Pyrene-appended α-cyclodextrin (3) in which a trimethylenediamine linker connected the pyrene residue to the α-cyclodextrin moiety showed pH-dependent fluorescence intensity changes. The fluorescence intensity was almost linearly changed within the pH range of 5 - 10. The unique fluorescence response of 3 to the pH was due not only to the favorable pKa values (pKa1 = 6.4 and pKa2 = 8.8), but also to the almost equal contributions of the amino groups to the pyrene's fluorescence quenching.
New fluorescent ionophores containing the 1-naphthylacetanilide moiety based on oligo-ethylene oxide (14 and 15) have been synthesized, and their photochemical behaviors have been studied. In the absence of a metal ion, the 1-naphthylacetanilide moiety showed a weak fluorescence emission (fluorescence “off state”). However, complexation with Ca2+ induced a large enhancement effect on the fluorescence intensity of 14 and 15 from the naphthalene ring (fluorescence “on” state). This behavior can be explained in terms of a similar twisted intramolecular charge-transfer relaxation mechanism. Such “off-on” fluorescence responses of 14 and 15 provide the digital detection of alkaline earth metal ions.
A novel electrochemical biosensor was developed to detect gene mutation by using a DNA-mismatch binding protein: MutS from Escherichia coli. The MutS protein was immobilized onto an Au-electrode surface via complex formation between a histidine tag of the MutS protein and a thiol-modified nitrilotriacetic acid chemically adsorbed on the Au-electrode surface. When a target double-stranded DNA having a single-base mismatch was captured by the MutS protein on the electrode, some electrostatic repulsion arose between polyanionic DNA strands and anionic redox couple ions. Consequently, their redox peak currents on a cyclic voltammogram with the Au electrode drastically decreased, depending on the concentration of the target DNA, according to the redox couple-mediated artificial ion-channel principle. By using this assay, one can detect all types of single-base mismatch and single-base deletion.
Ion transfer across the polarized interface between a room-temperature ionic liquid (RTIL) or room-temperature molten salt, tetrahexylammonium bis(trifluoromethylsulfonyl)imide (THAC1C1N), and water has been studied voltammetrically using a micro liquid-liquid interface formed at the orifice of a glass capillary micropipette. A small current of nanoampere level circumvents the problem of the iR drop in the viscous ionic liquid phase. Voltammograms for the transfer of moderately hydrophilic ions, such as BF4- and ClO4-, from the aqueous phase in the capillary to the bulk of THAC1C1N in which the capillary is submerged, show steady-state characteristics in that the current does not depend on the scan rate up to a few hundred millivolt per second, and the plateau in the limiting current region is proportional to the bulk concentration of analyte ions. Owing to the steady-state current, which is presumably ascribed to a noncylindrical geometry of the capillary tip, the relative magnitude of the hydrophobicity, or the affnity to the RTIL, of a series of ions can be determined from the half-wave potentials of voltammograms.
A new sulfate-selective electrode based on the complex N,N′-bis(2-amino-1-oxo-phenelenyl)phenylenediamine copper(II) (CuL) as the membrane carrier was developed. The electrode exhibited a good Nernstian slope of -29.5 ± 0.5 mV/decade and a linear range of 1.0 × 10-7 - 1.0 × 10-1 M for sulfate. The limit of detection was 1.0 × 10-8 M. It has a fast response time of 10 s and can be used for more than three months. The selective coefficients were determined by the fixed interference method (FIM). The electrode could be used in the pH range 3.5 - 8.0. It was employed as an indicator electrode for direct determination of sulfate in pharmacy and cement samples.
Gold ultra-microelectrode arrays are used to explore the electrochemical oxidation of hydroxide ions and are shown to be analytical useful. Two types of ultra-microelectrode arrays are used; the first consist of 256 individual electrodes of 5 µm in radius, 170 of which are electrochemically active in a cubic arrangement which are separated from their nearest neighbour by a distance of 100 µm. The second array compromises 2597 electrodes of 2.5 µm in radius and of which 1550 of which are electrochemically active in a hexagonal arrangement separated by the nearest neighbour by 55 µm. Well defined voltammetric waves are found with peak currents proportional to the concentration of hydroxide ions in the range 50 µM to 1 mM. Detection limits of 20 µM using the 170 ultra-microelectrode and 10 µM with the 1550 ultra-microelectrode array are shown to be possible but with a higher sensitivity of 4 mA M-1 observed using the 1550 ultra-microelectrode array compared to 1.2 mA M-1 with the 170 ultra-microelectrode array.
The electrochemical behavior of gatifloxacin (GTFX) and its interaction with natural calf thymus DNA (ctDNA) is investigated by differential pulse voltammetry (DPV) on a carbon paraffined electrode. According to the suggested electrochemical equation, a binding constant of 1.7058 × 105 (mol L-1)-1 and binding sizes s = 3.09 (base pairs) of GTFX with ctDNA are obtained by nonlinear fit analysis of electrochemical data. The results demonstrate that GTFX has the properties of an intercalative binder.
A novel voltammetric method for the determination of microamounts of fish sperm double-stranded (ds) DNA based on its interaction with phenosafranine (PSF) is proposed in this paper. In a pH 3.5 Britton-Robinson (B-R) buffer solution, PSF had a well-defined second-order derivative linear-sweep voltammetric reductive peak at -0.32 V (vs. SCE) on a mercury electrode. After the addition of dsDNA into the PSF solution, the reductive peak current decreased significantly without a shift of the peak potential, and no new peak appeared. The experiment results showed that a new supramolecular complex was formed after the interaction of dsDNA with PSF, which resulted in a decrease of the diffusion coefficient, and then a decrease of the reductive peak current. The interaction conditions and the electrochemical detection conditions were carefully investigated. Under the optimal conditions, the decrease of the peak current was proportional to the dsDNA concentration in the range 1.0 - 40.0 µg/mL with the linear regression equation ΔIp″(nA) = 32.59C(µg/mL) - 4.03 (n = 13, γ = 0.998) and a detection limit of 0.25 µg/mL (3 σ). The interaction mechanism was considered based on the aggregation of the dsDNA-PSF supramolecular complex; the stoichiometry of this supramolecular complex was calculated based on voltammetric data with a binding number of 3 and a binding constant of 2.76 × 1012. This method was successfully applied to the determination of synthetic samples and the polymerase chain reaction (PCR) product of the nopaline synthase gene (NOS) DNA from genetically modified organisms (GMOs) with satisfactory results.
Choline can be covalently grafted on glassy carbon electrodes using cyclic voltammetric method, forming a stable cationic monolayer-modified electrode (Ch/GCE). Keggin-type molybdophosphate anions, α-PMo12O403-, then were self-assembled on the Ch/GCE through electrostatic interactions for fabrication of an electrochemical sensor, which is denoted as α-PMo12/Ch/GCE. This two-layer modified electrode was carefully characterized by cyclic voltammetry and X-ray photoelectron spectroscopy. It was found that the sensor exhibits strong electrocatalytic activity and sensitivity toward the reduction of IO3-. The content of IO3- in a table salt was determined with satisfactory results. The sensor is promising as an electrochemical sensor for the detection of IO3-.
This paper presents a novel Hadamard transform (HT) fluorescence imaging microscope by combining multiplexed imaging technique with a conventional upright fluorescence microscope for single-cell imaging and quantitative cellular analysis. The HT imaging microscope can provide 511 × 512-pixel single-cell image with high sensitivity within 21 s. In this study, the high potential value of the microscope in biomedical analysis has been demonstrated by using it to evaluate the malignancy degree of thirty cases of human breast tumors based on the measurements of cellular DNA contents, with conclusions highly accordant with pathological diagnosis. The results show that the HT microscope has the ability to analyze very small specimens and the capability of detecting very high ploidy cells, which are advantages over flow cytometry. The microscope was also successfully applied to cellular morphological analysis, and it was demonstrated that a significant linear relationship exists between tumor nuclear DNA contents and the nuclear area, and malignant and benign tumors are significantly different in both DNA contents and nuclear area. The reliability of the HT microscope in cellular DNA measurements was also investigated.
The solid-phase extraction (SPE) method for the preconcentration of trace amounts of cadmium using synthetic zeolite A-4 and its determination by graphite furnace atomic absorption spectrometry (GFAAS) was investigated. The preconcentration conditions, such as the optimum pH range of the sample solution for the adsorption of cadmium and the kind of acid solution for dissolving the cadmium-adsorbed synthetic zeolite A-4, as well as the measurement conditions for the determination of cadmium by GFAAS, e.g., the ashing and atomizing temperature, were investigated. Quantitative recovery of cadmium onto zeolite A-4 from the sample solution over the pH range 2.0 - 9.0 was achieved by the batch method. After the solid-phase (cadmium-adsorbed zeolite A-4) was separated from the sample solution by a membrane filter, it was dissolved in 2.0 cm3 of 2.0 mol dm-3 nitric acid. An aliquot of the resulting solution was injected into the graphite furnace. In GFAAS measurements an alternate gas (Ar, 90%; O2, 10%) was used as a sheath gas, and the ashing temperature and atomizing temperature were 400°C and 1600°C, respectively. The detection limit (3 σ) for cadmium was 0.002 µg dm-3. The relative standard deviation at 0.010 µg dm-3 was 3.5 - 4.5% (n = 5). The proposed method has been successfully applied to the analysis of trace cadmium in environmental water samples.
In single-column anion-exchange chromatography, the retention volume of some monovalent inorganic anions (Cl-, Br-, NO3-, NCS- and NO2-) were observed as a function of the pH of a mobile phase at a fixed concentration of 2-phenylmalonic acid or 1,4-benzenediacetic acid used as an eluent. The experimental retention volume of such an anion was decreased with an increase in the pH of a mobile phase, and was able to be described by the following equation taking account of anion-exchange equilibria of a sample anion with a hydrogen dicarboxylate ion (HE-) and with a dicarboxylate ion (E2-): α1s/VR′[HE-] = 1/mTwKex1 + (2Ka2/mTw2Kex2)(VR′/α1s[H+]), where VR′, mT, w, Ka2, Kex1 and Kex2 are the adjusted retention volume of a given sample anion, the capacity for the anion-exchange of column packings and the weight of column packings packed into a separating column, the second acid-dissociation constant of the dicarboxylic acid used as an eluent, and equilibrium constants for the anion exchange of a sample anion with a monovalent hydrogen dicarboxylate ion and with a divalent dicarboxylate ion, respectively. The term α1s, defined as Kas/([H+] + Kas), where Kas is the acid-dissociation constant of HX, is the mole fraction of a sample anion, X-, and is equal to 1 when using a strong acid anion as a sample anion.
It is generally supposed that the preconcentration procedure is used for the determination of metal concentrations under the sensitivity of the measurement method. This study showed that preconcentration is also need for the beryllium (Be) concentration over the sensitivity of atomic absorption spectrometry. For this purpose, a simple and selective method for the determination of Be in solid samples is modified. The method is based on the preconcentration of the complexes of beryllium-acetylacetone plus morin, oxine, PAN and PAR on activated carbon at different pH values. The adsorbed beryllium was eluted with aqua regia and measured by flame atomic absorption spectrometry (FAAS). Recoveries of up to 85% were achieved. For removing chemical interferences and applying the method to Be determination in solid samples, the masking studies and reproducibility were examined. The detection limit was found to be 0.12 ng mL-1. The relative sandard deviations (RSD) were found to be 8% for 60 mL of 10.0 ng mL-1 using 10 replicate enrichment procedures. Beryllium concentrations in the studied solid samples were found in the range of 0.28 - 3.95 mg kg-1.
Using freshly precipitated manganese-diethyldithiocarbamate (Mn(DDTC)2) as a new reagent, a solid phase extraction method (SPE) has been developed for the extraction of Cd(II) and Zn(II) in aqueous fertilizer samples. A sample solution of 300 mL was taken and 0.10 g of freshly precipitated Mn(DDTC)2 was added. After adding a phosphate buffer solution, the mixture was stirred at 10 min, filtered with a glass filter and washed with deionized water. The solid product containing Mn(DDTC)2-Cd(DDTC)2-Zn(DDTC)2 complexes was dissolved in concentrated nitric acid and its volume was made complete up to 10 mL with deionized water. The metal contents of the solution were measured by an atomic-absorption spectrometer.
A method for direct determination of cadmium, chromium, copper and lead in sediments and soil samples by electrothermal atomic absorption spectrometry using Zr, Ir, etylenediamine acetic acid (EDTA), Zr + EDTA, Ir + EDTA, Zr + Ir and Zr + Ir + EDTA as chemical modifiers in 0.5% (v/v) Triton X-100 plus 0.2% (v/v) nitric acid mixture used as diluent was developed. The effects of mass and mass ratio of modifiers on analytes in sample solutions were studied. The optimum masses and mass ratios of modifiers: 20 µg of Zr, 4 µg of Ir, 100 µg of EDTA and 20 µg of Zr + 4 µg of Ir + 100 µg of EDTA, were used to enhance the analyte signals. Pyrolysis and atomization temperatures, atomization and background absorption profiles, characteristic masses, and detection limits of analytes in samples were compared in the presence or absence of a modifier. The detection limits and characteristic masses of analytes in a 0.5% (m/v) dissolved sample (dilution factor of 200 ml g-1) obtained with Zr + Ir + EDTA are 8.0 ng g-1 and 1.2 pg for Cd, 61 ng g-1 and 4.3 pg for Cr, 32 ng g-1 and 23 pg for Cu, and 3.4 ng g-1 and 19 pg for Pb, respectively. The Zr + Ir + EDTA modifier mixture was found to be preferable for the determination of analytes in sediment and soil-certified and standard reference materials. Depending on the sample type, the percent recoveries of analytes were increased from 81 to 103% by using the proposed modifier mixture; the results obtained are in good agreement with the certified values.
The effect of the surface charge density of heptakis-6-bromo-6-deoxy-β-cyclodextrin (β-CD-BR) bonded silica gels, which was used as the stationary phase of a packed capillary column for HPLC, was investigated concerning the retention behaviors of neutral cresol isomers. On the whole, the retention factors of the cresol isomers increased with an increase in the pH values of the mobile phase, although they were slightly smaller at pH 6.1 than at pH 4.7. An investigation on the retention variation using a van't Hoff plot revealed that the increase in the retention factor (k) at a higher pH region could be mainly attributed to the increase in ΔS, while a partial decrease in k around pH 5 - 6 was caused by a decrease in the -ΔH/T value. On the other hand, a measurement of the electroosmotic flow velocity under various pH of the mobile phase solutions revealed that the retention variations of the neutral cresol isomers were strongly correlated with the surface charge on the packing materials. The positive charge of secondary ammonium functional groups to bind β-CD-BR inhibit the insertion of the cresol isomers into the cavity of β-CD-BR while reducing the retention factor, whereas the negative charge of silanol group enhanced it through a local change in the mobile phase composition.
A simple and sensitive high-performance thin-layer chromatography (HPTLC) method has been developed for the quantitative estimation of gatifloxacin and ornidazole in its combined dosage forms. Gatifloxacin and ornidazole were chromatographed on silica Gel 60 F254 TLC plate using n-butanol:methanol:ammonia (6 M) (8:1:1.5 v/v) as the mobile phase and scanned at 302 nm using a Camag TLC Scanner 3. The Rf value of gatifloxacin and ornidazole was found to be 0.21 ± 0.02 and 0.76 ± 0.04, respectively. The linearity of gatifloxacin and ornidazole were in the range of 100 - 500 ng/spot and 250 - 1250 ng/spot, respectively. The limit of detection was found to be 40 ng/spot for gatifloxacin and 100 ng/spot for ornidazole. The proposed method was applied for the determination of gatifloxacin and ornidazole in combined dosage forms.
The investigation on capillary electrophoretic enantioseparation of six synthetic compounds containing vicinal diol groups has been undertaken to acquire the optimum conditions using native β-cyclodextrin (β-CD) as chiral selector and borate as a background electrolyte. The separation was carried out in an uncoated capillary (58.5 cm × 75 µm i.d., effective length 48.5 cm) and the effects of several important factors were investigated in detail. The results showed that β-CD as a chiral selector exhibited good enantioselectivity and that the enantioseparation was greatly influenced by the structure of the diols, the borate concentration and the buffer pH. The optimum performance was obtained for the chiral vicinal diols under the conditions of 200 mM borate buffer of pH 9.8 containing 1.7% β-CD at an applied voltage of 15 kV and a capillary temperature of 20°C. Under the conditions, four diols were baseline separated with fast analysis time and the good theoretical plate numbers (above 10 × 104) and favorable migration-time reproducibilities (RSDs below 3.0%) were obtained. The separation results were satisfactory.
The kinetics of streptomycin degradation by hydrogen peroxide at pH 7.4 was investigated. The reaction was catalyzed by traces of Cu(II) ions, and it was followed spectrophotometrically at 322 nm by applying the initial-rate method. The kinetic parameters of the reaction are reported, and a rate equation is suggested. From the dependence of the relative rate constants on the temperature, the activation energy was calculated to be 57.5 kJ/mol. Based on this reaction, a kinetic method for streptomycin determination is proposed. The calibration graph is linear in the ranges 1.94 - 15.48 µg/cm3 and 0.15 - 1.94 µg/cm3. The influence of foreign ions and molecules on the accuracy of the determinations was investigated. The proposed kinetic method has high selectivity and good sensitivity, and enabled to determine streptomycin in pharmaceutical samples.
The proposed work describes a simple spectrophotmetric as well as a titrimetric method to determine sulfur dioxide. The spectrophotometric method is based on a redox reaction between sulfur dioxide and iodine monochloride obtained from iodine with chloramine-T in acetic acid. The reagent iodine monochloride oxidizes sulfur dioxide to sulfate, thereby reducing itself to iodine. Thus liberated iodine will also oxidize sulfur dioxide and reduce itself to iodide. The obtained iodide is expected to combine with iodine to form a brown-colored homoatomictriiodide anion (460 nm), which forms an ion-pair with the sulfonamide cation, providing exceptional color stability to the system under an acidic condition, and is quantitatively relatd to sulfur dioxide. The system obeys Beer's law in the range 5 - 100 µg of sulfur dioxide in a final volume of 10 ml. The molar absorptivity is 5.03 × 103 l mol-1cm-1, with a relative standard deviation of 3.2% for 50 µg of sulfur dioxide (n = 10). In the titrimetric method, the reagent iodine monochloride was reduced with potassium iodide (10%) to iodine, which oxidized sulfur dioxide to sulfate, and excess iodine was determined with a thiosulfate solution. The volume difference of thiosulfate with the reagent and with the sulfur dioxide determined the sulfur dioxide. Reproducible and accurate results were obtained in the range of 0.1 - 1.5 mg of sulfur dioxide with a relative standard deviation of 1.2% for 0.8 mg of sulfur dioxide (n = 10).
Through the flow injection analysis experiments, we discovered that an unsaturated complex of Cu(II) and polyamines (spermine, spermidine, putrescine) had a strongly catalytic effect on luminol-H2O2 chemiluminescence (CL) reaction, and that the CL intensity is proportional to the concentrations of polyamines. Based on the automatic formation of an unsaturated complex of polyamines and Cu(II) when the solution containing polyamines passed through a column packed with solid Cu(OH)2, a new flow injection chemiluminescence analysis method was proposed for the determination of polyamines. The effects of pH, buffer concentration, the concentration of chemiluminescence reagent, and the influence of mixing coil length were examined. Under optimal conditions, the linear range was from 1.0 × 10-7 mol L-1 to 1.0 × 10-5 mol L-1, and the detection limits were 0.17, 0.38, 0.44 pmol for spermine, spermidine, and putrescine, respectively. Compared with other methods, the advantages of this method include convenience, time-saving and low cost.
A method for detecting and identifying cationic surfactant in some chemical samples for daily use that include Head & Shoulder Ampoule and Slek Shower Lotion has been developed. In an acid medium, chromium(VI) oxidizes I- to produce I2, I2 binds excess of I- to form I3-, and I3- can further react with a cationic surfactant (CS) (such as cetyldimethyl benzylammonium chloride (CDBAC), Zephiramine (Zeph), cetylpyridinium bromide (CPB), tetradecyl pyridinium bromide (TPB) and cetyltrimethylammonium bromide (CTAB)) to form ion-association complexes [CS][I3]. This results in a significant enhancement of resonance Rayleigh scattering (RRS) and appearance of new RRS spectra. The RRS spectral characteristics of the ion-association complexes, the influencing factors and the optimum conditions of the reactions have been investigated. The intensities of RRS are directly proportional to the concentration of CS. CS in samples are collected using a treated anion exchange column and subsequently complexed by I3-; then the RRS intensities of CS complex are determined at 495 nm. The reactions have high sensitivities, and their detection limits are 7.05 - 9.62 ng/mL for different CS. The effects of foreign substances are investigated and the results show that the method has good selectivity.
The nano-Ag-terbium(III)-mucleic acids system was observed by a resonance light scattering (RLS) technique for the first time, and the quantitative analysis of nucleic acids at nanogram levels was established. Studies showed that the RLS intensity of the nano-Ag-terbium(III) system can be obviously enhanced by nucleic acid, which was characterized by the RLS spectrum and the UV-Vis spectrum. In this system, the nanoparticles were only of a definite size and in a limited particle concentration region. Further research indicated that under the optimum conditions, the enhanced intensity of RLS is in proportion to the concentration of nucleic acids in the ranges of 7.0 × 10-9 g ml-1 to 8.0 × 10-6 g ml-1 for calf thymus DNA (ctDNA), 2.0 × 10-8 g ml-1 to 1.0 × 10-6 g ml-1 for fish sperm DNA (fsDNA) and 1.0 × 10-9 g ml-1 to 1.0 × 10-7 g ml-1 for yeast RNA (yRNA). The detection limits were 1.4 ng ml-1 for ctDNA, 1.2 ng ml-1 for fsDNA and 0.85 ng ml-1 for yRNA, respectively. Synthetic and real samples were determined satisfactorily.
A detection and fixation method of single and multiple gold nanoparticles on the wall of a microfluidic channel is demonstrated. A thermal lens microscope (TLM) with continuous-wave excitation (wavelength, 532 nm) and probe (wavelength, 670 nm) laser beams was used to realize the sensitive detection of heat generated by light absorption of individual gold nanoparticles (50 nm in diameter); fixation of the individual nanoparticles was realized simultaneously. The fixation mechanism was investigated and attributed to an absorption-based optical force. In addition to single nanoparticle detection, multiple-nanoparticle detection and fixation was demonstrated. An acceleration of fixation was observed when the number of fixed particles was increased. TLM is expected to be a powerful tool for both the quantitative detection and precise fixation of individual nanoparticles.
The potential of alkylammonium ion-bonded silica stationary phases for effective and simple pretreatment for determination of polychlorinated biphenyls (PCBs) in mineral oil samples is presented in this paper. The separation between PCBs and aliphatic hydrocarbons by normal phase chromatography was improved by using the alkylammonium ion-bonded silica stationary phases instead of alkylamine-bonded silica or other polar stationary phases. The number of alkyl residues bonded to the nitrogen atom was also an important factor of the separation.
We have already developed a HCHO monitoring system which is called FP-30. In this experiment, we have developed a NO2 detection tablet which can be used by the monitoring system. The detection tablet for the NO2 was constructed with the sensing paper: porous cellulose paper that contains silica gel as an adsorbent, N-1-naphthylethylenediamine dihydrochloride (NED), and glycerin. The NO2 in sample gas was blown over and adsorbed on the surface of the sensing paper. Then the NO2 reacted with NED, producing a yellow compound. The coloring reaction took place on the surface of the sensing paper. The degree of color change of paper from white to yellow was monitored as a function of the intensity of the reflected light (λ = 475 nm) of an LED. The detection limit was 0.01 ppm when the sampling time was 30 min, and the flow rate of sample gas was 250 ml/min. This sensing paper process was not interfered with by acetaldehyde, acetone, alcohols, hydrocarbons, carbon monoxide or carbon dioxide. The NO2 concentrations in the rooms of a house or school were monitored using this monitoring system and the standard chemiluminescence method. The concentrations of NO2 monitored by both methods were within 18% of the average. This highly sensitive, selective, and handy NO2 gas monitoring system will be widely applicable and convenient for users who are not specialists in this field.
The present paper describes a simple, selective and sensitive kinetic method for the determination of trace amounts of molybdenum(VI) based on its inhibitory effect on the reaction oxidation of 4-hydroxycoumarine by KMnO4 in the presence of hydrochloric acid, at pH 1.75 at 25°C. The rate of the indicator reaction was followed spectrophotometrically by measuring the decrease in the absorbance of KMnO4 at 525 nm. The development method includes optimization of the reagent concentration and temperature. The calibration graph was linear in the range of concentrations from 20 to 200 ng/cm3 of molybdenum(VI). The probable relative error was in the interval 3.10 - 10.52% for the concentration range of 200 - 20 ng/cm3 molybdenum(VI), respectively. The interference effects of the foreign ions were determined to assess the selectivity of the method. The developed method was found to have relatively good selectivity, sensitivity, simplicity and rapidity. The proposed method was applied to the determination of molybdenum(VI) in a particular type of steel and alloy (hastelloy).