Showing papers on "Color reaction published in 2003"
TL;DR: The analytical properties of 1-phenyl-1,2-propanedione-2-oxime thiosemi-carbazone (PPDOT) are described for the first time and these colour reactions have been advantageously used for the simultaneous spectrophotometric determination of copper( II) and nickel(II) in synthetic mixture and also in edible oils and seeds.
60 citations
TL;DR: The method is successfully employed for the determination of sulfonamides in various pharmaceutical preparations and common excipients used as additives in pharmaceuticals do not interfere in the proposed method.
Abstract: A rapid, simple and sensitive spectrophotometric method for the determination of some sulfa drugs is described. The method is based on the formation of orange yellow colored azo product by the diazotization of sulfonamides, viz., dapsone (DAP), sulfathiazole (SFT), sulfadiazine (SFD), sulfacetamide (SFA), sulfamethoxazole (SFMx), sulfamerazine (SFMr), sulfaguanidine (SFG) and sulfadimidine (SFDd) followed by a coupling reaction with 3-aminophenol in aqueous medium. Absorbance of the resulting orange yellow product is measured at 460 nm and is stable for 6 days at 27 degrees C. Beer's law is obeyed in the concentration range of 0.05-8.0 microg/ml at the wavelength of maximum absorption. The method is successfully employed for the determination of sulfonamides in various pharmaceutical preparations and common excipients used as additives in pharmaceuticals do not interfere in the proposed method. Plausible reaction mechanism is proposed for the formation of the azo product.
49 citations
TL;DR: A new analytical reagent 5-(p-aminobenzylidene)-rhodanine (ABR) was synthesized and the acidic dissociation constant has been determined and the properties, the acid-base behavior and the reactions of ABR with metallic ions have been studied.
26 citations
TL;DR: The kinetic of reaction was studied and found that reaction time has marked effect on the molar absorptivity of electron donor-acceptor (EDA) complex and the detection of methyl amine has been reported in three real samples of water.
26 citations
Patent•
10 Sep 2003
TL;DR: In this paper, a thermochromic color memorizing composition consisting of an electron donative colorable organic compound, an electron acceptive compound and a homogeneous phase solution of esters represented by general formula is presented.
Abstract: PROBLEM TO BE SOLVED: To provide a thermochromic material, in which color memorizing effects are revealed by selecting the reaction medium of a color reaction through the giving and receiving reaction of electrons to a specified compound, the new reaction medium is found out and the degree of freedom in selection is enlarged. SOLUTION: This thermochromic color memorizing composition comprises (A) an electron donative colorable organic compound, (B) an electron acceptive compound and (C) a homogeneous phase solution of esters represented by general formula (1) as a reaction medium for controlling the color reaction between (A) and (B), wherein R represents at least a 4C alkyl group or alkenyl group and also a thermochromic color memorizing microcapsule pigment containing the thermochromic color memorizing composition is dealt. COPYRIGHT: (C)2005,JPO&NCIPI
25 citations
TL;DR: A highly sensitive and selective spectrophotometric method for determination of trace lead in water after pre-concentration using mercaptosephadex (MS-50) has been developed, the method based on the color reaction of lead(II) with dibromohydroxylphenylporphyrin has been applied with satisfactory results.
23 citations
TL;DR: It was found that all the studied co-existing substances, especially cationic and anionic surfactants, which always seriously interfere in some reported methods, could be tolerated in considerable amounts.
19 citations
TL;DR: The proposed methods were successfully applied to the determination of albendazole in commercially available dosage forms and the reliability of the assays was established by parallel determination by the official method and recovery studies.
Abstract: Two simple, rapid and reliable methods for the determination of albendazole are described. Both methods involve the use of chloramine-T as the oxidimetric reagent. In the titrimetric method, a known excess of chloramine-T is added to an acidified solution of sample, and after a specified time, the residual oxidant is determined iodometrically. Spectrophotometric procedure also involves the addition of a measured excess of chloramine-T in buffer medium of pH 2.70±0.1 and after the reaction is ensured to be complete, the surplus oxidant is determined by a well established colour reaction involving metol and primary arylamine that results in charge-transfer complex measurable at 520 nm. In both methods, the amount of chloramine-T corresponds to the drug content. Reaction conditions were examined and optimised. Titrimetry is based on a 1:3 stoichiometric reaction between albendazole and chloramine-T and is applicable in the range of 1–15 mg. In spectrophotometry, the absorbance was found to decrease linearly with increasing concentration of albendazole, which is corroborated by the calculated correlation coefficient value of −0.9998. The system obeys Beer's law for 2.5–25 μg ml−1 of albendazole. The molar absorptivity and Sandell sensitivity were calculated to be 6.24×103 l mol−1 cm−1 and 42.54 ng cm−2, respectively. The limits of detection and quantification were calculated to be 1.15 and 3.83 μg ml−1, respectively. The proposed methods were successfully applied to the determination of albendazole in commercially available dosage forms. The reliability of the assays was established by parallel determination by the official method and recovery studies.
12 citations
TL;DR: The proposed method was used successfully to determine trace gold in geological samples and its sensitivity and selectivity are remarkably superior to other reagents in the literature.
Abstract: A excellent sensitive and selective method for spectrophotometric determination of trace gold has been developed, the method is based on the color reaction of gold(III) with new reagent 5-(2-hydroxy-5-nitrophenylazo)rhodanine (HNAR). Under optimal conditions, HNAR reacts with gold(III) to form a 1:5 orange complex, which has an maximum absorption peak at 480 nm. Maximum enhancement of the absorbance of the complex was obtained in the presence of the mixed surfactant of Triton X-100 and CTMAB; the reaction completed rapidly and the absorbance is stable for 5 h at least at 20 °C; 0–48 μg L–1 Au(III) obeyed Beer's law. The apparent molar absorptivity of the complex, Sandell's sensitivity, the limit of quantification, the limit of detection and relative standard deviation were found to be 2.0×106 L mol–1 cm–1, 0.000,098,483 µg cm–2, 1.02 ng mL–1, 0.35 ng mL–1 and 1.09%, respectively. The effect of co-existing ions was studied seriously; most metal ions can be tolerated in considerable amounts. Its sensitivity and selectivity are remarkably superior to other reagents in the literature. The proposed method was used successfully to determine trace gold in geological samples. Moreover, the synthesis, characteristics and analytical reaction of HNAR with gold are also described in detail.
11 citations
TL;DR: In this article, the resolution of the binary mixtures of compounds can be determined by a very simple, sensitive, and accurate spectrophotometric procedure, which is a basic analytical problem.
Abstract: Determination of two or more compounds in the same sample without previous chemical separation is a basic analytical problem. In the present study the resolution of the binary mixtures of compounds can be determined by a very simple, sensitive, and accurate spectrophotometric procedure. Five phenothiazine drugs namely, Promethazine HCl (PMH), Promethazine Theoclate (PMT), Chlorpromazine HCl (CPH), Trifluoperazine HCl (TFPH), Prochlorperazine Maleate (PCPM), in pure form and pharmaceutical formulations were assayed by a single chromogenic reagent (V2O5) in an acidic medium, to form a red colored complex having maximum absorbance range from 500 to 525 nm. The reaction is selective for these phenothiazine drugs with 0.05 mg/10 mL as visual limit of quantitation and thus provides a basis for a new spectrophotometric determination. The color reaction obeys Beer's Law from 0.05 mg/10 mL to 2 mg/10 mL for all five phenothiazines with a relative standard deviation from 0.63 to 0.80%. The quantitative ass...
11 citations
Patent•
03 Apr 2003
TL;DR: In this paper, the color reaction on the silica component in the water to yellow color by a light source of long life was performed by using an ultraviolet light emitting diode having a peak wavelength in 370 nm-400 nm.
Abstract: PROBLEM TO BE SOLVED: To provide a compact and inexpensive silica concentration automatic measuring device for the continuous automatic measurement capable of easily and quickly measuring a silica component of low concentration with high accuracy, and measuring its absorbance by performing the color reaction on the silica component in the water to yellow color by a light source of long life. SOLUTION: A transmittance of the reaction solution prepared by color reaction of silica ion in the sample water and the ammonium molybdate dripping reagent solution by mixing the sample water and the ammonium molybdate dripping reagent solution, is automatically measured by an ultraviolet light- emitting diode having a peak wavelength in 370 nm-400 nm.
TL;DR: In this paper, a test procedure was developed for the determination of mercury(I, II) on the surface of a polycaproamide membrane with a detection limit of <50 ng in the adsorbent zone.
Abstract: It was found that mercury(I, II) reacts with 5-chloro-2-hydroxy-3-[(tetrahydro-2,4-dithioxo-1,3-thiazin-5-yl)azo]benzenesulphonic acid (tyrodine) in weakly acid solutions in the presence of acetates, formates, and some organic solvents (ethanol and acetone) to give an intensely colored insoluble compound (λmax = 600 nm, e > 3 × 104). The composition of the solution affected the sensitivity of the color reaction between mercury and tyrodine. A test procedure was developed for the determination of mercury(I, II) on the surface of a polycaproamide membrane with a detection limit of <50 ng in the adsorbent zone. The procedure involves the quantitative and selective adsorption of the mercury complex of tyrodine on the support surface from 0.5 M acetate solutions of pH 3–4 in the dynamic mode; the sample volume was 5–25 mL. Mercury was then determined by the change in the support color using a color scale or by the change in diffuse reflectance at 600 nm. The adsorption of the mercury complex was accompanied by an abrupt change in the color of the support surface from pale crimson (reagent) to stable blue-violet. The test procedure was used in the analysis of an industrial sample of complex composition with a mercury concentration of lower than 0.05%. The determination error (relative standard deviation) was 20%.
Patent•
15 Aug 2003
TL;DR: In this article, the authors proposed a gas detection material for measuring a tested gas of a wide concentration range with high accuracy while keeping constant the concentration of a reaction reagent, which is equipped with a color reaction base material.
Abstract: PROBLEM TO BE SOLVED: To provide a gas detection material for measuring a tested gas of a wide concentration range with high accuracy while keeping constant the concentration of a reaction reagent. SOLUTION: This detection material is equipped with color reaction base material 4 in which the reaction reagent color-reacting with the tested gas is carried on a carrier and a film 3 having permeability with respect to the tested gas, and is structured so that the film 3 is layered at least on the inflow surface side of the base material 4. COPYRIGHT: (C)2004,JPO
Journal Article•
TL;DR: The analytical properties of 2-acetylthiophene-4-phenyl-3-thiosemicarbazone (ATPT) were described for the first time in this article.
Abstract: The analytical properties of 2-acetylthiophene-4-phenyl-3-thiosemicarbazone (ATPT) are described for the first time. The reagent gives yellowish green coloured complex with copper(II) in sodium acetate - acetic acid buffer (pH 3.0 - 6.0) medium. This colour reaction (molar absorptivity, 2.92 x 10 4 L mol - 1 cm - 1 at 385 nm) has been investigated for the spectrophotometric determination of copper in edible oils and seeds.
Journal Article•
TL;DR: In this paper, the colour reaction of palladium and α benzoinoxime in solid phase has been studied and the absorbance of the solid phase was measured by using dual wavelength spectrophotometry.
Abstract: The colour reaction of palladium and α benzoinoxime in solid phase has been studied. The complex can be quantitatively adsorbed in paraffin phase at pH 2.5 to pH 6.0.The absorbance of the solid phase was measured by using dual wavelength spectrophotometry. Beer's law is obeyed in the range of 0～0.8 mg/L of palladium. The new method has been applied to the determination of palladium in activator with satisfactory results.
TL;DR: In this paper, a new chromogenic reagent, 2-(2-quinolylazo)-5-dimethylaminoaniline (QADMAA), was synthesized.
Abstract: A new chromogenic reagent, 2-(2-quinolylazo)-5-dimethylaminoaniline (QADMAA) was synthesized. A highly sensitive, selective and rapid method for the determination of silver based on the rapid reaction of silver(I) with QADMAA was developed. In the presence of H = 6.5 sodium citrate-sodium hydroxide buffer solution and sodium dodecyl sulfonate (SDS) medium, QADMAA reacts with silver to form a violet complex of a molar ratio 1:2 (silver to QADMAA). The molar absorptivity of the complex is 1.26 x 10 5 L. mol - 1 .cm - 1 at 570 nm. Beer's law is obeyed in the range of 0.01-0.6 μg/mL. The relative standard deviation for eleven replicate samples of 0.2 μg/mL silver is 1.76%. This method was applied to the determination of silver in water with good results.
Journal Article•
TL;DR: A new method for the determination of the crude ammonia in meat was presented in this paper, which was based on the color reaction of ammonia-salicylic acid-sodium hypochlorite with the presence of sodium nitroprusside in basic medium.
Abstract: A new method for the determination of the crude ammonia in meat was presented in this paper.The method was basedon the color reaction of ammonia-salicylic acid-sodium hypochlorite with the presence of sodium nitroprusside in basic medium.It showed that the apparent molar absorptivity was 1.84×104L/mol·cm with the wavelength at 660nm.Beer's law was obeyedfor the nitrogen of ammonia in the range of 0～5μg/10ml. The correlation coefficient is 0.9999. The recoveries were between96%～103.3%.The method has been applied satisfactorily to the determination of the crude ammonia in meat samples.
Journal Article•
TL;DR: The color reaction of sulfide with p-diethylamino phenylamine to form ethyl thionine has been studied in this paper, where the addition of sodium dodecyl sulfonate could enhance the sensitivity of the reaction.
Abstract: The color reaction of sulfide with p-diethylamino phenylamine to form ethyl thionine has been studied. The addition sodium dodecyl sulfonate could enhance the sensitivity of the reaction. The maximum absorption of the association compound was at 675 nm and the molar absorptivity was 4.25×10~4 L·mol~(-1)·cm~(-1). The Beer's law was obeyed in the range of 0～0.8 μg/mL. The present method has been applied to the determination of sulfide in natural water with satisfactory results.
Patent•
02 Oct 2003
TL;DR: In this paper, a method and an instrument for measuring boron by which concentration of borons contained in a drain or environmental water can be measured accurately and easily though borofluoride ions exist.
Abstract: PROBLEM TO BE SOLVED: To provide a method and an instrument for measuring boron by which concentration of boron contained in a drain or environmental water can be measured accurately and easily though borofluoride ions exist. SOLUTION: After a first reagent containing at least aluminum ions and/or iron ions is added to a sample liquid, a color reaction is caused by adding a second reagent containing at least 1-amino-8-hydroxynaphtalene-3,6-disulfonic acid-based azo dye and a chelating agent to the sample liquid. Thereafter, absorbance of the sample liquid is measured. COPYRIGHT: (C)2004,JPO
Journal Article•
TL;DR: In this article, the high-sensitivity color reaction of Sb_(Ⅲ) as the product of the reaction of with Antimony KI and Rodamine B under condition of polyvinyl alcohol was dealt with.
Abstract: This deals with the high-sensitivity color reaction of Sb_(Ⅲ) as the product of the reaction of with Antimony KI and Rodamine B. under condition of polyvinyl alcohol. The determination results of Sb_(Ⅲ) were obtained through the mithod of continuous change of equal mole. Molar ratio of Sb:RB is 1:2. λ_(max) of the product is 605nm.The molar absorptivity is 6.24×10~(-6)L·mol~(-1)·cm~(-1). The amount of Sb_(Ⅲ) varies in the range of0-15 μg/25ml and is in accordance with Beer's Law. The condition of the color reaction and the interference of foreign ions were studied in detail. The recovery experiment of Antimony in water was carried out easily and quickly. The results are satisfactory.
Patent•
18 Sep 2003
TL;DR: In this paper, a process for encapsulating a solution of color reactants of color-reaction systems present in an aqueous emulsion accomplished by means of conventional microencapsulation processes is described.
Abstract: A process is described for encapsulating a solution of color reactants of color-reaction systems present in an aqueous emulsion accomplished by means of conventional microencapsulation processes, in which the color reactant is first dissolved in a solvent and a non-dissolver, which may insignificantly dissolve the color reactant, is mixed into the resulting solution in an amount that establishes a supersaturated solution while mixing at high speed, the supersaturated solution is emulsified immediately in the aqueous phase while mixing at high speed, and immediately thereupon the encapsulation is performed A vegetable oil C 1 -C 8 alkyl ester is used as the solvent This process has economic and technological advantages For example, it can be used to produce microcapsules that have an advantageous narrow monomodal particle distribution, which results in improved writing performance