University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Talasila Prasada Rao

Abbrev:
Prasada Rao, T.
Other Names:
Address:
CSIR, Regulatory Research Laboratory Center, Marine Analytical Reference and Standards, Trivandrum 695019, Kerala India
Phone:
+91 471-2490674
Fax:
+91-471-2491712

Citations 16

"Flow Injection On-line Solid Phase Extractive Preconcentration Of Palladium(II) In Dust And Rock Samples Using Exfoliated Graphite Packed Microcolumns And Determination By Flame Atomic Absorption Spectrometry"
Talanta 2006 Volume 70, Issue 2 Pages 437-443
R.S. Praveen, S. Daniel, T. Prasada Rao, S. Sampath and K. Sreenivasa Rao

Abstract: A sensitive and efficient flow injection pre-concentration and matrix-separation technique using exfoliated graphite (EG) as column material was developed prior to flame atomic absorption spectrometry (FAAS) determination of palladium(II) in street/fan blade dust and rock samples. The method is based on the sorption of palladium(II)-diethylammonium dithiocarbamate chelate (which was found to be better among various thioligands) complex on to EG material and its subsequent elution with acidified methanol (0.01 M HCl in methanol). Using 8 mL of the sample, the detection limit achieved was 1.0 µg l-1. The accuracy of the method developed was checked by analyzing certified reference material SARM-7. The precision obtained for five successive determination of 100 µg L-1 of palladium(II) was 2.4%. The performance of EG material was compared with allotropes of carbon in terms of pH, chelate concentration, weight of column material, sensitivity enhancement (w.r.t. conventional FAAS), detection limit, calibration range, selectivity and precision. Furthermore, performance of the EG material packed column was compared with commercially available C18 bonded silica gel/alumina columns for on-line FIA-FAAS determination of palladium(II).

"On-line And Off-line Preconcentration Of Trace And Ultratrace Amounts Of Lanthanides"
Talanta 2004 Volume 63, Issue 4 Pages 949-959
T. Prasada Rao and R. Kala

Abstract: The need for pre-concentration of trace and ultratrace amounts of lanthanides from environmental, geological and biological samples is brought out in introductory part. Both on-line and off-line pre-concentration procedures developed for lanthanides since 1980 are reviewed. The pre-concentration techniques covered in this review include liquid-liquid extraction (LLE), ion-exchange, co-precipitation, and solid phase or solid-liquid extraction. Separate sections are devoted to each of the pre-concentration techniques employed for enrichment of individual or mixtures of lanthanides. Future trends in singular or multielement pre-concentration of lanthanides are also discussed.

"Determination Of Arsenic In Sea Water By Sorbent Extraction With Hydride Generation Atomic Absorption Spectrometry"
Talanta 1999 Volume 49, Issue 3 Pages 523-530
S. Karthikeyan, T. Prasada Rao and C. S. P. Iyer

Abstract: A rapid and sensitive sorbent extraction hydride generation-flow injection analysis atomic absorption spectrometric (HG-FIAS-AAS) method is described for the determination of As(III) and As(V) based upon online pre-concentration on a microcolumn packed with activated alumina. In the present procedure these arsenicals are complexed with quinolin-8-ol-5-sulfonic acid from neutral solutions in the flow injection system and adsorbed on the column. The pre-concentrated species are eluted with 10% HCl, mixed with 0.5% sodium borohydride and carried to the HG-FIAS cell with a carrier gas flow rate of 75 mL min-1. The retention efficiency is found to be better than 98% with sensitivity enhancement of 12 and 10 for As(III) and As(V), respectively, for a 20 s pre-concentration period. The respective detection limits are 0.05 and 2 ng mL-1 for As(III) and As(V). The throughput of the samples is found to be 60 hr-1, with a loading time of 20 s. The method has been applied to sea water samples.
Tubular membrane Speciation

"Application Of Ternary And Multicomponent Complexes To Spectrophotometric And Spectrofluorimetric Analysis Of Inorganics"
Talanta 1998 Volume 46, Issue 5 Pages 765-813
T. Prasada Rao*, M. L. P. Reddy and A. Ramalingom Pillai

Abstract: The application of ternary and multicomponent complexes in spectrophotometric and spectrofluorimetric determination of trace elements is reviewed. Newer types of color systems employing mixed ligand, surfactant sensitized, ion-association, flotation, derivative and FIA systems are described. Separate sections are devoted to advances in both spectrophotometric and spectrofluorimetric determination of individual elements. Future trends in spectrophotometric and spectrofluorimetric analysis are discussed.
Metals, rare earth Fluorescence Spectrophotometry Ion pair formation Review

"Overview Of Flow Injection Analysis Of Inorganics In India"
Pollut. Res. 2003 Volume 22, Issue 4 Pages 553-560
TP Rao, VM Biju, JM Gladis

Abstract: Flow injection analysis (FIA) was invented in 1975 by professors Ruzicka and Hansen. Since its inception, various facets of FIA was developed over the years for the trace and ultratrace determination of inorganics. In India conjunction with spectrophotometric detection was initiated in late 1980's by Professor Mahadevappa. Subsequently, Professor Surekha Devi and our own group have developed FI on-line pre-concentration and flame atomic absorption spectrometric (FAAS) procedures for the determination of ultratrace amounts of different inorganics: In mid- 1990's, Professor Chakraborti's group has employed FI-hydride generation AAS methods for the determination of arsenic, mercury and lead. This article highlights salient features of various FIA procedures developed so far in India in conjunction with various molecular and atomic spectrometric detectors. Further, the future scenario of this potential technique in routine analysis of trace and ultratrace amounts of inorganics in various real samples has been brought out. © Enviromedia.

"Removal And Recovery Of Mercury(II) From Hazardous Wastes Using 1-(2-thiazolylazo)-2-naphthol Functionalized Activated Carbon As Solid Phase Extractant"
J. Hazard. Mater. 2004 Volume 113, Issue 1-3 Pages 75-79
A.M. Starvin and T. Prasada Rao

Abstract: As a part of removal of toxic heavy metals from hazardous wastes, solid phase extraction (SPE) of mercury(II) at trace and ultra trace levels was studied using 1-(2-thiazolylazo)-2-naphthol (TAN) functionalized activated carbon (AC). The SPE material removes traces of mercury(II) quantitatively in the pH range 6.0 [plus-or-minus sign] 0.2. Other parameters that influence quantitative recovery of mercury(II), viz. percent concentration of TAN in AC, amount of TAN-AC, pre-concentration time and volume of aqueous phase were varied and optimized. The possible means of removal of Hg(II) from other metal ions that are likely to be present in the wastes of the chloroalkali industry is discussed. The potential of TAN-functionalized AC SPE material for decontaminating mercury from the brine sludge and cell house effluent of a chloralkali plant has been evaluated.

"On-line Flow Injection Flame AAS Determination Of Cobalt In Soil And Sediment Samples With 5,7-dichloroquinoline-8-ol-embedded Polymeric Materials"
Atom. Spectrosc. 2006 Volume 27, Issue 2 Pages 35-43
PRAVEEN R. S.; DANIEL Sobhi; PRASADA RAO T.

Abstract: Dichloroquinoline-8-ol-embedded styrene-ethylene-glycol dimethacrylate polymer materials were prepared via the bulk, precipitation, and suspension polymerization methods using similar compositions. The polymerization was carried out by thermal means in the presence of 2,2?- azobisisobutyronitrile as initiator and 2-methoxy ethanol as porogen. The above synthesized polymer materials were characterized physically and morphologically by using the FTIR, TGA, CHN, and SEM techniques. These polymeric materials were packed into homemade µcolumns and used for on-line solid phase extraction (SPE) pre-concentration of trace amounts of cobalt. The pre-concentrated cobalt species were eluted with 0.01 mol L-1 of nitric acid and injected directly into the nebulizer of a flame atomic absorption spectrometer (FAAS) for quantification. The enrichment factors for bulk, precipitation, and suspension polymerization materials, were 12.5, 12.5, and 6.0, respectively, with a 1-min pre-concentration time and a sample throughput of 30 h-1. The detection limits corresponding to 3 times the standard deviation of the blank were found to be 10, 10, and 80 ?g L-1 with a precision of 2.1, 2.5, and 2.6% (RSD) for five successive determinations of 80 ?g L -1 of cobalt. Furthermore, the retention capacities determined by the batch method were 11.46, 11.42, and 8.52 mg of Co(II) per g of bulk, precipitation, and suspension polymerization materials, respectively. Thus, enrichment factor, detection limit, and retention capacities are in the order: precipitation ? bulk > suspension. No significant interference was observed from neutral electrolytes and 100-fold amounts of Fe(III), Ni(II), Mn(II), Cu(II), and Zn(II). In addition to testing the accuracy of the developed procedure for the determination of cobalt in certified reference materials of soil and marine sediments, the method was applied successfully to the determination of cobalt in real soil and sediment samples.

"On-line Solid Phase Extraction Preconcentration Of Ultratrace Amounts Of Cobalt And Nickel In Soil And Human Hair Samples For Determination By Flow Injection Flame AAS"
Atom. Spectrosc. 2004 Volume 25, Issue 6 Pages 238-244
Starvin, A M; Biju, V M; Rao, T Prasada

Abstract: A flow injection on-line solid phase extraction (SPE) pre-concentration system, coupled to a flame atomic absorption spectrometer (FAAS), was developed for the determination of cobalt and nickel at the ?g/L levels. Cobalt and nickel were complexed with 2,3-dihydroxy naphthalene (DHN) in the pH range of 2.0-8.0 in the flow injection system and adsorbed onto a C18-bonded silica gel microcolumn. The pre-concentrated metal-DHN complexes were eluted with acidified methanol (pH ?2). The eluent was injected directly into the nebulizer of a FAAS for measurement. The enrichment factors were 725 and 600 for cobalt and nickel, respectively, with a 1-min pre-concentration time and a sample throughput of 30/h. The detection limits, corresponding to three times the standard deviation of the blank, were found to be 0.1 ?g/L with a precision of 2.5 and 2.6% (RSD) for five successive determinations of 10 ?g/L of Co and Ni, respectively. No significant interference was observed from neutral electrolytes, Fe, Zn, and Cu. In addition to testing the accuracy of the developed procedure for the analysis of nickel soil reference material (IAEA, Soil-7), the method was also applied successfully to the determination of Ni in soil and Ni and Co in human hair samples.

"On-line Solid Phase Extraction Preconcentration Of Ultratrace Amounts Of Zinc In Fractionated Soil Samples For Determination By Flow Injection Flame AAS"
Atom. Spectrosc. 2003 Volume 24, Issue 4 Pages 118-124
CR PREETHA, VM BIJU, T PRASADA RAO

Abstract: A flow injection on-line solid phase extraction (SPE) pre-concentration system coupled to a flame atomic absorption spectrometer (FAAS) was developed for the determination of zinc at the ?g L-1 level. Zinc is complexed with 1-(2-thiazolylazo)-2-naphthol (TAN) in the pH range of 9.5-11.0 in the flow injection system and adsorbed onto a C18-bonded silica gel µcolumn. The pre-concentrated Zn-TAN complex was eluted with acidified methanol (pH-2). The eluent was injected directly into the nebulizer of a FAAS for measurement. The enrichment factor was 120 with a 1-min pre-concentration time and a sample throughput of 30 h-1. The detection limit corresponding to three times the standard deviation of the blank was 0.15 ?g L-1 with a precision of 2.5% (RSD) for five successive determinations of 5 ?g L-1 of Zn. No significant interference was observed from neutral electrolytes and cations of soil samples. The method was also applied successfully in the analysis of soils which were fractionated as per BCR (now Standards, Measurements and Testing Program) using both the direct and standard addition (SA) methods.

"On-line Solid Phase Extraction Of The 5,7-dichloroquinoline-8-ol Complex Onto C18 Bonded Silica Gel And Flame AAS Determination Of Cu In Seawater Samples"
Atom. Spectrosc. 2002 Volume 23, Issue 5 Pages 143-147
MARY GLADIS J, BIJU V M, PRASADA RAO T

Abstract: A flow injection on-line adsorption pre-concentration system coupled to flame atomic absorption spectrometry (FAAS) was developed for the determination of copper at the ?g L-1 level. Copper is complexed with 5,7-dichloroquinoline-8-ol in the pH range of 7.0-9.0 in the flow injection system and adsorbed onto the C18 bonded silica gel column. The pre-concentrated chelate complex was eluted with acidified methanol (pH >2) and injected directly into the nebulizer for atomization in an air- acetylene flame for measurement. With a 1-minute pre-concentration and sample frequency of 30 h-1, the enrichment factor was 100, which can be further improved by increasing the pre-concentration time. The detection limit was 0.05 ?g L-1 and the precision 1.4% at the 2 ?g L-1 Cu level. Validation of the developed method was carried out by analyzing certified seawater reference material (CASS 4) and determining copper at a concentration of 0.60±0.06 compared to a certified value of 0.592±0.05 ?g L-1. The method was also applied successfully to the analysis of seawater samples and the accuracy was tested by recovery measurements on spiked samples. No significant interferences from other substances usually occurring in seawater were found.

"Quinoline-8-ol And Its Derivatives As Preconcentration Agents In Flow Injection Analysis Coupled To Atomic And Molecular Spectrometric Techniques"
Anal. Sci. 2002 Volume 18, Issue 5 Pages 517-524
T. Prasada Rao And J. Mary Gladis

Abstract: Quinoline-8-ol, one of the most popular and versatile organic reagents, is known to react with several metals, because it has both a basic nitrogen and a phenolic group. Hence, quinoline-8-ol and its derivatives have been widely used as chelating and/or sorbent extraction agents in on-line flow injection analysis (FIA) along with a suitable detection technique. The state of the art for using quinoline-8-of and its derivatives in FIA was studied in terms of the selectivity, sensitivity and precision. Emphasis was placed on validating these procedures by analyzing certified reference materials and applying these analytical methodologies to real samples for the determination of inorganics.

"Online Flow Injection Preconcentration And Flame Atomic Absorption Spectrometric Determination Of Palladium(II) Using Inorganic And Inorganic-organic Hybrid Materials-packed Microcolumns"
Anal. Lett. 2006 Volume 39, Issue 6 Pages 1187-1199
Ramachandran Sarojam Praveen; Sobhi Daniel; Talasila Prasada Rao

Abstract: Various inorganic and inorganic-organic hybrid materials-packed columns, including commercially available C18 bonded silica gel and alumina columns, were tested for the on-line pre-concentration of palladium(II) and subsequent determination by flame atomic absorption spectrometry (AAS). Several thioligands were investigated for complexing palladium(II) and subsequent sorption, elution, and determination by flame atomic absorption spectrometer. Among them, diethyl ammonium dithiocarbamate was found to give the highest enrichment factor for a given concentration of palladium(II) under optimized conditions. After testing the accuracy of the developed method by analyzing certified reference material (SARM 7), it was applied for the analysis of street and domestic fan blade dust samples. Copyright © Taylor & Francis Group, LLC.

"Flow Injection Online Preconcentration And Flame AAS Determination Of Copper, Cadmium And Lead In Marine Sediment Samples"
Anal. Lett. 1997 Volume 30, Issue 5 Pages 1037-1050
S. Kartikeyan; B. Vijayalekshmy; S. Chandramouleeswaran; T. P. Rao; C. S. P. Iyer

Abstract: Marine sediment (0.25 g) was mixed with 5 mL of 48% HF, 30 mL of 70% HNO3 and 2-5 drops of 98% H2SO4 and the mixture was digested (details given). Sample and ammoniacal dithizonate solutions were pumped simultaneously and mixed online. Preconcentration was performed on a C18 column over 1 min and Cu, Cd and Pb were eluted with acidified methanol and injected directly into the nebulizer for atomization in an air-acetylene flame. The calibration graph was linear from 1-40, 0.6-8 and 3-40 ppb, with detection limits of 1.2, 0.6 and 3 ppb Cu, Cd, and Pb, respectively. RSD were
Copper Cadmium Lead Marine Sample preparation Spectrophotometry C18 Preconcentration

"Ternary Ion-association Complex Based Ion Imprinted Polymers (IIPs) For Trace Determination Of Palladium(II) In Environmental Samples"
Anal. Chim. Acta 2006 Volume 570, Issue 1 Pages 79-87
Sobhi Daniel, R.S. Praveen and Talasila Prasada Rao

Abstract: A new ion imprinted polymer (IIP) material was synthesized by co-polymerization of palladium-iodide-vinyl pyridinium/palladium-thiocyanate-vinyl pyridinium ion ternary ion-association complex taken in methanol/DMSO with 2-hydroxyethyl methacrylate (functional monomer) and ethylene glycol dimethacrylate (crosslinking monomer) in the presence of 2,2?-azobisisobutryonitrile (initiator). The imprinted anionic species [PdI4]2- or [Pd(SCN)4]2- were removed by leaching the dried and powdered materials particles for 18 h with 6 M HCl to obtain leached IIP particles. Non-imprinted/control polymers were also prepared in a similar fashion without the template. Various parameters that influence the percent extraction of palladium, viz. concentration of KI or KSCN, pH, weight of polymer particles, pre-concentration and elution times, aqueous phase volume, etc., were systematically studied for both the systems, i.e., in batch as well as flow injection modes. As the on-line flow injection-flame atomic absorption spectrometric (FI-FAAS) allow offer higher enrichment factor, better precision and can analyze more samples for a given time, compared to batch method, this procedure is preferred for the analysis of palladium present in the street/fan blade dust samples collected from busy cities of India and the values obtained were compared with the standard ICPMS values. © 2006 Elsevier B.V. All rights reserved.

"Speciative Determination Of Chromium(VI) And Chromium(III) Using Flow Injection Online Preconcentration And Flame Atomic-absorption Spectrometric Detection"
Anal. Chim. Acta 1998 Volume 369, Issue 1-2 Pages 69-77
T. Prasada Rao*, S. Karthikeyan, B. Vijayalekshmy and C. S. P. Iyer

Abstract: A rapid, sensitive and selective method for the speciative determination of Cr(VI) and Cr(III) in sea-water samples by flame atomic-absorption spectrometry, using online pre-concentration. on a micro-column packed with C18 bonded silica gel, was developed. This is based on the selective formation of diethyldithiocarbamate complexes of Cr(VI) in the 1-2 pH range and Cr(III) in the 4-9 pH range in the presence of Mn(II) (which enhances the Cr(III) signal 10-fold). The pre-concentrated species desorbed by MeOH directly from the column to the nebulizer-burner system using a flow rate of 4.0 mL/min. Five hundred-fold enrichment of Cr(VI) and Cr(III) was observed with a detection limit of 0.02 µg/l for a 5 min pre-concentration. time. The effect of probable concomitant species in seawater was determined and a satisfactory recovery of 95-105% could be obtained. Linear calibration curves were obtained for both the species, Cr(VI) and Cr(III), in the 0.2-200 µg/l concentration. range. Relative standard deviations were 3.5 and 5.1% for Cr(VI) and Cr(III), respectively, in the determination of 50 µg/l of each of these species. The developed procedure is suitable for the determination of Cr(VI) and Cr(III) species (Cr(total)) in various sea-water samples of western and eastern coasts of India. Further, the developed procedure was successfully applied for the determination of Cr(VI) and Cr(III) species in tannery and plating-bath effluents.
Chromium(III) Chromium(VI) Sea Industrial Spectrophotometry Speciation Preconcentration C18 Silica Diethyldithiocarbamate Complexation

"Flow Injection Online Preconcentration And Flame Atomic Absorption Spectrometric Determination Of Iron, Cobalt, Nickel, Manganese And Zinc In Sea-water"
Analyst 1999 Volume 124, Issue 2 Pages 191-195
Kurissery A. Tony, Satrugnan Kartikeyan, Bhavaniamma Vijayalakshmy, Talasila Prasada Rao and Chonatumatom S. Padmanabha Iyer

Abstract: A rapid and sensitive flow injection analysis-atomic absorption spectrometric procedure is described for the determination of iron, cobalt, nickel, manganese and zinc based upon online pre-concentration on a microcolumn packed with C-18 material. These metals were complexed with 5,7-dichlorooxine from weakly acidic or neutral solutions in the flow system and adsorbed on the column. The pre-concentrated elements were eluted with acidified methanol (pH greater than or equal to 2) and injected directly into the nebulizer for atomization in an air-acetylene flame for measurement. The retention efficiency was better than 98%, resulting in sensitivity enhancement factors of 60, 80, 80, 80 and 60 for a 1 min pre-concentration time for iron, cobalt, nickel, manganese and zinc, respectively. The respective detection limits were 4.0, 1.0, 1.0, 0.5 and 0.5 ppb, respectively. The throughput of samples was 30 hr-1, with a loading time of 1 min. The method was applied to sea-water samples.