Use of chelating resins and inductively coupled plasma mass spectrometry for simultaneous determination of trace and major elements in small volumes of saline water samples

For some saline environments (e.g. deeply percolating groundwater, interstitial water in marine sediments, water sample collected after several steps of fractionation) the volume of water sample available is limited. A technique is presented which enables simultaneous determination of major and trace elements after preconcentration of only 60 mL sample on chelating resins. Chelex-100 and Chelamine were used for the preconcentration of trace elements (Cd, Cu, Pb, Zn, Sc) and rare earth elements (La, Ce, Nd, Yb) from saline water before their measurement by inductively coupled plasma mass spectrometry. Retention of the major elements (Na, Ca, Mg) by the Chelamine resin was lower than by Chelex; this enabled their direct measurement in the solution after passage through the resin column. For trace metal recoveries both resins yield the same mass balance. Only Chelex resin enabled the quantitative recovery of rare earth elements. The major elements, trace metals and rare earth elements cannot be measured after passage through one resin only. The protocol proposes the initial use of Chelamine for measurement of trace and major elements and then passage the same sample through the Chelex resin for determination of the rare earth elements. The detection limit ranged from 1 to 12 pg mL(-1). At concentrations of 1 ng mL(-1) of trace metals and REE spiked in coastal water the precision for 10 replicates was in the range of 0.3-3.4% (RSD). The accuracy of the method was demonstrated by analyzing two standard reference waters, SLRS-3 and CASS-3.     

Determination of rare earth elements and heavy metals in river water by preconcentration on chelex 100 and neutron activation

The neutron activation determination of rare earth elements and heavy metals in river water has been studied with Chelex 100 resin as a preconcentration agent. The resin is applied directly as a support for irradiation and for radiochemical separation. The radioactive rare earth elements are recovered selectively and quantitatively from the irradiated resin by elution with hot 1 M sodium carbonate solution; radioactive heavy metals are recovered with 2 M nitric acid. Activities from each eluate are counted with a Ge(Li) detector connected to a multichannel analyzer; La, Sm, Eu, Dy, Mn, Cu and Zn can be determined. The recoveries were almost quantitative and the measurement of chemical yield was unnecessary.     

Determination of trace rare earth elements by inductively coupled plasma atomic emission spectrometry after preconcentration with multiwalled carbon nanotubes

A new method has been developed for the determination of trace rare earth elements (REEs) in water samples based on preconcentration with a microcolumn packed with multiwalled carbon nanotubes (MWNTs) prior to their determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). The optimum experimental parameters for preconcentration of REEs, such as pH of the sample, sample flow rate and volume, elution solution and interfering ions, have been investigated. The studied REEs ions can be quantitatively retained by MWNTs when the pH exceed 3.0, and then eluted completely with 1.0 mol L⁻¹ HNO₃. The detection limits of this method for REEs was between 3 and 57 ng L⁻¹, and the relative standard deviations (RSDs) for the determination of REEs at 10 ng mL⁻¹ level were found to be less than 6% when processing 100 mL sample solution. The method was validated using a certified reference material, and has been successfully applied for the determination of trace rare earth elements in lake water and synthetic seawater with satisfactory results.     

Multielement determination of trace metals in seawater by ICP-MS with aid of down-sized chelating resin-packed minicolumn for preconcentration

The multielement determination of trace metals in seawater was carried out by inductively coupled plasma mass spectrometry (ICP-MS) with aid of a down-sized chelating resin-packed minicolumn for preconcentration. The down-sized chelating resin-packed minicolumn was constructed with two syringe filters (DISMIC 13HP and Millex-LH) and an iminodiacetate chelating resin (Chelex 100, 200-400 mesh), with which trace metals in 50 mL of original seawater sample were concentrated into 0.50 mL of 2 M nitric acid, and then 100-fold preconcentration of trace metals was achieved. Then, 0.50 mL analysis solution was subjected to the multielement determination by ICP-MS equipped with a MicroMist nebulizer for micro-sampling introduction. The preconcentration and elution parameters such as the sample-loading flow rate, the amount of 1 M ammonium acetate for elimination of matrix elements, and the amount of 2 M nitric acid for eluting trace metals were optimized to obtain good recoveries and analytical detection limits for trace metals. The analytical results for V, Mn, Co, Ni, Cu, Zn, Mo, Cd, Pb, and U in three kinds of seawater certified reference materials (CRMs; CASS-3, NASS-4, and NASS-5) agreed well with their certified values. The observed values of rare earth elements (REEs) in the above seawater CRMs were also consistent with the reference values. Therefore, the compiled reference values for the concentrations of REEs in CASS-3, NASS-4, and NASS-5 were proposed based on the observed values and reference data for REEs in these CRMs.     

A solid phase extraction using a chelate resin immobilizing carboxymethylated pentaethylenehexamine for separation and preconcentration of trace elements in water samples

A chelate resin immobilizing carboxymethylated pentaethylenehexamine (CM-PEHA resin) was prepared, and the potential for the separation and preconcentration of trace elements in water samples was evaluated through the adsorption/elution test for 62 elements. The CM-PEHA resin could quantitatively recover various elements, including Ag, Cd, Co, Cu, Fe, Ni, Pb, Ti, U, and Zn, and rare earth elements over a wide pH range, and also Mn at pH above 5 and V and Mo at pH below 7. This resin could also effectively remove major elements, such as alkali and alkaline earth elements, under acidic and neutral conditions. Solid phase extraction using the CM-PEHA resin was applicable to the determination of 10 trace elements, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn, in certified reference materials (EnviroMAT EU-L-1 wastewater and ES-L-1 ground water) and treated wastewater and all elements except for Mn in surface seawater using inductively coupled plasma atomic emission spectrometry. The detection limits, defined as 3 times the standard deviation for the procedural blank using 500 mL of purified water (50-fold preconcentration, n = 8), ranged from 0.003 μg L⁻¹ (Mn) to 0.28 μg L⁻¹ (Zn) as the concentration in 500 mL of solution.     

Application of chitosan functionalized with 3,4-dihydroxy benzoic acid moiety for on-line preconcentration and determination of trace elements in water samples

Chitosan resin functionalized with 3,4-dihydroxy benzoic acid (CCTS-DHBA resin) was used as a packing material for flow injection (FI) on-line mini-column preconcentration in combination with inductively coupled plasma-atomic emission spectrometry (ICP-AES) for the determination of trace elements such as silver, bismuth, copper, gallium, indium, molybdenum, nickel, uranium, and vanadium in environmental waters. A 5-mL aliquot of sample (pH 5.5) was introduced to the minicolumn for the adsorption/preconcentration of the metal ions, and the collected analytes on the mini-column were eluted with 2 M HNO₃, and the eluates was subsequently transported via direct injection to the nebulizer of ICP-AES for quantification. The parameters affecting on the sensitivity, such as sample pH, sample flow rate, eluent concentration, and eluent flow rate, were carefully examined. Alkali and alkaline earth metal ions commonly existing in river water and seawater did not affect the analysis of metals. Under the optimum conditions, the method allowed the determination of metal ions with detection limits of 0.08 ng mL⁻¹ (Ag), 0.9 ng mL⁻¹ (Bi), 0.07 ng mL⁻¹ (Cu), 0.9 ng mL⁻¹ (Ga), 0.9 ng mL⁻¹ (In), 0.08 ng mL⁻¹ (Mo), 0.09 ng mL⁻¹ (Ni), 0.9 ng mL⁻¹ (U), and 0.08 ng mL⁻¹ (V). By using 5 mL of sample solution, the enrichment factor and collection efficiency were 8–12 fold and 96–102%, respectively, whereas the sample throughput was 7 samples/hour. The method was validated by determining metal ions in certified reference material of river water (SLRS-4) and nearshore seawater (CASS-4), and its applicability was further demonstrated to river water and seawater samples.     

Determination of gadolinium in river water by SPE preconcentration and ICP-MS

An analytical scheme was developed for the determination of Gd-diethylenetriaminepentaacetate (Gd-DTPA), Gd and the other rare earth elements (REE) in river water by inductively coupled plasma (quadrupole) mass spectrometry (ICP-Q-MS). The preconcentration step was essential, since the limits of detection of this multielemental analytical technique are higher than the trace concentrations of the interesting elements in river water.Solid phase extraction (SPE) with different commercially available complexing agents (Chelex 100, Toyopearl and ethylhexylphosphates) was employed for the preconcentration of REE. The investigations revealed that complex stability (varying in dependence of the pH value) has a strong influence on the degree of the enrichment of Gd-DTPA. Based on acidified water samples (pH<3) a procedure using ethylhexylphosphates was proposed for the preconcentration of Gd and REE from surface water samples. For this purpose C₁₈-cartridges loaded with ethylhexylphosphates were used, resulting in an enrichment factor of 40.     

Study of the preconcentration and determination of ultratrace rare earth elements in environmental samples with an ion exchange micro-column

A study was carried out on the preconcentration of ultratrace rare earth elements (REEs) in environmental samples with a micro ion-exchange column and determination by inductively coupled plasma mass spectrometry (ICP-MS). The preconcentration parameters were optimized and the REE recovery was ca. 100% in the pH range 4 to 6 with an ionic strength (μ) less than 0.18. The ion-exchange column capacity with respect to REEs was estimated as 0.96 mmol/g. The linear response coefficients ranged from 0.995 to 0.997 at the pg mL^–1 level. The concentration in the blank could be minimized (0.09 to 3.1 pg mL^–1) if the buffer solution and the water were purified. The detection limits ranged from 0.03 to 0.40 pg mL^–1, for a preconcentration factor of 100. The precision and accuracy of the method was evaluated with a synthetic standard solution and real samples. Results indicated that the REE recovery ranged from 88.1% to 100.2%, and the RSD ranged from 2.7% to 6.7%. Satisfactory results were achieved when this method was applied for the determination of REEs in raw water, purified water and tap water, as well as in environmental aquatic samples. Meanwhile, the method is simple and flexible.     

Determination of REEs in seawater by ICP-MS after on-line preconcentration using a syringe-driven chelating column

A syringe-driven chelating column (SDCC) was applied to develop an on-line preconcentration/inductively coupled plasma mass spectrometry (ICP-MS) method for preconcentration and determination of rare earth elements (REEs) in seawater samples. The present on-line preconcentration system consists of only one pump, two valves, an SDCC, an ICP-MS, several connectors, and Teflon tubes. Optimizations of adsorption pH condition, sample loading flow rate, and integration range were carried out to achieve optimum measurement conditions for REEs in seawater sample. Six minutes was enough for a preconcentration and measurement cycle using 10 mL of seawater sample, where the detection limits for different REEs were in the range of 0.005 pg mL⁻¹ to 0.09 pg mL⁻¹. Analytical results of REEs in a seawater certified reference material (CRM), NASS-5, confirmed the usefulness of the present method. Furthermore, concentrations of REEs in Nikkawa Beach coastal seawater were determined and discussed with shale normalized REE distribution pattern.     

Chelating resins for the concentration of trace elements from sea water and their analytical use in conjunction with atomic absorption spectrophotometry

An investigation has been made of the uptake of trace elements from both distilled water and sea water by the chelating ion-exchange resins Chelex-100 and Permutit S1005. The resins retained the following elements with an efficiency of ca. 100%: Ag, Bi, Cd, Cu, In, Pb, Mo, Ni, rare earths, Re (90% only), Sc, Th, W, V, Y and Zn. Manganese was retained quantitatively only by the Chelex resin. The following elements are removed with 100% efficiency by means of₂N mineral acids: Bi, Cd, Co, Cu, In, Ni, Pb, rare earths, Sc, Th, Y and Zn. Ammonia (4 N) completely removes molybdenum, tungsten, vanadium and rhenium. The resins have been used in conjunction with atomic absorption spectrophotometry for the simultaneous determination of zinc, cadmium, copper, nickel and cobalt in sea waters.     

Ion exchange micro columns for on-line preconcentration of heavy metals II. On-line break-through test for zinc, cadmium and lead

An on-line break-through test for zinc, cadmium and lead has been carried out by means of a flow-through cell and computerized potentiometric stripping analysis. This test has been applied to seventeen ion-exchange materials and enabled within a short time a predecision about the suitability of a resin for a special preconcentration problem. For the determination of the three trace elements in drinking water five ion exchangers are found to be appropriate without restriction and eight resins with some restrictions (not suitable for all three elements, weak matrix influences).     

Synthesis of chitosan resin possessing a phenylarsonic acid moiety for collection/concentration of uranium and its determination by ICP-AES

A chitosan resin possessing a phenylarsonic acid moiety (phenylarsonic acid type chitosan resin) was developed for the collection and concentration of trace uranium prior to inductively coupled plasma (ICP) atomic emission spectrometry (AES) measurement. The adsorption behavior of 52 elements was systematically examined by packing it in a minicolumn and measuring the elements in the effluent by ICP mass spectrometry. The resin could adsorb several cationic species by a chelating mechanism, and several oxo acids, such as Ti(IV), V(V), Mo(VI), and W(VI), by an anion-exchange mechanism and/or a chelating mechanism. Especially, U(VI) could be adsorbed almost 100% over a wide pH region from pH 4 to 8. Uranium adsorbed was easily eluted with 1 M nitric acid (10 mL), and the 25-fold preconcentration of uranium was achieved by using a proposed column procedure, which could be applied to the determination of trace uranium in seawater by ICP-AES. The limit of detection was 0.1 ng mL⁻¹ for measurement by ICP-AES coupled with 25-fold column preconcentration.     

A novel method for the simultaneous determination of Pb (II), Cd (II) and Zn (II) in environmental water samples

A novel UV-VIS spectrophotometric method was developed in this study by using solid phase extraction procedure for the simultaneous preconcentration, separation and determination of trace levels of Pb (II), Cd (II) and Zn (II) ions in various water samples by using Amberlite N,N-bis(salicylidene)cyclohexanediamine (SCHD) resin. This study presents the results of experimental procedures carried out like the adsorption of analytes to the resin, influences of some analytical parameters that effect the recovery such as pH, sample volume, sample flow rate, eluent type and concentration, eluent volume, eluent flow rate and the effects of alkaline metals, earth alkaline metals and some other transition metals. The analytes in the samples with the adjusted pH range of 4–7 were adsorbed on XAD-4-SCHD resin and eluted by using 1.0 mol L^?1 nitric acid. The amounts of ions were determined by using UV-VIS spectrometer. The limits of detection were 0.03, 0.07 and 0.05 µg mL^?1 for Pb (II), Cd (II) and Zn (II), respectively. The accuracy of the method was assured by the analysis of the certified standard water sample NW-TMDA-70.2 and the observed recoveries were above 93%. Different environmental water samples that contain trace amounts of Pb (II), Cd (II) and Zn (II) were analysed by using the method developed in this study. Same samples were also analysed by ICP-MS for comparison and almost the similar results were observed. The method developed in this study was successfully applied to the various environmental water samples to determine the trace levels of Pb (II), Cd (II) and Zn (II) ions.     

Determination of Rare Earth Elements in Natural Water Samples by Rapid Sequential High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR CS FAAS) and inductively Coupled Plasma-Mass Spectrometry (ICP-MS)

A method was developed to sequentially assay ten rare earth elements by high-resolution continuum source flame atomic absorption spectrometry. The rare earth elements Nd, Sm, Eu, Tb, Ho, Er, Tm, Yb, Y, and Sc were assayed in environmental water samples which were also analyzed by a reference inductively coupled plasma-mass spectrometry protocol. The samples did not require pretreatment or preconcentration. Interferences for the method were evaluated. Experimental parameters, including the flame composition, burner height, ionization buffers and number of pixels, were optimized. The volume necessary to run measurements in triplicate was only 15?mL per sample. The accuracy, precision and linear range were evaluated. The limits of detection ranged from 0.003 to 0.473?µg mL^?1 for the most sensitive (Yb) to the least sensitive (Tb) element.     

Ion exchange micro columns for on-line preconcentration of heavy metals

An on-line break-through test for zinc, cadmium and lead has been carried out by means of a flow-through cell and computerized potentiometric stripping analysis. This test has been applied to seventeen ion-exchange materials and enabled within a short time a predecision about the suitability of a resin for a special preconcentration problem. For the determination of the three trace elements in drinking water five ion exchangers are found to be appropriate without restriction and eight resins with some restrictions (not suitable for all three elements, weak matrix influences).     

Determination of heavy metals and rare earth elements in environmental samples by ICP-MS after solid phase preconcentration with chelating resin fibers and anion exchanger filters.

A solid phase collection/concentration method using anion exchanger filters and a small syringe packed with chelating resin fibers is adopted as a preconcentration tool for trace elements and a separation tool for matrices in aqueous samples prior to the measurement by inductively coupled plasma-mass spectrometry (ICP-MS). The effects of fiber volume, sample volume, eluent volume, and sample flow rate on metal recoveries were investigated in detail to obtain optimum pretreatment conditions. Several heavy metals (HMs) such as, V, Mn, Co, Ni, Cu, Zn, Ga, Cd, Pb, Th and U, as well as 14 rare earth elements (REEs) in sample solutions at pH 6 were quantitatively collected on the solid phase. These adsorbed elements were completely recovered by eluting with 2 ml of 1.0 M nitric acid. At pH 6, more than 99% of alkali and alkaline earth metals in sample solutions were eliminated. The proposed method was evaluated by analyzing two standard reference materials (SRM): peach leaves (NIST 1547) and pond sediment (NIES No. 2). The solid samples were decomposed by microwave-heating and pressurizing acid digestion technique, and then treated by the proposed syringe-type pretreatment method, followed by the ICP-MS measurement. The analytical results for HMs in the SRMs obtained by the present method agreed well with the certified values.     

Reversed-phase extraction chromatography–neutron activation analysis (RPEC–NAA) for copper in natural waters using Amberlite XAD-4 resin coated with 1-(2-thiazolylazo)-2-naphthol

A preconcentration neutron activation analysis method has been developed for the determination of trace levels of Cu in natural waters including seawater with an absolute detection limit of 0.106 μg. The method involves the preconcentration of Cu onto Amberlite XAD-4 resin coated with 1-(2-thiazolylazo)-2-naphthol using reversed-phase extraction chromatography (RPEC). Copper is assayed through its neutron activation product ⁶⁶Cu (half-life = 5.10 min) by direct irradiation of the resin bed. Factors affecting the uptake of Cu onto the ligand-impregnated resin have been investigated; these include flow rate, pH, column height, presence of other trace elements, major elements, and interfering matrix. The RPEC–NAA method has been validated by analyzing NIST and NRC water reference materials.     

Application of iminodiacetate chelating resin muromac A-1 in on-line preconcentration and inductively coupled plasma optical emission spectroscopy determination of trace elements in natural waters

On-line system incorporating a microcolumn of Muromac A-1 resin was used for the developing of method for preconcentration of trace elements followed by inductively coupled plasma (ICP) atomic emission spectrometry determination. A chelating type ion exchange resin has been characterized regarding the sorption and subsequent elution of 24 elements, aiming to their preconcentration from water samples of different origins. The effect of column conditioning, pH and flow rate during the preconcentration step, and the nature of the acid medium employed for desorption of the retained elements were investigated. A sample (pH 5) is pumped through the column at 3 ml min⁻¹ and sequentially eluted directly to the ICP with 3 M HNO₃/HCl mixtures. In order to remove residual matrix elements from the column after sample loading a short buffer wash was found to be necessary. The effectiveness of the matrix separation process was illustrated. The procedure was validated by analyzing several simple matrices, Standard River water sample as well as artificial seawater. Proposed method can be applied for simultaneous determination of In, Tl, Ti, Y, Cd, Co, Cu and Ni in seawater and for multielement trace analysis of river water. Recovery at 1 μg l⁻¹ level for the determination of investigated 24 elements in pure water ranged from 93.1 to 96% except for Pd (82.2%) and Pb (88.1%). For the same concentration level for seawater analysis recovery was between 81.9 and 95.6% except for Hg (38.2%).     

Improved detection of transition and rare earth elements in marine samples with the CETAC DSX-100 preconcentration/matrix elimination system and ICP-MS

A new method for detection of trace metals in saline samples is described using batch preconcentration with subsequent ICP-MS analyses after direct sample insertion of the analyte loaded chelating resin. The samples were prepared using a CETAC DSX-100 system, which preconcentrates analytes and removes matrix components by a suspended particulate reagent (SPR). The SPR is consisting of polymeric beads of 0.2 μm size that selectively binds the trace metals by iminodiacetic chelating groups. The beads with bound analytes are then nebulized directly into the ICP-MS. The enrichment factors lay between 40 and 48 due to the enrichment of 120 mL suspension to 2.5–3.0 mL eluate. The method was applied and validated to the successful determination of traces of the transition metals Mn, Fe, Ni, Co, Cu, Zn, Cd, and Pb in the Open Ocean Seawater certified reference material NASS-4 and the Coastal Seawater certified reference material CASS-3. In addition to the certified constituents the rare earth elements La, Ce, Eu, Gd, Yb, and Lu were determined. Received: 15 Oktober 1999 / Revised: 1 February 2000 / Accepted: 3 February 2000     

Simultaneous multi-element analysis for trace metals in sea water by inductively-coupled plasma/atomic emission spectrometry after batch preconcentration on a chelating resin

Batch treatment with Chelex-100 resin was investigated for preconcentration of trace metals in sea water followed by determination by inductively-coupled plasma atomic emission spectrometry. The preconcentration conditions such as resin weight, stirring time, and amount of ammonium acetate buffer solution were carefully examined for effective multi-element preconcentration from sea water. The resin weight could be decreased to 0.5 g (dry weight) for 1 l of sea water, which was much less than that required in the column method, and a preconcentration factor of 100 was achieved. Al, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Y, Mo, Cd and Pb in sea water were measured with good precision. The detection limits ranged from 6 to 180 ng l^?1. The time required for one sample by the batch method was only 3 h.