Beryllium In Water Samples Research Articles

Separation and preconcentration of ultra trace amounts of beryllium in water samples using mixed micelle-mediated extraction and determination by inductively coupled plasma-atomic emission spectrometry

In the present study a cloud point extraction process using mixed micelle of the cationic surfactant cetyl-pyridinium chloride (CPC) and non-ionic surfactant Triton X-114 for extraction of beryllium from aqueous solutions is developed. The extraction of analyte from aqueous samples was performed in the presence of 1,8-dihydroxyanthrone as chelating agent in buffer media of pH 9.5. After phase separation, the surfactant-rich phase was diluted with 0.4 mL of a 60:40 methanol–water mixture containing 0.03 mL HNO 3. Then, the enriched analyte in the surfactant-rich phase was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The different variables affecting the complexation and extraction conditions were optimized. Under the optimum conditions (i.e. 1.6 × 10 −4 mol L −1 1,8-dihydroxyanthrone, 1.2 × 10 −4 mol L −1 CPC, 0.15% (v/v) Triton X-114, 50 °C equilibrium temperature) the calibration graph was linear in the range of 0.006–80 ng mL −1 with detection limit of 0.001 ng mL −1 and the precision (R.S.D.%) for five replicate determinations at 18 ng mL −1 of Be(II) was better than 2.9%. In this manner the preconcentration and enrichment factors were 16.7 and 24.8, respectively. Under the presence of foreign ions no significant interference was observed. Finally, the proposed method was successfully utilized for the determination of this cation in water samples.

Cloud-Point Formation Based on Mixed Micelles for the Extraction, Preconcentration and Spectrophotometric Determination of Trace Amounts of Beryllium in Water Samples

A cloud-point extraction process using a mixed micelle of the cationic surfactant cetyl pyridinium chloride (CPC) and non-ionic surfactant Triton X-114 to extract beryllium from aqueous solutions was investigated. The method is based on the color reaction of beryllium with Chrome Azurol S (CAS) in acetate buffer and the mixed micelle-mediated extraction of the complex. This complex was concentrated in a surfactant-rich phase after separation. The optimal extraction and reaction conditions (e.g. pH, reagent and surfactant concentrations, temperature, incubation and centrifuge times) were evaluated and optimized. Under the optimized conditions, the analytical characteristics of the method (e.g. limit of detection, linear range and preconcentration factor) were obtained. Linearity was obeyed in the range of 0.30 - 18 ng mL(-1) of beryllium and the detection limit of the method was 0.05 ng mL(-1). The interference effect of some cations and anions was also studied. The proposed method was successfully applied to the determination of beryllium in real water samples.

Micelle-mediated extraction for simultaneous spectrophotometric determination of aluminum and beryllium using mean centering of ratio spectra

A new micelle-mediated extraction method for preconcentration of ultra-trace quantities of beryllium and aluminum as a prior step to their simultaneous spectrophotometric determination has been developed. Chrome Azurol S (CAS), cetyltrimethylammonium bromide (CTAB) and Triton X-114 were used as chelating agent, cationic surfactant for extraction and co-extraction agent, respectively. Mean centering (MC) of ratio spectra has been used for simultaneous analysis of beryllium and aluminum. The optimal extraction and reaction conditions were studied, and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration, and improvement factors) were obtained. Linearity was obeyed in the range of 5-40ngmL(-1) of beryllium and 3-100ngmL(-1) of aluminum. The detection limit of the method is 0.98 and 0.52ngmL(-1) for beryllium and aluminum, respectively. The interference effect of some anions and cations was also tested. The method was applied to the simultaneous determination of beryllium in water samples.

Micellanized spectrophotometric method for the determination of beryllium using haematoxylin

A simple and sensitized spectrophotometric method for the determination of trace amounts of beryllium has been described. The method is based on the formation of a ternary complex by the reaction of beryllium with haematoxylin in the presence of micellar medium (cationic surfactant, cetyltrimethylammonium bromide). The ternary complex of beryllium has a maximum absorbance at 592 nm and showed an excellent sensitivity (molar absorption coefficient of 7.07 × 10 4 L mol −1 cm −1 and the Sandell's sensitivity being 1.27 × 10 −4 μg cm −2) and reproducibility (within-day precision: R.S.D. ≤ 0.36%, n = 5, between-day precision: R.S.D. ≤ 0.65%, n = 5). Linearity was achieved over the range 0.01–0.1 μg mL −1 of beryllium with a correlation coefficient of 0.9999. The effect of foreign substances on the determination has been examined. The proposed procedure has been applied to the determination of beryllium in water samples.

Spectrophotometric determination of beryllium in water samples after micelle-mediated extraction preconcentration

A new micelle-mediated phase preconcentration method for preconcentration of ultra-trace quantities of beryllium as a prior step to its determination by spectrophotometry has been developed. Chrome Azurol S (CAS) and cetyltrimethylammonium bromide (CTAB) were used as chelating agent and cationic surfactant, respectively. The method evaluates and eliminates the blank bias error present in such procedures using mean centering of ratio spectra. This procedure gives more accurate results than the traditional approach using absorbance values against reagent blank. The optimal extraction and reaction conditions were studied and the analytical characteristics of the method (e.g., limit of detection, linear range, preconcentration and improvement factors) were obtained. Linearity was obeyed in the range of 0.9–18.0 ng mL −1 (1.00 × 10 −7–2.00 × 10 −6 mol L −1) of beryllium. The detection limit of the method is 0.51 ng mL −1 (5.66 × 10 −8 mol L −1) of beryllium. The interference effect of some anions and cations was also tested. The method was applied to the determination of beryllium in spring water samples.

Preconcentration of trace amounts of beryllium in water samples on octadecyl silica cartridges modified by quinalizarine and its determination with atomic absorption spectrometry

A simple method has been developed for rapid and selective extraction, preconcentration and determination of trace amounts of beryllium. The extraction is carried out by octadecyl silica cartridge, modified with quinalizarine as a chelating agent. The effect of different parameters, such as sample matrix, flowrates of sample solution and eluent, pH, type and least amount of eluent for elution of Be +2 ions from cartridge, breakthrough volume and limit of detection, were evaluated. Also, the effects of various cationic and anionic interferences on percent recovery of Be +2 were studied. Be +2 was extracted from solution at pH 6–6.6 and was eluted from modified cartridge with 5 ml of 0.5 M HNO 3. Extraction efficiencies >99% were obtained by elution of the cartridges with minimal amount of eluent. A preconcentration factor of 200 and a detection limit of 200 ng per 1000 ml were obtained. The method was applied to the recovery and determination of Be +2 in different water and alloy samples.

Sensitive and selective ion chromatographic method for the determination of trace beryllium in water samples

A selective and sensitive ion chromatographic method has been developed for the determination of beryllium in a number of water samples at low-μg/l concentrations. The separation was performed on a 250×4.0 mm I.D. iminodiacetic acid functionalised silica gel column. Chromatographed Be(II) was detected using visible detection at 590 nm following post-column reaction with chrome azurol S (CAS). The optimum separation and derivatisation conditions were studied in detail. The optimum eluent conditions were found to be 0.4 M KNO 3, adjusted to pH 2.5 using HNO 3, with optimum post-column detection being achieved using a solution containing 0.26 m M CAS, 2% Triton X-100, 50 m M 2-( N-morpholino)ethanesulfonic acid, pH 6.0. Under the above conditions, the concentration detection limit for Be(II) was found to be 3 μg/l in a standard solution and 4 μg/l in a typical tap water sample, using a 250 μl injection. The method was linear over the investigated range of 10 μg/l to 10 mg/l and highly reproducible. The method was successfully applied to a number of water samples of varying matrix complexity, including simulated seawater, and also to a natural freshwater certified reference material NIST 1640.

Determination of beryllium in natural and waste waters using on-line flow-injection preconcentration by precipitation/dissolution for electrothermal atomic absorption spectrometry

A flow injection (FI) on-line precipitation–dissolution was developed for electrothermal atomic absorption spectrometry (ETAAS) determination of (ultra)trace amounts of beryllium in water samples. Beryllium was precipitated quantitatively with NH 4OH+NH 4Cl and collected in a knotted tube of Tygon without using a filter, while the other matrix components flowed downstream to waste. The precipitate was dissolved with nitric acid and a sub-sample was collected in a capillary of a sampling arm assembly, to introduce 10 μl volumes into the graphite tube by means of positive displacement with air through a time-based injector. This sequence was timed to synchronize with the previous introduction of 6 μg of Lu (in 20 μl) by the spectrometer autosampler. The effect of a number of possible cations on the beryllium precipitation process was studied. While, the addition of Ba 2+, Sr 2+, Ca 2+, Mg 2+, Mn 2+, Zn 2+, Co 2+ and Ni 2+ did not produce any perceptible precipitate on the reaction coil walls, the addition of Al 3+, Cr 3+ and Fe 3+ produced large precipitated particles. However, their tolerance limit was well above the levels at which theses species are commonly found in most natural waters. The detection limit (3σ) of 25 ng l −1 in the sample solution was obtained. The precision of the method, evaluated by ten replicate analyses of solutions containing 20 and 200 pg of beryllium were 4.8 and 4.0% ( n=5), respectively. Enrichment factors from 7.0 to 10.3 and from 10.5 to 13.8 were obtained for precipitation times from 25 to 38 s and from 43 to 50 s for waste and tap waters, respectively. These results indicate that the enrichment factor was limited by the interference of some matrix metals which could precipitate as hydroxides (or related species) and be retained in the reaction coil. The integrated system permits fully automated operation, avoiding time-consuming manual work and enhancing the reproducibility and precision of the determination of beryllium. The results obtained for the determination of beryllium in certified reference materials (trace elements in water), together with the good recovery of spiked analytes, demonstrate the applicability of the procedure to the analysis of natural waters.

Determination of Beryllium in the Primary Cooling Water of the BER II Research Reactor by Inductively Coupled Plasma Optical Emission Spectrometry and Zeeman Electrothermal Atomic Absorption Spectrometry

In modern swimming pool research reactors the stable isotope 9 Be from the neutron reflector made of metallic beryllium is converted into 10 Be via a (n, γ )-reaction. This isotope contaminates the primary cooling water as a corrosive of the reflector material and has to be monitored continually. Since 10 Be can only be determined with nuclear spectrometric methods after an extensive radiochemical procedure, an indirect two step procedure was worked out: ( a ) calculation of the specific 10 Be-activity from the accumulated radiation periods since installation of the reflector into the reactor and ( b ) determination of the total amount of beryllium in the cooling water by using a sufficiently sensitive analytical technique. Knowledge of both values allows the immediate calculation of the 10 Be contamination of the pool water. It is shown that the inductively coupled plasma optical emission spectrometry (ICP-OES) coupled with ultrasonic nebulization is applicable to the determination of beryllium in water samples in the sub-ppb region. Comparing the three different emission lines, 234.861 nm, 313.042 nm and 313.107 nm, the first one proved to be best suited for the above mentioned analytical problem. The Be determination in the reactor water samples was also carried out using electrothermal atomic absorption spectrometry (ETAAS) with longitudinal heating of the graphite tube and Zeeman background compensation. The samples were measured without matrix-modification using the 234.861 nm absorption line. Quality assurance for both analytical methods was done determining two reference water samples. Detection limits (3σ) were similarly low: 0.012 µg l -1 for ICP-OES and 0.005 µg l -1 for ETAAS. Parallel analysis of seven different reactor pool water samples using both methods showed concentration values in fairly good agreement. The concentrations obtained were in the range 0.02–0.46 µg l -1 and yielded 10 Be activities of 0.3–9 Bq l -1 .

Determination of a trace amount of beryllium in water samples by graphite furnace atomic absorption spectrometry after preconcentration and separation as a beryllium-acetylacetonate complex on activated carbon

A rapid and simple preconcentration method by selective adsorption using activated carbon as an adsorbent and acetylacetone as a complexing agent is described for the determination of a trace amount of beryllium by graphite furnace atomic absorption spectrometry. The beryllium-acetyl-acetonate compler is adsorbed easily onto activated carbon at pH 8-10. The activated carbon which adsorbed the beryllium-acetylacetonate complex was separated and dispersed in pure water. The resulting suspension was introduced directly into the graphite furnace atomizer. The determination limit was 0.6 ng/L (S/N=3), and the relative standard deviation at 0.25 μg/L was 3.0-4.0 (n=6)

Separation and concentration of beryllium by coprecipitation with hafnium hydroxide prior to determination by graphite furnace atomic absorption spectrometry

Hafnium hydroxide coprecipitates 0.01–0.2 µg of beryllium from 100–400 ml of sample solution at pH 6.0–10.5. The presence of hafnium quantitatively increases the atomic absorbance of beryllium by about 1.5 times, and the reproducibility of the measurement is improved. The calibration graph is linear for 0.4–8 ng ml–1 of beryllium. The interference induced by large amounts of aluminium can be eliminated by raising the pH of the solution to 13–13.5 with sodium hydroxide solution after the coprecipitation procedure has been carried out at about pH 9.5. Several other ions tested did not produce serious interference effects. This method is applicable to the determination of trace amounts of beryllium in water samples and in aluminium.