Field procedures to assess soils and waste disposals

The aim of this research was the development of rapid analytical test methods for arsenic, lead, cadmium, chromium(VI), copper, nickel, and zinc to classify waste materials into waste classes and assess contaminated soils for purification purposes. In order to estimate the danger potentials of contaminated soils, a rapid ecotoxicological method was developed (A. Götzl, H. Malissa, W. Riepe, FACT 3 (6) (1999) 329.). These rapid analytical and ecotoxicological tests offer an instrument to comprehensively assess soils and wastes. The developed rapid methods are suitable for the elution of different soils and wastes, the analysis of the eluates and also for waste waters with concentrations greater than 0.1 mg l⁻¹ arsenic, 0.5 mg l⁻¹ lead, 0.01 mg l⁻¹ cadmium, 0.1 mg l⁻¹ chromium(VI), 0.3 mg l⁻¹ copper, 0.5 mg l⁻¹ nickel and 0.1 mg l⁻¹ zinc in the eluate. Our developed rapid analytical test methods described below can be implemented on site, are of low cost and are not time-consuming (about 30 min). They also do not need to be carried out by highly qualified specialists only, they can also be easily applied by persons with some experience. The comparability of results obtained using the developed rapid test method and standardised methods was tested with various matrices.     

Exploiting flow injection and sequential injection anodic stripping voltammetric systems for simultaneous determination of some metals

Flow injection (FI) and sequential injection (SI) systems with anodic stripping voltammetric detection have been exploited for simultaneous determination of some metals. A pre-plated mercury film on a glassy carbon disc electrode was used as a working electrode in both systems. The same film can be repeatedly applied for at least 50 analysis cycles, thus reducing the mercury consumption and waste. A single line FI voltammetric system using an acetate buffer as a carrier and an electrolyte solution was employed. An injected standard/sample zone was mixed with the buffer in a mixing coil before entering a flow cell. Metal ions were deposited on the working electrode by applying a potential of −1.1 V vs Ag/AgCl reference electrode. The stripping was performed by anodically scanning potential of working electrode to +0.25 V, resulting a voltammogram. Effects of acetate buffer concentration, flow rate and sample volume were investigated. Under the selected condition, detection limits of 1 μg l⁻¹ for Cd(II), 18 μg l⁻¹ for Cu(II), 2 μg l⁻¹ for Pb(II) and 17 μg l⁻¹ for Zn(II) with precisions of 2–5% (n=11) were obtained. The SI voltammetric system was similar to the FI system and using an acetate buffer as a carrier solution. The SI system was operated by a PC via in-house written software and employing an autotitrator as a syringe pump. Standard/sample was aspirated and the zone was then sent to a flow cell for measurement. Detection limits for Cd(II), Cu(II), Pb(II) and Zn(II) were 6, 3, 10 and 470 μg l⁻¹, respectively. Applications to water samples were demonstrated. A homemade UV-digester was used for removing organic matters in the wastewater samples prior to analysis by the proposed voltammetric systems.     

Determination of selenium, zinc and cadmium in antidandruff shampoos by atomic spectrometry after microwave assisted sample digestion

Microwave assisted pre-treatments for atomic spectrometric determination (inductive coupled plasma-optical emission spectrometry, ICP-OES or flame atomic absorption spectrometry, FAAS) of metallic elements, usually present in antidandruff shampoos, are proposed. They are based on the digestion of the sample with HNO₃ into a closed reactor, which is irradiated at 800 W for a few minutes. Selenium was determined by ICP-OES. The limit of detection was 0.11 mg l⁻¹; the relative standard deviation (R.S.D.) for the selenium content in the samples was in the 0.6–3.6% range. The results obtained were in agreement with the label contents and the recovery of the proposed method was in the 100–106% range. Zinc and cadmium were determined by FAAS. The limit of detection for zinc determination was 0.078 mg l⁻¹; the R.S.D. for zinc contents was in the 0.8–8.6% range. A limit of detection of 0.09 mg l⁻¹ was obtained for cadmium determination; the R.S.D. for cadmium contents was in the 0.7–2.7% range. The determinations were performed after two different sample mineralization pre-treatments — dry ashing (in an electric furnace) and wet mineralization (in a microwave oven). Both methodologies provided comparable results for zinc and cadmium determination in shampoos. The proposed microwave assisted digestion procedures allow a precise and accurate determination of selenium, zinc and cadmium in commercial antidandruff shampoos, and the sample pre-treatment is less time-consuming than the classic methods.     

Determination of ammonia in beers by pervaporation flow injection analysis and spectrophotometric detection

A pervaporation flow injection (PFI) method is described for the determination of ammonia in beers. After injecting the sample into a NaOH donor solution, ammonia and other volatiles are transferred in the pervaporation unit from the donor stream to an acceptor stream containing sodium salicylate and nitroprusside, which subsequently mixes with alkaline sodium dichloroisocyanurate to allow the classical Berthelot reaction to take place. The blue-coloured complex formed is monitored spectrophotometrically at 655 nm. A linear calibration curve with a range of 0.1–40 mg l⁻¹ was obtained. The method has a detection limit of 0.05 mg l⁻¹ and is capable of a sampling frequency of 11 h⁻¹ at 4 mg l⁻¹ ammonia. It was applied successfully to the determination of ammonia in synthetic samples and unfiltered lager beers. The advantages of the present method over the ammonia ion-selective electrode method and the PFI system based on mixed indicator detection are discussed.     

Biosorption of heavy metals on Aspergillus fumigatus immobilized Diaion HP-2MG resin for their atomic absorption spectrometric determinations

A solid phase extraction procedure based on biosorption of copper(II), lead(II), zinc(II), iron(III), nickel(II) and cobalt(II) ions on Aspergillus fumigatus immobilized Diaion HP-2MG has been investigated. The analytical conditions including amounts of A. fumigatus, eluent type, flow rates of sample and eluent solutions were examined. Good recoveries were obtained to the spiked natural waters. The influences of the concomitant ions on the retentions of the analytes were also examined. The detection limits (3sigma, N = 11) were 0.30 μg l⁻¹ for copper, 0.32 μg l⁻¹ for iron, 0.41 μg l⁻¹ for zinc, 0.52 μg l⁻¹ for lead, 0.59 μg l⁻¹ for nickel and 0.72 μg l⁻¹ for cobalt. The relative standard deviations of the procedure were below 7%. The validation of the presented procedure is performed by the analysis of three standard reference materials (NRCC-SLRS 4 Riverine Water, SRM 1515 Apple leaves and GBW 07605 Tea). The procedure was successfully applied for the determination of analyte ions in natural waters microwave digested samples including street dust, tomato paste, black tea, etc.     

Cathodic adsorptive stripping voltammetric behaviour of guanine in the presence of copper at the static mercury drop electrode

The cathodic adsorptive electrochemical behavior of guanine in the presence of some metal ions at the static mercury drop electrode was investigated. A 1.0×10⁻³ mol l⁻¹ NaOH or a 2.0×10⁻² mol l⁻¹ Hepes buffer at pH 8.0 solutions were used as supporting electrolytes. The reduction peak potential for guanine was found to be around −0.15 V, which is very close to the mercury reduction wave. A new peak appears at −0.60 V in the presence of copper or at −1.05 V in the presence of zinc. A square wave voltammetric procedure for electroanalytical determination of guanine in 2.0×10⁻² mol l⁻¹ Hepes buffer at pH 8.0 containing 1.6×10⁻⁵ mol l⁻¹of copper ions, was developed. An accumulation potential of −0.15 V during 270 s for the prior adsorption of guanine at the electrode surface was used. The response of the system was found to be linear in the range of guanine concentration from 6.62×10⁻⁸ to 1.32×10⁻⁷ mol l⁻¹ and the detection limit was 7.0×10⁻⁹ mol l⁻¹. The influence of DNA bases such as adenine, cytosine and thymine was also examined. Cyclic voltammetry was used to characterize the interfacial and redox mechanism.     

Determination of fenoterol and salbutamol in pharmaceutical formulations by electrogenerated chemiluminescence

Fenoterol and salbutamol were determined by electrogenerated chemiluminescence (ECL) coupled with flow injection analysis (FIA), using Ru(bpy)₃²⁺ as the luminescent substance. Fenoterol and salbutamol oxidize together with the ruthenium 2,2-bipyridyl at a platinum electrode, which leads to an increase in the luminescent intensity, and this increase is proportional to the analyte concentration. For fenoterol a linear calibration curve within the range from 1.0 × 10⁻⁵ to 1.0 × 10⁻⁴ mol l⁻¹ was obtained with a correlation coefficient of 0.998 (n = 5) and for salbutamol the linear analytical curve was also obtained in this range with a correlation coefficient of 0.995 (n = 5). The relative standard deviation was estimated as ≤2.5% for 3 × 10⁻⁵ mol l⁻¹ for fenoterol solution and as ≤1.3% for 5.0 × 10⁻⁵ mol l⁻¹ salbutamol solution for 15 successive injections. The limit of detection for fenoterol was 2.4 × 10⁻⁷ mol l⁻¹ and for salbutamol was 4.0 × 10⁻⁷ mol l⁻¹. Fenoterol and salbutamol were successfully determined in drug tablets and the soluble components of the matrix did not interfere in the luminescent emission. The results obtained using the luminescent methodology were not statistically different from those obtained by UV-spectrophotometry at 95% confidence level.     

Methods for separation of trace amounts of platinum and investigation of the influence of interfering elements during platinum determination in copper ores and copper concentrates by graphite furnace atomic absorption spectrometry

A THGA graphite furnace with Zeeman background correction has been used to determine platinum content in copper ore and copper concentrate at the part per billion (ppb) concentration level. Two different procedures for the separation of trace platinum have been applied: (i) use of an ion exchange resin; and (ii) a two-stage method based on platinum separation on inorganic carriers. The influence of interfering elements in the matrix (Cu, Pb, Fe, Ti, V, Au, Pd, Ir, Rh and Al) has been examined using a graphite furnace. It was found that the presence of Cu (12.5–100 mg l⁻¹), Pb (100–500 mg l⁻¹), Fe (100–2000 mg l⁻¹), Ti (25–100 mg l⁻¹), V (25–100 mg l⁻¹), Au (25–300 mg l⁻¹), Pd (20–250 mg l⁻¹), Ir (0.5–3.5 mg l⁻¹) and Rh (0.025–1 mg l⁻¹) in the samples analyzed has no effect on the platinum absorption signal when using a recommended temperature program (T_pyr=1300°C, T_at=2450°C). Spectral interference was observed, which was due to aluminum, as a result of the close neighborhood of the Pt 265.945-nm and Al 266.039-nm lines. This interference could not be eliminated by the Zeeman background correction.     

Simultaneous flow injection determination of calcium and fluoride in natural and borehole water with conventional ion-selective electrodes in series

An on-line automated system for the simultaneous flow injection determination of calcium and fluoride in natural and borehole water with conventional calcium-selective and fluoride-selective membrane electrodes as sensors in series is described. Samples (30 μl) are injected into a TISAB II (pH=5.50) carrier solution as an ionic strength adjustment buffer. The sample-buffer zone formed is first channeled to a fluoride-selective membrane electrode and then via the calcium-selective membrane electrode to the reference electrodes. The system is suitable for the simultaneous on-site monitoring of calcium (linear range 10⁻⁵–10⁻² mol l⁻¹ detection limit 1.94×10⁻⁶ mol l⁻¹ recovery 99.22%, RSD<0.5%) and fluoride (linear range 10⁻⁵–10⁻² mol l⁻¹ detection limit 4.83×10⁻⁶ mol l⁻¹ recovery 98.63%, RSD=0.3%) at a sampling rate of 60 samples h⁻¹.     

Use of silica gel chemically modified with zirconium phosphate for preconcentration and determination of lead and copper by flame atomic absorption spectrometry

An analytical method using silica gel chemically modified with zirconium (IV) phosphate for preconcentration of lead and copper, in a column system, and their sequential determination by flame atomic absorption spectrometry (FAAS), was developed. Sample solutions are passed through a glass column packed with 100 mg of the sorbent material, at pH 4.5, and lead and copper are eluted with 1.0 mol l⁻¹ HNO₃ at a flow rate of 2.0 ml min⁻¹. The extraction of copper is affected by Fe(II), Mn(II), Zn(II), Ni(II) and Co(II) while only Fe(II) interferes in the lead determination. These interferences may be overcome with an appropriate addition of a KI or NaF solution. An enrichment factor of 30 was obtained for both metals. While the limits of detection (3σ) were 6.1 and 1.1 μg l⁻¹, for Pb and Cu, respectively, the limits of determination were 16.7 and 3.3 μg l⁻¹. The precision expressed as relative standard deviation (R.S.D.) obtained for 3.3 μg l⁻¹ of Cu and 16.7 μg l⁻¹ of Pb were 4.3 and 4.7%, respectively, calculated from ten measurements. The proposed method was evaluated with reference material and was applied for the determination of lead and copper in industrial and river waters.     

Determination of nanomolar concentrations of phosphate in freshwaters using flow injection with luminol chemiluminescence detection

A simple and rapid flow injection (FI) method is reported for the determination of phosphate (as molybdate reactive P) in freshwaters based on luminol chemiluminescence (CL) detection. The molybdophosphoric heteropoly acid formed by phosphate and ammonium molybdate in acidic conditions generated chemiluminescence emission via the oxidation of luminol. The detection limit (3× standard deviation of blank) was 0.03 μg P l⁻¹ (1.0 nM), with a sample throughput of 180 h⁻¹. The calibration graph was linear over the range 0.032–3.26 μg P l⁻¹ (r²=0.9880) with relative standard deviations (n=4) in the range 1.2–4.7%. Interfering cations (Ca(II), Mg(II), Ni(II), Zn(II), Cu(II), Co(II), Fe(II) and Fe(III)) were removed by passing the sample through an in-line iminodiacetate chelating column. Silicate interference (at 5 mg Si l⁻¹) was effectively masked by the addition of tartaric acid and other common anions (Cl⁻, SO₄²⁻, HCO₃⁻, NO₃⁻ and NO₂⁻) did not interfere at their maximum admissible concentrations in freshwaters. The method was applied to freshwater samples and the results (26.1±1.1–62.0±0.4 μg P l⁻¹) were not significantly different (P=0.05) from results obtained using a segmented flow analyser method with spectrophotometric detection (24.4±4.45–84.0±16.0 μg P l⁻¹).     

Amperometric detection of amino acids in a flow-injection system with a nickel(II)-modified electrode with an Eastman-AQ polymer film

Amperometic flow measurements were made at +0.55 V (vs. Ag/AgCl) in 0.1 mol l⁻¹ KOH electrolyte with an Ni(II) chemically modified electrode (CME) with an Eastman-AQ polymer film. The use and characteristics of a Ni(II)-containing crystalline and polymer-modified electrode obtained by a double coating step as a detector for amino acids in a flow-injection system using reversed-phase liquid chromatography are described. The detection of these analytes is based on the higher oxidation state of nickel (NiOOH) controlled by the applied potential. The electroanalytical parameters and the detection current for a series of amines and amino acids were investigated. The use of such a CME in the flow-injection technique was found to be suitable in a solution at low pH. The linear range for glycine is 5 × 10⁻⁶-0.1 mol l⁻¹ with a detection limit of 1.0×10⁻⁶ mol l⁻¹. A 1 × 10⁻⁴ mol l⁻¹ mixture of serine and tyrosine was also detected after separation on an Nucleosil C₁₈ column.     

Evaluation of ammonia as diluent for serum sample preparation and determination of selenium by graphite furnace atomic absorption spectrometry

A method for the determination of total selenium in serum samples by graphite furnace atomic absorption spectrometry was evaluated. The method involved direct introduction of 1:5 diluted serum samples (1% v/v NH₄OH+0.05% w/v Triton X-100^®) into transversely heated graphite tubes, and the use of 10 μg Pd+3 μg Mg(NO₃)₂ as chemical modifier. Optimization of the modifier mass and the atomization temperature was conducted by simultaneously varying such parameters and evaluating both the integrated absorbance and the peak height/peak area ratio. The latter allowed the selection of compromise conditions rendering good sensitivity and adequate analyte peak profiles. A characteristic mass of 49 pg and a detection limit (3s) of 6 μg 1⁻¹ Se, corresponding to 30 μg l⁻¹ Se in the serum sample, were obtained. The analyte addition technique was used for calibration. The accuracy was assessed by the determination of total selenium in Seronorm™ Trace Elements Serum Batch 116 (Nycomed Pharma AS). The method was applied for the determination of total selenium in ten serum samples taken from individuals with no known physical affection. The selenium concentration ranged between 79 and 147 μg l⁻¹, with a mean value of 114±22 μg l⁻¹.     

Copper determination in natural water samples by using FAAS after preconcentration onto amberlite XAD-2 loaded with calmagite

A procedure for separation and preconcentration of trace amounts of copper in natural water samples, has been proposed. It is based on the adsorption of copper(II) ions onto a column of Amberlite XAD-2 resin loaded with calmagite reagent. This way amounts of copper within the range from 0.0125 to 25.0 μg, in a sample volume of 25 to 250 ml, and pH from 3.7 to 10.0 was concentrated as calmagite complex in a column of 0.50 g of Amberlite XAD-2 resin. Copper (II) ion was desorpted by using 5.0 ml of 2 mol l⁻¹ hydrochloric acid. Detection and determination limits of the proposed procedure for 250 ml sample volume were 0.15 and 0.50 μg l⁻¹, respectively. Selectivity test showed that (in the indicated concentration), calcium(II) (500 mg l⁻¹), magnesium(II) (500 mg l⁻¹), strontium(II) (50 mg l⁻¹), iron(III) (10 mg l⁻¹), nickel(II) (10 mg l⁻¹), cobalt(II) (10 mg l⁻¹), cadmium(II) (10 mg l⁻¹) and lead(II) (10 mg l⁻¹) did not interfere in copper determination by this procedure. Precision of the method, evaluated as the relative standard deviation by analyzing a series of seven replicates, was 2.42% for a copper mass of 1.0 μg in a sample volume of 100 ml. The accuracy of the proposed procedure was evaluated by means of copper determination in reference biological samples. The achieved results were in good agreement with certified values. The extractor system had a sorption capacity of 1.59 μmol of copper per gram of resin loaded with calmagite. The proposed procedure was applied for copper determination by FAAS in natural water samples. Samples were collected from different places of Salvador city, Bahia, Brazil. The achieved recovery, measured by the standard addition technique, showed that the proposed procedure had good accuracy. A good enrichment factor (50×) and simplicity are the main advantages in this analytical procedure.     

Electrochemiluminescence sensor using tris(2,2′-bipyridyl)ruthenium(II) immobilized in Eastman-AQ55D–silica composite thin-films

An electrochemiluminescence (ECL) sensor with good long-term stability and fast response time has been developed. The sensor was based on the immobilization of tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) into the Eastman-AQ55D–silica composite thin films on a glassy carbon electrode. The ECL and electrochemistry of Ru(bpy)₃²⁺ immobilized in the composite thin films have been investigated, and the modified electrode was used for the ECL detection of oxalate, tripropylamine (TPA) and chlorpromazine (CPZ) in a flow injection analysis system and showed high sensitivity. Because of the strong electrostatic interaction and low hydrophobicity of Eastman-AQ55D, the sensor showed no loss of response over 2 months of dry storage. In use, the electrode showed only a 5% decrease in response over 100 potential cycles. The detection limit was 1 μmol l⁻¹ for oxalate and 0.1 μmol l⁻¹ for both TPA and CPZ (S/N=3), respectively. The linear range extended from 50 μmol l⁻¹ to 5 mmol l⁻¹ for oxalate, from 20 μmol l⁻¹ to 1 mmol l⁻¹ for TPA, and from 1 μmol l⁻¹ to 200 μmol l⁻¹ for CPZ.     

Flow injection determination of bismuth in urine by successive retention of Bi(III) and tetrahydroborate(III) on an anion-exchange resin and hydride generation atomic absorption spectrometry

Bismuth as BiCl₄⁻ and BH₄⁻ ware successively retained in a column (150 mm × 4 mm, length × i.d.) packed with Amberlite IRA-410 (strong anion-exchange resin). This was followed by passage of an injected slug of hydrochloric acid resulting in bismuthine generation (BiH₃). BiH₃ was stripped from the eluent solution by the addition of a nitrogen flow and the bulk phases were separated in a gas–liquid separator. Finally, bismutine was atomized in a quartz tube for the subsequent detection of bismuth by atomic absorption spectrometry. Different halide complexes of bismuth (namely, BiBr₄⁻, BiI₄⁻ and BiCl₄⁻) were tested for its pre-concentration, being the chloride complexes which produced the best results. Therefore, a concentration of 0.3 mol l⁻¹ of HCl was added to the samples and calibration solutions. A linear response was obtained between the detection limit (3σ) of 0.225 and 80 μg l⁻¹. The R.S.D.% (n = 10) for a solution containing 50 μg l⁻¹ of Bi was 0.85%. The tolerance of the system to interferences was evaluated by investigating the effect of the following ions: Cu²⁺, Co²⁺, Ni²⁺, Fe³⁺, Cd²⁺, Pb²⁺, Hg²⁺, Zn²⁺, and Mg²⁺. The most severe depression was caused by Hg²⁺, which at 60 mg l⁻¹ caused a 5% depression on the signal. For the other cations, concentrations between 1000 and 10,000 mg l⁻¹ could be tolerated. The system was applied to the determination of Bi in urine of patients under therapy with bismuth subcitrate. The recovery of spikes of 5 and 50 μg l⁻¹ of Bi added to the samples prior to digestion with HNO₃ and H₂O₂ was in satisfactory ranges from 95.0 to 101.0%. The concentrations of bismuth found in six selected samples using this procedure were in good agreement with those obtained by an alternative technique (ETAAS). Finally, the concentration of Bi determined in urine before and after 3 days of treatment were 1.94 ± 1.26 and 9.02 ± 5.82 μg l⁻¹, respectively.     

Determination of paracetamol in pharmaceutical formulations using a sequential injection system

A simple method for the rapid determination of paracetamol in pharmaceutical formulations is described. The method involves oxidation of paracetamol by potassium hexacyanoferrate(III) and a subsequent reaction with phenol in the presence of ammonia. The blue complex formed is measured at 630 nm. The system has a sample frequency of 27 samples per h with a detection limit of 0.2 mg l⁻¹. The calibration curve is linear up to 60 mg l⁻¹ with a relative standard deviation of 1.2% (n=10).     

A novel homocystine-agarose adsorbent for separation and preconcentration of nickel in table salt and baking soda using factorial design optimization of the experimental conditions

Homocystine was for the first time, chemically linked to a highly cross-linked agarose support (Novarose) to be employed as a chelating adsorbent for preconcentration and AAS determination of nickel in table salt and baking soda. Nickel is quantitatively adsorbed on a small column packed with 0.25 ml of the adsorbent, in a pH range of 5.5–6.5 and simply eluted with 5 ml of a 1 mol l⁻¹ hydrochloric acid solution.

A factorial design was used for optimization of the effects of five different variables on the recovery of nickel. The results indicated that the factors of flow rate and column length, and the interactions between pH and sample volume are significant.

In the optimized conditions, the column could tolerate salt concentrations up to 0.5 mol l⁻¹ and sample volumes beyond 500 ml. Matrix ions of Mg²⁺ and Ca²⁺, with a concentration of 200 mg l⁻¹, and potentially interfering ions of Cd²⁺, Cu²⁺, Zn²⁺ and Mn²⁺, with a concentration of 10 mg l⁻¹, did not have significant effect on the analyte's signal. Preconcentration factors up to 100 and a detection limit of 0.49 μg l⁻¹, corresponding to an enrichment volume of 500 ml, were obtained for the determination of the analyte by flame AAS. Application of the method to the determination of natural and spiked nickel in table salt and baking soda solutions resulted in quantitative recoveries. Direct ETAAS determination of nickel in the same samples was not possible because of a high background observed.     

Differential-pulse voltammetric determination of low μg l cyanide levels using EDTA, Cu(II) and a hanging mercury drop electrode

The proposed method for cyanide determination at the ultratrace level by differential pulse voltammetry is based in the sensitivity enhancement obtained when both Cu(II) and EDTA are present in the background electrolyte. Comparison of the detection limits and linear dynamic ranges using the conventional borate (pH 9.75), and the proposed borate-EDTA–Cu(II) background electrolytes was carried out. Best results have been obtained with the addition of 0.5 mmol l⁻¹ EDTA and 0.02 mmol l⁻¹ of Cu(II), which allow a detection limit of 1.7 μg l⁻¹ CN⁻ (65 nmol l⁻¹ — absolute detection limit 34 ng) with a precision better than ±2% for a 40 μg l⁻¹ level. Calibration range extended from detection limit up to 100 μg l⁻¹. Cyclic voltammetry indicates that the measured cyanide peak is obtained when the electrogenerated CuCN adsorbed onto the hanging mercury drop electrode surface, is oxidised at positive going potential scan. The method has been successfully applied to various industrial waste waters such as metal-finishing waste waters, water/sand mixtures from cleaning processes of coke production, leachates from wastes obtained from electrolytic cells of aluminium production, and liquors from gold extraction industry. Results obtained by the proposed method showed good agreement with those obtained by the standard methods (ion-selective potentiometry and the spectrophotometric pyridine method).     

Automated sequential injection fluorimetric determination and dissolution studies of Ergotamine Tartrate in pharmaceuticals

A fully automated flow system for drug-dissolution studies based on the sequential injection analysis (SIA) was described and used for monitoring dissolution profiles of Ergotamine Tartrate (ET) in pharmaceutical formulations. 50 μl of dissolution medium was taken for each measurement at a flow rate of 40 μl s⁻¹ and detected by fluorescence detector using λ_ex=236 nm (λ_em≥390 nm). The calibration curve was linear over the range 0.03–0.61 mg l⁻¹ of ET (sufficient for the dissolution tests). Equation of the calibration curve was calculated giving the following values: F=117.7 c+0.80 (n=6); r=0.9998. Detection limit was 0.01 mg l⁻¹ of ET. The R.S.D. is less than 0.54 and 0.86% (n=10) when determining 0.61 and 0.03 mg l⁻¹ of ET in standard solution, respectively. The dissolution test of Bellaspon tablets (0.3 mg of ET in 1 tablet) was programmed for 20 min, with a continuous sampling rate of 120 h⁻¹ under conditions required by BP 1993.