Determination of trace metals by neutron activation after coprecipitation with lead phosphate

Lead phosphate quantitatively coprecipitates trace amounts of Ag(I), Cd(II), Cr(III), Cu(II), Mn(II), Th(IV), U(VI) and Zr(IV). The trace elements are determined in the precipitate by instrumental neutron activation analysis (INAA); detection limits are given. The practical application to the determination of U and Th is described.     

Determination of selenium(IV) and selenium(VI) in natural water samples by neutron activation analysis after chemical pre-collection

Neutron activation analysis using shortlived^77mSe (T=17.5 s) preceded by chemical pre-collection of Se on activated carbon (AC) has been applied to the fractional determination of Se(IV) and Se(VI) in natural water samples such as river water and sea water. Two chemical procedures were adopted: adsorption of Se(IV)/Bismuthiol-II complex on AC and adsorption of Se(VI)/Bismuthiol-II on AC after reduction of Se(VI) to Se(IV). It was shown that Se(IV) and Se(VI) can be determined at a <g l^–1 (ppb) level in natural waters by the present method.     

Determination of 19 elements in mineral waters by coprecipitation with PbS and by neutron activation analysis

Concentrations of Ag, Al, Ba, Br, Cl, Cu, I, In, K, La, Mg, Mn, Na, Sb, Sn, Sr, U, V and Zn were determined in 34 samples of mineral waters from Canada and from 9 other countries. The concentrations of elements which were frequently determined ranged (in ppb): Ag 0.1–6, Al 3–173, Cu 2–137, La 0.04–10, Mg 9–1140, Mn 0.1–99, Sb 1–50, V 0.01–2.6 and Zn 3–613.     

Preconcentration of silver from rocks by extraction with bismuth dibenzyldithiocarbamate prior to neutron activation analysis

The method developed for determining trace levels of silver in geological materials involves the extraction of silver with a toluene solution of bismuth dibenzyldithiocarbamate followed by neutron activation of the extract. At pH 2 and in the presence of 0.1M EDTA, silver is quantitatively extracted. Under these conditions only small amounts of copper are coextracted. The detection limits of silver for three different modes of neutron activation analysis: /three cycles with Ge/Li/ detector, one cycle with Ge/Li/ detector and one cycle with NaI/Tl/ detector/ were 12, 20 and 11 ng g^–1, respectively.     

Determination of impurities in niobium metal by a radiochemical neutron activation analysis

A radiochemical separation method using an anion exchange resin has been applied to 3N grade Nb for determining nine impurity elements. Five elements (Cr, Fe, Co, Zn and Se) were separated in 2M HF, three elements (Mo, W and Hf) in 32M HF, Nb in 0.5M HF/3M HCl, and Ta in 1M NH₄F/4M NH₄CCl. The contents of the elements were calculated by a single comparator method using two monitors of Au and Co. The main impurity was revealed to be Ta with a content of over 160 ppm.     

Determination of trace elements in surface water by neutron activation analysis

In order to assure the public health, simple and relibable analytical methods must be established for effective surveillance of polluted surface water. Since the pollutants in surface water are usually found at ultratrace levels, preconcentration is generally required to ensure the quality of the analytical results. An analytical procedure consisting of preconcentration using hydrous magnesium oxide followed by neutron activation analysis has been proposed and applied to the determinations of trace elements in surface water.     

Determination of some trace metals in water and sediment samples by flame atomic absorption spectrometry after coprecipitation with cerium (IV) hydroxide

A cerium(IV) hydroxide coprecipitation method was developed for the determination of some trace elements (Cu, Co, Pb, Cd, Ni) in aqueous solutions, water and sediment samples by flame atomic absorption spectrometry (AAS). Several parameters governing the efficiency of the coprecipitation method were evaluated including pH of sample solution, amount of carrier element, volume of sample solution and the effect of possible matrix ions The procedure was validated by the analysis of GBW 07309 standard reference material sediment and by use of a method based on a solid phase extraction.     

Determination of selenium in water samples by molecular emission cavity analysis after coprecipitation

Selenium (0.2–5 ppb) is coprecipitated with hydrated iron(III) oxide, dissolved in acid, reprecipitated as the element and determined by molecular emission cavity analysis. For a 250-ml water sample, the detection limit is 0.2 ppb. For <5 ppb selenium there is no need for coprecipitation.     

Determination of cadmium in water samples by co-precipitation and neutron activation analysis

Lanthanide (Ln) levels in plasma and tissues from colorectal patients and healthy subjects were determined by radiochemical neutron activation analysis. Results, precision, accuracy and sensitivity are presented and discussed. Mean plasma levels of La, Ce, Nd, Eu and Yb were significantly higher (p<0.01) in adenoma and adenocarcinoma patients compared to control subjects. Increasing concentrations of plasmatic La, Eu and Yb as well as Ln levels in tissue from healthy subjects, adenomatous polyps, and adenocarcinoma (ADK) patients were observed. Measured tissue levels of Ln were constantly higher in ADK and adenomatous polyps than in the adjacent normal tissues. These findings may reflect impaired calcium metabolism possibly involved in the early process of carcinogenesis leading to the development of ADK.Presented at the MTAA-8 Conference, September 16–20, 1991, Vienna, Austria.     

Determination of sodium and chlorine in pure water by neutron activation analysis

Neutron activation analysis was applied to determine sodium and chlorine in high purity water samples. After irradiation of the sample,³⁸Cl was purified from⁸²Br and other nuclides by carbon tetrachloride extraction and silver chloride precipitation, and²⁴Na was separated from other alkali elements and other nuclides by adsorption of²⁴Na on HAP. The activities of both elements were measured by conventional G.M. counter. The contamination of the elements from container walls during neutron irradiation and the interference with³⁸Ar(n, p)³⁸Cl reaction on argon dissolved in water were also examined. Water samples containing 3 ppb of chlorine could not be determined accurately, owing to the above mentioned interfering reaction.     

Determination of mercury and arsenic in fresh water by neutron activation analysis

Neutron activation analysis has been applied for the determination of Hg and As in freshwater samples. Preconcentration of Hg and As from the samples before irradiation by using active carbon for scavenging the chelate complex of Hg with dithizone at pH 1 and Fe(OH)₃ for co-precipitating arsenic was used. After irridiation, mercury was determined by direct counting of the irradiated active carbon. Arsenic was separated from Fe(OH)₃ by precipitating arsenic in the metal form after removing¹²²Sb by extraction in 2N HCl with Ni-diethyldithiophosphoric acid in carbon tetrachloride. The method is simple and reliable.     

Preconcentration neutron activation analysis of trace elements in surface waters by coprecipitation with pyrrolidinedithiocarbamate in the presence of Bi(III)

A simple preconcentration method is described for the simultaneous coprecipitation of Cd(II), Co(II), Cu(II), Mo(VI), U(VI), V(V) and Zn(II) from surface water samples followed by quantitation using neutron activation analysis. Ammonium pyrrolidinedithiocarbanate (APDC), anthranilic acid and 8-hydroxyquinoline have been investigated as possible coprecipitating agents. The suitability of Bi³⁺, Fe³⁺, Ni²⁺ and Pb²⁺ ions as metal carriers has also been studied. It has been found that the above elements can be quantitatively coprecipitated with APDC in the presence of Bi³⁺ carrier at pH 4. The precision and accuracy of the method for all elements are found to be between ±2 and 10%. The enrichment factors are of the order of 10³. The detection limits are in the ppb range varying between 0.04 ng · ml^–1 for Co and V and 5 ng · ml^–1 for Zn. The method has been applied to tap and well waters, and river and lake water samples collected from Halifax County, Nova Scotia.     

Determination of rare earth elements in hot spring water and crater lake water samples by neutron activation analysis incorporating coprecipitation process using aluminium as a collector

Hot spring water and crater lake water samples were analyzed for their rare earth elements: (REE's) by neutron activation method, which, in the irradiation, sample preparation, incorporated a coprecipitation process in which aluminium was used as a collector. Ten REE's, La, Ce, Sm, Eu, Gd, Tb, Dy, Tm, Yb and Lu, were consequently detected and determined at the ppb level with satisfactory precision. It was shown that the aluminium coprecipitation is effective in enhancing concentrations of the REE's and reducing the amounts of interfering nuclides before neutron irradiation.     

Determination of trace impurities in rhodium metal by destructive and non-destructive neutron activation analysis

Trace amounts of Ir, Au, Cu, Pd and Pt were determined in rhodium metal by instrumental neutron activation analysis with Ge(Li) spectrometry as well as by the radiochemical version of the method. The latter was based on a specially developed procedure of the dissolution of Rh, followed by group separation with the aid of ion exchange chromatography. The results obtained by destructive and non-destructive methods are critically discussed and compared. Special attention was paid to self-shielding effect and an accurate method of the correction of this effect is presented.     

Determination of Se(IV) and Se(VI) in Italian mineral waters

This paper deals with determination of selenium and analysis of its speciation in some Italian mineral waters. Selenium was determined by differential pulse cathodic stripping voltammetry (DPCSV) even if square wave cathodic stripping voltammetry (SWCSV) was also taken into consideration. The selenium determined in the mineral waters here investigated is not over 600 ng L(-1); in three samples, it was found below the detection limit. Analysis of speciation revealed that Se(VI) is the highly prevailing form present: only two of the examined samples revealed a detectable amount (few ng L(-1)) of Se(IV). DPCSV made possible to detect, in two of the samples, the presence of a specie(s) able to interact with Se(IV). The apparent interaction constant for the adduct formation was evaluated and the species concentration determined. However, the nature of such compound(s) remains unknown.     

Determination of boron in water samples by chemical prompt gamma neutron activation analysis

Boron concentration has been determined in groundwater samples, collected from Khuchch, Gujarat, India, by prompt gamma neutron activation analysis (PGNAA) after selective separation and pre-concentration by solvent extraction with 10% 2-ethyl hexane 1,3-diol in CHCl₃. Solvent extraction separation helped to eliminate the interfering elements in PGNAA determination of boron. The sensitivity of PGNAA is found to be 18.83 cps/mg B based on the slope of a calibration plot obtained by carrying out measurements on synthetic boric acid samples containing boron in the range of 30–150 μg. Detection limit of the method is 0.2 μg/g counted for 35,000 seconds at a sample size of 15 gram. The precision (relative standard deviation at 1σ level) and accuracy of the method is 5%. The analytical results of the present method agreed well with well-established spectrophotometric determination of boron as boron-curcumin complex and inductively coupled plasma atomic emission spectroscopy (ICP-AES).     

Multielemental determination in water by neutron activation analysis

Instrumental neutron activation analysis (INAA) technique has been applied to a water sample to determine the elemental concentrations. The sample was irradiated at a neutron flux of 1.2·10¹² n·cm^–2·s^–1 for two different periods followed by counting at three different decay times, using two coaxial type high-resolution Ge(Li) detectors. The dominant elements detected in the water sample are Ca, Cl, Na, Mg, and K present in levels while Co, I, Mn, Sm, and Sb are present in smaller amounts approximately on the average 0.01 ppm. Only traces of other elements such as rare-earth elements, Ag, As, Ba, Cu, Cd, Fe, Sr, W, Zn, seem to be present in the water samples.     

Determination of trace elements in small water samples by total reflexion X-ray fluorescence (TXRF) and by neutron activation analysis (NAA)

The problems encountered in the determination of trace elements in small sample volumes of the order of 1 to 10 l (e.g. in droplets of water) are discussed. Total reflexion X-ray fluorescence (TXRF) and neutron activation analysis (NAA) are applied for the determination of Na, Mg, K, Ca, Mn, Fe, Co, and Cu in concentrations of 0.01 to 10 mg/L in 1 to 10 L of water. The applied methods are described, the results are discussed and the advantages of TXRF are brought forward.     

Determination of trace elements in water by non-destructive neutron activation

A systematic study was undertaken in order to find out which of the most relevant elements can be determined in water under normal conditions by non-destructive neutron activation simultaneously using a suitable monostandard method. Standardized water samples as well as natural water of different kind were used, brought to dryness by freeze-drying and irradiated in quartz at a neutron flux of 10¹⁴ cm⁻² s⁻¹ for 1 day. The trace element content in quartz ampoules of different origin was determined separately. The following elements are discussed in detail including possible interferences: As, Au, Br, Ca, Cd, Co, Cr, Cu, Eu, Fe, Hg, K, La, Mo, Na, Ni, Sb, Sc, Se, U, Zn. Presented at the Euroanalysis II Conference, Budapest, 25–30. Aug. 1975.