Multiwalled carbon nanotubes for speciation of chromium in environmental samples

A solid phase extraction procedure has been established for chromium speciation in natural water samples. The procedure is based on the solid phase extraction of the Cr(VI)-ammonium pyrrolidine dithiocarbamate (APDC) chelate on multiwalled carbon nanotubes (MWNTs). After oxidation of Cr(III) to Cr(VI) by using hydrogen peroxide, the presented method was applied to the determination of the total chromium. The level of Cr(III) is calculated by difference of total chromium and Cr(VI) levels. The procedure was optimized for some analytical parameters including pH, eluent type, flow rates of sample and eluent, matrix effects, etc. The detection limit based on 3 sigma criterion was 0.90 mu g L-1 for Cr(VI). The adsorption capacity of multiwalled carbon nanotubes was 9.50 mg g(-1) Cr (VI). The presented method was applied for the speciation of chromium in natural water sample with satisfactory results (recoveries > 95%, R.S.D.'s < 9%). (C) 2007 Elsevier B.V. All rights reserved

Column system using diaion HP-2MG for determination of some metal ions by flame atomic absorption spectrometry

A column solid-phase extraction method for the preconcentration and determination of cadmium(H), copper(H), cobalt(II), iron(RI), lead(H), nickel(II) and zinc(II) dithizone chelates by atomic absorption spectrometry has been described. Diaion HP-2MG was used as adsorbent for column studies. The influences of the various analytical parameters including pH of the aqueous solutions, amounts of ligand and resin were investigated for the retentions of the analyte ions. The recovery values are ranged from 95 to 102%. The influences of alkaline and earth alkaline ions were also discussed. The preconcentration factor was 375, when the sample volume and final volume are 750 and 2 ml, respectively. The detection limits of the analyte ions (k = 3, N = 21) were varying 0.08 mug/l for cadmium to 0.25 mug/l for lead. The relative standard deviations of the determinations at the concentration range of 1.8 x 10(-4) to 4.5 x 10(-5) mmol for the investigated elements were found to be lower than 9%. The proposed solid-phase extraction procedure were applied to the flame atomic absorption spectrometric determinations of analyte ions in natural waters (sea, tap, river), microwave digested samples (milk, red wine and rice) and two different reference standard materials (SRM1515 apple leaves and NRCC-SLRS-4 riverine water). (C) 2003 Elsevier B.V. All rights reserved

Column solid-phase extraction of nickel and silver in environmental samples prior to their flame atomic absorption spectrometric determinations

A biosorption procedure for preconcentration-separation of nickel(II) and silver(I) at trace levels on Bacillus sphaericus-loaded Chromosorb 106 (BSLC106) has been presented in this work. The conditions like pH, amounts of microorganism, eluent type, etc. for the quantitative adsorption of the analyte ions on BSCL106 column were investigated. The analyte ions were quantitatively recovered and desorbed at pH range of 6.0-7.0 and 10mL of 1 M HCl. respectively. The effects of various cationic and anionic interferences on the recoveries of nickel(II) and silver(I) were studied. The detection limits for nickel(II) and silver(I) are 1.42 and 1.05 mu g L-1, respectively. The accuracy of the developed procedure was tested by analyzing NIST SRM 2711 Montana soil and GBW 07310 Stream sediment certified reference materials. The proposed enrichment-separation procedure was successfully applied to the determination of analytes in natural water, black tea, tobacco, soil and sediment samples with satisfactory results. (C) 2008 Elsevier B.V. All rights reserved

iosorption of Aluminum on Pseudomonas aeruginosa Loaded on Chromosorb 106 prior to its Graphite Furnace Atomic Absorption Spectrometric Determination

A biosorption procedure for separation-enrichment of aluminum in environmental samples has been presented in this work. Pseudomonas aeruginosa loaded on Chromosorb 106 has been used as biosorbent for that purpose. P. aeruginosa is a gram-negative, aerobic rod. The influences of pH of the aqueous solution, eluent type, eluent volume, sample volume, etc. were examined on the quantitative recovery of aluminum in R aeruginosa loaded on Chromosorb 106. The effects of concomitant ions on the recoveries of aluminum were also investigated. The detection limit based on 3 sigma for aluminum is 30 ng L(-1). Three certified reference materials (LGC 6010 Hard Drinking Water, NIST-SRM 1568a Rice Flour and NRCC-DORM-2 Dogfish Muscle) were analyzed for the validation of the presented procedure. The proposed procedure was applied to the determination of aluminum in environmental samples including natural water and food samples. The concentration of aluminum in real samples was found at ppb level. (C) 2007 Elsevier B.V. All rights reserved

Determination of trace metals in canned fish marketed in Turkey

The levels of trace metals of canned fish samples collected from markets in Turkey were determined by flame and graphite furnace atomic absorption spectrometry after microwave digestion. The accuracy of the method was corrected by standard reference material (NRCC-DORM-2 Dogfish Muscle). The contents of investigated trace metals in canned fish samples were found to be in the range 1.10-2.50 mu g/g for copper, 7.57-34.4 mu g/g for zinc, 0.90-2.50 mu g/g for manganese, 10.2-30.3 mu g/g for iron, 0.96-3.64 mu g/g for selenium, 0.45-1.50 mu g/g for aluminium, 0.97-1.70 mu g/g for chromium, 0.42-0.85 mu g/g for nickel, 0.09-0.40 mu g/g for lead and 0.06-0.25 mu g/g for cadmium. The results were compared with the literature values. (c) 2006 Elsevier Ltd. All rights reserved