University of North Florida
Browse the Citations

Contact Info

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

View Stuart Chalk's profile on LinkedIn

Inorganic compound

Classification: Inorganic compound

Citations 5

"Flow Injection Spectrophotometric Determination Of Trace Iron In Various Salts. Elimination Of Blank Peak Effect And Use Of 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol As Chromogenic Agent"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 433-438
Takeshi Yamane* and Hiroyo Yamada

Abstract: A flow injection method for the determination of Fe in various salts was developed with use of 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol (Nitro-PAPS) as chromogenic agent. A 1-2 g portion of salt was dissolved in 5 mL water and 10 mL 2 M HCl by heating for 5-10 min. The resulting solution was filtered and the filtrate was diluted to 50 mL after the addition of 9.5 mL 1 M Na2CO3 and 8 mL 10 mM N-(dithiocarboxy)sarcosine. A 10 portion of this solution was injected into a 5 mM HCl carrier stream (0.8 ml/min) using an injector loop of 5 m x 0.5 mm i.d. The flow was merged with the reagent stream containing 60 µM-Nitro-PAPS and 0.01 M ascorbic acid in acetate buffer of pH 4.9. After passing through the reaction coil (2.5 m x 0.25 mm i.d.) the absorbance of the merged stream was measured at 582 nm. The calibration graph for Fe was linear up to 100 ng/ml in the absence and presence of 1 M NaCl. The detection limit was 1 ng/ml which corresponded to 0.05 g/g in a 1 g sample. The RSD (n = 5) for the determination of 50 ng/ml Fe was 1.3%. The sampling frequency was 15 samples/h.
Iron Spectrophotometry Refractive index Chromogenic reagent

"Flow Injection Systems For Determination Of Trace Manganese In Various Salts By Catalytic Photometric Detection"
Talanta 1996 Volume 43, Issue 6 Pages 963-969
Takeshi Yamanea,* and Kazuo Koshinoa

Abstract: Solar salt was dissolved in water and filtered for soluble Mn determination and in water, 2 M HCl and 1.5% H2O2 with heating for 5-10 min followed by filtering for determination of total Mn. The sample containing 0.85 M NaCl was injected into a carrier stream (0.8 ml/min) at water. The stream merged with reagent streams (0.5 ml/min) of 0.26 mM 3,4-dihydroxybenzoic acid/0.75% H2O2 and 1 M sodium carbonate solution. The merged streams passed through a reaction coil (5 m x 0.5 mm i.d.) in a water bath at 40°C and the absorbance was measured at 480 nm. The same system was also used with an online separation step. The sample was injected into a carrier stream of 0.15 M sodium tartrate/4.5 mM tartaric acid/0.3 M NaCl which passed to a borosilicate glass column (7 cm x 4 mm i.d.) packed with 15.5 µm strong cation exchange resin before merging with the reagent streams as above. Calibration graphs were linear for 2-15 ppb Mn and 0-15 ppb Mn in the absence and presence of online separation, respectively, with corresponding detection limits of 2 ppb and 0.5 ppb. RSD (n = 5) was 0.9% for 8 ppb Mn without online separation and 1.4% (n = 5) for 7 ppb Mn.
Manganese Ion exchange Spectrophotometry Heated reaction Column Resin

"Flow Analysis Preconcentration Of Magnesium And Zinc Using Emulsions For Flame Atomic Absorption Spectrometry"
Fresenius J. Anal. Chem. 1997 Volume 357, Issue 7 Pages 860-863
T. Yokoyama, Takashi Watarai, Takeo Uehara, Koh-ichi Mizuoka, Kenji Kohara, Masato Kido, Michio Zenki

Abstract: A pre-concentration method combining Water/Oil/Water (W/O/W) emulsions with flow injection manifolds has been developed for determinations of Mg and Zn. The system consists of a mixing coil filled with Span 80 as a surfactant, palmitic acid or di(2-ethylhexyl) phosphate as an extractant, kerosene as a solvent in the oil phase, and HCl in the inner aqueous phase to form W/O emulsions, an extraction coil for the sample solution to form W/O/W emulsions, a phase separator to waste the outer aqueous phase, a dry bath to demulsify W/O emulsions with 2-ethylhexanol, a phase separator to waste the oil phase, and an air pump to deliver the concentrated sample solution to the flame atomic absorption spectrophotometer. This method proved to be excellent regarding the reproducibility, the rapidity, and the small quantity of sample, compared with the W/O/W emulsions method without the flow injection manifolds. The signal of flame atomic absorption spectrometry (FAAS) after pre-concentration of Mg by this method was 2.4 times as large as that before pre-concentration. Also, this method suppressed some interferences. The system was applied to FAAS determinations of Mg and Zn in duralumin alloys and Zn in commercial reagents. 10 References Samples were injected into a stream (2.4 ml/min) of water, which merged with an emulsified stream of 0.55-1.1 M HCl and kerosene containing 0.4-0.5% Span 80 (Nacalai tesque, Kyoto, Japan) and 0.5-2% palmitic acid (details given) then passed through a PTFE extraction coil (10 m x 0.5 mm i.d.) and a phase separator. The emulsion then merged with a stream (0.4 ml) of 2-ethylhexanol (demulsifier), and passed through a dry bath at 130°C for demulsification (details given) and a second phase separator; the aqueous phase was carried in air (42 ml/min) to an AAS instrument for analysis. The detection limits using 1 mL samples were 20 ng/ml Mg and 100 ng/ml Zn. The calibration graphs were linear from 20-200 and 100-500 ng/ml, respectively. RSD and recoveries are not given. The method was applied to commercial reagents and duralumin alloys (results presented).
Magnesium Zinc Spectrophotometry Sample preparation Extraction Emulsion Phase separator Preconcentration Surfactant Interferences

"Automatic Liquid-liquid Extraction Flow Injection Analysis Determination Of Trace Amounts Of Perchlorate With Spectrophotometric Detection"
Anal. Lett. 1998 Volume 31, Issue 1 Pages 167-177
Ali A. Ensafi; B. Rezaei

Abstract: An extractive flow injection analysis for rapid, sensitive and selective determination of perchlorate by spectrophotometric detection is proposed. The method is based on the extraction of perchlorate with Brilliant Cresyl Blue into Me iso-Bu ketone at pH 6.0. Perchlorate can be determined at 0.008-1.00 µg/mL with a limit of detection of 0.003 µg/mL and rate of 30 ± 5 samples/h. The effects of reagent concentration, pH, manifold variables and diverse ions are completely studied. The usefulness of the method was tested for the determination of perchlorate in salt samples.
Perchlorate Spectrophotometry Solvent extraction MIBK Optimization

"FIA - Extraction Applied To The Limit Test For Heavy Metals"
J. Pharm. Biomed. Anal. 1989 Volume 7, Issue 8 Pages 937-945
Lars-Göran Danielsson* and Zhao Huazhang

Abstract: Heavy metals in various samples were determined by flow injection extraction - spectrophotometry (e.g., at 274 nm) as their diethyldithiocarbamate complexes. Analytical parameters were chosen such that the sensitivities for toxic metals were enhanced compared with those for less toxic ones; e.g., at pH 3.5 in the presence of 3 mM EDTA the response to Fe, Mn, Ni and Zn was suppressed, but that to Pb was not. Calibration was effected with standard Pb solution, and the heavy metal content was calculated as Pb. The system was more sensitive than the standard procedure based on precipitation of colloidal sulfides. Relative responses for various ions at pH 3.5 and 4.7 in the presence and absence of EDTA are reported, as are results obtained on analytical-grade salts, pharmaceutical raw materials and household commodities. A method is presented that allows rapid determination of the total concentration of heavy metals in a sample. The method is based on FIA-extraction and photometric measurement of the metals as their dithiocarbamate complexes. The analytical parameters have been chosen such that the sensitivities for toxic elements are enhanced compared with those of less toxic heavy metals. The sampling capacity of the system is 40 samples h-1 and the repeatability (RSD) is 1.9% at 0.1 mg 1-1. Raw materials for the production of pharmaceuticals as well as analytical grade salts and household commodities have been tested.
Metals, heavy Lead Spectrophotometry Sample preparation Sensitivity Calibration Extraction Complexation