Speciation determination of chromium(III) and (VI) using preconcentration cloud point extraction with flame atomic absorption spectrometry (FAAS).

bis-[2-Hydroxy-1-naphthaldehyde] thiourea was synthesized and preconcentration cloud point extraction (CPE) for speciation determination of chromium(III) and (VI) in various environmental samples with flame atomic absorption spectrometry (FAAS) has been developed. Chromium(III) complexes with bis-[2-hydroxynaphthaldehyde] thiourea is subsequently entrapped in the surfactant micelles. After complexation of chromium(III) with reagent, the analyte was quantitatively extracted to the surfactant-rich phase in the non-ionic surfactant Triton X-100 after centrifugation. The effect of pH, concentration of chelating agent, surfactant, equilibration temperature and time on CPE was studied. The relative standard deviation was 2.13% and the limits of detection were around 0.18 microg L(-1).

Preconcentration and solid phase extraction method for the determination of Co, Cu, Ni, Zn and Cd in environmental and biological samples using activated carbon by FAAS.

2-{[1-(2-Hydroxynaphthyl) methylidene] amino} benzoic acid (HNMABA) was synthesized for solid phase extraction (SPE) to the determination of Co, Cu, Ni, Zn and Cd in environmental and biological samples by flame atomic absorption spectrophotometry (FAAS). These metals were sorbed as HNMABA complexes on activated carbon (AC) at the pH range of 5.0+/-0.2 and eluted with 6 ml of 1M HNO3 in acetone. The effects of sample volume, eluent volume and recovery have been investigated to enhance the sensitivity and selectivity of proposed method. The effect of interferences on the sorption of metal ions was studied. The concentration of the metal ions detected after preconcentration was in agreement with the added amount. The detection limits for the metals studied were in the range of 0.75-3.82 microg ml(-1). The proposed system produced satisfactory results for the determination of Co, Cu, Ni, Zn and Cd metals in environmental and biological samples.

Facile and sensitive spectrophotometric determination of carbosulfan in formulations and environmental samples.

Facile, selective and sensitive spectrophotometric method has been developed for the determination of carbosulfan in insecticidal formulations, fortified water, food grains, agriculture wastewater and soil samples with newly synthesized reagents. The method was based on acid and alkaline hydrolysis of the carbosulfan pesticide, and the resultant hydrolysis product of carbosulfan was coupled with 2,6-dibromo-4-methylaniline to give a yellow color product with lambda(max) of 464 nm or interaction with 2,6-dibromo-4-nitroaniline to produce yellow colored product with lambda(max) of 408 nm or coupling with 2,4,6-tribromoaniline to form red colored product has a lambda(max) of 471 nm. Under optimal conditions, Beer's law range for 2,6-dibromo-4-methylaniline (DBMA) was found to be 0.2-12.0 microg ml(-1), 0.6-16.0 microg ml(-1) for 2,6-dibromo-4-nitroaniline (DBNA) and 0.4-15.0 microg ml(-1) for 2,4,6-tribromoaniline (TBA). The molar absorptivity of the color systems were found to be 3.112 x 10(4) l mol(-1) cm(-1) for DBMA, 3.214 x 10(4) l mol(-1) cm(-1) for DBNA and 3.881 x 10(4) l mol(-1) cm(-1) for TBA. Sandell's of the color reactions are 0.013 microg cm(-2) (DBMA), 0.012 microg cm(-2) (DBNA) and 0.011 microg cm(-2) (TBA) respectively. The effect of the non-target species on the determination of carbosulfan was studied to enhance the selectivity of the proposed methods. The formation of colored derivatives with the coupling agents is instantaneous and stable for 28, 30, and 26 h. Performance of the proposed methods were compared statistically in terms Student's F and t-tests with the reported methods.

Preconcentration technique for the determination of trace elements in natural water samples by ICP-AES.

A procedure was developed for the determination of Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in water samples by inductively coupled plasma atomic emission spectrometry (ICP-AES) after preconcentration on a morpholine dithiocarbamate (mor-DTC) supported by bagasse (Saccharam aphisinaram). The sorbed elements were subsequently eluted with 4,M HNO3 and the acid eluates were analysed by ICP-AES. The influence of various parameters such as pH, flow rate of sample, eluent concentration, volume of the sample and volume of eluent were investigated to enhance the sensitivity of the present method. A 20,mL disposable syringe served as preconcentration column. Under the optimal conditions Cd, Cu, Zn, Co, Ni, Mn, Pb and Mo in aqueous sample was concentrated about 100-fold. The sorption recoveries of elements were higher than 99.6%. The method is also applied for the analysis of natural and spiked water samples.

Development of simple and sensitive spectrophotometric method for the determination of bendiocarb in its formulations and environmental samples.

Facile, selective and sensitive spectrophotometric method has been developed for the determination of bendiocarb in its insecticidal formulations, fortified water, food grains, agriculture wastewater and agriculture soil samples with prepared reagents. The method was based on alkaline hydrolysis of the bendiocarb pesticide, and the resultant hydrolysis product of bendiocarb was coupled with 2,6-dibromo-4-methylaniline to give a yellow color product with lambda max of 457 nm or coupling with 2, 6-dibromo-4-nitroaniline to produce a red colored product with lambda max of 474 nm or coupling with 2, 4, 6-tribromoaniline to form orange red colored product has a lambda max of 465 nm. Under optimal conditions, Beer's law range for 2, 6-dibromo-4-methylaniline (DBMA) was found to be 0.6-14.0 microg mL (-1), 0.8-10.0 microg mL (-1) for 2, 6-dibromo-4-nitroaniline (DBNA) and 0.4-10.0 microg mL (-1) for 2, 4, 6-tribromoaniline (TBA). The molar absorptivity of the color systems were found to be 4.126 x 10(4) l mol (-1) cm (-1) for DBMA, 3.254 x 10(4) l mol (-1) cm (-1) for DBNA and 2.812 x 10(4) l mol (-1) cm (-1) for TBA. Sandell's of the color reactions are 0.018 microg cm (-2)(DBMA), 0.052 microg cm (-2)(DBNA) and 0.065 microg cm (-2) (TBA) respectively. The effect of the non-target species on the determination of bendiocarb was studied. The formation of colored derivatives with the coupling agents is instantaneous and stable for 18 h, 30 h, and 12 h. Performance of the proposed methods were compared statistically in terms Student's F and t-tests with the reported methods.

RETRACTED: Development of novel reactions for the simple and sensitive spectrophotometric determination of vanadium in various samples.

This article has been retracted at the request of the Editors-in-Chief. Please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). Reason: Considerable concern was raised about the research purportedly conducted at Sri Venkateswara University, India with the alleged involvement of Professor P. Chiranjeevi. Questions were raised as to the volume of publications, the actual capacity (equipment, orientation and chemicals) of the laboratory in which Professor Chiranjeevi worked, the validity of certain of the research data identified in the articles, the fact that a number of papers appear to have been plagiarized from other previously published papers, and some aspects of authorship. Professor Chiranjeevi was given the opportunity to respond to these allegations. Thereafter, a committee was constituted by the University to look into these allegations. Based on the enquiry committee report, we have been informed by the head of the Department of Chemistry at Sri Venkateswara University that the university authorities have taken disciplinary action against ProfessorChiranjeevi, as the university considers that there are grounds for such action. Therefore, based on the results of this investigation, the Editors-in-Chief are retracting this article.