Determination Of Rare Earth Elements In Seawater Research Articles

Development of an automatic pH-adjustment system for solid phase extraction prior to the determination of REEs in seawater by ICP-MS

An automatic pH adjustment instrument was developed for solid phase extraction (SPE) of rare earth elements (REEs) using chelating resins. The automation of pH adjustment was carried out by using a spectrometer, an input/output (I/O) board, an automatic-switching valve, and a personal computer with LabVIEW® programming platform. Contactless monitoring of the pH was carried out by measuring the intensity of transmitted light at 550 nm that passed through a sample solution with an added pH-indicator, i.e. methyl red. A reagent for adjusting the pH, i.e. an aqueous ammonia solution, was sprayed into the sample solution using a nebuliser, which permitted the addition of a small amount of the reagent and the precise adjustment of the pH. The pH value of the sample was monitored by measuring the intensity of the transmitted light using the spectrometer, while the open-time of the valve to add the reagent was automatically controlled simultaneously with the measurement of the transmitted light. The precision of the pH adjustment was tested and confirmed by using a seawater sample. The blank values and detection limits of REEs were given as the analytical figures of merits. The usefulness of the present method was confirmed by analysing seawater samples from the Nikkawa Beach, the Kashima Bay, and the Ishigaki Island. The results of REEs in these samples were discussed with shale normalised REE distribution pattern.

Determination of rare earth elements in seawater by inductively coupled plasma mass spectrometry with off-line column preconcentration using 2,6-diacetylpyridine functionalized Amberlite XAD-4

An off-line column preconcentration technique using a micro-column of 2,6 diacetylpyridine functionalized Amberlite XAD-4 with inductively coupled plasma mass spectrometry (ICP-MS) as a means of detection has been developed. The aim of the method was to determine rare earth elements (REEs) (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in seawater. Sample solutions (2–10 mL) were passed through the column which was then washed with ultra-pure water to remove residual matrix. The adsorbed cations on the resin were eluted by using 2 mL of 0.1 mol L −1 HNO 3 containing 10 ng mL −1 indium as an internal standard. The eluent was analyzed for the metal concentrations using ICP-MS. Sample pH as well as the sample and eluent flow rates were optimized. The sorption capacity of resin was determined by the batch process, by equilibrating 0.05 g of the resin with solutions of 50 mL of 25 mg L −1 of individual metal ions for 4 h at pH 6.0 at 26 °C. The sorption capacities for the resin were found to range between 47.3 μmol g −1 (for Lu) and 136.7 μmol g −1 (for Gd). Limits of detection (3σ), without any preconcentration, ranged from 2 ng L −1 to 10.3 ng L −1 (for Tm and Lu respectively). The proposed method was applied to the determination of REEs in seawater and tap water samples.

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.

Determination of rare earth elements in seawater by on-line column preconcentration inductively coupled plasma mass spectrometry

A home made column of commercially available iminodiacetate resin, Muromac A-1 (50–100 mesh) was used to concentrate rare earth elements (REEs) (15 elements: Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in seawater. An automated low pressure flow analysis method with on-line column preconcentration/inductively coupled plasma mass spectrometry (ICP-MS) is described for the determination of REEs in seawater. Sample solutions (adjusted to pH of 3.0) passed through the column. After washing the column with water, the adsorbed elements were subsequently eluted into the plasma with 0.7 M nitric acid. Calibration curves were accomplished by means of purified artificial seawater with a sample loading time of 120 s. Detection limits (DLs) of the on-line column preconcentration/ICP-MS by eight replicate operations were between 0.040 and 0.251 pg ml −1 for REEs in the artificial seawater. The precision was less than 8.9% for REEs and one sample can be processed in 7 min using a 7 ml of sample. The proposed method was applied to determine REEs in coastal seawater of Hiroshima Bay, Japan.

Determination of Rare Earth Elements in Seawater by On-line Column Preconcentration Inductively Coupled Plasma Mass Spectrometry

Abstract A home made column of commercially available iminodiacetate resin, Muromac A-1 (50–100 mesh) was used to concentrate rare earth elements (REEs) (15 elements: Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in seawater. An automated low pressure flow analysis method with on-line column preconcentration/inductively coupled plasma mass spectrometry (ICP-MS) is described for the determination of REEs in seawater. Sample solutions (adjusted to pH of 3.0) passed through the column. After washing the column with water, the adsorbed elements were subsequently eluted into the plasma with 0.7 M nitric acid. Calibration curves were accomplished by means of purified artificial seawater with a sample loading time of 120 s. Detection limits (DLs) of the on-line column preconcentration/ICP-MS by eight replicate operations were between 0.040 and 0.251 pg ml−1 for REEs in the artificial seawater. The precision was less than 8.9% for REEs and one sample can be processed in 7 min using a 7 ml of sample. The proposed method was applied to determine REEs in coastal seawater of Hiroshima Bay, Japan.

Preconcentration of Rare Earth Elements in Seawater with Poly(acrylaminophosphonic dithiocarbamate) Chelating Fiber Prior to Determination by Inductively Coupled Plasma Mass Spectrometry

A new ion-exchange chelating fiber with aminophosphonic and dithiocarbamate groups based on polyacrylonitrile was developed for the preconcentration of rare earth elements (REEs) in seawater prior to their determination by inductively coupled plasma mass spectrometry. REEs can be easily separated from the high-saline matrix using the fiber. The optimum experimental parameters such as pH, flow rate, sample volume, and effect of matrix ions for preconcentration of REEs were investigated. All REEs in water can be quantitatively retained in the acidity range of pH 3−6 by the fiber and then eluted quantitatively with 0.01 mol L-1 ammonium citrate. The fiber has been applied to the concentration of REEs in seawater. The relative standard deviations for the determination of REEs in seawater at nanogram per liter levels were found to be less than 5%. A reasonably good agreement is obtained with the data reported in the literature.