Determination of traces of gallium based on stripping voltammetry with adsorptive accumulation

Trace levels of gallium can be quantified by linear-sweep voltammetry after absorptive preconcentration of the gallium/solochrome violet RS chelate on the hanging mercury-drop electrode. The interfacial and redox behaviors are evaluated by cyclic voltammetry. The adsorbed chelate yields two distinct reduction peaks that can be utilized to quantify gallijm. The effects of preconcentration time and potential, dye concentration, bulk concentration of gallium, and other variables on the chelate peaks are investigated. For a 2-min preconcentration time, the detection limit is 0.08 μg l^?1. With preconcentration for 60 s, calibration plots are linear for the range 0–16 μg ml^?1 gallium. Possible interferences by other trace metals and surface-active organic materials are investigated. Gallium added to samples of sea and rain water was quantified readily.     

Determination of copper in zinc by proton activation analysis

A method for the determination of copper in zinc by proton activation analysis using the⁶³Cu(p, n)⁶³Zn reaction has been developed.⁶³Zn has to be separated chemically from gallium and copper activities formed out of the zinc matrix and from indium activity formed out of cadnium impurity. Gallium radionuclides are retained on a cation exchanger in chloride medium and the residual activity is extracted in di-isopropyl ether. Copper and indium are subsequently extracted with cupferron in chloroform. The method was applied to BCR reference materials with a copper concentration at the μg.g^?1 level. The detection limit amounts to 0.5 μg.g^?1.     

Multi-element characterization of high-purity titanium dioxide by neutron activation analysis

A radiochemical neutron activation analysis method for the determination of 34 elements in titanium dioxide has been developed. For the assay of indicator radionuclides with short and with long half-lives, the radiochemical separation was performed by anion exchange on a Dowex 1 × 8 column and by combination of cation and anion exchange on a Dowex 50W × 8 and a Dowex 1 × 8 column from HF- and HF/NH₄F-medium, respectively. With both separation modes, a selective removal of the matrix-produced radionuclides ⁴⁶Sc, ⁴⁷Sc and ⁴⁸Sc was achieved. A selective extraction of copper with dithizone from 15 mol/L HF enabled counting the intensive but unspecific 511-keV rays of ⁶⁴Cu for the determination of Cu. The limits of detection achieved were between 0.004 ng/g for Sm and 0.8 μg/g for Sn (via ¹²⁵Sb). The elements La, Mn and Th were determined by instrumental neutron activation analysis only. These techniques were applied to the analysis of two titanium dioxide samples of different purity grade. The results and limits of detection are compared with those of other methods.     

Spectrophotometric determination of gallium with 1-(2,4-dihydroxyphenylazo)-2-naphthol-4-sulfonic acid

A new spectrophotometric method for the determination of gallium is described using 1-(2,4-dihydroxyphenylazo) -2-naphthol-4-sulfonic acid (DHPAN) as a reagent. The color reaction has a sensitivity of 0.013 μg Ga per cm² for log 1₀/1=0.005 at 500 mμ and obeys Beer's law up to 2.8 p.p.m. The effects of pH, time, order of addition of the reagents, temperature and diverse ions were investigated. Gallium is separated from interfering ions by solvent extraction.     

Instrumental activation analysis for determining the composition of micro-ingots of multi-constituent alloys

A procedure for the instrumental neutron activation analysis of micro-ingots of alloys containing In, Sb, Au, Ga, Ni, Sn and Bi is proposed. The non-destructive analysis of the irradiated samples is performed by γ-spectrometry techniques including one-crystal scintillation detectors, dual-crystal sum-coincidence scintillation detectors and Ge(Li) semiconductor detectors. As a result, the cumbersome operations of radiochemical separation can be eliminated. The sensitivity of quantitative determinations using scintillation detectors in alloys of the above composition is 10⁻¹⁰ g for indium, gold, antimony and gallium and 10⁻⁶ g for nickel and tin. The use of semiconductor detectors yields sensitivities of 10⁻¹⁰ g for indium and gold and 10⁻⁹ g for gallium and antimony.     

Determination of micro-amounts of indium in zinc and in gallium by radioactivation

Summary A method was developed to determine micro-amounts of indium in zinc and in gallium by radioactivation analysis, using 1 g Ra-Be as thermalneutron source. By activation of an amount of 10 g metallic zinc during 5 hours and counting the activity in a well-type NaI-scintillation counter, 17.4 counts per sec. per 10 g Zn were obtained. This activity is practically entirely due to the 13.8 h.⁶⁹Zn, the 52-mn isotope being a pure-emitter.By activation of indium in the same conditions the¹¹⁶In, 54-mn isotope, gives a counting rate of 28.9 counts per second per 10 mg metal, so that it was possible to determine amounts of indium in zinc, using 10 g samples varying from 0.004% to 0.16% with a mean error of 2.3%, without chemical separation. To determine trace amounts of Indium in Gallium by activation at the same conditions as described above, it was necessary to carry out a chemical separation. 1 g metallic Ga gave indeed rise to an activity of 115 counts per second, mainly due to the 14.1-h.⁷²Ga. The activation of the Ga-In samples was therefore carried out in an aqueous solution of their sulfates. After activation, potassium iodide and sulfuric acid were added as to obtain a 2 M solution of HI. The indium iodide was then extracted with diethyl ether and the ethereal solution introduced in a vial fitting the well-type crystal. Using 0.5-g Ga samples it was possible to determine indium amounts down to 0.2 mg, with a mean error of about 5%.

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Zusammenfassung Eine Methode zur Bestimmung kleiner Mengen Indium in Zink und in Gallium durch Aktivierungsanalyse wurde unter Verbindung von 1 g Ra-Be als thermische Neutronenquelle entwickelt. Nach Aktivierung von 10 g metallischem Zink durch 5 Stunden und Bestimmung der Aktivität in einem becherförmigen NaJ-Szintillationszähler wurden 17,4 Stöße pro Sekunde pro 10 g Zn beobachtet. Diese Aktivität kommt praktisch völlig dem⁶⁹Zn von der Halbwertszeit 13,8 Stunden zu, da das Isotop mit der Halbwertszeit 52 Minuten ein reiner-Strahler ist.Durch Aktivierung von Indium unter den gleichen Bedingungen gibt¹¹⁶In mit der Halbwertszeit 54 Minuten 28,9 Stöße pro Sekunde für 10 mg Metall, so daß es möglich war, unter Verwendung von 10 g Zink Indiummengen zwischen 0,004% und 0,16% mit einem mittleren Fehler von 2,3% ohne vorhergehende chemische Trennung darin zu bestimmen. Zur Bestimmung von Indiumspuren in Gallium durch Aktivierung unter den gleichen Bedingungen war es notwendig, eine chemische Trennungsmethode auszuarbeiten. 1 g metallisches Gallium zeigte tatsächlich einen Anstieg der Aktivität auf 115 Stöße pro Sekunde pro 1 g, die vor allem dem⁷²Ga der Halbwertszeit 14,1 Stunden zukommt. Die Aktivierung der Ga-In-Proben wurde daher in einer wäßrigen Lösung ihrer Sulfate durchgeführt. Nach der Aktivierung wurde Kaliumjodid und Schwefelsäure bis zu 2-m Konzentration an Jodwasserstoff zugesetzt. Das Indiumjodid wurde dann mit Diäthyläther extrahiert und die ätherische Lösung in eine dem becherförmigen Kristall angepaßte Schale gebracht. Unter Verwendung von 0,5 g Gallium war es möglich, Indiummengen bis herab zu 0,2 mg mit einem mittleren Fehler von etwa 5% zu bestimmen.

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Résumé On a mis au point une méthode de microdosage de 1'indium dans le zinc et le gallium par radioactivation à l'aide d'une source de neutrons thermiques de 1 g de Ra-Be. Après irradiation de 10 g de zinc métallique pendant 5 heures, on a compté 17,4 coups par seconde lors de la mesure de l'activité dans un compteur à scintillations à cristal creux d'iodure de sodium. Pratiquement, cette activité est entièrement due au⁶⁹Zn de période 13,8 h, son isotope de période 52 mn étant un émetteur-pur.Lorsqu'on active l'indium dans les mêmes conditions, l'isotope¹¹⁶In de période 54 mn donne au compteur 28.9 coups par seconde pour 10 mg de métal de sorte qu'il est possible de déterminer la teneur en indium du zinc sur des échantillons de 10 g pour des valeurs variant de 0,004% à 0 16%, avec une erreur moyenne de 2,3% et sans séparation chimique. Pour effectuer le dosage de traces d'indium dans le gallium par application de la même méthode d'activation, il est nécessaire d'effectuer une séparation chimique. 1 g de gallium métallique donne en effet naissance à une activité de 115 coups par seconde qui sont principalement dûs à l'isotope⁷²Ga de période 14,1 h. En conséquence, l'activation des échantillons de Ga-In a été effectuée dans une solution aqueuse des sulfates de ces métaux. Après activation, on ajoute de l'iodure de potassium et de l'acide sulfurique de façon à obtenir une solution 2 M d'acide iodhydrique. L'iodure d'indium est alors extrait dans l'éther diéthylique et la solution éthérée est introduite dans une fiole s'ajustant dans le cristal creux. En employant des échantillons de gallium de 0,5 g, il a été possible de déterminer des quantités d'indium de 0,2 mg avec une erreur moyenne d'environ 5%.

     

Donorstabilisierte Galliumdihalogenide Ga2X4·2D (X = Cl,Br; D = Donormolekül): Ein experimenteller Beitrag zu den Variationsmöglichkeiten der Ga‐Ga‐Einfachbindung

Donor‐stabilized Galliumdihalides Ga₂X₄·2D (X = Cl, Br; D = Donor): An Experimental Contribution on the Variation of the Gallium‐Gallium Single Bond During the disproportionation of metastable GaX‐solutions (X= Cl, Br) donor‐stabilized galliumdihalides are formed as oxidized products. According to X‐ray structure analyses they all exhibit dimeric entities DX₂Ga‐GAX₂D (D= THF, NHEt2, NEt3, 4‐^tButylpyridin or Br^‐), which means these compounds are isoelectronic with ethane and could schematically be regarded as representatives of catenulate or alkane‐like gallium subhalides: Ga_n(X, D)_2n+2. The gallium‐gallium bond in these compounds is shorter than in the organometallic compounds such as R₂Ga‐GaR₂. The comparison of the bonding situation in the galliumdihalides, particularly of the gallium‐gallium bond, shows clearly the influence by donor molecules as well as by halogen ligands.     

Spektralphotometrische Bestimmung von Gallium mit 4-(2-Pyridylazo)-resorcin

Zusammenfassung 4-(2-Pyridylazo)-resorcin bildet mit Gallium in schwach saurem Medium stufenweise zwei Chelate GaRH⁺ und GaR₂ ⁻, die sich gut als Grundlage für eine empfindliche spektralphotometrische Bestimmung von Gallium (≤ 0,1 μg Ga/ml) bei p_H 3,5–5,0 oder in Formiatpuffer bei p_H 4 eignen. Der Einflu? einiger Ionen, Puffer und der Ionenst?rke der L?sung auf die Bestimmung wird diskutiert.

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Summary Gallium forms by steps two coloured chelates GaRH⁺ and GaR₂ ⁻ with 4-(2-pyridylazo)-resorcinol (PAR) in aqueous solution, which are a convenient basis for the spectrophotometric determination of gallium (≤ 0,1 μg Ga/ml) at p_H 3,5–5,0 or in the presence of formiate buffer at P_H 4. The influence of buffers, ionic strength and some other ions is discussed.

     

INAA with anticoincidence counting significantly reduces interferences from the 554.3-keV photopeak of <Superscript>82</Superscript>Br to allow reliable measurements of nanogram levels of arsenic in solid biological materials via the 559.1-keV photopeak of <Superscript>76</Superscript>As

It is rather difficult to measure low levels of arsenic by instrumental neutron activation analysis (INAA) in biological materials containing high levels of bromine and antimony in particular, as well as sodium and potassium. The 559.1-keV photopeak of ⁷⁶As is interfered with by the 554.3- and 564.1-keV photopeaks of ⁸²Br and ¹²²Sb, respectively. The use of INAA in conjunction with anticoincidence spectrometry (INAA-AC) was found to reduce the background under the 559.1-keV photopeak by factors of 4–16 for the biological reference materials analyzed and to decrease the detection limit to 0.35 µg kg^?1 making the measurement of nanogram amounts arsenic in them possible.     

Determination of arsenic in food and dietary supplement standard reference materials by neutron activation analysis

Arsenic was measured in food and dietary supplement standard reference materials by neutron activation analysis for the purpose of assigning certified or reference As mass fractions and to assess material homogeneity. Instrumental neutron activation analysis was used to value assign As in candidate SRM 3532 Calcium Dietary Supplement and candidate SRM 3262 Hypericum perforatum (St. John’s Wort) Aerial Parts down to about 100 μg/kg. Values were also determined for two additional candidate St. John’s Wort SRMs with As mass fractions <100 μg/kg. The presence of significant amounts of ²⁴Na and ⁸²Br limited the reproducibility of the method below 100 μg/kg. For measurement of lower As mass fractions, a radiochemical neutron activation analysis method with extraction of As³⁺ into diethyl-dithiocarbamate in chloroform and detection limits down to 0.1 μg/kg. As was used to value-assign As mass fractions for SRM 3280 Multivitamin/Multielement Tablets and for candidate SRM 3233 Fortified Breakfast Cereal, and at <10 μg/kg in candidate SRM 1845a Whole Egg Powder.     

Application of Graphene as a Sorbent for Simultaneous Preconcentration and Determination of Trace Amounts of Cobalt and Nickel in Environmental Water and Vegetable Samples

A new method using a column packed with graphene as adsorbent was developed for the preconcentration of trace amounts of cobalt (Co) and nickel (Ni) prior to their determinations by flame atomic absorption spectrometry. Several factors influencing the extraction efficiency of Co and Ni and their subsequent determinations, such as pH, amounts of the chelating agent, flow rates of sample and eluent solution, eluent type and its volume, breakthrough volume, and adsorption capacity were established. Under the optimum conditions, the calibration graphs were linear in the range of 4.0‐200.0 μg L^?1 and 5.0‐200.0 μg L^?1 with detection limits of 0.36 μg L^?1 and 0.51 μg L^?1 for Co and Ni, respectively. Good relative standard deviations for ten determinations of 100.0 μg L^?1 of Co and Ni were 3.2 and 3.6%, respectively. The results for determination of Co and Ni in tap water, river water, sea water, vegetable and spiked samples have demonstrated the accuracy and applicability of the proposed method. To validate the proposed method, three certified reference materials of environment water (GSBZ 50030‐94 and GSB 07‐1186‐2000) and tomato leaf (GSBZ 51001‐94) were analyzed, and the determined values were in good agreement with the certified values.     

Gallium determination in biological samples

A sensitive, simple and time-saving method has been developed for the neutron activation analysis of gallium at concentrations around 10⁻⁴ ppm in biological tissues. After a 24-hour irradiation in a thermal neutron flux of 2.8·10¹³ n·cm⁻²·s⁻¹ and a purification by ion-exchange chromatography to eliminate troublesome elements such as sodium, iron and copper, the⁷²Ga activity is measured with enough accuracy for the method to be applicable in animal physiology and clinical toxicology.     

Performance and application of controlled temperature-gradient lamps in atomic absorption spectrometry

An improved design of controlled temperature-gradient lamp (CTGL) is suitable for arsenic, cadmium, phosphorus, potassium, rubidium, selenium, sodium, sulphur and zinc. Intensity and linewidth measurements indicate that the CTGL is significantly more intense than an electrodeless discharge lamp (EDL) at the same linewidth. CTGL's also compare favourably with EDL's when used as light sources for a.a.s. Arsenic and selenium can be determined at very low concentrations (ng ml^-1) by the hydride generation technique. Sulphur and phosphorus can be detected in the vacuum ultra-violet region using nitrogen-separated flames; the limits of detection are 13 and 10 μg ml^-1, respectively.     

Differential Pulse Polarographic Determination of Gallium and Niobium in Samples After Preconcentration of Their Quinolin-8-Olate Complexes on Microcrystalline Naphthalene

Abstract

Gallium and niobium react with quinolin-8-ol to form water insoluble complexes which are quantitatively adsorbed on microcrystalline naphthalene from the large volume of their aqueous solutions in the pH range of 3.5 - 8.2 and 6.2 - 9.4, respectively. After filtration, the metal complexes were desorbed with 10 ml of HCl (1M for Ga and 11 M for Nb) and determined by using a differential pulse polarograph (DPP). The dissolved oxygen is removed by adding a few milliliters of 4% NaBH₄ solution in the case of gallium. The detection limits are 0.04 ppm for gallium and 0.05 ppm for niobium at the minimum instrumental settings (signal to noise ratio = 2). The linearities are maintained in the concentration range 0.1 - 5.0 ppm for gallium and 0.4 - 6.0 ppm for niobium with correlation factors of 0.9997 and 0.9996 and relative standard deviations of 0.81 and 0.95%, respectively.

Characterization of the electroactive process included an examination of the degree of reversibility. Various parameters such as the effect of pH volume of aqueous phase, reagent and naphthalene concentrations and the interference of a large number of anions and cations on the estimation of these elements were studied in detail. The method is found to be highly selective, fairly sensitive, rapid, simple and economical. It has been applied for the trace determination of gallium and niobium in various standard alloys and may be applied safely for the analyses of complex materials like environmental samples and ores.

     

Novel Sensitive Voltammetric Detection of Trace Gallium(III) with Presence of Catechol Using Mercury Film Silver Based Electrode

A new adsorptive stripping voltammetric method for the determination of trace gallium(III) based on the adsorption of gallium(III)‐catechol complex on the cyclic renewable mercury film silver based electrode (Hg(Ag)FE) is presented. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition are optimized. The calibration graph is linear from 2 nM (0.14 μg L^?1) to 100 nM (6.97 μg L^?1) for a preconcentration time of 30 s, with correlation coefficient of 0.9993. For a Hg(Ag)FE with a surface area of 9.7 mm² the detection limit for a preconcentration time of 90 s is as low as 7 ng L^?1. The repeatability of the method at a concentration level of the analyte as low as 0.05 μg L^?1, expressed as RSD is 3.6% (n=5). The proposed method was successfully applied by studying the natural samples and simultaneous recovery of Ga(III) from spiked water and sediment samples.     

Spectrophotometric determination of aluminium and gallium with pyrogallol red and cetyltrimethylammonium ions

Spectrophotometric methods are described for the determination of microgram amounts of aluminium and gallium based on the formation of a ternary complex between the metal, pyrogallol red, and cetyltrimethylammonium bromide. The complexes have absorbance maxima at 610 and 615 nm, respectively, with molar absorptivities of 4.8 × 10⁴(Al)and 1.0 × 10⁵ liter mol^?1 cm^?1 (Ga). Numerous metals interfere. Gallium can be separated by extraction of gallium from 7 M hydrochloric acid with di-isopropyl ether. However, aluminium can be separated by extraction of interfering ions with cupferron.     

Determination of 17 trace elements in gallium arsenide by reactor neutron activation analysis

A method has been developed for the simultaneous determination of 17 trace elements in gallium arsenide. The method involves reactor neutron irradiation of the samples, distillation of the arsenic matrix activity and Ge(Li) γ-ray spectrometry. For a sample size of 0.1 g and a 10-day irradiation at 2·10¹³ n cm^-2 s^-1, the detection limits vary from 70 p.p.b. (tin) down to 5·10^-3 p.p.b. (scandium).     

Bestimmung von Spurenverunreinigungen in Gallium und Galliumarsenid durch Neutronenaktivierungsanalyse

Zusammenfassung Bei der Neutronenbestrahlung von Gallium und Galliumarsenid werden recht hohe spezifische Aktivitäten der Radionuklide ⁷²Ga und ⁷⁶As gebildet. Ihre ziemlich kurzen Halbwertszeiten von 14,1 bzw. 26,5 h ermöglichen erne relativ ungestörte Bestimmung aller Fremdelemente mit langlebigen Radionukliden nach weitgehendem Abklingen der Matrixaktivitäten; zu diesen Elementen gehören u. a. Ag, Cd, Co, Cr, Fe, Hg, Ni, Zn. Für die Bestimmung von Elementen mit kurzlebigen Radionukliden, wie Mn, Cu, Ge u. a. muß dagegen die hochradioaktive Probe (Aktivität 1–10 Ci) möglichst frühzeitig nach Bestrahlungsende hinter entsprechend starken Abschirmungen aufgearbeitet werden. Sowohl für die Bestimmung der langlebigen als auch der kurzlebigen Radionuklide wurden chemische Trennungsgänge ausgearbeitet, die leicht in bezug auf Zahl und Art der zu bestimmenden Verunreinigungselemente variiert werden können. Die bei Einsatz optimaler Bestrahlungsbedingungen erreichbaren unteren Bestimmungsgrenzen liegen zwischen 2·10^–3 und 2·10^–6 ppm. Mögliche Störungen der Bestimmung durch Nebenreaktionen sowie durch Kontamination des während der Bestrahlung flüssigen Galliums durch im Verpackungsmaterial vorhandene Verunreinigungen werden diskutiert.

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Determination of trace impurities in gallium and gallium-arsenide by neutron activation analysis

In neutron activation of gallium and gallium arsenide very high specific activities of the radionuclides ⁷²Ga and ⁷⁶As are formed. Their rather short half-life values of 14.1 and 26.5 h respectively permit relatively undisturbed determination of all foreign elements with long-lived radionuclides after a certain degree of decay of the matrix activities. These elements include Ag, Cd, Co, Cr, Fe, Hg, Ni, Zn and others. However, for the determination of elements with short-lived radionuclides, such as Mn, Cu, and Ge, it is necessary to radiochemically process the highly radioactive sample (activity 1 to 10 Ci) behind suitable shielding as soon as possible after irradiation. Chemical separating schemes have been developed for the determination of both long-lived and short-lived radionuclides. These can be varied easily according to the number and nature of the impurity elements to be determined. The sensitivity attainable under optimal irradiation conditions lies between 2×10^–3 and 2×10^–6 ppm. The authors discuss possible disturbance of the analysis due to side reactions and contamination of the liquid gallium by impurities in the packing material during irradiation.

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Vortrag bei der Tagung Analytische Probleme der Reindarstellung von Halbleitern, Wiesbaden 24/25.9.1968.

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Wir danken Herrn Dr. Sirtl, Forschungslaboratorium München der Siemens AG.. und Herrn Dr. Raab, Forschungslaboratorium Erlangen der Siemens A.G. für die Überlassung der Analysenproben sowie Herrn Prof. Dr. Gebauhr für anregende Diskussionen.     

Determination of rhodium by thermal neutron activation analysis using g-ray spectrometry

Trace amounts of rhodium have been determined by thermal neutron activation analysis using both destructive and non-destructive methods. With a neutron flux of 10¹² n cm^-2 sec^-1 the lower limits of detection are about 0.1 μg and 0.01 μg, respectively. A rapid sodium-peroxide fusion followed by a pyridine extraction was used in the destructive method to separate the 4.4-mm ^104mRh from its matrix. The 44-sec¹⁰⁴Rh was used in the non-destructive method. Both radioactive isomers were measured by γ-ray spectrometry with a multichannel pulse height analyzer. The average time required per non-destructive analysis was 7 min while the chemical method averaged 20 min.     

Ultratrace characterization of AlSiCu sputter targets for Th,U and 35 other elements by neutron activation analysis

Instrumental and radiochemical neutron activation analysis has been applied to a comprehensive trace characterization of AlSiCu sputter targets. By instrumental neutron activation analysis via long-lived indicator radionuclides, up to 33 elements were assayed with detection limits between 0.01 and 200 ng·g^–1. The high activity of⁶⁴Cu and²⁴Na produced from the matrix significantly limits the instrumental performance via short- and medium-lived indicator dionuclides. For this reason, a radiochemical separation was developed based on adsorption of²⁴Na on hydrated antimony pentoxide and extraction of⁶⁴Cu by diethylammonium diethyldithiocarbamate from HCl medium. By this radiochemical method, As, Ga, K, La, Mn, Mo, Re, Sb, U and W could be assayed via medium-lived radionuclides and the achievable limits of detection were between 0.1 and 25 ng·g^–1. Further improvement of detection limits for U and Th was achieved by a selective radiochemical separation of²³⁹Np and²³³Pa on a Dowex 1×8 column in HF and HF/NH₄F medium providing limits of detection for U and Th of 0.06 and 0.02 ng·g^–1, respectively. These techniques were applied to the analysis of two AlSiCu sputter target materials. Results are compared with those of glow discharge mass spectrometry.