Spectrophotometric Determination Of Lead Research Articles

Indirect micellar spectrophotometric determination of lead in various soybean based products using green chemistry

The study was conducted for the purpose of quantifying lead in various samples of soy-products by micellar spectrophotometry using green chemistry approach. The ligandN2P4HB was synthesized for the purpose with the help of weak acid and is found to be soluble in alcohol, acetone and in chlorinated hydrocarbons such as chloroform. It dissolves in alkaline aqueous media but is practically insoluble in water at pH less than 6. In the presence of surfactants its solubility has been found to be increased significantly. On addition of solution of ligand in presence of surfactants to metal ion solution, colored complex were formed. The local nonpolar microenvironment of the micelles incorporates the non-polar colored complex. Secondly a marked increase in absorption intensity has also been observed. This phenomenon of micellar solubilization with increasing absorption intensity has been used to develop a novel, green, simple, inexpensive and sensitive spectrophotometric method for determination of heavy metal ion in various soy products.

Spectrophotometric Determination of Lead in Tea Leaf Sample with Dibromo-p-chloro-arsenazo

Spectrophotometric Determination of Lead in Tea Leaf Sample with Dibromo-p-chloro-arsenazo

Solid-phase spectrophotometric determination of lead using chromazurol S

The complex formation between lead and chromazurol S in the phase of an AB17×8 ion-exchanger has been studied. The data obtained have been used to develop a procedure for the solid-phase spectrophotometric determination of lead in drinking water. The sensitivity of the determination is 0.02 μg/mL.

Flow injection spectrophotometric determination of lead using 1,5-diphenylthiocarbazone in aqueous micellar

A simple flow injection colorimetric procedure for determining lead was established. It is based on the reaction of lead in sulfuric acid with 1,5-diphenylthiocarbazone and sodium dodecyl sulfate, resulting in an intense red-blue complex with a suitable absorption at 500 nm. A standard or sample solution was injected into the sulfuric acid stream (flow rate of 2.0 ml min(-1)), which was then merged with sodium dodecyl sulfate stream (flow rate of 2.0 ml min(-1)) and 1,5-diphenylthiocarbazone stream (flow rate of 1.5 ml min(-1)). Optimum conditions for determining lead were investigated by univariate method. Under the optimum conditions, a linear calibration graph was obtained over the range 1.0-12.0 microg ml(-1) and the detection limit was 0.027 microg ml(-1) (s/n=3). The relative standard deviation of the proposed method calculated from 12 replicate injections of 4.0 and 8.0 microg ml(-1) of lead was 0.42% and 0.38%, respectively. The sample throughput was 80 h(-1). The proposed method has been satisfactorily applied to the determination of lead in water samples.

Spectrophotometric determination of lead in traditional Chinese medicines with dibromop-methyl-acethylsulfonazo

A new highly sensitive and selective chromogenic reagent dibromo-p-methyl-acethylsulfonazo (DBMASA) has been synthesized and purified. A method has been proposed for the spectrophotometric determination of lead with DBMASA in traditional Chinese medicines. The content of lead in the samples was low, so we used sulfhydryl cotton fiber (SCF) to separate and enrich trace Pb(II), which lead to a satisfactory result. In 0.25 M phosphoric acid medium, which greatly increased the selectivity, lead reacted with DBMASA to form a 1: 2 blue complex, having an intense absorption peak at 640 nm. Under the optimal conditions, Beer’s law is obeyed over the range 0.01–1.0 µg/mL of Pb(II) and the apparent molar absorptivity is 1.06 × 105 L/mol cm. The detection limit and variation coefficient are found to be 2.1 ng/mL and 1.3%, respectively. The method has been applied to the determination of lead in traditional Chinese medicines with satisfactory results.

Spectrophotometric determination of lead after preconcentration of its diphenylthiocarbazone complex on an Amberlite XAD-1180 column

A simple methodology has been developed for the solid phase extraction of lead based on the adsorption of its diphenylthiocarbazone complex on an Amberlite XAD-1180 column. The effect of various parameters such as eluting agents, stability of the column, sample volume, interfering ions, etc. were studied in detail. The adsorbed complex could be eluted using acetone and the concentration of lead was determined using visible spectrophotometry at a wavelength maximum of 486 nm. A detection limit of 3.5 μg L −1 could be achieved and the validity of the proposed method was checked in spiked tap water, well water and industrial wastewater samples. The relative standard deviation of the method was found to be 3.0%. The highest preconcentration factor attainable for quantitative recovery (>95%) of lead was 25 for a 250 mL sample volume.

Spectrophotometric Determination with a Chromogenic Reagent of Lead in Vegetables

A method was developed for the simple, selective, and sensitive spectrophotometric determination of lead in vegetables with synthesized chromogenic reagent 3-[(2,6-dibromo-4-methylphenyl)diazenyl]-4,5-dihydroxy-6-[(2,4,6-tribromophenyl)diazenyl]naphthalene-2,7-disulfonic acid (DBMTBA; 1). In 0.25 M phosphoric acid medium, which greatly increases the selectivity, lead reacts with DBMTBA to form a 1:2 blue complex, which shows maximum absorption at 646 nm. Under optimal conditions, Beer's law is obeyed over the range from 0.09 to 0.8 microg ml(-1) Pb2+, and the apparent molar absorptivity is 1.024x10(5) l mol(-1) cm(-1). The detection limit and the variation coefficient were found to be 2.09 microg ml(-1) and 1.0%, resp. The proposed method has been applied successfully for the determination of lead in vegetables (Solanum melongena fruits, tomato fruits, Ablemoschus esculentus leaves, and Daucous carota leaves) with satisfactory results.

Α Review of Reagents for Spectrophotometric Determination of Lead (II)

Α Review of Reagents for Spectrophotometric Determination of Lead (II)

Spectrophotometric Determination of Lead(II) Ion by 96-Well Microplate Electrostatically Immobilized Porphyrin

A water-soluble 5,10,15,20-tetrakis(4-N-methylpyridyl)porphine (TMPyP) was used as a highly sensitive chromogenic reagent for the lead(II) ion. When this TMPyP was complexed with the lead(II) ion, the absorption spectra of TMPyP significantly changed in the Soret band {H2TMPyP: λmax = 423 nm (ε: 2.6 × 105 M− cm−1), Pb(II)-tmpyp: λmax =476 nm (ε: 1.8 × 105 M−1cm−1)}. In this study, the spectrophotometric multi-determinations of the lead(II) ion were developed using a microplate electrostatically immobilized TMPyP on the surface of the well. As a result, the lead(II) ion was quantitatively reacted within 15 min with TMPyP at pH 9 and 60°C. The determination range of the lead(II) ion was 7.5 × 10−7 M to 1.0 × 10−4 M, the relative standard deviation at median was 4.04% (n = 96), and the detection limit (3σ) was 5.0 × 10−7 M. Also, the same plate was able to be reused ten times. Furthermore, the determination of the lead(II) ion present in tap water was possible with citric acid as a masking agent.

Ion Exchange Separation of Lead from Strontium in Certified Reference Samples and Spectrophotometric Determination of Lead as Extractable Ion-Pair of Eosin2−and the Lead–Cryptand (2.2.2)2+Complex

Abstract A two-step procedure including anion exchange separation of lead from strontium in geological reference samples and a spectrophotometric determination of the separated lead as lead–cryptate (2.2.2) complex is presented. The exchangeable anion Cl− of the ion exchange resin (Dowex 1 × 4) is changed to Br− in 6 M HBr solution. Lead is quantitatively retained in the column from 0.5 M HBr medium, while Sr2+, Ba2+, Ca2+, Mg2+, Na+, K+, Fe3+, Cr3+, and Al3+ are passed through. Subsequently the retained Pb is eluted from the column with 6 M HBr. The separation efficiency of the resin is controlled using mixed standard solution of (Pb, Sr, Ca, Mg, Ba, Na, K, Fe, Cr and Al), and radioactive tracers of 85Sr and 131Ba. The resin selectivity coefficient (K) of separating Pb from Sr is found to be . The Spectrophotometric method of lead determination is based on the formation of lead–cryptate (2.2.2) complex at pH 8.3 using borate/HCl as a buffer solution. Then the ion-pair of eosin2+ and lead–cryptand (2.2.2)...

Spectrophotometric determination of lead in industrial, environmental, biological and soil samples using 2,5-dimercapto-1,3,4-thiadiazole

A very simple, ultra-sensitive and fairly selective non-extractive spectrophotometric method for the determination of trace amounts of lead with 2,5-dimercapto-1,3,4-thiadiazole (DMTD) has been developed. DMTD reacts in slightly acidic (0.0015–0.01 M HCl) aquatic media with lead(II) to give a greenish-yellow chelate, which has an absorption maximum at 375 nm. The reaction is instantaneous and absorbance remains stable for 24 h. The average molar absorption coefficient and Sandell's sensitivity were found to be 4.93×10 4 l mol −1 cm −1 and 15 ng cm −2 of Pb, respectively. Linear calibration graphs were obtained for 0.1–40 μg ml −1 of Pb; the stoichiometric composition of the chelate is 1:2 (Pb–DMTD). The interference from over 50 cations, anions and complexing agents has been studied at 1 μg ml −1 of Pb. The method developed was used successfully in the determination of lead in several standard reference materials (alloys and steels), environmental waters (potable and polluted), biological samples (human blood and urine), soil samples, solutions containing both lead(II) and lead(IV) and complex synthetic mixtures. The method has high precision and accuracy ( S=±0.01 for 0.5 μg ml −1).

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 μg ml−1 Pb(II). The molar absorptivity and Sandell's sensitivity are 1.02×105 l mol−1 cm−1 and 0.00203 μg 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.

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 μg ml −1 of lead(II). The molar absorptivity of the extracted species is 1.93 × 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.

Spectrophotometric Determination of Lead by Extraction of the Mixed-Metal Complex Pb(II)-Ca-Purpurin (1,2,4-Trihydroxyanthraquinone)

Abstract Mixtures of Lead(II) and Ca(II) form with purpurin (P; 1,2,4-Trihydroxyanthraquinone) the mixed-metal-complex PbCaP3, which is extracted with isobutyl methyl ketone (IBMK) at pH 7.8. The molar absorptivity of the complex is 2.8 × 104 l.mol−1.cm−1 at 575 nm and its conditional extraction constant 2.5 × 1017 14.mole−4. The use of this complex for the spectrophotometric determination of lead up to 40 μg has been investigated. The proposed procedure has been successfully applied to the analysis of this metal in different samples.

Fourth Order Derivative Spectrophotometric Determination of Lead with 1,10-Phenanthroline and Rose Bengal

Abstract Higher order derivative techniques are mainly used in deconvoluting the overlapping absorption spectra of various analytes in their determination. The procedure utilizing higher order derivatives in molecular absorption spectrophotometry essentially are based on the formation of either binary or ternary complex formation. This paper deals with fourth order derivative spectrophotometric procedure for the determination of traces of lead based on the liquid-liquid extraction of ternary ion association complex lead with 1,10-phenanthroline and rose bengal into chloroform. The ternary ion associate is stable for over 24 hours. The developed procedure is simple, rapid, reliable and allows the determination of as low as 20 ppb of lead in sea water samples.

Spectrophotometric determination of lead in tap water with 5,10,15,20-tetra(4-N-sulfoethylpyridinium)porphyrin using merging zones flow injection.

Determination of lead at concentrations of > or = 15 micrograms I-1 in aqueous samples was achieved by selective reaction with 5,10,15,20-tetra(4-N-sulfoethylpyridinium)porphyrin at pH 9.4 and 30 degrees C in a merging zones flow injection manifold followed by detection at 480 nm after an elapsed time of 45 s. Interference by aluminium (125-fold excess), cadmium (25-fold excess), copper (25-fold excess), manganese (200-fold excess) and zinc (200-fold excess) was eliminated by the use of 1.0 mol I-1 NH3-NH4CI as a buffer/masking agent; interference by iron (10-fold excess) was eliminated by the addition of 1% v/v of acetylacetone to the reagent mixture and use of the method of standard additions for sample analysis. Recoveries from tap water samples, to which various amounts of lead had been added, ranged from 98 to 109% with a detection limit of 10 micrograms I-1 when iron was present in the sample matrix and 4.2 micrograms I-1 when it was not. Results of analyses of tap water samples using this method were in good agreement with those obtained by electrothermal atomic absorption spectrometry.

Spectrophotometric Determination of Lead with Dithizone after Selective Separation on Polyurethane Foam Sorbents

A spectrophotometric method has been developed for determination of small amounts of lead in glass and some ceramic raw materials. The method involves selective separation of lead with 5.85 × 10−5M dithizone and 7.5 × 10−2M KCN at pH∼10 followed by elution of the complex with acetone and making it alkaline with 0.2 ml of 2.5M NH3 in a total volume of 10 ml. The method obeys Beer's law from 0.1 to 2.5 μg Pb.ml−1 at 500 nm. Correlation coefficient calculated from the linearity curve is 0.99. Interferences due tp Cu(II), Co(II), Ni (II), Zn(II), Cd(II), Mn(III) and Fe (II) have been eliminated automatically by using KCN. Effect of Fe(III) could be eliminated by extraction with MIBK prior to the separation of lead. The developed method has been standardized against National Bureau of Standards opal glass sample (NBS 91). Standard deviation of the results has been found to be ±0.0021.

Spectrophotometric determination of lead in environmental objects with the new highly effective reagent HOCAC

A simple method has been developed for determination of traces of lead with the new organic reagent HOCAC (hexaoxacycloazochrom). The method was used for lead determinations in waters, soils and food after extraction or sorption of the lead followed by direct reagent addition to the acid re-extract or eluate. It is possible to determine Pb down to 2 μg in 1 l water after extraction or down to 10 μg in 1 l water and down to 500 μg in 1 kg potatoes or soil after sorption.

Spectrophotometric Determination of Lead in some propellants

A new sensitive method has been proposed for the determination of lead in some single- and double-base propellants. The method is based on the color reaction of lead(II) with hematoxylin in presence of the cationic surfactant cetyltrimethylammonium bromide. At pH 8.0, the formed ternary system possesses an absorption maximum at 605 nm with a molar absorptivity of 5.5 × 104l · mol−1 · cm−1. The system adheres to Beer's law up to 1.78 ppm of lead, and the sensitivity index is 0.0039 μg · cm 2. The susceptibility of interference of common ions is studied and some masking agent solutions are recommended to improve the selectivity of the method. The proposed method shows good agreement with the results obtained by atomic absorption spectrometry. An average recovery of 99.3% with a standard deviation not exceeding 1.7% is observed.

Spectrophotometric determination of lead with Pyrocatechol Violet and cationic surfactants

The optimum conditions for the formation of ternary lead complexes with Pyrocatechol Violet and cationic surfactants have been evaluated. The examined ternary systems form a basis for simple and sensitive spectrophotometric methods for lead (ϵ = 4.20−5.06 × 10 4 liters · mol −1 · cm −1). Using the most sensitive method, lead content in zinc powder has been determined. Lead does not form ternary complexes with the other triphenylmethane reagents, Chrome Azurol S and Eriochrome Cyanine R, in the presence of cationic surfactants because of its too “soft” properties.