Study on the solid phase extraction of Co(II)-QADEAB chelate with C(18) disk and its application to the determination of trace cobalt

A sensitive, selective and rapid method has been developed for the determination mug l(-1) level of cobalt based on the rapid reaction of cobalt(II) with 2-(2-quinolylazo)-5-diethylaminobenzoic acid (QADEAB) and the solid phase extraction (SPE) of the colored chelate with Waters Porapak(R) Sep-Park C(18) disk. The QADEAB can react with Co(II) in the presence of pH 3.8 acetic acid-sodium acetate buffer solution and cetyl trimethylammonium bromide (CTMAB) medium to form a violet chelate of a molar ratio 1:2 (cobalt to QADEAB). This chelate can retained on Waters Porapak(R) Sep-Park C(18) disk quantitatively when they passed the disk as aqueous solution. After the enrichment finished, the retained chelate can be eluted from disk by 2.5 ml of ethanol (contain 5% acetic acid). In the measured solution, the molar absorptivity of the chelate is 1.58x10(5) l mol(-1) cm(-1)at 635 nm, and Beer's law is obeyed in the range of 0.01-0.4 mug ml(-1). The relative standard deviation for 11 replicate sample of 0.01 mug ml(-1) level is 2.23%. The detection limit is 0.01 mug l(-1) (in original samples). This method can be applied to the determination of mug l(-1) level of cobalt in drinking water with satisfactory results.     

Extraction and spectrophotometric determination of lead(II) with pyridine-2-acetaldehyde salicyloylhydrazone

Lead(II) reacts with pyridine-2-acetaldehyde salicyloylhydrazone (PASH) in the pH range 8.6-9.3 to form a yellow-green, 1:2 chelate which can be extracted into chloroform. Beer's law is obeyed in the concentration range 1.5-6.2 mug ml(-1) of lead(II). The molar absorptivity of the extracted species is 1.93 x 10(4) l mol(-1) cm(-1) at 380 nm. The proposed method is sensitive, simple, rapid, accurate and has been satisfactorily applied for the determination of lead in synthetic mixtures, alloys, water and soil samples.     

Nonextractive spectrofluorimetric determination of aluminium in real, environmental and biological samples using chromotropic acid

An ultra-sensitive and highly selective nonextractive fluorimetric method is presented for the rapid determination of aluminium at nano-trace levels using chromotropic acid as a fluorimetric reagent [lambda(ex) = 360 nm and lambda(em) = 390 nm] in the pH range of 4.1-4.7. The fluorescence intensity of the metal chelate (2:3 complex) reaches a constant value within 1/2 hr and remains unchanged for over 48 hr. The fluorescence intensity aluminium concentration calibration curve is collinear between 1 and 300 ng/ml of Al. A constant fluorescence intensity is obtained over a wide range (1:50-1:1500) of Al:reagent molar concentrations. Large excesses of over 60 cations, anions and complexing agents (like tartrate, oxalate, phosphate, thio-urea, SCN(-), etc.) do not interfere in the Al determination. The developed method was successfully used in assaying aluminium in several standard reference materials (Al-bronze, brass, stainless steel) as well as in some environmental and biological samples. The method is very precise and accurate (S.D = +/-0.001 on 10 ng/ml; 11 determinations).     

Resonance double light scattering method for the determination of proteins with morin-CTMAB

A new determination method of proteins with the limit of determination at nanogram levels is proposed by using a common spectrofluorimeter to detect intensity of resonance double line scattering (RDLS). Proteins including bovine serum albumin (BSA), human serum albumin (HSA) can combine with morin and cetyltrimethylammonium briomide (CTMAB) in the pH range 7.0-8.0 and produce enhanced RDLS signal at lambda(ex)/lambda(em) 305.0/610.0 nm. Optimization conditions for the morin-protein-CTMAB interaction were tested. In the studied system, BSA/CTMAB/morin = 1:2:3. The association constant of morin with BSA is 5.2 x 10(4). Under the optimum conditions, the linear range is 7.5 x 10(-8)-1.0 x 10(-5) g/ml for BSA, 2.5 x 10(-8)-5.0 x 10(-6) g/ml for HSA. The detection limits (S/N = 3) are 66.0 ng/ml for BSA and 23.0 ng/ml for HSA, respectively. Four synthetic samples were analyzed satisfactorily.     

Simultaneous determination of manganese and zinc in mixtures using first- and second-derivative spectrophotometry

A new direct spectrophotometric determination of manganese with 5,8-dihydroxy-1,4-naphthoquinone (naphthazarin,NAZA) is reported. Absorption maximum, molar absorptivity and Sandell's sensitivity of 1:2 (M:L) complex are 695 nm, 1.88x10(4) l mol(-1) cm(-1) and 2.92 ng cm(-2), respectively. A linear calibration graph is obtained up to a concentration of 7.2 mug ml(-1) of manganese. The optimum range for determination (Ringbom) is between 0.20 and 6.8 mug ml(-1). A rapid method for simultaneous determination of manganese and zinc in their mixture using derivative spectra is described. The range 0.28-5.6 mug ml(-1) manganese could be determined in the presence of 0.33-6.8 mug ml(-1) zinc and vice versa. The developed method was applied to the simultaneous spectrophotometric determination of manganese and zinc in some synthetic mixtures and was found to give satisfactory results.     

An insight into the solution equilibria of magnesium(II) with purpurin and spectrophotometric determination of magnesium

The complexation equilibria of magnesium(II) with purpurin (PURP) are studied spectrophotometrically as a function of pH in 50% (v/v) ethanol-water medium at 20 degrees C. The uncharged complex formed at pH 9.5 allows precise and accurate determination of magnesium over the concentration range 0.8-4.3 mug ml(-1). The molar absorptivity of the Mg-PURP complex at 540 nm and detection limit for Mg are 9.2x10(3) l mol(-1) cm(-1) and 75 ng ml(-1), respectively. The proposed method is rapid and possesses reasonable selectivity. Under the optimum conditions, the use of first-derivative spectrophotometry has the advantage of high sensitivity than normal spectrophotometry and allows the determination of 0.2 mug ml(-1) of magnesium. The validity of the method is examined by analysing several SRM Portland cement samples and a variety of cement materials of variable magnesia content.     

Derivative spectrophotometric determination of copper(II) in non-ionic micellar medium

A photometric method for trace analysis of Cu(II) with 1-(2-pyridylazo)-2-naphthol (PAN) in presence of a neutral surfactant, Triton X-100, has been reported in normal and derivative modes. The molar absorption coefficient () and Sandell's sensitivity (S) of PAN-Cu(II) complex at 555 nm is 5.21 x 10(4) l mol(-1) cm(-1) and 1.22 ng cm(-2) respectively. The detection limit of Cu(II) is 4.0 ng ml(-1) and Beer's law is obeyed in the range 0.08-4.00 mug ml(-1) of the analyte. Copper content of a number of commercially available alcoholic beverages, biological and standard alloy samples is reported. The results obtained are in excellent agreement with those obtained using AAS.     

Rapid spectrophotometric determination of chromium(III)

A spectrophotometric procedure is suggested for the determination of Cr(III). The reaction between Cr(III) and 2-(5-bromo-2-pyridylazo)-5-dimethylaminophenol is accelerated by sodium dodecyl sulphate(SDS), sodium benzoate causes a further increase in the absorbance of the chelate. The optimum pH range for the reaction is 5-5.8(benzoate buffer). The chelate exhibits maximum absorbance at 590 nm, obeys Beer's law over the concentration range 0.02-0.56 microg/ml of Cr(III), has molar absorptivity of 7.8 x 10(4) 1. mol(-1) cm(-1) and a Sandell sensitivity of 0.66 ng/cm. The metal to ligand ratio is 1:2 in the absence of SDS and 1:1 in its presence. A procedure for the determination of Cr(III) and Cr(VI), when present together, is described. The method has been applied to the analysis of Cr(III) in tap water.     

Zincsulphate induced metallothionein in pancreatic islets and protected against the diabetogenic toxin streptozotocin

A new azoamino reagent amido black diazoaminoazobenzene (ABDAB) has been synthesized, and found to be a good chromogenic reagent for cadmium. In pH 10.4 Na(2)B(4)O(7)NaOH buffer solution cadmium reacts with ABDAB to form an orange-red chelate (1:2), exhibiting an absorption maximum at 520 nm. The apparent molar absorptivity is 1.62x10(5) l mol(-1) cm(-1). Beer's law is obeyed in the range 0-8 mug/25 ml Cd. The method is simple and rapid, with high sensitivity and good selectivity and is applied to the determination of trace amounts of cadmium in waste water and metal materials with satisfactory results.     

Spectrophotometric determination of mercury in environmental sample and fungicides based on its complex with o-carboxy phenyl diazoamino p-azobenzene

In the present method a new reagent o-carboxyphenyl diazoamino p-azobenzene has been synthesised for the determination of mercury spectrophotometrically. The method is based on the reaction of mercury with the reagent in alkaline medium where the reagent is in the aci-form. The purple violet coloured dye-mercury complex showed an absorption maxima at 540 nm. Beer's law is valid over the concentration range of mercury from 0.08 to 0.8 mug ml(-1) (0.08-0.8 ppm). The molar absorptivity and Sandell's sensitivity were found to be 2.22x10(5) mol(-1) cm(-1) and 0.0009 mug cm(-2), respectively. The method has been successfully applied to the determination of mercury in air, water, soil and fungicide samples.     

A rapid spectrophotometric method for the determination of molybdenum in industrial, environmental, biological and soil samples using 5,7-dibromo-8-hydroxyquinoline.

A very simple, ultra-sensitive and highly selective non-extractive spectrophotometric method for the determination of trace amount of molybdenum(VI) using 5,7-dibromo-8-hydroxyquinoline (DBHQ) has been developed. 5,7-Dibromo-8-hydroxyquinoline reacts in a slightly acidic solution (0.05 - 1.0 M H2SO4) with molybdenum(VI) to give a deep greenish-yellow chelate which has an absorption maximum at 401 nm. The reaction is instantaneous and the absorbance remains stable for over 24 h. The average molar absorption coefficient and Sandell's sensitivity were found to be 4.13 x 10(3) L mol(-1) cm(-1) and 7 ng cm(-2) of molybdenum(VI), respectively. Linear calibration graphs were obtained for 0.1 - 50 microg mL(-1) of molybdenum(VI). The stoichiometric composition of the chelate is 1:3 (Mo:DBHQ). A large excess of over 50 cations, anions and some common complexing agents (e.g. EDTA, oxalate, citrate, phosphate, thiourea, SCN-) do not interfere with the determination. The method was successfully used in the determination of molybdenum in several Standard Reference Materials (alloys, steels and waters) as well as in some environmental waters (inland and surface), biological samples (human blood and urine), soil samples, solution containing both molybdenum(V) and molybdenum(VI) and complex synthetic mixtures. The method has high precision and accuracy (S = +/-0.01 for 0.5 microg mL(-1)).     

Analytical application of a new thiazolylazo reagent, 2-(2-benzothiazolylazo)-5-dimethylamino-4-tolylarsonic acid Spectrophotometric determination of palladium

A new thiazolylazo reagent, 2-(2-benzothiazolylazo)-5-dimethylamino-4-tolylarsonic acid, has been synthesized and found to be a good chromogenic reagent for palladium. A 1:1 blue chelate (lambda(max) = 718 nm) is formed in a sulphuric or nitric acid medium. The molar absorptivity is 6.65 x 10(4) l. mole(-1).cm(-1). Beer's law is obeyed in the range 0-1.6 mug/ml Pd. Relatively large amounts of co-existing elements, including noble metals, can be tolerated.     

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.     

Spectrophotometric determination of zinc with hydrazidazol in the presence of Triton X-100 and its application in metal analysis

A new spectrophotometric method for the determination of zinc is proposed. The chromogenic agent Hydrazidazol forms a 1:1 chelate with zinc in the presence of Triton X-100 in a medium containing 20-40% ethanol. The molar absorptivity and conditional formation constant have been found to be 2.7 x 1O(4) l.mole(-1).cm(-1) (at 640 nm) and 10(5.32) respectively. Beer's law is obeyed for zinc over the range of 0.2-0.8 mug/ml with a standard deviation of 0.024 mug/ml. The method can be applied to the determination of zinc in cadmium metal and its oxide after preconcentration by selective extraction of zinc thiocyanate into ethyl acetate in the presence of EDTA and thiosulphate as masking agents.     

Spectrophotometric determination of lead in biological samples with dibromo-p-methyl-methylsulfonazo

A new highly sensitive and selective chromogenic reagent, dibromo-p-methyl-methylsulfonazo (DBM-MSA), was studied for determination of lead. In 0.24 mol l(-1) phosphoric acid medium, which greatly increases the selectivity, lead reacts with DBM-MSA to form a 1:2 blue complex which has a sensitive absorption peak at 642 nm. Under the optimal conditions, Beer's law was obeyed over the range 0-0.6 mug ml(-1) Pb(II). The molar absorptivity and Sandell's sensitivity are 1.02x10(5) l mol(-1) cm(-1) and 0.00203 mug cm(-2), respectively. The limit of quantification, limit of detection and relative standard deviations were found to be 7.30 and 2.21 ng ml(-1) and 1.1%, respectively. It is found that, except for Ca(II) and Ba(II), all foreign ions studied do not interfere with the determination. The interference caused by Ca(II) and Ba(II) can be easily eliminated by prior extraction with potassium iodide-methylisobutylketone. The method has been applied to the determination of lead in some biological samples with satisfactory results.     

Determination of aluminum in environmental and biological samples by reversed-phase high-performance liquid chromatography via pre-column complexation with morin

Morin was used as a pre-column reagent for the determination of aluminum by RP-HPLC with fluorescence detection. This method has been successfully applied to direct determination of trace Al in environmental and biological samples. The response was linear from 6 x 10(-9) to 6 x 10(-5) M with a detection limit of 2 x 10(-9) M. In addition, the different Al complexes with morin were separated by the proposed HPLC procedure and their coordination ratios were depicted by molar-ratio method. The results showed that 1:1 and 2:1 Al-morin complexes formed.     

Non-extractive derivative spectrophotometric determination of cobalt in neutral micellar medium

A sensitive derivative spectrophotometric method using 1-nitroso-2-naphthol has been developed for determination of trace amounts of cobalt in the presence of a neutral surfactant. Photometric parameters, viz., lambda(max), molar absorption coefficient and analytical sensitivity of the complex formed in micellar media are 420 nm, 3.18x10(4) l mol(-1) cm(-1) and 2.05 ng ml(-1), respectively. Beer's law holds from 0.20 to 3.0 mug ml(-1) of the analyte concentration. The method has a high sensitivity with a detection limit of 1.68 ng ml(-1). A selective determination of cobalt in presence of copper(II) or iron(III) using derivative spectral profiles and without any masking or pre-separation is also reported. Samples of drugs and standard alloys analysed by the proposed method yielded results comparable to those obtained using recommended procedures.     

Spectrofluorimetric method for determination of aluminium with chromotropic acid and its application to water samples

A rapid and sensitive method for the trace level determination of aluminium based on the formation of a 1:1 complex with chromotropic acid (1,8-dihydroxynaphthlene-3,6-disulfonic acid) in an methanol medium is reported. The fluorescence intensity of the system was 50 times greater than that of the system without aluminium. This method is very sensitive and selective for the direct determination of aluminium ion. The fluorescence is excited at 346 nm and measured at 370 nm. The optimum conditions are a chromotropic acid concentration of 5.0 ml (1.0x10(-4) M) and pH 4.0+/-0.5 (acetic acid-sodium acetate buffer). The fluorescence intensity is a linear function of the concentration of Al(III) in the range 2-100 ng ml(-1) and the detection limit is 1.0 ng ml(-1). The method has been applied successfully to the determination of trace amount of Al(III) in tap, river and sea-water samples.     

A simple spectrophotometric method for the determination of copper in industrial, environmental, biological and soil samples using 2,5-dimercapto-1,3,4-thiadiazole.

A simple spectrophotometric method is presented for the rapid determination of copper at a trace level using 2,5-dimercapto-1,3,4-thiadiazole (DMTD) as a new spectrophotometric reagent. The method is based on the reaction of non-absorbent DMTD in a slightly acidic (0.002-0.014 mol dm(-3) sulfuric acid) aqueous solution with copper(II) to produce a highly absorbent greenish-yellow chelate product that has an absorption maximum at 390 nm. The reaction is instantaneous and the absorbance remains stable for 24 h. The average molar absorption coefficient and Sandell's sensitivity were found to be 5.65 x 10(4) dm3 mol(-1) cm(-1) and 10 ng cm(-2) of CuII, respectively. Linear calibration graphs were obtained for 0.1-20 microg cm(-3) of CuII; the stoichiometric composition of the chelate is 1:2 (Cu:DMTD). A large excess of over 50 cations, anions and complexing agents (e.g. tartrate, oxalate, citrate, phosphate, thiourea, SCN-) do not interfere in the determination. The method was successfully used for the determination of copper in several Standard Reference Materials as well as in some environmental water samples, biological samples, soil samples and solutions containing both copper(I) and copper(II) and complex synthetic mixtures. The method has high precision and accuracy (s = +/-0.01 for 0.5 microg cm(-1)).     

Separation of antimony(III) with iodide and dithizone by sorption on polyurethane foam from sulphuric acid medium for its spectrophotometric determination in glasses

A method for quantitative separation of antimony(III) by sorption on polyether based polyurethane foam and its spectrophotometric determination has been described. The method involves formation of a pink-red complex of antimony(III) with iodide (0.045M) and dithizone (2.3 x 10(-5)M) in 0.25-0.75M H(2)SO(4) medium, sorption of the complex on polyurethane foam (within 45 min) at room temperature followed by its elution with acidified acetone (acetone containing 0.008% H(2)SO(4)) and spectrophotometric measurement at 507.2 nm ( = 2.56 x 10(4) l mol cm). The method obeys Beer's law from 0.1 to 6.0 mug antimony(III). Tolerance limits of other ions are Co (100 mug), Ni (100 mug), Fe (10 mug), Cu (0.5 mug), Sn (20 mug), Zn (100 mug), As (100 mug), Mn (200 mug), Pb (50 mug), Ti (100 mug), V (50 mug), etc. Interference by iron and copper have been eliminated by treating with KOH prior to the extraction of antimony. The method has been standardized with glass samples spiked with known amounts of antimony and applied to the determination of antimony in various glasses.