A highly sensitive spectrophotometric method for the determination of some phenothiazine antipsychotics using chloramine-T and indigocarmine.

A new simple, accurate and precise spectrophotometric method for the determination of six phenothiazine drugs in pure form and in dosage forms is described. The method is based on the oxidation of the studied drugs by a known excess of Chloramine-T in hydrochloric acid medium and subsequent determination of the unreacted oxidant by reacting it with indigocarmine in the same acid medium. The reacted oxidant corresponds to the drug content. The colored species exhibits maximum absorption at 610 nm. The apparent molar absorptivity values and Sandell sensitivity values are in the range 1.53 x 10(4)-2.96 x 10(4) l mol-1 cm-1 and 13.75-37.15 ng cm-2, respectively. The method is highly sensitive and suitable for 1-15 micrograms ml-1 concentrations with the detection limits being in the range, 0.0651-0.1724 microgram ml-1. The method was successfully applied to the studied drugs in their dosage forms. The results are reproducible within +/- 1% and compare favorably with those obtained by the procedures of the British Pharmacopeia.     

Spectrophotometric determination of trace copper in water samples with thiomichlersketone

A simple and sensitive spectrophotometric method for determination of trace copper in water samples is proposed. In the presence of pH 4.6 HAc-NaAc buffer solution and surfactant polyethylene octyl phenyl ether (OP) medium, copper reacts with thiomichlersketone (TMK) to form a stable 1:4 complex. The complex Cu(II)-TMK-OP shows maximum absorbance at 500 nm with a molar absorptivity value of 5.7x10(4) l mol-1 cm-1. Beer's law is obeyed for copper concentrations in the range of 0-15 microg/25 ml. The average recovery of copper is between 95.8 and 106%. The method has been applied for determination of trace copper in different water samples with satisfactory results.     

Simultaneous determination of titanium and molybdenum in steel samples using derivative spectrophotometry in neutral micellar medium

A simple, selective and sensitive spectrophotometric method has been developed for the individual and simultaneous determination of Ti(IV) and Mo(VI) using resacetophenone p-hydroxybenzoylhydrazone (RAPHBH) in presence of Triton X-100, without any prior separation. Beer's law is obeyed between 0.13-1.2 microg mL-1 and 0.18-1.90 microg mL-1 concentration of Ti(IV) and Mo(VI) at 455 nm and 405 nm, respectively. The molar absorptivity and Sandell's sensitivity of the coloured complexes at pH 3.0 are 3.1x10(4) L mol-1 cm-1, 4.2x10(4) L mol-1 cm-1, and 1.6 ng cm-2, 2.3 ng cm-2 for Ti(IV) and Mo(VI), respectively. The stoichiometry of the complexes were found to be 1:2 and 1:1 (metal:ligand) for Ti(IV) and Mo(VI), respectively. These metal ions interfere with the determination of each other in zero-order spectrophotometry. The first derivative spectra of these complexes permitted a simultaneous determination of Ti(IV) and Mo(VI) at zero crossing wavelengths of 500.0 nm and 455.0 nm, respectively. The effect of foreign ions in the determination of Ti(IV) and Mo(VI) were investigated. The proposed method has been successfully applied for the determination of titanium and molybdenum in standard alloy steel, mineral and soil samples.     

Dapsone a new diazotizing reagent for the spectrophotometric determination of nitrite in waste and natural water samples

A new diazotizing reagent for the spectrophotometric determination of nitrite is described. The method is based on diazotization-coupling reaction between dapsone and phloroglucinol in hydrochloric acid medium. The reactions were conducted at room temperature, the molor absorptivity at 425 nm is 4.28 x 10(4) l mol-1cm-1 and was stable for 50 h. Beer's law was obeyed in the nitrite range of 0.008-1.0 microgram ml-1. Tolerance limits were tested for 33 species. The method has been found to be applicable for the determination of nitrite in natural and wastewater.     

Individual and simultaneous spectrophotometric determination of dapsone and metoclopramide HCl in pharmaceutical dosage forms and synthetic binary mixtures

A rapid, sensitive and selective spectrophotometric method has been developed for the quantitative determination of dapsone (DAP) and metoclopramide hydrochloride (MCP) in both pure and dosage forms. Individual and simultaneous methods are based on the diazo coupling reaction of these drugs with benzoylacetone (BAC) in alkaline medium. The resulting azo dyes exhibit maximum absorption at 437 and 411 nm with a molar absorptivity of 4.14x10(4) and 2.97x10(4) l mol-1 cm-1 for DAP and MCP, respectively. Simultaneous determination of DAP and MCP was developed utilizing first-order digital derivative spectrophotometry. All variables have been optimized. No interferences were observed from drug excipients and the validity of the methods was tested against reference methods.     

Synthesis of meso-tetra-(3,5-dibromo-4-hydroxylphenyl)-porphyrin and its application to second-derivative spectrophotometric determination of lead in clinical samples

A new very sensitive and selective chromogenic reagent, meso-tetra-(3,5-dibromo-4-hydroxylphenyl)porphyrin [T(DBHP)P], was synthesized and studied for the determination of trace lead in detail. In 0.10 mol l-1 NaOH medium, lead reacts with T(DBHP)P to form a 1:2 yellow complex, which gives a maximum absorption at 479 nm; 0-0.48 microgram ml-1 Pb(II) obeyed Beer's law. The molar absorptivity of the complex and Sandell's sensitivity are 2.5 x 10(5) 1 mol-1 cm-1 and 0.000812 microgram cm-2, respectively. Second-derivative spectrophotometry is better than conventional spectrophotometry in sensitivity and selectivity, and its limit of quantification, limit of detection and relative standard deviation are 0.70 ng ml-1, 0.21 ng ml-1 and 1.0%, respectively. Ca (3250-fold), Mg (2000-fold), Sr (1000-fold), Ba (750-fold), Al (1000-fold), Bi (500-fold), Fe (2000-fold), Co (750-fold), Ni (1000-fold), Cu (750-fold), Zn (1250-fold), Cd (2500-fold) and Ag (550-fold) do not interfere with the determination of lead. The chromogenic system is remarkably superior to other reagents, especially porphyrin compounds. The influence caused by oxygen in air or in solution can be easily eliminated by adding Na2SO3. The reaction is very stable, the stability constant of the complex being 1.2 x 10(45). The chromogenic reaction is completed within 1 min at room temperature when 8-hydroxylquinoline is used as catalyst. The proposed method has been applied to the direct determination of trace lead in clinical samples. The accuracy and precision are both very satisfactory.     

A facile spectrophotometric method for the determination of selenium.

A rapid and sensitive spectrophotometric method is described for the determination of trace amounts of selenium using Variamine Blue (VB) as a chromogenic reagent. The proposed method is based on the reaction of selenium with potassium iodide in an acidic medium to liberate iodine, which oxidizes Variamine Blue to form a violet-colored species having an absorption maximum at 546 nm. Beer's law is obeyed in the range 2-20 g of selenium in a final volume of 10 ml. The molar absorptivity and Sandell's sensitivity were found to be 2.6 x 10(4) l mol-1 cm-1 and 0.003 microgram cm-2, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The effect of interfering ions on the determination is described. The proposed method has been successfully applied to the determination of selenium in real samples of water, soil, plant materials, human hair, and synthetic samples of cosmetics and pharmaceutical preparations.     

N,N-diethyl-N'-benzoylthiourea--a new spectrophotometric reagent for rhenium determination

The reagent N,N-diethyl-N'-benzoylthiourea produces a green complex with rhenium in hydrochloric acid medium in the presence of tin(II) chloride. The complex extracted into toluene shows an absorption maximum at 383 nm, obeys Beer's law from 1.5 to 22 micrograms ml-1 of rhenium while its molar absorptivity and Sandell sensitivity are 6.66 x 10(3) L mol-1 cm-1 and 0.028 microgram cm-2, respectively. It tolerates the presence of a large number of ions, including Mo(VI), W(VI) and some platinum metals. Job's and the mole ratio methods indicate that the rhenium metal and the chelating agent ratio of 1:2 in solution. The system has been applied to the determination of rhenium on synthetic samples and alumina based catalysts.     

Spectrophotometric determination of acetone using vanillin

A sensitive method is described for the spectrophotometric determination of acetone in water. Acetone reacts with vanillin in alkaline medium forming a yellow-orange dye with an absorption maximum at 430 nm. Beer's law is obeyed in the range from 0.5 to 5 p.p.m. of acetone in water. Molar absorptivity and Sandell's sensitivity were found to be 11.0 x 10(3) +/- 100 l mol-1 cm-1 and 0.005 micrograms cm-2, respectively. The important parameters for complete colour development were optimised and the method was used for the determination of acetone in biological samples. The method was also applied successfully to the determination of acetone in air after absorption in sodium hydrogen sulphite solution.     

Extraction spectrophotometric determination of maneb with 1-(2'-pyridylazo)-2-naphthol (PAN)

A rapid, sensitive, simple and selective spectrophotometric method has been developed for the determination of micro-quantities of maneb (manganese ethylenebisdithiocarbamate) after extraction of the manganese-PAN complex in isobutyl methyl ketone (MIBK). The complex absorbs strongly at 550 nm. Beer's law is obeyed over the concentration range 0.37-3.75 microg/ml. The molar absorptivity was found to be 4.1 x 10(4) l. mole(-1) . cm(-1). The developed method has been applied to the determination of maneb in commercial formulations, synthetic mixtures, grain and in the presence of various other dithiocarbamates.     

镉—溴化物—罗丹明B高灵敏显色反应的研究：离心光度法测定镉

本研究了一个高灵敏的测定镉的方法，离心光度法，该体系络合物λｍａｘ＝５６０ｎｍ，表观摩尔吸系数ε５６０＝５．０６×１０＾８Ｌ．ｍｏｌ＾－１．ｃｍ＾－１，Ｃｄ＾２＋浓度０．１０×１０＾－２－１．０×１０＾－２μｇ／１０ｍＬ呈线性关系，本法已用于血清和水中痕量镉的测定，探讨了高灵敏的显色反应机理。     

铑-钨酸盐-罗丹明B缔合显色反应的研究及应用

在聚乙烯醇 (PVA)存在下 ,铑 ( )与钨酸盐及罗丹明 B(RB)形成的离子缔合物在 570 nm处产生最大吸收。建立了测定铑 ( )的光度分析方法 ,其表观摩尔吸光系数 ε达 1 0 7(L·mol-1·cm-1)数量级。方法的检测范围为 0～ 50ng/2 5m L ,检出下限为 0 .2 9ng/2 5m L。大量存在的常见离子对 Rh( )的测定不干扰。用此方法测定了催化剂及工业产品中铑的含量 ,结果与标准方法 (Sn Cl2法 )一致。     

Spectrophotometric and atomic absorption determination of ramipril, enalapril maleate and fosinopril through ternary complex formation with molybdenum (V)-thiocyanate (Mo(V)-SCN)

Three different sensitive and accurate spectroscopic procedures were developed for the determination of three angiotensin-converting enzyme inhibitors, namely, ramipril, enalapril maleate and fosinopril. The first two spectrophotometric (extractive and non-extractive) procedures were based on ternary complex formation with molybdenum(V) thiocyanate. The formed complex can be determined by extraction with chloroform measured at lambdamax 517 nm Beer's law was obeyed in the concentration range from (10--90 microg ml(-1)) for ramipril and fosinopril and (4--36 microg ml(-1)) for enalapril maleate with molar absorptivity 1.2x10(4), 2x10(4) and 3.4x10(4) l mol(-1) cm(-1), respectively, or by direct measurement after addition of benzalkonium chloride as surfactant and measuring the formed ternary complex at lambdamax 545 nm with a linear relationship in the concentration range from (8-7-2 microg ml(-1)), (3--27 microg ml(-1)) and (8--72 microg ml(-1)) for ramipril, enalapril maleate and fosinopril with molar absorptivity 1.5x10(4), 5x10(4) and 2.1x10(4) l mol(-1) cm(-1), respectively. The third procedure is atomic absorption measurement through the quantitative determination of molybdenum content of the complex. These methods hold their accuracy and precision well when applied to the determination of ramipril, enalapril maleate and fosinopril in their dosage forms.     

分光光度法连续测定发样中铜和铁

建立了一种在表面活性剂OP存在下,用2－（5－溴－2－吡啶偶氮）－5二乙氨基酚（5－Br-PADAP)作显色剂分光光度法同时测定铜和铁含量的新方法,用该法测定铜和铁,显色络合物最大吸收波长均为558nm,PH3．5时,测得Cu-5-Br-PADAP的为9．1＊1010^4ug/10mL,铁线性范围为0－5．0ug/10mL,此法应用于人发样品分析,方法简便,快速结果,准确,满意。     

Determination of amodiaquine in pharmaceuticals by reaction with periodate and spectrophotometry or by high-performance liquid chromatography

Two methods are described for the determination of amodiaquine in pharmaceuticals. In the first method, amodiaquine was treated with periodate at pH 7.5-8.5 to yield a chromogen, which is believed to be a 1,4-benzoquinone imine derivative, and extracted into chloroform for spectrophotometric assay. The maximum molar absorptivity was found to be 2.17 x 10(3) l mol-1 cm-1 at 442 nm. Primaquine and chloroquine, if present also, do not interfere. The second method, which was used for the simultaneous determination of amodiaquine, primaquine and chloroquine, is based on high-performance liquid chromatography on an octadecylsilane column using a mobile phase of methanol-water (80 + 20) containing 0.5% anhydrous acetic acid and an over-all concentration of sodium dodecyl sulphate of 0.5 mM, with detection at 340 nm.     

Spectrophotometric determination of hydroxylamine and its derivatives in pharmaceuticals

A sensitive spectrophotometric method for the determination of hydroxylamine is described. The method is based on the oxidation of hydroxylamine to nitrite using sodium arsenate under alkaline condition. The formed nitrite is determined based on the diazo coupling reaction between p-nitroaniline and N-(1-naphthyl)ethylenediamine dihydrochloride [NEDA]. The system obeys Beer's law over the concentration range 0-7 microg of hydroxylamine at 545 nm and the colour is stable for 3 h. The molar absorptivity of the colour system is found to be 6.7 x 10(4) l mol(-1) cm(-1). The relative standard deviation is 1.2% for ten determinations at 4 microg of hydroxylamine. Interferences due to various foreign ions have been studied and the method has been applied to the determination of hydroxylamine and its derivatives used in pharmaceutical formulations after hydrolysis.     

5—（2—苯并噻唑偶氮）—8—氨基喹啉作为镍的光度分析试剂及应用研究

研究了新试剂 5- (2 -苯并噻唑偶氮 ) - 8-氨基喹啉与镍的显色反应。在弱碱性介质中 ,阳离子表面活性剂溴化十六烷基三甲基铵存在下 ,试剂与镍形成 3∶ 1的蓝色配合物 ,其最大吸收波长位于 61 0 nm处 ,表观摩尔吸光系数为 1 .2 6× 1 0 5L· mol-1· cm-1,镍的浓度在 0～ 8.0μg/2 5ml范围内 ,符合比耳定律。应用于铝合金中微量镍的测定 ,获得了满意的结果。     

溴酚蓝分光光度法测定盐酸西布曲明

在pH 3.70的B-R缓冲溶液中,盐酸西布曲明与溴酚蓝以摩尔比1比2反应形成具有正吸收和负吸收的离子缔合物,最大正吸收波长为436nm,最大负吸收波长为590nm,线性范围分别在3.4×10-6 mol·L-1(正吸收)、3.8×10-6 mol·L-1(负吸收)以内,表观摩尔吸光率为1.83×105L.mol-1.cm-1(正吸收)、5.51×104L.mol-1.cm-1(负吸收),据此建立了测定盐酸西布曲明含量的分光光度法。方法用于合成样品及尿样中盐酸西布曲明的测定,回收率在96.8%～102.5%,相对标准偏差(n=6)在0.9%～1.7%之间。     

Spectrophotometric determination of thorium in standard samples and monazite sands based on the floated complex of thorium with N-hydroxy-N,N′-diphenylbenzamidine and thorin

A selective and sensitive spectrophotometric method for the determination of Th(IV) has been based on the reaction with thorin and subsequent extraction of the red-orange coloured complex with N-hydroxy-N,N'-diphenylbenzamidine (HDPBA) in benzene as floated complex at pH 2.2. The complex in ethanol exhibits a maximum absorbance at 495 nm, with a molar absorptivity of 6.0x10(4) l mol(-1) cm(-1), with a Sandell's sensitivity of 3.9x10(-3) microg cm(-2). The method follows Beer's law up to 3.0 microg Th(IV) ml(-1). None of the common cations and anions tested interfere. The detection limit of the method is 0.04 microg Th(IV) ml(-1), the RSD (n=10) is 1.4%. The method has been successfully employed for the determination of thorium in various standard and monazite samples.     

Solid phase extraction and spectrophotometric determination of silver with 2-(2-quinolylazo)-5-diethylaminophenol as chromogenic reagent.

A new chromogenic reagent, 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP), was synthesized. A sensitive, selective and rapid method has been developed for the determination of microg/L level silver ion based on the rapid reaction of silver(l) with QADEAP and the solid phase extraction of the colored chelate with C18 cartridge. The QADEAP reacts with Ag(l) to form a violet chelate of a molar ratio 1:2 (silver to QADEAP) in pH 3.5-8.0. This chelate was prconcentrated by solid phase extraction with C18 cartridge. An enrichment factor of 100 was achieved. The molar absorptivity of the chelate is 1.30 x 10(5) L mol(-1) cm(-1) at 590 nm in measured solution. Beer's law is obeyed in the range of 0.01-0.6 microg/ml. The relative standard deviation for eleven replicate samples of 0.01 microg/ml is 1.15%. The detection limit is 0.02 microg/L in the original samples. This method was applied to the determination of microg/L level silver ion in water with good results.