Reversed flow injection spectrophotometric determination of chlorate

An interfacing has been developed to connect a spectrophotometer with a personal computer and used as a readout system for development of a simple, rapid and sensitive reversed flow injection (rFI) procedure for chlorate determination. The method is based on the oxidation of indigo carmine by chlorate ions in an acidic solution (dil. HCl) leading to the decrease in absorbance at 610 nm. The decrease in absorbance is directly related to the chlorate concentration present in the sample solutions. Optimum conditions for chlorate were examined. A linear calibration graph over the range of 0.1-0.5 mg L⁻¹ chlorate was established with the regression equation of Y = 104.5X + 1.0, r² = 0.9961 (n = 6). The detection limit (3σ) of 0.03 mg L⁻¹, the limit of quantitation (10σ) of 0.10 mg L⁻¹ and the RSD of 3.2% for 0.3 mg L⁻¹ chlorate (n = 11) together with a sample throughput of 92 h⁻¹ were obtained. The recovery of the added chlorate in spiked water samples was 98.5 ± 3.1%. Major interferences for chlorate determination were found to be BrO₃⁻, ClO₂⁻, ClO⁻ and IO₃⁻ which were overcome by using SO₃²⁻ (as Na₂SO₃) as masking agent. The method has been successfully applied for the determination of chlorate in spiked water samples with the minimum reagent consumption of 14.0 mL h⁻¹. Good agreement between the proposed rFIA and the reference methods was found verified by Student's t-test at 95% confidence level.     

Highly selective flow injection spectrophotometric determination of gold based on its catalytic effect on the oxidation of variamine blue by potassium iodate in aqueous N,N-dimethylformamide medium

A highly selective and simple flow injection method is reported for the determination of Au(III) in jewel samples. The method is based on the catalytic effect of Au(III) on the oxidation of 4-amino-4′-methoxydiphenylamine hydrochloride (Variamine Blue B base, VB) by KIO₃. The colored reaction product was monitored spectrophotometrically at 546 nm. A volume fraction of 40% N,N-dimethylformamide (DMF) greatly enhances the selectivity of the method. The chemical (pH and concentrations of reagents) and instrumental variables (sample injection volume, reagents flow rates, reaction coil length) affecting the determination were studied and optimized. Under the selected values, the analyte could be determined in the range of 0.1-12.0 mg L⁻¹ (r = 0.9997), at a sampling rate of 120 h⁻¹. The proposed assay was precise (s_r = 0.8% at 5.0 mg L⁻¹ Au(III), n = 12) and adequately sensitive with a 3σ limit of detection of 0.03 mg L⁻¹. The method was successfully applied to the analysis of jewel samples. The obtained results were favorably compared to flame atomic absorption spectrometry (FAAS) used as a reference method.     

Catalytic activity of iron hexacyanoosmate(II) towards hydrogen peroxide and nicotinamide adenine dinucleotide and its use in amperometric biosensors

Hydrogen peroxide and nicotinamide adenine dinucleotide (NADH) may be determined amperometrically using screen-printed electrodes chemically modified with iron(III) hexacyanoosmate(II) (Osmium purple) in flow injection analysis (FIA). The determination is based on the exploitation of catalytic currents resulting from the oxidation/reduction of the modifier. The performance of the sensor was characterized and optimized by controlling several operational parameters (applied potential, pH and flow rate of the phosphate buffer). Comparison has been made with analogous complexes of ruthenium (Ruthenium purple) and iron (Prussian blue). Taking into account the sensitivity and stability of corresponding sensors, the best results were obtained with the use of Osmium purple. The sensor exhibited a linear increase of the amperometric signal with the concentration of hydrogen peroxide in the range of 0.1-100 mg L⁻¹ with a detection limit (evaluated as 3σ) of 0.024 mg L⁻¹ with a R.S.D. 1.5% for 10 mg L⁻¹ H₂O₂ under optimized flow rate of 0.4 mL min⁻¹ in 0.1 M phosphate buffer carrier (pH 6) and a working potential of +0.15 V versus Ag/AgCl. Afterwards, a biological recognition element - either glucose oxidase or ethanol dehydrogenase - was incorporated to achieve a sensor facilitating the determination of glucose or ethanol, respectively. The glucose sensor gave linearity between current and concentration in the range from 1 to 250 mg L⁻¹ with a R.S.D. 2.4% for 100 mg L⁻¹ glucose, detection limit 0.02 mg L⁻¹ (3σ) and retained its original activity after 3 weeks when stored at 6 °C. Optimal parameters in the determination of ethanol were selected as: applied potential +0.45 V versus Ag/AgCl, flow rate 0.2 mL min⁻¹ in 0.1 M phosphate buffer carrier (pH 7). Different structural designs of the ethanol sensor were tested and linearity obtained was up to 1000 mg L⁻¹ with a maximum R.S.D. of 5.1%. Applications in food analysis were also examined.     

Sequential injection spectrophotometric determination of phenylephrine hydrochloride in pharmaceutical preparations

A fully automated sequential injection spectrophotometric method for the determination of phenylephrine hydrochloride in pharmaceutical preparations is reported. The method is based on the condensation reaction of the analyte with 4-aminoantipyrine in the presence of potassium ferricyanide. The absorbance of the condensation product was monitored at 503 nm. A linear relationship between the relative peak height and concentration was obtained in the range 0.5-17.5 mg l⁻¹. The detection limit (as 3σ value) was 0.09 mg l⁻¹ and repeatability was 0.8 and 0.6% at 2.5 and 5 mg l⁻¹, respectively. Results obtained by this method agreed very well with those obtained by the AOAC official method.     

Determination of nitrogen in hydrolyzed protein formulations by continuous vapour phase FTIR

An on-line system with vapour generation (VG) and Fourier transform infrared (FTIR) spectrometric detection has been developed for the determination of free ammonium and organic nitrogen in agrochemical formulations containing hydrolyzed proteins. Commercial samples were digested, in batch mode, with sulphuric acid and the obtained solution was alkalinized on-line to transform the NH₄⁺ to NH₃ that was continuously monitored by FTIR. Free ammonium was determined in the same system after simple dilution of undigested samples with water. Different gas phase separators were assayed in order to introduce gaseous NH₃ into a home made IR gas cell of 10 cm pathlength, where the corresponding FTIR spectra were acquired by accumulating 10 scans per spectrum. The 967.0 cm⁻¹ band was used for the quantification of ammonia. The figures of merit of the proposed method involve a linear range up to 100 mg L⁻¹, a limit of detection (3σ) of 1.4 mg L⁻¹ of N, a limit of quantification (10σ) of 4.8 mg L⁻¹ of N, a precision (R.S.D.) of 3.0% for 10 replicate determinations of a 10.0 mg L⁻¹ of N and a sample measurement frequency of 60 h⁻¹. The method was successfully applied to the determination of free ammonium and total N in commercial amino acid formulations and results compare well with those obtained by the Kjeldhal method.     

A green analytical procedure for flow-injection determination of nitrate in natural waters

Nitrate determination in waters is generally carried out with cadmium filings and carcinogenic reagents or by reaction with phenolic compounds in highly concentrated sulfuric acid medium. In this work, it was developed a green analytical procedure for nitrate determination in natural waters based on direct spectrophotometric measurements in ultraviolet, using a flow-injection system with an anion-exchange column for separation of nitrate from interfering species. The proposed method employs only one reagent (HClO₄) in a minimum amount (equivalent to 18 μL concentrated acid per determination), and allowed nitrate determination within 0.50-25.0 mg L⁻¹, without interference of up to 200.0 mg L⁻¹ humic acid; 1.0 mg L⁻¹ NO₂⁻; 200.0 mg L⁻¹ PO₄³⁻; 75.0 mg L⁻¹ Cl⁻; 50.0 mg L⁻¹ SO₄²⁻ and 15.0 mg L⁻¹ Fe³⁺. The detection limit (99.7% confidence level) and the coefficient of variation (n = 20) were estimated as 0.1 mg L⁻¹ and 0.7%, respectively. The results obtained for natural water samples were in agreement with those achieved by the reference method based on nitrate reduction with copperized cadmium at the 95% confidence level.     

Indirect determination of fluoride in aqueous samples by inductively coupled plasma atomic emission spectrometry following precipitation of CeF3

An indirect fluoride determination method has been developed based on the ICP-AES determination of excess cerium(III) ion after precipitation. From four cations—Y(III), Sr(II), Ce(III), La(III)-cerium(III) proved to be the best precipitate forming cation in the 0-20 mg L⁻¹ fluoride concentration range with the limit of detection of 1.4 mg L⁻¹. The precision (RSD) of the proposed method is 0.71% at 8 mg L⁻¹ fluoride. The role of sulphate ions in the formation of the fluoride precipitate was studied as well. The applicability of the technique for the study of solid hazardous wastes as well as for groundwater monitoring of a fluoride contaminated area is demonstrated.     

Sequential injection method for the direct spectrophotometric determination of bismuth in pharmaceutical products

A spectrophotometric method is reported for the determination of bismuth in pharmaceutical products using sequential injection analysis. Methylthymol blue (MTB) was used as a color forming reagent and the absorbance of the Bi(III)-MTB complex was monitored at 548 nm. The various chemical and physical variables that affected the reaction were studied. A linear calibration graph was obtained in the range 0.0-75.0 mg l⁻¹ Bi(III) at a sampling frequency of 72 h⁻¹. The reagent consumption was considerably reduced compared to conventional flow injection systems, as only 150 μl of MTB were consumed per run. The precision was very satisfactory (s_r=0.5%, at 50.0 mg l⁻¹ Bi(III), n=12) and the limit of detection, c_L, was 0.250 mg l⁻¹. The developed method was applied successfully to the analysis of various pharmaceutical products containing Bi(III). The relative errors e_r, were <1.5% in all cases and were evaluated by comparison of the obtained results with those found using atomic absorption spectrometry as the reference method.     

Alternative method for measurement of albumin/creatinine ratio using spectrophotometric sequential injection analysis

A simple, automatic and practical system for successive determination of albumin and creatinine has been developed by combining sequential injection analysis (SIA) and highly sensitive dye-binding assays. Albumin detection was based on the increase in the absorbance due to complex formation between albumin and eosin Y in acidic media. The absorbance of the complex was monitored at 547 nm. For the creatinine assay, the concentration of creatinine was measured by reaction with alkaline picrate to form a colored product which absorbs at 500 nm. The influences of experimental variables such as effects of pH, reagent concentration, standard/sample volume and interferences were investigated. Under optimal conditions, the automated method showed linearity up to 20 mg L⁻¹ for albumin and 100 mg L⁻¹ for creatinine. The 3σ detection limits were 0.6 and 3.5 mg L⁻¹ for albumin and creatinine, respectively, and the relative standard deviations (n = 10) were 2.49% for 20 mg L⁻¹ albumin, and 3.14% for 20 mg L⁻¹ creatinine. Application of the proposed method to the direct analysis of urinary samples yielded results which agreed with those obtained from the Bradford protein assay and a creatinine enzymatic assay according to a paired t-test. The results obtained should be a step towards developing a fully automated and reliable analytical system for clinical research, which requires direct determination of albumin and creatinine and/or its ratios.     

Silica gel modified with lumogallion for aluminum determination by spectroscopic methods

Simple, easy to use and selective method of Al(III) sorption-spectroscopic (SS) determination was proposed. For this purpose, silica modified with tridecyloctadecylammonium chloride(SGII) using adsorption technique and glass slide modified with thin silica-poly(dimethyldiallyl-ammonium chloride) (SGI) composite film obtained by sol-gel technique were worked out. It was shown that lumogallion (LG) easily absorbs on SGI and SGII. Obtained sorbents SGIII and SGIV, respectively, were used for aluminum(III) determination by diffuse reflectance and spectrophotometric methods. The ranges of determination were (mg L⁻¹): (0.08-0.54), s_r ≤ 0.13, n = 4 for SGIII and (0.05-2.0), s_r ≤ 0.11, n = 4 for SGIV. The detection limits (blank + 3σ) for aluminum were 70 and 30 μg L⁻¹ using SGIII and SGIV, respectively, where σ is the standard deviation of blank estimation. The accuracy of the developed spectrophotometric method was examined by the determination of standard addition of aluminum in alcohol-free beverages. The relative error did not exceed 9%. SGIII can be regenerated by 0.05 M EDTANa₂H₂ solution and reused. SGIV was shown to be perspective for determination of aluminum in solution in the range of 0.01-0.13 mg L⁻¹ by solid phase luminescent technique.     

Flow injection determination of aluminium by spectrofluorimetric detection after complexation with N-o-vanillidine-2-amino-p-cresol: the application to natural waters

An on-line flow injection spectrofluorimetric method for the direct determination of aluminium in water samples is described. The method is based on the reaction of aluminium with N-o-vanillidine-2-amino-p-cresol (OVAC) in acidic medium at pH 4.0 to form a water-soluble complex. The excitation and emission wavelengths were 423.0 and 553.0 nm, respectively, at which the OVAC-Al complex gave the maximum fluorescence intensity at pH 4.0 in a 50% methanol-50% water medium at 50 °C. An interference from fluoride ions was minimised by the addition of Be²⁺. Other ions were found not to interfere at the concentrations likely to be found in natural waters. The proposed methods were validated in terms of linearity, repeatability, detection limit, accuracy and selectivity. Under these conditions, the calibration was linear up to 1000 μg L⁻¹ (r = 0.999). The limit of detection (3σ) for the determination of Al(III) was 0.057 μg L⁻¹ and the precision for multiple determinations of 3 ng mL⁻¹ Al(III) prepared in ultra-pure water was found to be 0.62% (n = 10).The Schiff base ligand could be used to determine ultra-trace aluminium from natural waters. Analysis of environmental certified reference materials showed good agreement with the certified values. The procedure was found to be equally applicable to both freshwater and saline solutions, including seawater.     

Analysis of potassium formate in airport storm water runoff by headspace solid-phase microextraction and gas chromatography–mass spectrometry

Potassium formate was extracted from airport storm water runoff by headspace solid-phase microextraction (HS-SPME) and analyzed by GC–MS. Formate was transformed to formic acid by adding phosphoric acid. Subsequently, formic acid was derivatized to methyl formate by adding methanol. Using sodium [²H]formate (formate-d) as an internal standard, the relative standard deviation of the peak area ratio of formate (m/z 60) and formate-d (m/z 61) was 0.6% at a concentration of 208.5 mg L⁻¹. Calibration was linear in the range of 0.5–208.5 mg L⁻¹. The detection limit calculated considering the blank value was 0.176 mg L⁻¹. The mean concentration of potassium formate in airport storm water runoff collected after surface de-icing operations was 86.9 mg L⁻¹ (n = 11) with concentrations ranging from 15.1 mg L⁻¹ to 228.6 mg L⁻¹.     

Development of a cloud point extraction and preconcentration method for determination of trace aluminum in mineral waters by FAAS

A cloud point extraction (CPE) method has been developed for the preconcentration of trace aluminum prior to its determination by flame atomic absorption spectrometry (FAAS). The CPE method is based on the complex of Al(III) with Xylidyl Blue (XB) and then entrapped in non-ionic surfactant Triton X-114. The main factors affecting CPE efficiency, such as pH of sample solution, concentration of XB and Triton X-114, equilibration temperature and time, were investigated in detail. An enrichment factor of 50 was obtained for the preconcentration of Al(III) with 50 mL solution. Under the optimal conditions, the detection limit of this method for Al(III) is 1.43 μg L^− 1, and the relative standard deviation is 2.7% at determination of 100 μg L^− 1 Al(III). The proposed method has been applied for determination of trace amount of aluminum in mineral water samples with satisfactory results. Also, the proposed method was applied to the certified reference materials. The results obtained were in good agreement with certified values.     

Automatic flow system for the sequential determination of copper in serum and urine by flame atomic absorption spectrometry

In this work, a fully automated flow system exploiting the advantages of the association of multi-pumping, multicommutation, binary sampling and merging zones, to accomplish the sequential determination of copper in serum and urine by flame atomic absorption spectrometry, is described. The developed flow system allowed multiple tasks, such as serum samples preparation (samples and standard solutions viscosity adjustment), serum copper (SCu) measurement, urine copper (UCu) pre-concentration and its subsequent elution and measurement, to be carried out sequentially. The implemented flow manifold presented a modular configuration consisting on two quasi-independent modules, each one accountable for a specific sample manipulation and whose combined operation under computer control enabled the determination of copper in a wide concentrations range.Once optimised and with a sample consumption of about 0.250 mL of serum and 7 mL of urine, the developed flow system allowed linear calibration plots up to 5 mg L⁻¹ with a detection limit of 0.035 mg L⁻¹ for SCu and linear calibration plots up to 300 μg L⁻¹ with a detection limit of 0.67 μg L⁻¹ for UCu. The sampling rate varied according to the module employed and was about 360 determinations h⁻¹ (SCu module), 12 determinations h⁻¹ (UCu module) or 24 determinations h⁻¹ (12 urine and 12 serum samples; UCu and SCu modules simultaneously). Repeatability studies (R.S.D.%, n = 10) showed good precision for UCu at concentrations of 25 μg L⁻¹ (2.54%), 50 μg L⁻¹ (0.90%) and 100 μg L⁻¹ (1.62%) as well as for SCu at concentrations of 0.25 mg L⁻¹ (8.11%), 1 mg L⁻¹ (3.11%) and 5 mg L⁻¹ (0.90%). A comparative evaluation showed a good agreement between the results obtained in the analysis of UCu and SCu (n = 18) by both the developed methodology and the reference procedures. Accuracy was further evaluated by means of the analysis of reference samples (Seronorm™ Trace Elements Urine and Seronorm™ Trace Elements Serum) and the obtained results complied with the certified values.     

A potential visual fluorescence probe for ultratrace arsenic (III) detection by using glutathione-capped CdTe quantum dots

The interaction between mercaptoacetic acid (MA)-capped CdTe QDs, MA-capped CdTe/ZnS QDs or glutathione (GSH)-capped CdTe QDs with As(III) was studied using fluorescence spectrometry. As (III) has a high-affinity to reduced-GSH to form As(SG)₃, and the emission of the GSH-capped CdTe QDs (λ_em. = 612 nm) is quenched effectively. Thus, a novel fluorescence spectrometric method was developed for As (III) determination by using GSH-CdTe QDs. Under optimal conditions, the quenched fluorescence intensity (F₀/F) increased linearly with the concentration of As (III) ranging from 5.0 × 10⁻⁶ to 25 × 10⁻⁵ mol L⁻¹. The limit of detection (3σ) for As (III) was found to be 2 × 10⁻⁸ mol L⁻¹. This method is potentially useful in visual detection of As (III) under irradiation of the ultraviolet light.     

Selective stopped-flow sequential injection method for the spectrophotometric determination of titanium in dental implant and natural Moroccan phosphate rock

The present work reports the first sequential injection (SI) method for the spectrophotometric determination of Ti(IV). The method is based upon the reaction of Ti(IV) with chromotropic acid (CA) in acidic medium to form a water-soluble complex (λ_max = 420 nm). The chemical and instrumental variables of the system that affected the reaction were studied. Selectivity was greatly enhanced using ascorbic acid. A linear calibration graph was obtained in the range 0.2-10.0 mg l⁻¹ Ti(IV) at a sampling frequency of 24 h⁻¹. The precision was satisfactory (s_r = 1.5% at 5.0 mg l⁻¹ Ti(IV), n = 12) and the 3σ limit of detection, c_L, was 0.7 mg l⁻¹ (n = 10). The developed method proved to be adequately selective and was applied successfully to the analysis of real samples (dental implant and natural Moroccan phosphate rock) giving accurate results based on recovery studies (98-105%).     

New procedure of selected biogenic amines determination in wine samples by HPLC

A new procedure for determination of biogenic amines (BA): histamine, phenethylamine, tyramine and tryptamine, based on the derivatization reaction with 2-chloro-1,3-dinitro-5-(trifluoromethyl)-benzene (CNBF), is proposed. The amines derivatives with CNBF were isolated and characterized by X-ray crystallography and ¹H, ¹³C, ¹⁹F NMR spectroscopy in solution. The novelty of the procedure is based on the pure and well-characterized products of the amines derivatization reaction. The method was applied for the simultaneous analysis of the above mentioned biogenic amines in wine samples by the reversed phase-high performance liquid chromatography. The procedure revealed correlation coefficients (R²) between 0.9997 and 0.9999, and linear range: 0.10–9.00 mg L⁻¹ (histamine); 0.10–9.36 mg L^-1 (tyramine); 0.09–8.64 mg L⁻¹ (tryptamine) and 0.10–8.64 mg L⁻¹ (phenethylamine), whereas accuracy was 97%–102% (recovery test). Detection limit of biogenic amines in wine samples was 0.02–0.03 mg L⁻¹, whereas quantification limit ranged 0.05–0.10 mg L⁻¹. The variation coefficients for the analyzed amines ranged between 0.49% and 3.92%. Obtained BA derivatives enhanced separation the analytes on chromatograms due to the inhibition of hydrolysis reaction and the reduction of by-products formation.     

Evaluation of alternate lines of Fe for sequential multi-element determination of Cu, Fe, Mn and Zn in soil extracts by high-resolution continuum source flame atomic absorption spectrometry

The usefulness of the secondary line at 252.744 nm and the approach of side pixel registration were evaluated for the development of a method for sequential multi-element determination of Cu, Fe, Mn and Zn in soil extracts by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). The influence of side pixel registration on the sensitivity and linearity was investigated by measuring at wings (248.325, 248.323, 248.321, 248.329, and 248.332 nm) of the main line for Fe at 248.327 nm. For the secondary line at 252.744 nm or side pixel registration at 248.325 nm, main lines for Cu (324.754 nm), Mn (279.482 nm) and Zn (213.875 nm), sample flow-rate of 5.0 mL min⁻¹ and calibration by matrix matching, analytical curves in the 0.2-1.0 mg L⁻¹ Cu, 1.0-20.0 mg L⁻¹ Fe, 0.2-2.0 mg L⁻¹ Mn, 0.1-1.0 mg L⁻¹ Zn ranges were obtained with linear correlations better than 0.998. The proposed method was applied to seven soil samples and two soil reference materials (IAC 277; IAC 280). Results were in agreement at a 95% confidence level (paired t-test) with reference values. Recoveries of analytes added to soil extracts containing 0.15 and 0.30 mg L⁻¹ Cu, 7.0 and 14 mg L⁻¹ Fe, 0.60 and 1.20 mg L⁻¹ Mn, 0.07 and 0.15 mg L⁻¹ Zn, varied within the 94-99, 92-98, 93-101, and 93-103% intervals, respectively. The relative standard deviations (n = 12) were 2.7% (Cu), 1.4% (Fe - 252.744 nm), 5.7% (Fe - 248.325 nm), 3.2% (Mn) and 2.8% (Zn) for an extract containing 0.35 mg L⁻¹ Cu, 14 mg L⁻¹ Fe, 1.1 mg L⁻¹ Mn and 0.12 mg L⁻¹ Zn. Detection limits were 5.4 μg L⁻¹ Cu, 55 μg L⁻¹ Fe (252.744 nm), 147 μg L⁻¹ Fe (248.325 nm), 3.0 μg L⁻¹ Mn and 4.2 μg L⁻¹ Zn.     

Hybrid sequential injection-flow injection manifold for the spectrophotometric determination of total sulfite in wines using o-phthalaldehyde and gas-diffusion

A new automated spectrophotometric method for the determination of total sulfite in white and red wines is reported. The assay is based on the reaction of o-phthalaldehyde (OPA) and ammonium chloride with the analyte in basic medium under SI conditions. Upon on-line alkalization with NaOH, a blue product is formed having an absorption maximum at 630 nm. The parameters affecting the reaction - temperature, pH, ionic strength, amount concentration and volume of OPA, amount concentration of ammonium chloride, flow rate and reaction coil length - and the gas-diffusion process - sample and HCl volumes, length of mixing coil, donor flow rate - were studied. The proposed method was validated in terms of linearity (1-40 mg L⁻¹, r = 0.9997), limit of detection (c_L = 0.3 mg L⁻¹) and quantitation (c_Q = 1.0 mg L⁻¹), precision (s_r = 2.2% at 20 mg L⁻¹ sulfite, n = 12) and selectivity. The applicability of the analytical procedure was evaluated by analyzing white and red wine samples, while the accuracy as expressed by recovery experiments ranged between 96% and 106%.     

The development of sequential injection analysis coupled with lab-on-valve for copper determination

A sequential injection analysis (SIA) using lab-on-valve with air segmentation and spectrophotometric detection was designed for copper(II) determination. It is based on the reaction of copper(II) and 2-carboxy-2′-hydroxy-5′-sulfoformazyl benzene (Zincon) in a weak alkaline solution between the air zones. Beer's Law was obeyed over the range of 0.1-2.0 mg L⁻¹ copper(II) with a correlation coefficient 0.9985 and a slope of 0.2893 absorbance unit/mg L⁻¹. The relative standard deviation was 2.0% for a series of 10 measurements of 0.5 mg L⁻¹ copper(II) solution. The detection limit (3 S/N) and the limit of quantification (LOQ) were 0.05 and 0.17 mg L⁻¹ respectively. This method has been successfully applied to determination of copper(II) in wastewater with a sample throughput of 120 h⁻¹. The method is superior to the batchwise method in that it provides fully automation, rapidity, less reagents and sample consumption with little waste generation.