Preconcentration/Cleanup Studies of Tin from Environmental Water Samples by Oxidized Multiwall Carbon Nanotubes Packed Column and its Determination by ETAAS

Abstract

The use of multiwall carbon nanotubes (MWCNT) as an efficient solid extractor in preconcentration/cleanup studies for tin determination in water samples by electrothermal atomic absorption spectrometry (ETAAS) is proposed. In the proposed method, tin adsorption onto MWCNT was carried out by percolating the solution previously buffered (pH 4.79 with 0.24 molL −1 acetic acid/acetate buffer) at 4.0-mLmin −1 flow rate, followed by elution with 1.0 mL of 2.7 molL −1 HNO 3 . Factors such as sample pH, preconcentration/cleanup flow rate, type and concentration of eluent, and buffer concentration were appraised and optimized from chemometric tools based on fractional factorial design and Doehlert design. A limit of detection of 0.73 μgL −1 and precision (n=8) assessed as relative standard deviation of 8.6% and 7.0% for tin concentration of 8.0 and 43.0 μgL −1 , respectively, were achieved. Foreign metallic ions (Ni 2+ , Pb 2+ , Co 2+ , Zn 2+ , Cd 2+ , Mn 2+ , and Fe 3+ ) were checked as potential interferents, and no interference was observed up to an analyte/ interference ratio of 1:10 (m/v). Direct tin determination by ETAAS in water samples containing high salt amount is drastically affected by background signal. However, previous cleanup of sample by MWCNT has promoted a significant improvement and makes the method useful for tin monitoring in water samples (mineral, lake, mine, and natural waters) by ETAAS. Quantitative recovery values ranging from 91.5% to 103.0% attested the applicability of the proposed preconcentration/cleanup for tin determination in water samples.

Preconcentration of Sn in Real Water Samples by Solid Phase Extraction Based on the Use of Helvella leucopus as a Fungal Biomass Prior to its Determination by ICP-OES

“…The direct determination of Sn by flame atomic absorption spectrometry (FAAS) and inductively coupled plasma optical emission spectrometry (ICP-OES) is limited due to the poor sensitivity of these techniques and a preconcentration procedure is generally required before instrumental detection. Cloud point extraction (CPE) (4,5), solid phase extraction (SPE) (1,(6)(7)(8), coprecipitation (3), and liquid-liquid extraction (9) allow the detection of tin. However, they require the use of chemical ligands and time-consuming steps such as centrifugation.…”

“…In addition, synthesis procedures for ligands are eliminated when biomass is used as the sorbent. However, methods for the preconcentration of Sn were focused on the sorption of batch conditions (13), SPE on ligands (6)(7)(8), CPE (2,4,5,14), coprecipitation (3), and solvent extraction (9). Reports on the use of preconcentration methods for Sn using biomass are still very few.…”