Copper interference on the spectrophotometric determination of iron and their simultaneous determination using bathophenantroline-disulfonic acid disodium salt

The interference of copper on the spectrophotometric determination of iron with bathophenantroline-disulfonic acid disodium salt was studied using an experimental design. Copper interferes even below pH 5 [1], forming a yellow complex with bathophenantroline which turned to green after 5 min. This complex showed a maximum at 425 nm with a molar absorptivity of 7.5 × 10³ L mol^–1 cm^–1. Microgram quantities of iron and copper were determined simultaneously in water standard samples using bathophenantroline-disulfonic acid disodium salt at pH 4.8 and measuring the absorbances at two wavelengths. The interference of iron on the copper determination was also estimated. The RSDs of the method for both Cu and Fe were below 1.7%. Recoveries for Cu and Fe were within the ranges 97.2% to 98% and 99.7 to 100.5%, respectively. The method was applied to the determination of copper and iron in the waste water from a water treatment plant. The results obtained by spectrophotometry were compared with those obtained by flame AAS.     

Chemiluminescence flow system for the determination of Fe(II) and Fe(III) in water

A novel chemiluminescence (CL) flow system has been developed for the sequential determination of Fe(II) and Fe(III) in water. Fe(II) was detected by its catalytic effect on the CL reaction between luminol immobilized on an anion exchange resin column and dissolved oxygen; Fe(III) was determined by difference measurement after on-line conversion to Fe(II) in a reducing mini-column packed with Cu plated Zn granules. For both ions, the calibration graph was linear in the range 1 × 10^–9 to 1 × 10^–6 g/mL, and the detection limit was 4 × 10^–10 g/mL. A complete analysis could be performed in 1.5 min with a relative standard deviation of less than 5%. The system could be reused for over 200 times and has been applied successfully to the determination of Fe(II) and Fe(III) in natural water samples. Received: 13 March 1997 / Revised: 3 June 1997 / Accepted: 6 June 1997     

The application of butanol as dilution agent for the inductively coupled plasma-atomic emission spectrometric determination of boron and phosphorus in lubricating oils

An evaluation of butanol-1 as dilution solvent for the determination of boron (B) and phosphorus (P) in lubricating oils by inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been performed. Standard solutions of boric acid and tri-n-butyl phosphate (TBP) in butanol were employed as calibrants for B and P, respectively. Solutions of phosphoric acid and tris(2-ethylhexyl)phosphate (TEHP) in butanol were also tested as possible P standards. Increased concentrations of oil in the sample in the range of 0 to 20% showed no significant effects on B and P emission intensities indicating that matrix matching is not required for lubricating oils of about 2–15 cPoise. Detection limits in absence of spectral interferences were 0.06 μg B/g oil and 2 μg P/g oil. Overall estimated precision was 2.5% for B concentrations above 4 μg/g oil, and 6.5% for P concentrations above 20 μg/g oil. We evaluated the performance of a high resolution scanning spectrometer for mitigating the effects of overlapping spectral interferences from iron (Fe) and copper (Cu) on B and P emission lines. An interference from Fe 249.782 nm on the primary B line at 249.773 nm is observed for Fe concentrations higher than 100 μg/g oil, but a secondary B line at 249.678 nm is completely resolved from Fe 249.653 nm. In the case of P 213.618 nm, a contribution of the right wing of a Cu line at 213.598 nm generates a signal equivalent to P 18 μg/g oil for Cu 1000 μg/g oil. Received: 25 June 1997 / Revised: 16 September 1997 / Accepted: 7 October 1997     

Development of a voltammetric method for the determination of iron(III) in Zn-Fe alloy galvanic baths

A square wave voltammetric method whith a static mercury drop electrode (SMDE) was developed for the quantitative determination of iron (III) in Zn-Fe alloy galvanic baths. Real alloy bath samples were analyzed by the standard addition method and recovery tests were carried out. 0.50 mol L^–1 sodium citrate (pH 6.0) or 0.20 mol L^–1 oxalic acid (pH 4.0) were applied as supporting electrolytes resulting in both cases in a peak potential of about –0.20 V vs. Ag|AgCl (saturated KCl). The iron (III) concentration in the alloy bath was 9.0 × 10^–4 mol L^–1. A good correlation (r = 0.9999) was achieved between the iron (III) concentration and the peak current in the electrolytes studied, with linear response ranges from 1.0 × 10^–6 to 1.2 × 10^–4 mol L^–1. Interference levels for some metals such as copper (II), lead (II), chromium (III) and manganese (II) that can hinder the Zn-Fe alloy deposition were evaluated; only copper (II) interferes seriously. Received: 4 April 2000 / Revised: 19 June 2000 / Accepted: 22 June 2000     

The application of butanol as dilution agent for the inductively coupled plasma-atomic emission spectrometric determination of boron and phosphorus in lubricating oils

An evaluation of butanol-1 as dilution solvent for the determination of boron (B) and phosphorus (P) in lubricating oils by inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been performed. Standard solutions of boric acid and tri-n-butyl phosphate (TBP) in butanol were employed as calibrants for B and P, respectively. Solutions of phosphoric acid and tris(2-ethylhexyl)phosphate (TEHP) in butanol were also tested as possible P standards. Increased concentrations of oil in the sample in the range of 0 to 20% showed no significant effects on B and P emission intensities indicating that matrix matching is not required for lubricating oils of about 2–15 cPoise. Detection limits in absence of spectral interferences were 0.06 μg B/g oil and 2 μg P/g oil. Overall estimated precision was 2.5% for B concentrations above 4 μg/g oil, and 6.5% for P concentrations above 20 μg/g oil. We evaluated the performance of a high resolution scanning spectrometer for mitigating the effects of overlapping spectral interferences from iron (Fe) and copper (Cu) on B and P emission lines. An interference from Fe 249.782 nm on the primary B line at 249.773 nm is observed for Fe concentrations higher than 100 μg/g oil, but a secondary B line at 249.678 nm is completely resolved from Fe 249.653 nm. In the case of P 213.618 nm, a contribution of the right wing of a Cu line at 213.598 nm generates a signal equivalent to P 18 μg/g oil for Cu 1000 μg/g oil. Received: 25 June 1997 / Revised: 16 September 1997 / Accepted: 7 October 1997     

Updated investigation of the reaction between copper and naphthol blue black b and determination of trace amounts of copper in water

The biological dye, naphthol blue black B (NBBB) was found to produce a sensitive reaction with copper(II) at pH over 7. This reaction was very interesting. The complexation of Cu(II) with NBBB happened at pH between 6 and 11 but the redox catalytic reaction happened at pH over 11, where copper(II) served as a catalyst. In this study, ordinary spectrophotometry was limited for use because of the serious interference of excess reactant. A new method, Β-correction principle, was applied because it can eliminate the above interference. This method can give the simple determination of properties of Cu-NBBB complex solution at pH 9.5, which involved the complex ratio, real molar absorptivity, and stability constant (K). Results showed that the formed Cu-NBBB complex occurred as Cu(NBBB) at pH 9.5, its real rather than apparent absorptivity was equal to 7.62 x 10³ L mol^-1 cm^-1 at 630 nm, and its stability constant was 1.32 x 10⁶. The redox catalytic reaction between Cu(II) and NBBB at pH 13 was used to determine trace amounts of copper in water. This reaction was very sensitive and highly selective. Most of the metals did not interfere with the direct determination of copper. The detection limit of copper was 0.002 mg/L, and the recovery was between 90 and 104% with the relative standard deviation of less than 11%. This article was submitted by the author in English.     

ETAAS determination of aluminium and copper in dialysis concentrates after microcolumn chelating ion-exchange preconcentration

A procedure was developed for the preconcentration and determination of aluminium and copper in dialysis concentrates at the ng cm^–3 level. The preconcentration was achieved on microcolumns filled with Chelex-100 resin adjusted to a pH of 4.0. Five repetitive cycles of the sample through the column ensured a sufficient contact time for quantitative retention of aluminium and copper ions. The retained ions were eluted with HNO₃ (0.5 mol dm^–3). Aluminium and copper were determined in the eluate by Zeeman ETAAS using the standard addition technique. The procedure was performed under clean room conditions (class 10,000), The reliability of the results was evaluated by recovery tests, using dialysis concentrates spiked with aluminium and copper. The recoveries obtained ranged from 86 to 106% for aluminium and from 92 to 97% for copper. Using the recommended procedure, the LOD of aluminium and copper in dialysis concentrates (preconcentration factor 2) was found to be 0.5 ng cm^–3 and 0.2 ng cm^–3, respectively. Received: 19 December 1997 / Revised: 10 March 1998 / Accepted: 28 March 1998     

Determination of copper in sulfide minerals by Zeeman electrothermal atomic absorption spectrometry

A method for the determination of copper in some sulfide minerals (lorandite, realgar, orpiment, marcasite, stibnite, galenite and sphalerite) by Zeeman electrothermal atomic absorption spectrometry is presented. After the dissolution of samples, copper was extracted with sodium diethyldithiocarbamate into different organic solvents (carbon tetrachloride, chloroform and methylisobutyl ketone) at pH 11.0–12.0. The procedure was verified by standard addition. The standard deviation (SD) for 0.5 ng Cu is 0.01 ng, the relative standard deviation ranges from 3.5 to 5.5% and the detection limit of the method, calculated as 3 SD of the blank, was found to be 0.05 μg · g^–1. Received: 26 May 1997 / Revised: 10 September 1997 / Accepted: 16 September 1997     

Sensitive spectrophotometric determination of vanadium with hydrogen peroxide and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol after extraction with N-benzoyl-N-phenylhydroxylamine

A selective and precise spectrophotometric determination of vanadium(V) is performed after preceding extraction with N-benzoyl-N-phenylhydroxylamine (BPHA). The color is developed in a water-ethanol solution with hydrogen peroxide and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol (5-Cl-DMPAP). The molar absorptivity at 588 nm is (6.57 ± 0.05) × 10⁴ L mol^–1 cm^–1 at pH 2.1. The method permits the determination of vanadium (V) at trace levels in the presence of large amounts of other ions. It is applied to the determination of vanadium in aluminium (analytical reagent grade) and in human hair. High accuracy and precision is obtained. Received: 18 April 1997 / Revised: 20 June 1997 / Accepted: 25 June 1997     

ETAAS determination of aluminium and copper in dialysis concentrates after microcolumn chelating ion-exchange preconcentration

A procedure was developed for the preconcentration and determination of aluminium and copper in dialysis concentrates at the ng cm^–3 level. The preconcentration was achieved on microcolumns filled with Chelex-100 resin adjusted to a pH of 4.0. Five repetitive cycles of the sample through the column ensured a sufficient contact time for quantitative retention of aluminium and copper ions. The retained ions were eluted with HNO₃ (0.5 mol dm^–3). Aluminium and copper were determined in the eluate by Zeeman ETAAS using the standard addition technique. The procedure was performed under clean room conditions (class 10,000), The reliability of the results was evaluated by recovery tests, using dialysis concentrates spiked with aluminium and copper. The recoveries obtained ranged from 86 to 106% for aluminium and from 92 to 97% for copper. Using the recommended procedure, the LOD of aluminium and copper in dialysis concentrates (preconcentration factor 2) was found to be 0.5 ng cm^–3 and 0.2 ng cm^–3, respectively. Received: 19 December 1997 / Revised: 10 March 1998 / Accepted: 28 March 1998     

Study on the Catalytic Determination of Vanadium (V) Using the Rhodamine 6G-Periodate Redox Reaction and its Analytical Application

 A fluorescence quenching method for the determination of vanadium (V) based on the vanadium- catalyzed oxidation of rhodamine 6G (R6G) with periodate in the presence of ethylenediaminetetraacetic acid disodium salt (EDTA) in sulfuric acid medium is described. The fluorescence was measured with excitation and emission wavelengths of 525 and 555 nm, respectively. The calibration graph for vanadium (V) had linear ranges of 3.0 × 10⁻⁹–1.5 × 10⁻⁸ mol/l and 1.5 × 10⁻⁸–4.0 × 10⁻⁸ mol/l, respectively. The detection limit was 1.7 × 10⁻⁹ mol/l. The proposed method was successfully applied to the determination of vanadium (V) in river water, rain water and cast iron samples. Received June 29, 2001 Revision October 9, 2001     

A preliminary study on the effect of mineralization parameters on determination of metals in <Emphasis Type="Italic">Viscum album</Emphasis> species

An increasing interest in determination of various macro- and microelements in medicinal plants has been observed. The majority of studies are carried out using one mineralization method without any optimization. The present study demonstrates that changes in mineralization parameters can significantly affect the recovery of the elements determined. In the study, the dried plant material was mineralized in 12 ways and iron (Fe), copper (Cu), zinc (Zn), nickel (Ni) and manganese (Mn) levels were determined. The samples were mineralized in the dry or open microwave mode as well as 10 closed microwave modes. The influence of acid amounts, irradiation power and time, addition of hydrogen peroxide and perfluoric acid was examined. All parameters were shown to be critical — good efficiency was observed with larger amounts of acid. The determined content varied significantly in the same sample and were in the ranges (ug g⁻¹): 46–136 (Fe), 1.4–11.8 (Cu), 4.0–11.3 (Ni), 15.4–53.8 (Zn) and 9.5–67.6 (Mn). Increased irradiation resulted in the loss of copper and zinc and better recovery of nickel. The results demonstrate that such determinations should include the mineralization optimization step.      

Organic solvent-soluble membrane filters for the preconcentration and spectrophotometric determination of iron(II) traces in water with Ferrozine

An organic solvent-soluble membrane filter (MF) is proposed for the simple and rapid reconcentration with subsequent spectrophotometric determination of trace levels of iron (II) in water. Iron (II) is collected on a nitrocellulose membrane filter as ion associate of an anionic complex, which is formed by iron (II) and Ferrozine and a cation-surfactant. The ion-pair compound and the MF can be dissolved in small volumes of 2-ethoxyethanol and the absorbance of the resulting solution is measured at 560 nm against a reagent blank with molar absorptivity of 4.01 × 10⁴ L mol^–1 cm^–1. Beer’s law is obeyed over the concentration range 0–10 μg L^–1 of iron (II) in water and the detection limit is 0.03 μg L^–1 with a 50-fold enrichment factor. The proposed method can satisfactorily be applied to the determination of iron (II) in natural water and sea water. Received: 23 June 1998 / Revised: 21 July 1998 / Accepted: 25 August 1998     

Copper determination after FI on-line sorbent preconcentration using 1-nitroso-2-naphthol as a complexing reagent

The suitability of 1-nitroso-2-naphthol as a complexing agent for on-line preconcentration of copper using RP-C₁₈ material in a microcolumn with flow injection coupled with flame atomic absorption spectrometry (FI-FAAS) has been tested. Various parameters affecting complex formation, such as pH, sample flow rate, etc. and its elution into the nebulizer of FAAS were optimized. ?A 5 × 10^–3 mol/L reagent was on-line mixed with aqueous sample solution acidified with 0.1% (v/v) nitric acid ?(pH 3–4) and flowed through the microcolumn for 30 s. The adsorbed complexes in the microcolumn were eluted with ethanol in 10 s into the nebulizer of FAAS. A good precision (1.7% for 50 μg/L copper, n = 12), high enrichment factor (19) with detection limit (3σ) 2.0 μg/L, and sample throughput (90 h^–1) were obtained. The method was applied to certified reference materials seawater, mussel (biological), NBS-362 and NBS-364 (special low alloy steel), for the determination of copper, and the results were in good agreement with the certified values. Received: 4 May 1999 / Revised: 25 June 1999 / Accepted: 29 June 1999     

Photometric determination of aqueous cobalt (II), nickel (II), copper (II) and iron (III) with 1-nitroso-2-naphthol-3,6-disulfonic acid disodium salt in gelatin films

Photometric determination of aqueous Co(II), Cu(II), Ni(II) and Fe(III) was performed using indicator films prepared by immobilization of 1-nitroso-2-naphthol-3,6-disulfonic acid disodium salt (NRS) into hardened photographic film. Immobilization was based on electrostatic interaction of reagent and metal complexes with the gelatin. The isoelectric point pH of hardened gelatin (4.46±0.04) was evaluated by viscometry. Co(II), Fe(III), Ni(II) form 1:3 complexes with NRS in gelatin at pH 2 and Cu(II) forms 1:2 complexes. Their log β′ values were: Co-6.7, Fe-8.6, Cu-8.0, and Ni-6.4. The absorption maxima were: 370nm for NRS, and 430nm, 470nm, 495nm and 720nm for complexes of Co(II), Ni(II), Cu(II) and Fe(III). An algorithm for their simultaneous determination using the indicator films was developed. The detection limits were: c_lim(Co²⁺) = 0.45×10⁻⁵ M, c_lim(Fe³⁺) = 0.50×10⁻⁵ M, c_lim(Cu²⁺) = 0.67×10⁻⁵ M, c_lim(Ni²⁺) = 0.75×10⁻⁵ M,; and their sum c_lim(ΣMn⁺) = 0.82×10⁻⁵ M.      

Determination of wear metals in lubricating oils by flame atomic absorption spectrophotometry

A simple, rapid and reliable method was developed for the determination of copper, nickel, iron and lead in fresh and used lubricating oil samples by flame atomic absorption spectrophotometry (FAAS). In the present study, a mixture of organic solvents containing propionic acid and iso-butylmethyl ketone (1: 1) was used to extract the metals from lubricating oil samples followed by FAAS analysis. Aqueous standard solutions can be easily employed with the proposed mixed solvent system instead of organometallic standards. The analytical results obtained by employing the proposed solvent extraction system were found to be in good agreement with the results for aqueous media obtained after the destruction of oil samples matrix. Percentage recovery studies showed 88–98% for Cu, 92–95% for Fe, 96–106% for Ni and 84–100% for Pb with relative standard deviation of 2–6%. The developed method was effectively applied to routine determination of Cu, Ni, Fe, and Pb in lubricating oil samples.     

Novel catalytic oxidative coupling reaction of N,N-dimethyl-p-phenylenediamine with 1,3-phenylenediamine and its applications to the determination of copper and iron at trace levels by flow injection technique

A new catalytic oxidative coupling reaction of N,N-dimethyl-p-phenylenediamine (DPD) with 1,3-phenylenediamine (mPD) in the presence of hydrogen peroxide has been developed for trace metals analysis. The rate of the oxidation/coupling reaction can be enhanced significantly by iron, copper and cobalt. These metal ions can catalyze the oxidation reaction of DPD to form an oxidized product; the oxidized DPD was then coupled with mPD to give a blue-colored product which was measured spectrophotometrically at 650 nm. On the basis of such a reaction scheme, two simple flow injection analysis methods for the determination of copper and iron have been developed. Detailed studies on chemical and FIA variables affecting the sensitivity of the detection were carried out. Interferences from several ionic species were examined for the determination of copper: the interference effect by Fe(III) and Fe(II) up to 1.5 mg L⁻¹ was successfully suppressed by pretreating sample with ammonium acetate buffer solution (pH 8.4). Good linearity of a standard calibration graph was obtained over the ranges of 0-8 and 0-2 μg L⁻¹ of copper and iron, respectively, and the detection limits were 0.05 and 0.02 μg L⁻¹ for copper and iron, respectively. The precision of the methods in terms of relative standard deviation were 1.4 and 1.5% of R.S.D. which were obtained from 10 injections of 2.0 and 1.0 μg L⁻¹ of standard copper and iron, respectively. The proposed methods were successfully applied to the determination of copper and iron in tap and river water samples. The accuracy of the proposed methods was assessed by the analysis of certified reference material of river water.     

Continuous sonoassisted digestion coupled to flow injection minicolumn separation for the determination of total and labile Cu and Fe in fresh waters by flame atomic absorption spectrometry

An automatic on-line system is developed for the trace determination of copper and iron species in fresh waters by flame atomic absorption spectrometry using only 5 and 2?mL of sample, for copper and iron determination, respectively. This system, which includes a home-made minicolumn of commercially available resin containing aminomethylphosphonic acid functional groups (Chelite P), comprises two operational modes. The first, used for the determination of the dissolved labile fraction (free copper and iron ions and their weak complexes) is based on the elution of this fraction from a minicolumn containing the chelating resin loaded in-situ with the sample. The second mode is used for the determination of total trace copper and iron concentrations. This last mode is based on the retention/preconcentration of total metals on the Chelite P resin after on-line sonoassisted digestion of water samples acidified with nitric acid (0.5?mol?L^?1 final concentration) to break down metal organic complexes present in fresh waters as river waters. The figures of merit for copper and iron determination in both fractions are given and the obtained values are discussed. The analytical method was characterized and the limit of detection and limit of quantification for the two metals were 0.5 and 1.6?µg?L^?1 for Cu and 2.3 and 6.1?µg?L^?1 for Fe, respectively. The repeatability, expressed as relative standard deviation, was in the range 1.0–2.1%. The speciation scheme was applied to the analysis of river surface water samples collected in Galicia (Northwest, Spain).     

Rapid and interference free determination of ultra trace level of uranium in potable water originating from different geochemical environments by ICP-OES

Direct determination of uranium in the concentration range of 8 μg L⁻¹ to mg L⁻¹ in water samples originating from different geochemical environments has been done using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). Uranium detection with 2–3% RSD (relative standard deviation) has been achieved in water samples by optimizing the plasma power, argon and sheath gas flow. These parameters were optimized for three different emission lines of uranium at 385.958, 409.014 and 424.167 nm. Interference arising due to the variation in concentration of bicarbonate, sodium chloride, calcium chloride, Fe and dissolved organic carbon (DOC) on the determination of uranium in water samples was also cheeked as these are the elements which vary as per the prevailing geochemical environment in groundwater samples. The concentration of NaHCO₃, CaCl₂ and NaCl in water was varied in the range 0.5–2.0%; whereas Fe ranged between 1 and 10 μg mL⁻¹ and DOC between 0.1–1%. No marked interference in quantitative determination of uranium was observed due to elevated level of NaHCO₃, CaCl₂ and NaCl and Fe and DOC in groundwater samples. Concentration of uranium was also determined by other techniques like adsorptive striping voltametry (AdSv); laser fluorimetry and alpha spectrometry. Results indicate distinct advantage for uranium determination by ICP-OES compare to other techniques.     

Study of the preconcentration and determination of ultratrace rare earth elements in environmental samples with an ion exchange micro-column

A study was carried out on the preconcentration of ultratrace rare earth elements (REEs) in environmental samples with a micro ion-exchange column and determination by inductively coupled plasma mass spectrometry (ICP-MS). The preconcentration parameters were optimized and the REE recovery was ca. 100% in the pH range 4 to 6 with an ionic strength (μ) less than 0.18. The ion-exchange column capacity with respect to REEs was estimated as 0.96 mmol/g. The linear response coefficients ranged from 0.995 to 0.997 at the pg mL^–1 level. The concentration in the blank could be minimized (0.09 to 3.1 pg mL^–1) if the buffer solution and the water were purified. The detection limits ranged from 0.03 to 0.40 pg mL^–1, for a preconcentration factor of 100. The precision and accuracy of the method was evaluated with a synthetic standard solution and real samples. Results indicated that the REE recovery ranged from 88.1% to 100.2%, and the RSD ranged from 2.7% to 6.7%. Satisfactory results were achieved when this method was applied for the determination of REEs in raw water, purified water and tap water, as well as in environmental aquatic samples. Meanwhile, the method is simple and flexible. Received: 17 January 1997 / Revised: 23 April 1997 / Accepted: 29 April 1997