Abstracts

Abstract

ELECTROCHEMICAL METHODS IN PESTICIDES CONTROL by E. M. Garrido and C. Delerue‐Matos, REQUIMTE/Instituto Superior de Engenharia do Porto, Instituto Politécnico do Porto, 4200‐485 Porto, Portugal; J. L. F. C. Lima, REQUIMTE/Departamento de Química Física, Faculdade de Farmácia, Universidade do Porto, 4050‐047 Porto, Portugal; and A. M. O. Brett, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3000 Coimbra, Portugal

ABSTRACT: The state of the art of voltammetric and amperometric methods used in the study and determination of pesticides in crops, food, phytopharmaceutical products, and environmental samples is reviewed. The main structural groups of pesticides, i.e., triazines, organophosphates, organochlorides, nitrocompounds, carbamates, thiocarbamates, sulfonylureas, and bipyridinium compounds are considered with some degradation products. The advantages, drawbacks, and trends in the development of voltammetric and amperometric methods for study and determination of pesticides in these samples are discussed.

Analytical Letters, 37(9), 1755–1791, 2004

Abstract

A NOVEL FLOW‐INJECTION ANALYSIS METHOD OF GLUCOSE BASED ON TEMPLATE‐SYNTHESIZED SOL–GEL NANOTUBE ARRAY ENZYME MEMBRANE REACTOR by Wei Yang, Hui‐Ying Qu, Huang‐Hao Yang, and Jin‐Gou Xu, Department of Chemistry, The Key Laboratory of Analytical Science of MOE, Xiamen University, Xiamen 361005, P.R. China

ABSTRACT: A synthetic enzyme‐loading nanotube membrane was developed and used in flow‐injection analysis (FIA) for the first time. The membrane was based on an anodic alumina oxide (AAO) film that has cylindrical pores with monodisperse nanoscopic diameters, and silica nanotubes (SNTs) were chemically synthesized within the pores of this film through sol–gel chemistry. Horseradish peroxidase (HRP) was immobilized on the inner walls of the SNTs. The fabrication and initial testing of a flow‐through membrane reactor design for heterogeneous enzyme reactions were presented and applied to the determination of glucose in real samples. This novel immobilized enzyme membrane reactor possesses some advantages over both open‐tubular and packed‐bed reactors often used in FIA. The present work shows that the membrane containing SNTs offers considerable potential and new perspectives for the use of such nanomaterials.

Analytical Letters, 37(9), 1793–1809, 2004

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APPLICATION OF ORGANIC NANOPARTICLES AS FLUORESCENCE PROBE IN THE DETERMINATION OF NUCLEIC ACIDS by Leyu Wang, Ling Dong, Guirong Bian, Tingting Xia, Hongqi Chen, Lun Wang, Qin Cao, and Long Li, Institute of Analytical Chemistry, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, China

ABSTRACT: Organic fluorescent nanoparticles (NPs) have been successfully synthesized by reprecipitation method under ultrasonic irradiation. In comparison with single organic fluorophores, these NPs are brighter, photo‐chemically stable, and water‐soluble. At acidic medium, the fluorescence of NPs is 60 times strong as that of 1‐pyrenemethylamine. They also have high room temperature fluorescence quantum yields (∼20%) and twice long fluorescence lifetime (∼0.2 µsec) as that of single organic fluorophores. A fluorescence method has been developed for rapid determination of DNA with these organic NPs as a fluorescence probe, based on the fluorescence quenching of NPs in the presence of DNA. Maximum fluorescence quenching is produced at pH 2.0 with maximum excitation and emission wavelengths of 238 and 400 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4–10.5 µg mL⁻¹ for calf thymus DNA (ct‐DNA) and 0.8–20.0 µg mL⁻¹ for fish sperm DNA (fs‐DNA). The corresponding detection limit is 0.019 µg mL⁻¹ for ct‐DNA and 0.022 µg mL⁻¹ for fs‐DNA. The relative standard deviation of six replicate measurements is 1.3–2.2%. The method is simple, rapid, and sensitive. The recovery and relative standard deviation are very satisfactory.

Analytical Letters, 37(9), 1811–1822, 2004

Abstract

DETERMINATION OF MALIC ACID IN REAL SAMPLES BY USING ENZYME IMMOBILIZED REACTORS AND AMPEROMETRIC DETECTION by Alexandra Manzoli, Inês N. Tomita, Fernando L. Fertonani, and Hideko Yamanaka, Instituto de Química, Unesp, C. P. 355, 14800‐900 Araraquara (SP), Brazil; Graciliano de Oliveira‐Neto, Instituto de Química, Unicamp, C. P. 6154, 13083‐970 Campinas (SP), Brazil; and Marco Mascini, Dip. Chimica, Universita di Firenze, Via Lastruccia 3, 50019 Sesto Fiorentino, FI, Italy

ABSTRACT: The malate dehydrogenase (MDH) and ascorbate oxidase were immobilized independently, onto silanized controlled porous silica and packed in a tygon tube. The reactors were inserted in the flow system, and the malic acid was determined by measurement of NADH produced by enzymatic reaction. The NADH was reoxidized in a wall jet cell that consisted of spectrographic graphite, Ag/AgCl, KCl_(sat), and steel needle as work, reference, and counter electrodes, respectively. The current intensities were measured at 390 mV. The malate calibration curve shows a linear range from 5.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol L⁻¹, the lifetime was 40 analyses, after that a decrease of 20% on the response is observed. Three different citric juices were analyzed and a good correlation between the proposed method and spectrophotometric commercial kit were obtained.

Analytical Letters, 37(9), 1823–1832, 2004

Abstract

JACK FRUIT‐CAPRIC ACID BIOSENSOR FOR TOTAL PHENOLS DETERMINATION IN WASTEWATERS by Karina Omuro Lupetti and Orlando Fatibello‐Filho, Departamento de Química, Universidade Federal de São Carlos, P.O. Box 676, 13560‐970, São Carlos‐SP, Brazil; and Iolanda Cruz Vieira, Departamento de Química, Universidade Federal de Santa Catarina, 88040‐900, Florianópolis‐SC, Brazil

ABSTRACT: A biosensor based on capric acid/graphite modified with crude extract of jack fruit (Artocarpus integrifolia L.) as the source of polyphenol oxidase (PPO) was developed for determining total phenols in wastewater samples using differential pulse voltammetry (DPV). This enzyme catalyzes the oxidation of phenols to o‐quinones in presence of oxygen and the electrochemical reduction of the product was obtained at a fixed potential of +0.18 V vs. Ag/AgCl (3.0 mol L⁻¹ KCl). The novelty of this biosensor was the application of fatty acids (capric (C₁₀), lauric (C₁₂), miristic (C₁₄), palmitic (C₁₆), stearic (C₁₈), and oleic (C₁₈) acids) as agglutinating agents. Capric acid was found to be the best agglutinating agent. A rectilinear analytical curve for catechol concentration from 5.25 × 10⁻⁶ to 7.80 × 10⁻⁴ mol L⁻¹ (r = 0.9982) with a detection limit of 2.00 × 10⁻⁷ mol L⁻¹ and the recovery of catechol from the sample ranging from 98% to 104% were obtained. The relative standard deviation was <3.0% for a solution of 2.50 × 10⁻³ mol L⁻¹ catechol in 0.1 mol L⁻¹ phosphate buffer solution, pH 7.0 (n = 10) and the results obtained for catechol in wastewater samples using the proposed DPV procedure are in agreement with those obtained using the APHA official methodology. The lifetime of this biosensor was 6 months (at least 300 determinations).

Analytical Letters, 37(9), 1833–1846, 2004

Abstract

ENGINEERED PQQ GLUCOSE DEHYDROGENASE‐BASED ENZYME SENSOR FOR CONTINUOUS GLUCOSE MONITORING by Junko Okuda, Junko Wakai, Satoshi Igarashi, and Koji Sode, Department of Biotechnology, Faculty of Technology, Tokyo University of Agriculture and Technology, 2‐04‐16 Naka Machi, Koganei, 184‐8588, Tokyo, Japan

ABSTRACT: Continuous glucose monitoring (CGM) is expected to become an ideal way to monitor the glycemic level of diabetic patients. A recent trend in the disposable self blood glucose sensing development has been the use of pyrroloquinoline quinone‐harboring glucose dehydrogenase (PQQGDH). However, due to a number of limitations of PQQGDH, conventionally utilized glucose oxidase (GOD) remains widely utilized in CGM. Two major problems that arose in the application of PQQGDH for CGM are the poor stability and its requirement for artificial electron acceptors for electrochemical measurement. To solve these problems, we investigated the amenability of our engineered PQQGDH Ser415Cys, which has a far superior thermal stability over the wild‐type enzyme, for the CGM system, and the applicability of cyt b ₅₆₂ as the electron mediator to construct a CGM system free of synthetic mediator. As a result, the operational stability of CGM system employing Ser415Cys co‐immobilized with cyt b ₅₆₂ was far superior to that of the wild‐type enzyme‐based electrode, with more than 60% of the initial response observed after 72 hr at 37°C. We achieved the successful application of PQQGDH in continuous operation without a significant decrease in the sensor signal.

Analytical Letters, 37(9), 1847–1857, 2004

Abstract

DETERMINATION OF ANTIOXIDANT ACTIVITY OF MARSHMALLOW FLOWER (ALTHAEA OFFICINALIS L.) by Mahfuz Elmastas, Isa Gokce, and Ramazan Erenler, Department of Chemistry, Faculty of Art and Science, University of Gaziosmanpasa, 60240, Tasliciftlik Campus Tokat, Turkey; Lokman Ozturk, Department of Biology, Faculty of Art and Science, University of Gaziosmanpasa, 60240, Tasliciftlik Campus, Tokat, Turkey; and Hassan Y. Aboul‐Enein, Pharmaceutical Analysis Laboratory, Biological and Medical Research (MBC 03‐65), King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia

ABSTRACT: The antioxidant properties of marshmallow (Althaea officinalis L., Fam. Malvaceae) ethanolic extract was evaluated using different antioxidant tests, including reducing power, free radical scavenging, superoxide anion radical scavenging, and metal chelating activities. The extract of marshmallow (A. officinalis L.) exhibited strong total antioxidant activity. The concentration of 50, 100, and 250 µg/mL of ethanol extract of marshmallow (A. officinalis L.) showed 85.5%, 91.2%, and 96.4% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, 100 µg/mL of standard antioxidant such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and α‐tocopherol exhibited 94.5%, 99.1%, and 80% inhibition on peroxidation of linoleic acid emulsion, respectively. The extract of marshmallow (A. officinalis L.) had effective reducing power, free radical scavenging, superoxide anion radical scavenging, and metal chelating activities at same concentration (50, 100, and 250 µg/mL). Those various antioxidant activities were compared with standard antioxidants such as BHA, BHT, and α‐tocopherol.

Analytical Letters, 37(9), 1859–1869, 2004

Abstract

THE INVESTIGATION OF β‐CYCLODEXTRIN NONCOVALENT COMPLEX WITH PROTEIN OR DIPEPTIDE BY ELECTROSPRAY IONIZATION MASS SPECTROMETRY by Shuxia Cao, Yuqian Su, Xiaoli Yang, Xiaolan Chen, and Yufen Zhao, Key Laboratory of Chemical Biology, Department of Chemistry, Zhengzhou University, Zhengzhou, 450052, P.R. China; and Yufen Zhao, Key Laboratory for Bioorganic Phosphorus Chemistry of Ministry of Education, Department of Chemistry School of Life Sciences and Engineering, Tsinghua University, Beijing 100084, P.R. China

ABSTRACT: Electrospray ionization ion trap mass spectrometry was used for the investigation of noncovalent complexes formed between β‐cyclodextrin (CD) and protein or dipeptide in aqueous solution. After one of those noncovalent complexes has formed, it was found that addition of the other ligand compound would produce the competitive noncovalent complexes. Measurements were obtained with four proteins, such as hen egg lysozyme, cytochrome c, insulin and RNase A, and three dipeptides, respectively. The data obtained from the investigated systems show that ESI‐MS is not only a reliable, sensitive, and fast technique for the analysis of the β‐CD/protein and β‐CD/dipeptide complexes, but also an interesting tool to observe the transformation from one complex to the other in aqueous solution.

Analytical Letters, 37(9), 1871–1883, 2004

Abstract

FLUORESCENCE STUDY OF THE INTERACTION BETWEEN A MODIFIED β‐CYCLODEXTRIN AND METACYCLINE–Eu³⁺ AND ITS ANALYTICAL APPLICATION by Chongqiu Jiang and Faju Hou, Department of Chemistry, Shandong Normal University, Jinan, 250014, China

ABSTRACT: A simple sensitive spectrofluorimetric method was developed for the determination of metacycline. Ethyl substituted β‐cyclodextrin (DE‐β‐CD) can remarkably enhance the fluorescence intensity of the metacycline (MC)–Eu³⁺ complex at λ = 612 nm and the enhanced fluorescence intensity of Eu³⁺ ion is in proportion to the concentration of MC. Optimum conditions for the determination of MC were also investigated. The linear range and the detection limit of this method for the determination of MC are 2.20 × 10⁻⁷–1.47 × 10⁻⁵ mol/L and 3.60 × 10⁻⁸ mol/L, respectively. The recommended method is practical and relatively free interference from coexisting substances and can be successfully applied to determination of MC in samples of serum and urine. The interaction mechanism between the complex MC–Eu³⁺ and DE‐β‐CD has been studied. The enhancement of the fluorescence at λ_em = 612 nm of Eu³⁺ ion is because of the inclusion complex MC–Eu³⁺–DE‐β‐CD.

Analytical Letters, 37(9), 1885–1895, 2004

Abstract

STUDY OF THE INTERACTION OF SOME STEROIDAL DRUGS WITH CYCLODEXTRIN DERIVATIVES by Esther Forgács and Tibor Cserháti, Institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, P.O. Box 17, H‐1525 Budapest, Hungary

ABSTRACT: Spectral mapping (SPM) technique has been employed for the separation of the strength and selectivity of interaction among 13 steroidal drugs and 7 different cyclodextrins (CDs) or CD derivatives. The potency values were considered as the best indicators of the capacity of drugs and CDs to interact with each other. Both drugs and CDs show marked differences in their capacity to form inclusion complexes. Because of the larger diameter of the cavity τ‐CDs showed higher interactive forces than β‐CD derivatives did. Substituents on the CD ring also modified the strength and selectivity of interaction. Stepwise regression analysis proved that the electron withdrawing power of substituents exerted the highest impact on both strength and selectivity of interaction. The data suggest that the interaction between steroidal drugs and CDs depends on the sterical correspondence between the dimensions of the CD cavity and the bulky ring structure of drugs and on the polar interactions between the hydrophilic substituents of drugs pointing outward from the CD cavity and the polar hydroxyl groups in the outer sphere of CD molecules.

Analytical Letters, 37(9), 1897–1908, 2004

Abstract

DETERMINATION OF TRACE METALS IN FUEL ALCOHOL BY FAAS USING Nb₂O₅–SiO₂ AS SORBENT MATERIAL IN A FLOW INJECTION ON‐LINE PRECONCENTRATION SYSTEM by Edson Luiz da Silva, Dilma Budziak, and Eduardo Carasek, Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, 88040‐900, Brazil

ABSTRACT: This paper describes an on‐line preconcentration system for the determination of copper(II), cadmium(II), cobalt(II), and zinc(II) in samples of fuel alcohol. The analytes were enriched in a minicolumn containing with silica gel chemically modified with niobium(V) oxide (Nb₂O₅–SiO₂). The metals were desorbed from the minicolumn with a solution of nitric acid and determined on‐line by flame atomic absorption spectrometry (FAAS). Enrichment factors for copper(II), cadmium(II), cobalt(II), and zinc(II) were 21.3, 23.1, 16.6, and 27.5, respectively, using a preconcentration time of 2 min. Detection limits for copper(II), cadmium(II), cobalt(II), and zinc(II) were 1.4, 0.2, 1.4, and 1.0 µg L⁻¹, respectively. Method precision was evaluated by analyzing an alcoholic solution containing 30 µg L⁻¹ of Cu(II), 15 µg L⁻¹ of Cd(II), 45 µg L⁻¹ of Co(II), and 15 µg L⁻¹ of Zn(II), and their respective relative standard deviation (RSD) were 1.3%, 4.2%, 1.7%, and 1.7% (n = 7). The accuracy of the method was assessed by testing analyte recovery in the fuel alcohol samples.

Analytical Letters, 37(9), 1909–1924, 2004

Abstract

MICROWAVE AND WET DIGESTION PROCEDURES FOR ATOMIC ABSORPTION SPECTROMETRIC DETERMINATION OF TRACE METALS CONTENTS OF SEDIMENT SAMPLES by Mustafa Tuzen and Hayati Sari, Chemistry Department, Faculty of Science and Arts, Gaziosmanpasa University, 60250 Tokat, Turkey and Mustafa Soylak, Department of Chemistry, Faculty of Art and Science, Erciyes University, 38039 Kayseri, Turkey

ABSTRACT: The comparison of wet digestion and microwave digestion of Cd, Co, Cr, Cu, Mn, Pb, Zn, Fe, and Ni contents of the river bottom and sea floor sediments from the various locations of Turkey was performed in the present work. After digestions, the heavy metal concentrations were determined by flame atomic absorption spectrometry (FAAS). The heating programs for microwave digestion, different combinations, and volumes of acid mixtures were evaluated for microwave digestion efficiency. The studies in the present work show that the microwave‐assisted digestions in closed system are easier and faster than the wet digestion. Also the results found by the microwave and the wet digestions were reliable and accurate. The procedures were also checked with two‐stream sediment reference material (GBW 07309 and GBW 07310). Results for standard reference material (SRM) were in good agreement with certified values. The relative standard deviations for all metal concentrations were found to be lower than 10%.

Analytical Letters, 37(9), 1925–1936, 2004

Abstract

EVALUATION OF SYRINGE‐CONNECTED MINICOLUMN TECHNIQUE FOR PRECONCENTRATION OF SOME TRACE ELEMENTS USING CHROMOSORB‐103 AND DETERMINATION BY FLAME ATOMIC ABSORPTION SPECTROMETRY by Yasemin Bakircioglu and Dilek Bakircioglu, Department of Chemistry, Faculty of Art and Science, Trakya University, 22030 Edirne, Turkey and Suleyman Akman, Department of Chemistry, Faculty of Art and Science, Istanbul Technical University, 34469 Maslak Istanbul, Turkey

ABSTRACT: A syringe‐connected minicolumn (SCM) technique has been developed for preconcentration and enrichment of cobalt, iron, and lead in river‐water samples prior to their determination by flame atomic absorption spectrometry (FAAS). The proposed technique is substituted for the classical batch and column techniques all of which are off‐line methods. The method proposed was compared with the column technique with respect to easiness, rapidness, simplicity and some analytic performances such as recovery, precision, accuracy and risk of contamination. The minicolumn was filled with Chromosorb‐103 as a sorbent. In order to retain the analyte elements, the sample solution was drawn into the syringe and discharged back passing through the sorbent in the minicolumn. The analyte elements were quantitatively retained at pH ≥4 if they were complexed with ammonium pyrrolidine dithiocarbamate (APDC) prior to passing through to the sorbent. The analytes sorbed on the minicolumn was then eluted with 1.0 mol L⁻¹ HNO₃ in acetone again drawing and discharging the eluent. Optimum flow rates of sample or eluent for sorption and elution procedure were 20 mL min⁻¹ for both drawing and discharging cases. The proposed technique was successfully applied to the determination of analytes in certified reference material and spiked river‐water samples. The recoveries of analytes from certified reference material (Bovine liver) and river‐water samples were quantitative and reproducible (>96%, with relative standard deviation (RSD) of 1–5%). The developed technique is simple, fast, and accurate. Detection limits (3σ) were 4.8 µg L⁻¹ for Co, 14 µg L⁻¹ for Fe, and 15 µg L⁻¹ for Pb. Very high preconcentration factors up to 200‐fold could be achieved.

Analytical Letters, 37(9), 1937–1952, 2004

Abstract

SIMPLE AND SELECTIVE METHOD FOR DETERMINATION OF PLATINUM WITH TIN(II) CHLORIDE AND AMIDES by Khageshwar Singh Patel, Kamlesh Shrivash, and Paresh Chandra Sharma, School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur 492010, Chattisgarh, India; Madhurama Pandey, Department of Chemistry, Bhilai Institute of Technology, Durg, Chattisgarh, India; and Peter Hoffmann, Technische Universität Darmstadt, Material‐ und Geowissenschaften Chemische Analytik, Petersenstr. 23, D‐64287 Darmstadt, Germany

ABSTRACT: A new, simple, and selective method for rapid spectrophotometric determination of Pt is described. It is based on extraction of Pt(II)–SnCl₃ ⁻ complex with chloroform (CF) solution of amide, i.e., N‐alkylacetamide (alkyl = butyl to octyl). The value of apparent molar absorptivity of the complex (with four N‐alkylacetamides) lie in the range of (3.40–3.50) × 10⁴ L mol⁻¹ cm⁻¹ at λ_max 400–405 nm. The most sensitive compound, i.e., N‐butylacetamide (BAA) has been selected for the detailed studies. The detection limit (absorbance 0.007 more than thrice of standard deviation of the method) of the method is 40 ppb Pt. The types of the halide and amide in the extraction as well as spectral characteristics of the complex are discussed. The reaction mechanism involved in the extraction of the metal is described. The optimization of analytical variables for the determination of Pt is carried out. The method has been applied for the determination of Pt in the catalytic materials.

Analytical Letters, 37(9), 1953–1963, 2004

Abstract

ANALYTICAL STUDY OF AN ENVIRONMENTALLY HAZARDOUS ELEMENT, ARSENIC, BY INDIRECT SPECTROFLUORIMETRIC METHOD IN DIVERSE FIELDS by Suchandra Biswas, Bhaskar Chowdhury, and Bidhan Chandra Ray, Department of Chemistry, Jadavpur University, Calcutta 700 032, India

ABSTRACT: An inexpensive and virtually specific non‐extractive method for the determination of arsenic(III) at trace and ultra trace levels (5 ng mL⁻¹–1 µg mL⁻¹) in 0.09–0.45 (M) sulphuric acid has been developed. The method is based on the quantitative oxidation of arsenic(III) by chromium(VI) in the presence of iodine as catalyst. A known excess of chromium(VI) was taken and after oxidation of arsenic (III) the leftover chromium(VI) quantitatively quenches the fluorescence developed by murexide in acid medium. Measurement of the fluorescence intensity was carried out at 424 nm with excitation at 336 nm. The measurement is repeated without arsenic(III) addition and the increase in fluorescence intensity gives arsenic(III) concentration with the help of a calibration graph. The method is very precise and accurate [S.D = ± 0.71 and R.S.D = 0.71% for the determination of 0.1 µg mL⁻¹ of arsenic(III) in 11 replicates]. Relatively large excesses of over 35 cations and anions do not interfere. The method has been successfully applied for arsenic determination in various complex matrices, certified reference materials (alloys), and environmental and biological samples.

Analytical Letters, 37(9), 1965–1979, 2004

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DIRECT CHROMATOGRAPHIC METHOD FOR DETERMINATION OF HYDROGEN CYANAMIDE AND DICYANDIAMIDE IN AQUEOUS SOLUTIONS by Maciej Turowski and Balasaheb Deshmukh, The Dow Chemical Company, Analytical Sciences, 897 Building, Midland, MI 48667, USA

ABSTRACT: A simple high‐performance liquid chromatographic method to separate and determine hydrogen cyanamide and dicyandiamide was developed. A reversed‐phase chromatographic system consisted of 100% purified water as a mobile phase and highly hydrophobic triacontyl (C30) stationary phase used at ambient temperature with UV detection at 200 nm. The linearity was very high (R > 0.999) for both analytes, in the range of 500 ppb to 5000 ppm for cyanamide and 100 ppb to 100 ppm for dicyandiamide. Immediate formation of dicyandiamide was observed when dissolving pure cyanamide in water. Sample solvent appeared very important for successful component separation, as its variation may cause peak deterioration and loss of the stationary phase selectivity. The chromatographic procedure can also be employed to detect urea in the presence of cyanamide and dicyandiamide.

Analytical Letters, 37(9), 1981–1989, 2004

Abstract

DETERMINATION OF THIOCYANATE IN WASTE WATER by Aditya Shukla, Pradeep Agnihotri, and Khageshwar Singh Patel, School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur 492010, Chattisgarh, India and Peter Hoffmann, Technische Universität Darmstadt, Material‐ und Geowissenschaften, Chemische Analytik, Petersenstr. 23, D‐64287 Darmstadt, Germany

ABSTRACT: The present work proposes a new, simple, selective, and sensitive method for the on‐site spectrophotometric determination of SCN⁻ ions in the industrial and municipal waste water. The method is based on color reaction of SCN⁻ ions with V(V) and chelating agent: N‐hydroxy‐N,N′‐diphenylbenzamidine (HODPBA), and subsequent extraction of the deep green colored complex into chloroform. The value of apparent molar absorptivity (at enrichment factor of 5) is 7.00 × 10³ L mol⁻¹ cm⁻¹ at λ_max = 610 nm. The calibration curve is linear up to 5.0 µg mL⁻¹ SCN⁻ with slope, intercept, and correlation coefficient of 8.3, −0.008, and +0.99, respectively. The detection limit (an absorbance identical to blank absorbance +3s) of the method is 66 ng mL¹ SCN⁻ of the aqueous solution. Most of the ions associated did not interfere in the determination of SCN⁻. Only phenol interfered in the determination of SCN⁻, and could be removed by the prior extraction with chloroform solution. The method has been used for analysis of SCN⁻ in industrial and municipal waste water samples.

Analytical Letters, 37(9), 1905–2005, 2004