Gold In Water Samples Research Articles

Ion-association dispersive liquid–liquid microextraction of trace amount of gold in water samples and ore using Aliquat 336 prior to inductivity coupled plasma atomic emission spectrometry determination

An extraction method employing dispersive liquid–liquid microextraction (DLLME) and ICP-OES has been developed for rapid separation, pre-concentration and determination of ultra-trace amount of Au(III). The extraction of the analyte was performed in the presence of a quaternary ammonium cation, N-Methyl-N, N, N-trioctylammonium chloride, (Aliquat 336) as an extractant based on ion-association extraction system. 1-octanol and acetonitrile were used as extraction and disperser solvents, respectively. The variables affecting the extraction conditions were optimized. Calibration curve in the range of 0.3–100 ng mL−1, the detection limit of 0.09 ng mL−1, enrichment factor of 150 and extraction recovery of 74% were obtained. The precision (R.S.D. %) of the method was 6% for 5 replicates and recoveries of 10 ng mL−1 Au(III). The combined DLLME method with ICP-OES can readily determine Au(III) at trace (μg L−1) level using only 10 mL of sample solution (tap, lake, and mining water) and ore sample without interference by the matrices. This methodology is simple, fast, and low cost which can be used in routine analytical laboratories.

Determination of gold in water samples using electromembrane extraction

ABSTRACTIn this work, an electromembrane extraction (EME) technique was used for the extraction and determination of gold from water samples prior to UV-Vis spectrophotometry. An artificial neural network (ANN) combined with imperialist competitive algorithm (ICA) has been applied to optimize the EME. The effective parameters including pH of acceptor phase, extraction time (t), volume of sample solution (V), stirring rate (S), and voltage (E) were chosen as input variables and the extraction recovery of gold was considered as output variable. The mean of squared error (i.e., 0.0009) and determination coefficient (i.e., 0.9821) were applied to estimate the performance of the ANN model. The limit of detection was 4.5 µg L−1 (S/N = 3) on the optimized variables. The intra- and interday precisions (%) were found to be 6.7% and 2.6%, respectively. This technique was then applied for analysis of gold from environment water samples.

Ion-association dispersive liquid–liquid microextraction of ultra-trace amount of gold in water samples using Aliquat 336 prior to inductively coupled plasma atomic emission spectrometry determination

Gold is a rare and noble metal with atomic number of 79. Several techniques including both spectrometric and electrochemical methods are widely used to determine gold level in real samples. As a result of low concentration of gold in environmental samples, sample preparations such as extraction, clean-up, and pre-concentration before instrumental analysis are mandatory. Thus, a pre-treatment method (dispersive liquid–liquid microextraction (DLLME)) for gold pre-concentration and inductively coupled plasma optical emission spectrometry (ICP-OES) determination is proposed. An extraction method employing DLLME and ICP-OES has been developed for rapid separation, pre-concentration, and determination of ultra-trace amount of Au (III). The extraction of the analyte was performed in the presence of a quaternary ammonium cation, N-methyl-N,N,N-trioctylammonium chloride, (Aliquat 336) as an extractant based on ion-association extraction system. 1-Octanol and acetonitrile were used as extraction and disperser solvents, respectively. The variables affecting the extraction conditions were optimized. A calibration curve in the range of 0.3–100 ng mL−1, the detection limit of 0.09 ng mL−1, an enrichment factor of 150, and an extraction recovery of 74 % were obtained. The precision (RSD %) of the method was 6 % for five replicates and recoveries of 10 ng mL−1 Au(III). The combined DLLME method with ICP-OES can readily determine Au(III) at trace (μg L−1) level using only 10 mL of sample solution (tap, lake, and mining water) without interference by the matrices. This methodology is simple, fast, and low cost which can be used in routine analytical laboratories.

Salt saturated single drop microextraction of gold from water samples and its determination by graphite furnace atomic absorption spectrometry

A new microextraction procedure, termed salt saturated single drop microextraction, combined with graphite furnace atomic absorption spectrometry (GFAAS) was introduced and developed for the determination of gold in water samples. This is the first report of the extraction of a cationic species by direct immersion SDME utilizing a polar solvent. A mixture of benzyl alcohol–isopropyl alcohol was used as the extracting solvent from the brine sample, which can be considered as a form of salting-out solvent extraction. The factors influencing the extraction efficiency, such as type and volume of extracting solvent, extraction time, pH, agitation of sample, temperature and volume of sample were investigated and optimized. The developed protocol was found to yield a linear calibration curve in the concentration range of 25 and 550 μg L−1 with a limit of detection of 7.4 μg L−1. The total analysis time including microextraction was less than 10 min. The method has been successfully applied for the analysis of gold in three spiked tap, lake and seawater samples.

Liquid-Liquid Microextraction with Vortex-Assisted for Determination of Palladium and Gold in Water Samples by Flame Atomic Absorption Spectrometry

Liquid-Liquid Microextraction with Vortex-Assisted for Determination of Palladium and Gold in Water Samples by Flame Atomic Absorption Spectrometry

Chemically modified activated carbon with tris(hydroxymethyl)aminomethane for selective adsorption and determination of gold in water samples

In the current study, a sensitive and simple method for selective separation of gold, Au(III), from water samples prior to its determination by inductively coupled plasma-optical emission spectrometry (ICP-OES), was investigated. The method utilized activated carbon modified with tris(hydroxymethyl)aminomethane (AC–TRIS) as a solid-phase extractant. Surface properties of the AC–TRIS phase were characterized by Fourier transform infrared (FT-IR) spectroscopy. The separation parameters for effective adsorption of Au(III), including effects of pH, Au(III) concentration, shaking time, and common coexisting ions were examined using batch method. The optimum pH value for the separation of Au(III) on the new sorbent was 1.0, and the maximum static adsorption capacity of Au(III) onto the AC–TRIS was 33.57mgg−1 at this pH and after 1h contact time. The Au(III) adsorption data were modeled using both Langmuir and Freundlich classical adsorption isotherms. Results demonstrated that the adsorption of Au(III) onto activated carbon followed second-order kinetic model. In addition, the efficiency of this methodology was confirmed by applying it to real environmental samples.

New method for microextraction of ultra trace quantities of gold in real samples using ultrasound-assisted emulsification of solidified floating organic drops

A method was developed for the determination of gold ion in water samples using microextraction based on the ultrasound-assisted emulsification of solidified floating organic drops, followed by the flame atomic absorption spectrometry. N-(4-{4-[(anilinocarbothioyl)amino]benzyl}phenyl)-N-phenylthiourea was used as chelating agent. The parameters affecting the extraction and complex formation (including the type and volume of the extracting solvent, time of sonication and centrifugation, pH, amount of the chelating agent, and sample ionic strength) were optimized. Under the optimum conditions, the calibration graph is linear in the range from 1.5 to 400 ng mL−1, with a limit of detection of 0.45 ng mL−1. The relative standard deviation for ten replicate determinations of gold ion in a concentration of 175 ng mL−1 was 1.7%. The procedure was successfully applied to the determination of gold in water samples, in pharmaceutical and synthetic samples, and in a standard reference material.

Ion pair-based dispersive liquid–liquid microextraction for gold determination at ppb level in solid samples after ultrasound-assisted extraction and in waters by electrothermal-atomic absorption spectrometry

A new methodology was developed for the determination of ultratrace levels of gold in water samples, soils and river sediments. Dispersive liquid–liquid microextraction was used to preconcentrate the ion pair formed between AuCl 4 − and [CH 3(CH 2) 3] 4N + in a microliter-range volume of chlorobenzene using acetone as disperser solvent. When solid samples were analyzed, the method consisted of a combination of ultrasound-assisted extraction and dispersive liquid–liquid microextraction with final detection by electrothermal-atomic absorption spectrometry. Since an HCl medium was required for the formation of the AuCl 4 − complex, HCl together with HNO 3 was used as extractants for ultrasound-assisted extraction. After optimization, the enrichment factor obtained was 220 for water samples. Moreover, the extraction efficiency was around 96%. The repeatability, expressed as relative standard deviation ranged from 3.6% to 9.7%. The instrumental detection limit was 8.4 ng L −1, whereas the procedural detection limits were 42 ng L −1 for water samples and 1.5 ng g −1 for environmental solid samples.

Simplified cloud point extraction-inductively coupled plasma mass spectrometry for the preconcentration/analysis of ultra-trace gold

A new cloud point extraction method for the preconcentration of ultra-trace gold as a prior step to its determination by inductively coupled plasma mass spectrometry (ICP-MS) has been developed. The method is based on the cloud point extraction (CPE) of gold in the non-ionic surfactant Triton X-114 without a chelating agent. The parameters of CPE were investigated in detail. At optimum conditions, the linear range of 5.0–200.0 ng L −1 of Au(III) and the detection limits of 1.1 ng L −1 for Au(III) along with enrichment factors of 7.5, were obtained. The proposed method was applied to determination of ultra-trace amounts of gold in water samples with satisfactory results.

Separation and preconcentration trace amounts of gold by using modified organo nanoclay closite 15A

The application of organo nanoclay 5-(4-dimethylamino-benzylidene) rhodanine-immobilized as a new, easily prepared, and stable solid sorbent for preconcentration trace amounts of Au(III) ions in aqueous solution is presented. The sorption of Au(III) ions was quantitative in the pH range of 2-4, and quantitative desorption occurred instantaneously with 10.0 mL of a mixture containing 0.5 mol L-1 Na2S2O3 and KSCN. Various parameters, such as the effect of pH, breakthrough volume, extraction time, and interference of a large number of anions and cations have been studied. The proposed method has been applied for determination of trace amount of gold in water samples.