Carrier Element-free Coprecipitation Research Articles

A green and simplified approach for the quantitative and sensitive analysis of heavy metal ions in sea and stream waters

Abstract Elimination of the matrix effect is a major challenge in developing a method for the quantification of heavy metals (HMs) in water samples. In this regard, the current research describes the simultaneous analyses of Cu(II), Cd(II), and Ni(II) ions in water matrices through flame atomic absorption spectrophotometry (FAAS) after preconcentration with carrier element-free co-precipitation (CEFC) technique by the help of an organic co-precipitant, 3-{[5-(4-Chlorobenzyl)-3-(4-chlorophenyl)-1H-1,2,4-triazol-1-yl]-methyl}-4-[2,4-(dichlorobenzylidene)amino]-1H-1,2,4-triazole-5(4H)-thione (CCMBATT). Based on our literature research, CCMBATT was employed for the first time in this study as an organic co-precipitant for the preconcentration of HMs. Factors such as solution pH, concentration of co-precipitant, sample volume, standing time, centrifugation rate, and time were thoroughly examined and optimized to achieve the highest efficiency in terms of HM recovery. The limits of detection (LODs) (with 10 number of tests) of 0.54, 0.34, and 1.95 μg L−1 and the relative standard deviations (RSD %) of 2.1, 3.3, and 3.0 were determined for Cu(II), Cd(II) and Ni(II) ions, respectively. Recovery results of HMs for the spiked samples were in the range of 92.8–101.0%, demonstrating the trueness of the method and its applicability to the water samples matrix.

Development of a New and Facile Carrier Element-Free Coprecipitation Procedure for Separation, Preconcentration and Sensitive Determination of Cu(II) and Cd(II) Ions in Water and Vegetable Samples

A facile and sensitive method predicated on carrier element free coprecipitation (CEFC) using 2-(2-(2-(4-bromobenzyl)-1H-benzo[d]imidazole-1-yl)acetyl)-N-ethylhydrazine-1-carbothioamide (BIMANEC) is reported for trace determination of Cu(II) and Cd(II) in vegetables and water. BIMANEC was used for the first time for the quantitative determination of these trace heavy metals. Flame atomic absorption spectrometer (FAAS) was used for quantitation. The preconcentration conditions were optimized with respect to pH (8.0), BIMANEC mass (4.0 mg), volume of sample (100 mL), standing time (5 min), and centrifugation time and rate (3 min and 2500 rpm). The influence of potentially interfering ions was scrutinized for the recovery of analyte ions. Under the optimum conditions, the limits of detection (LODs) were 0.51 and 2.28 µg L−1 for Cu(II) and Cd(II), respectively. The relative standard deviations were < 5% for both. The recoveries from the spiked vegetable samples were from 94.9 to 102.8% and from the spiked water samples between 93.2 and 101.6%. Consequently the developed new, facile, rapid, and highly efficient CEFC process was employed for the trace determination of Cu(II) and Cd(II).

A facile and sensitive coprecipitation method coupled with flame atomic absorption spectrometry for quantification of Cu(II) ions in complex matrices

In the present investigation, the application of an organic coprecipitant, 2-[5,6-dichloro-2-(2-bromobenzyl)-1H-benzimidazole-1-yl]acetohydrazide (DIBBA), for separation and preconcentration of Cu(II) ions in fruit and water samples through a new carrier element free coprecipitation (CEFC) method was researched for the first time. Flame atomic absorption spectrometer (FAAS) was used for the analyses of Cu(II) ions. The main effective experimental factors such as solution pH, DIBBA quantity, waiting time, centrifuge speed and duration and volume of sample on the recovery efficiency of Cu(II) ions were explored in detail. Under the optimized conditions the preconcentration factor (PF), relative standard deviation (RSD), and limits of detection (LOD) was achieved as 50, 3.4 % and 0.44 ?g L-1, respectively. No interference effects were detected by virtue of the presence of various foreign ions. Satisfactory recoveries (in the range of 94.4 to 103.0 %) in the environmental sample matrix were acquired. After being validated the recommended selective, low cost, simple and rapid CEFC method by spike/recovery tests, it was properly implemented for the low levels detection of Cu(II) ions in sour cherry, mulberry, apple, and peach as fruit samples and stream and sea water samples without any significant matrix effects.

A new carrier element-free coprecipitation method with 3-benzyl-4-p-nitrobenzylidenamino-4,5-dihydro-1,2,4-triazole-5-thiol for separation, preconcentration, and determination of some metal ions in water and food samples

ABSTRACT A new, simple, and accurate carrier element-free coprecipitation method has been developed to separate and preconcentrate of Cd(II), Cu(II), Ni(II), and Pb(II) ions from water and food samples. The proposed method was based on utilisation of 3-benzyl-4-p-nitrobenzylidenamino-4,5-dihydro-1,2,4-triazole-5-thiol (BNBATT) as a new organic co-precipitant at pH 7.0 and the determination of the metal ions being examined using FAAS. To recover the metal ions analysed, The influencce of many parameters including pH, sample volume, co-precipitant quantity, and the rate and time of centrifugation, was tested. There was also monitoring the effect of matrix ions, and no interferences were found. The validity of the proposed method was verified by test of certified reference materials. The analyte ions recovery values were measured and found to be in the range of 95–100%. The relative standard deviation (RSD%) was measured to determine the precision of the proposed approach and was found to be ≤ 5.0%. The limits of detection (K = 3.0, N = 10), were determined in the range of 0.3–0.8 μg L−1. The calculated preconcentration factor was 100 for Cd(II), Cu(II) and Ni(II) and 80 for Pb(II). Satisfactory results for separation and preconcentration trace amounts of the studied metal ions in water, food, and certified reference materials samples.

A novel carrier element‐free co‐precipitation method for separation/preconcentration of lead and cadmium ions from environmental matrices

A new separation and pre‐concentration method was presented in this study for two trace heavy metal ions, lead (Pb2+) and cadmium (Cd2+) from aqueous solutions, based on a carrier element free co‐precipitation (CEFC) method using a triazole derivate, 3‐(4‐tert‐butylphenyl)−5‐phenyl‐4‐(2‐hydroxy‐5‐methoxybenzylamino)−4H‐1,2,4‐triazole as an organic co‐precipitating agent. The method was optimized with some analytical parameters which affect the quantitative recoveries of study metals. According to the results, optimum pH of solution, quantity of co‐precipitating agent, centrifugation and incubation time, and sample volume were determined as 6.0, 1.5 mg, 10 min, and 10 min, and 100 mL, respectively. In addition, no significant matrix interferences were observed over the recovery of the metal ions. For analytical figure of merit, RSD values of the method were found as 5.7 and 4.8 for Pb2+ and Cd2+, respectively. LOD values were also calculated as 2.0 µg L−1 for Pb2+ and 0.2 µg L−1 for Cd2+. The accuracy of method was checked with spiked/recovery tests and analysis of a standard reference material. The developed method was finally applied to the real liquid/solid samples under the optimum conditions. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1709–1715, 2016

Separation and preconcentration of Pb(II) and Cu(II) ions via carrier element-free coprecipitation using an acetohydrazide derivative

A new method based on the combination of carrier element-free coprecipitation and flame atomic absorption spectrometric determination has been investigated for simultaneous separation and preconcentration of Pb(II) and Cu(II) ions in some environmental solid and liquid samples. The 2-{3-(4-methylbenzyl)-4-[2-(1H-indol-3-yl)ethyl]-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl} -N'-(phenylmethylene) acetohydrazide (MITA) was utilized as an organic coprecipitating agent without using a carrier element for coprecipitation of the analyte ions. The effects of experimental conditions including aqueous solution pH, MITA quantity, sample volume, standing time, and centrifugation rate and time were investigated in detail and optimized. The influences of some foreign ions were also evaluated on the quantitative recoveries of the analyte ions. The preconcentration factors were 125 for both analyte ions. The detection limits were 1.32 $\mu $g L$^{-1}$ and 0.47 $\mu $g L$^{-1}$ for Pb(II) and Cu(II) ions, respectively, and the relative standard deviations (RSDs) were lower than 4% for both analyte ions. After the accuracy of the method was checked, it was applied to sea and stream water as liquid samples and waste tea and tobacco as solid samples to determine the levels of Pb(II) and Cu(II) ions.

A new coprecipitation method without carrier element for separation and preconcentration of some metal ions at trace levels in water and food samples

A new simple and sensitive preconcentration, separation and environmentally friendly method based on carrier element free coprecipitation (CEFC) was developed using 4-(2-hydroxybenzylideneamino)-1,2-dihydro-2,3-dimethyl-1-phenylpyrazol-5-one (APSAL) as a new organic co-precipitant to precipitate Cr3+, Cu2+, Fe3+, Pb2+ and Zn2+ ions from water and food samples. The levels of the studied elements were detected by flame atomic absorption spectrometry (FAAS). The impact of several analytical parameters, such as pH, sample volume and coprecipitant amount as well as centrifugation rate and time was investigated to recover the examined metal ions. The influence of matrix ions was also tested, and no interferences were observed. The recovery values of the analyte ions were calculated and found to be in the range of 95–101%. The detection limits, corresponding to three times the standard deviation of the blank (N=10), were found to be in the range of 0.2–1.2μgL−1. The relative standard deviation (RSD) was calculated to evaluate the precision of the proposed method and was found to be ≤5.0%. The calculated preconcentration factor was 100. The proposed method was successfully applied to separate and preconcentrate trace amounts of ions in several water and food samples. To confirm the accuracy and validate the proposed method, certified reference materials were analyzed with satisfactory results.

Carrier element-free coprecipitation and speciation of inorganic tin in beverage samples and total tin in food samples using N-Benzoyl-N,N-diisobutylthiourea and its determination by graphite furnace atomic absorption spectrometry

A new, simple, rapid and selective separation, preconcentration and speciation of Sn(II) and Sn(IV) has been developed. The procedure is based on coprecipitation of Sn(II) on N-Benzoyl-N,N-diisobutylthiourea without carrier element. While Sn(II) can be quantitatively precipitated on N-Benzoyl-N,N-diisobutylthiourea in the pH range of 8.0–9.0, recovery of Sn(IV) was below 10%. Total tin was determined after the reduction of Sn(IV) to Sn(II) with 0.1 M NaBH4 in 1 M NaOH solution. Sn(IV) concentrations were calculated as difference between total tin and Sn(II). Determination of tin concentrations was performed by graphite furnace atomic absorption spectrometry (GFAAS). Various analytical parameters including pH, amount of precipitant, sample volume, etc. were optimized. The effects of matrix ions were also examined. Enrichment factor was found as 50. The relative standard deviation was 5%. The detection limit was found 0.013 μg L−1 for Sn(II). The validation of this method was performed by using certificate reference materials (NIST SRM 1568a Rice flour and NRCC DORM-2 Dogfish muscle). Optimized method was applied to bottled mineral water, soda and ice tea samples for tin speciation. This procedure was also applied to microwave digested food samples for the determination of total tin.

Simultaneous separation and preconcentration of Cd(II), Co(II), and Ni(II) ions in environmental samples by carrier element-free coprecipitation method prior to their flame atomic absorption spectrometric determination

ABSTRACTIn the present study, Cd(II), Co(II), and Ni(II) ions were separated and preconcentrated via carrier element-free coprecipitation (CEFC) method by using an organic coprecipitating agent, 1,2-bis-(2-tosyl ethoxy) benzene (BTEB), prior to their flame atomic absorption spectrometric (FAAS) detections. The experimental conditions were optimized in terms of pH of the aqueous solution, BTEB amount, standing time, centrifugation rate and time, and sample volume. Under the optimum experimental conditions, the detection limits for Cd(II), Co(II), and Ni(II) ions were found to be 0.13, 0.67, and 0.46 μg L−1, respectively, and the relative standard deviations for the analyte ions were found to be lower than 4.0%. The accuracy of the method was tested by analyzing certified reference material and spike tests. The method was applied to determine the levels of Cd(II), Co(II), and Ni(II) ions in sea and stream water, macaroni, red lentil, and cracked wheat samples.

Cadmium and nickel determinations in some food and water samples by the combination of carrier element-free coprecipitation and flame atomic absorption spectrometry

A procedure for separation and enrichment of Cd(II) and Ni(II) ions based upon carrier element-free coprecipitation by using an organic coprecipitant, 2-{4-[2-(1H-Indol-3-yl)ethyl]-3-(4-methylbenzyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl}-N′-(3-fluoro-phenylmethyliden) acetohydrazide, prior to their flame atomic absorption spectrometric detections has been developed. The effects of varied experimental conditions on the performance of the developed method such as pH, sample volume, amount of coprecipitating agent, etc. were evaluated in detail on the recovery of analyte ions, and the influences of some anions and cations were investigated. The limits of detection for Cd(II) and Ni(II) ions based on three times the standard deviation of the blanks (N: 10) were obtained as 0.70 μg L−1 and 1.21 μg L−1, respectively. The accuracy of the method was tested by analyzing a certified reference material and by spike tests. The method was applied to determine the levels of cadmium and nickel in stream and sea water, rice, red lentil, and wheat samples.

Acetohydrazide Derivative for Selective Separation and Preconcentration of Cu(II) Ions by Coprecipitation Method Without Using a Carrier Element

ABSTRACT A simple and rapid procedure based on the combination of carrier element free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations has been developed for selective separation and preconcentration of Cu(II) ions in some environmental solid (Turkish and import coffee) and liquid (sea and stream waters) samples. In this method, acetohydrazide derivative was used as an organic coprecipitant without adding any carrier element for coprecipitation of Cu(II) ions. The preconcentration factor was found to be 50, the limit of detection (LOD) was 0.31 µg L−1, while the relative standard deviation (RSD) was found to be 1.6% for Cu(II) ions.

Preconcentration of Cd(II) and Cu(II) ions by coprecipitation without any carrier element in some food and water samples

A simple, rapid, sensitive and environmentally friendly separation and preconcentration procedure, based on the carrier element free coprecipitation (CEFC) of Cu(II) and Cd(II) ions by using an organic coprecipitant, 2-{[4-(4-fluorophenyl)-5-sulphanyl-4H-1,2,4-triazol-3-yl]methyl}-4-{[(4-fluorophenyl) methylene]amino}-5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (MEFMAT) was developed. The analyte ions were determined by flame atomic absorption spectrometric (FAAS) determinations. The optimum conditions for the coprecipitation process were investigated on several commonly tested experimental parameters such as pH of the solution, amount of MEFMAT, sample volume, standing time, centrifugation rate and time. The influences of some anions, cations and transition metals on the recoveries of analyte ions were also investigated, and no considerable interference was observed. The preconcentration factor was found to be 50. The detection limits for Cu(II) and Cd(II) ions based on the three times the standard deviation of the blanks ( N:10) were found to be 1.49 and 0.45 μg L − 1 , respectively. The relative standard deviations were found to be lower than 3.5% for both analyte ions. The method was validated by analyzing two certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) and spike tests. The procedure was successfully applied to sea water and stream water as liquid samples and tobacco, hazelnut and black tea as solid samples.

Carrier element-free coprecipitation (CEFC) method for separation and pre-concentration of some metal ions in natural water and soil samples

A simple, rapid and sensitive separation/pre-concentration procedure for Cd(II), Cr(III), Co(II), Cu(II), Fe(III), Pb(II) and Mn(II) ions in environmental samples has been established. The present procedure is based on a combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations of understudy trace metal ions. A cationic surfactant (N-cetyl N,N,N trimethyl ammonium bromide (CTAB)) as coprecipitant was used without adding any carrier element for coprecipitation of understudy ions. The optimum conditions for the coprecipitation process were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant. The pre-concentration factor was found to be 10. The detection limits corresponding to three times the standard deviation of the blank ( N = 20) for Cd(II), Cr(III), Co(II), Cu(II), Fe(III), Pb(II) and Mn(II) ions were found as 0.61, 16.8, 12.7, 1.36, 2.08, 4.30 and 0.22 μg L −1, respectively. The present procedure was successfully applied for separation and pre-concentration of investigated ions in several liquid environmental samples. In order to support the accuracy of the method, the certified reference materials (BCR 141 R calcareous loam soil and CRM025-050 soil) were analyzed. The experimental results are in good agreement with the certified values.

Carrier element-free coprecipitation with 3-phenly-4-o-hydroxybenzylidenamino-4,5-dihydro-1,2,4-triazole-5-one for separation/preconcentration of Cr(III), Fe(III), Pb(II) and Zn(II) from aqueous solutions

A separation/preconcentration procedure, based on the coprecipitation of Cr 3+, Fe 3+, Pb 2+ and Zn 2+ ions using a new organic coprecipitant, 3-phenly-4-o-hydroxybenzylidenamino-4,5-dihydro-1,2,4-triazole-5-one (POHBAT) without adding any carrier element has been developed. The method, thus, has been called carrier element-free coprecipitation (CEFC). The resultant concentrated elements were determined by flame atomic absorption spectrometric determinations. The influences of some analytical parameters including pH of the solution, amount of the coprecipitant, standing time, centrifugation rate and time, sample volume and diverse ions were investigated on the quantitative recoveries of analyte ions. The validation of the present preconcentration procedure was performed by the analysis of two certified reference materials. The recoveries of understudy analytes were found in the range of 93–98%, while the detection limits were calculated in the range of 0.3–2.0 μg L −1. The precision of the method evaluated as relative standard deviation (R.S.D.), was in the range of 3–7% depend on the analytes. The proposed method was successfully applied to environmental samples for the determination of the analytes.

Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative

A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H 2SO 4 and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank ( N = 10) was found 0.7 μg L −1. The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values.