EP) and dipyrone (DI) in mixtures (in the microgram g-1 range) was successfully performed by using an array of microelectrodes with units modified by the electrodeposition of different noble metals, together with multivariate calibration analysis. The four groups of microelectrodes utilized included a pure gold electrode and electrodes modified by electrodeposition of platinum, palladium or a mixture of platinum + palladium. The array of microelectrodes was inserted in a flow cell and the amperometric data acquisition was performed with a four-channel potentiostat. The analysis of the resulting signals was carried out by a multivariate calibration method, using a group of 16 standard mixtures selected by a two-level factorial design. The analysis of synthetic samples and pharmaceutical compounds containing AA and DI led to very similar values to those obtained by the classical iodimetric analysis. The average absolute errors (in microgram g-1) calculated for each analyte were 0.3, 0.2, 0.4 and 0.4 for AA, DA, EP and DI, respectively.     

Beryllium-7 as a tracer of stratospheric ozone: A case study

A new method is presented for the determination of Au and Pt in biological materials based on neutron activation analysis with radiochemical separation of gold. Separation of gold by electrolytic deposition on a niobium cathode ascertains the highest radiochemical purity without any interference from calcium or other major elements. With¹⁹⁹Au as indicator for platinum the gold content of the sample not only strongly affects the limit of detection, but also causes interference by double neutron capture. Replicate analyses of BCR Certified Reference Materials No. 184, 185 and 186 were carried out.Presented at the MTAA-8 Conference, September 16–20, 1991, Vienna, Austria.     

Determination of microgram amounts of the six platinum-group metals in iron and stony meteorites

Microgram amounts of the 6 platinum-group metals in 5 stony and 3 iron meteorites were determined spectrophotometrically after perchloric acid decomposition and ion-exchange separation. The accuracy of the determinations of osmium, ruthenium and platinum was improved by the use of more sensitive procedures; arsenazo III was used for the determination of palladium in presence of platinum, rhodium and iridium. The data for platinum-group metals thus obtained are compared with published data obtained by neutron activation and spectrographic methods for the same meteorites or for other meteorites of the same class. With a few exceptions, the agreement between the new data and published data is satisfactory.     

Assay of platinum and gold in biological material by neutron activation analysis

Compounds of both gold and platinum are used in medicine, the former as salts to treat arthritides and the latter as the metal complex cisplatin to treat cancer. We have investigated neutron activation analysis with the Slowpoke II reactor as an assay method for both elements using human blood plasma as a matrix. Neutron activation of platinum gives rise to 3.15 day¹⁹⁹Au while that of gold produces 2.7 day¹⁹⁸Au. Activated samples are dissolved during heating in test tubes and the gold extracted by adding dibutyl sulphide to the same tube. The latter is formed to able to quantitate Pt down to 60 ng and Au down to 60 pg. The dissolution technique and possible interferences in the assay are discussed.     

Studies on iridium and platinum determination in metallic rhodium by NAA and CPAA

The determination of Ir and Pt in rhodium neutron monitors was investigated via¹⁹²Ir and¹⁹⁹Au after neutron activation, via¹⁹¹Pt and¹⁹⁴Au–¹⁹⁶Au after proton activation. Ir was determined by instrumental NAA. A chemical separation of gold, with a yield measurement method by a radioactive tracer, was developed for platinum determination after neutron or proton irradiation.