University of North Florida
Browse the Citations
-OR-

Contact Info

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

View Stuart Chalk's profile on LinkedIn

Silicate

Classification: Geological -> rock -> silicate

Citations 21

"Extraction Flow Injection Spectrophotometric Determination Of Bismuth With Lead Tetramethylenedithiocarbamate"
Anal. Chim. Acta 1991 Volume 251, Issue 1-2 Pages 275-280
Joanna Szpunar-Lobinska

Abstract: Powdered silicate rock (0.5 g) was mixed with concentrated HNO3 (2 ml) and the mixture was evaporated to dryness. The residue was dissolved in concentrated HF (5 ml) and concentrated HClO4 (1 ml), the solution was evaporated to dryness and the process was repeated. The final residue was dissolved in 1 M HCl (3 ml) and diluted to 10 mL with water. A 500 µL portion was injected into 0.4 M NH3 buffer solution (pH 9.0; carrier solution) in the flow system described (with diagram). The carrier stream was mixed with a masking stream containing 1.5% KCN and 0.1% EDTA in a mixing coil. The resulting stream was merged with 0.05% Pb tetramethylenedithiocarbamate in CHCl3 (extraction reagent stream) and the color forming reaction was allowed to take place in an extraction coil. Phases were separated with a PTFE membrane separator and the absorbance of the organic phase was measured at 380 nm. The calibration graph was rectilinear up to 5 ppm of Bi. The detection limit was 0.1 mg L-1 of Bi. At 3 mg L-1 of Bi, the coefficient of variation was 1.4%. The sampling rate was 72 h-1. Results compared well with those by ICP-AES.
Bismuth Spectrophotometry Sample preparation Buffer EDTA Extraction Phase separator Teflon membrane Method comparison

"Flow Injection Analysis Of Silicate Rocks For Total Iron And Aluminum"
Talanta 1982 Volume 29, Issue 8 Pages 659-662
Tadashi Mochizuki, Yasuhiko Toda and Rokuro Kuroda*

Abstract: A flow-injection method is described for the spectrophotometric determination of total iron and aluminium in silicate rocks. Rock samples are opened up by fusion with a mixture of lithium carbonate and boric acid, the melt is taken up in 1 M hydrochloric acid and the resulting solution is used for the determination of both iron and aluminium. The flow system for the determination of iron needs no particular reagents, involving simply measurement of the absorbance of the chloro-complex of iron(III) at 335 nm. The system for aluminium consists of the reduction of iron(III) to iron(II), color development with Xylenol Orange (XO), destruction of XO-chelates other than that of aluminium by addition of EDTA and subsequent measurement of the absorbance of the aluminium-XO complex at 506 nm. The systems permit semi-automatic, rapid analysis of silicate rocks for iron and aluminium. Results obtained for standard rocks were in good agreement with the recommended values. The precision ranged from 0.1 to 0.9% for iron and from 0.3 to 0.7% for aluminium.
Aluminum Iron Spectrophotometry

"Spectrophotometric Determination Of Silicon In Silicate By Flow Injection Analysis"
Talanta 1985 Volume 32, Issue 5 Pages 353-357
Rokuro Kuroda, Iwao Ida and Hideki Kimura

Abstract: Silicon in silicate rocks was determined at 70 samples h-1, with coefficient of variation of 0.5%. The rock was fused with Li2CO3 - H3BO3 (1:1) at 1000°C for 15 min, cooled and dissolved in HCl. Silicic acid was isolated on a column (3 cm x 8 mm) of Bio-Rad AG 50W-X8 (H+-form) and then depolymerized in alkaline medium before determination by either a static or flow injection spectrophotometric method as silicomolybdic acid (λmax = 440 nm). The flow injection analysis system consisted of two channels containing the carrier solution (0.1 M NaOH) and the 1% ammonium molybdate reagent in 0.2 M H2SO4, and which allowed the color reaction to proceed in a coil (3 m x 1 mm) at 50°C. The proposed method was applied to 14 standard rock samples to give results in good agreement with the certified values and with the values obtained by conventional spectrophotometry. Up to ~2% of P2O5 did not interfere.
Silicon Silicate Spectrophotometry Interferences Heated reaction Reference material Biorad

"Flow Analysis Of Silicate Rocks For Zirconium"
Talanta 1991 Volume 38, Issue 10 Pages 1119-1123
R. Kuroda, K. Oguma, K. Kitada and S. Kozuka

Abstract: A flow analysis system involving online configuration of an anion-exchange column has been examined to enrich and determine trace concentration of Zr of several ppm to hundred ppm levels in silicate rocks and minerals. About 100 mg of sample was decomposed by fusion with boric acid - Li2CO3 and taken up with 1 M HCl to 100 mL. A 1- or 4 mL portion of sample was introduced into an aqueous carrier stream, merged with H2SO4 and passed through a Bio-Rad AG1-X8 (100 to 200 mesh; Cl- form) column, eluted with HCl, color-developed with Arsenazo III and detected spectrophotometrically at 665 nm. Effects of foreign ions are tabulated.
Zirconium Spectrophotometry Sample preparation Column

"Flow Injection Analysis Of Silicate Rocks For Titanium"
Analyst 1982 Volume 107, Issue 1279 Pages 1255-1260
Tadashi Mochizuki and Rokuro Kuroda

Abstract: A flow injection spectrophotometric method has been developed for the accurate, continuous determination of titanium in silicate rocks. A rock sample solution is prepared by fusion with a mixture of lithium carbonate and boric acid and subsequent dissolution of the melt with 1 M hydrochloric acid. The preparation technique is the same as that used for the determination of total iron and aluminium in silicate rocks by flow injection spectrophotometry. An aliquot of the sample solution is injected directly into the apparatus with no pre-treatment. The system consists of the reduction of iron(III) with ascorbic acid and measurement of the absorption of the titanium-diantipyrylmethane (DAM) complex at 388 nm. In spite of the slow reaction of titanium with DAM, satisfactory results are obtained with an appropriate optimized system. This system permits high throughput of 60 solutions per hour. The procedure has been applied to standard silicate rocks of the US Geological Survey and the Geological Survey of Japan. The precision ranges from 0.1 to 0.8% for titanium(IV) oxide contents of 0.2-2.2%.
Titanium Spectrophotometry

"Simultaneous Determination Of Trace Amounts Of Iron(III) And Titanium(IV) By Flow Injection With Spectrophotometric Detection"
Analyst 1990 Volume 115, Issue 4 Pages 431-434
Shoji Kozuka, Kenichi Saito, Koichi Oguma and Rokuro Kuroda

Abstract: Powdered silicate rock sample was fused with Li2CO3 - H3BO3 (1:1) and the melt was dissolved in 1 M HCl. The solution was injected simultaneously into a carrier stream of 1 M HCl at 2 mL min-1 at two inlet points separated by a Ag reductor column that reduced Fe(III) to Fe(II). The stream was merged with a reagent solution of 0.5% disodium 1,2-dihydroxybenzene-3,5-disulfonate in acetate buffer, pH 4.9, at 2.0 mL min-1 and monitored at 430 nm. The absorption of the first peak represented the total Fe(III) and Ti(IV) content and that of the second, the Ti(IV) concentration. The method was applied in the analysis of reference materials, the results obtained agreed closely with certified values with mean coefficient of variation of 1.0 and 0.87% for Fe and Ti respectively. There was no interference.
Iron(III) Titanium(IV) Spectrophotometry Column Buffer Reference material Interferences Reduction column Differential detection

"Flow Injection Microwave-assisted Dissolution Of Silicate Rocks For Magnesium Determination By Flame Atomic Absorption Spectrometry"
J. Anal. At. Spectrom. 1997 Volume 12, Issue 10 Pages 1235-1238
Marcelo Dominguez De Almeida, Kátia Christina Leandro, Christian Vidal Da Costa, Ricardo Erthal Santelli and Miguel De La Guardia

Abstract: A flow injection system based on online microwave-assisted digestion was tested as a tool to-perform silicate rock dissolution in acid medium (HF + HNO3). A 50 mg portion of the powdered rocks was dispersed with the acid mixture add stirred for a few minutes. Using a 3.8 mL min-1 flow rate, the sample slurry was digested inside a microwave oven for 10 s. A 20 µl volume of the digested sample slurry was introduced to an aqueous carrier stream and mixed with a reagent stream containing boric acid before introduction into the AAS system. Chemical variables were studied and the best conditions mere obtained with 4 M HF + 1 M HNO3. Magnesium was selected as a test element, The developed procedure enables-about ten samples to be analyzed per hour (including sample preparation) and affords a linear dynamic range from 0.5 to 4 µg mL-1 Mg, an RSD of 0.82% (n=5) and a detection limit of 60 ng mL-1. Reference rock samples mere analyzed and the results obtained agreed with the certified values. 29 References
Magnesium Sample preparation Spectrophotometry Microwave Online digestion Optimization Reference material Linear dynamic range Slurry

"Atomic Absorption Determination Of Copper In Silicate Rocks By Continuous-precipitation Preconcentration"
Anal. Chem. 1989 Volume 61, Issue 13 Pages 1427-1430
Ricardo E. Santelli, Mercedes Gallego, and Miguel Valcarcel

Abstract: Sample solution (10 to 250 ml; containing 0.1 to 2 µg of Cu) in 0.2 M acetic acid - ammonium acetate buffer (pH 4.8) was mixed (at 4 mL min-1) with 0.1% rubeanic acid (1 mL min-1); the ppt. was filtered off and the solution was run to waste. A stream (5 mL min-1) of 83 mM K2Cr2O7 in 1 M HNO3 was then pumped through the filter, and Cu was determined by AAS at 324.7 nm. Calibration graphs covered the range 0.3 to 200 ng mL-1. The sampling rate was 20 h-1, and the coefficient of variation was 1.4 to 3% (n = 11).
Copper Spectrophotometry Precipitation Filter Preconcentration

"Extraction Of Tetrafluoroborate With Crown Ethers And Its Application To Silicate Rock Analysis"
Fresenius J. Anal. Chem. 1992 Volume 343, Issue 3 Pages 287-291
Hideko Koshima, Contact Information and Hiroshi Onishi

Abstract: The extraction behavior of BF4- with crown ethers was investigated (details given). Good results were obtained by extraction with dicyclohexano-18-crown-6 (DC18C6) in an organic solvent with a high dielectric constant from a 0.2 M HF - 2 M KF solution The method was applied to the analysis of silicate rocks. Sample was fused with K2CO3 and borate present was converted to BF4-1 before separation by extraction with DC18C6 in 1,2-dichloroethane. Hexane was added to the organic phase and BF4- was back-extracted by shaking with phosphate buffer. The aqueous phase was mixed with phosphate buffer solution (pH ~6), benzene and 0.4% brilliant green solution (C.I. Basic Green 1) in a flow injection system and, after reaction, the absorbance of the organic phase was measured at 640 nm. The calibration graph was rectiliniear up to 15 µM-BF4-. Coefficients of variation were 4% and recoveries were 95%; determination limits were at the ppm level. The effects of foreign substances are tabulated.
Tetrafluoroborate Spectrophotometry Sample preparation Organic phase detection Expert system Interferences Crown ether Solvent extraction

"Determination Of Phosphorus In Silicate Rocks By Flow Injection Method Of Analysis"
Microchim. Acta 1984 Volume 82, Issue 5-6 Pages 377-383
Rokuro Kuroda, Iwao Ida and Koichi Oguma

Abstract: A 0.1-g sample of powdered rock is fused for 15 min at 1000°C with 0.3 g each of Li2CO3 and H3BO3, the melt is dissolved to 100 mL in 1 M HCl, and a 3 mL portion is diluted to 10 mL with water. A six-way loop valve is used to inject 318 µL of this solution into a carrier stream of 0.3 M HCl (1.5 mL min-1), which meets a stream of 0.13% (NH4)6Mo7O24.4H2O - 0.024% Sb K tartrate solution [containing also tartaric acid and poly(vinyl alcohol)] and one of 0.096% ascorbic acid solution (each 0.75 mL min-1). The mixture is passed through a mixing coil immersed in a water bath at 90°C and then through a water-cooled coil, after which the absorbance is measured at 710 nm vs. air. Two levels of P2O5 (0.123 and 0.247%) have been determined successfully in the presence of 28.5 to 85.6% of SiO2. The method has been applied to eight US and Japanese standard rocks, with generally good agreement with recommended or reported values. Twenty samples can be analyzed in the flow system per hour.
Phosphorus Phosphorus pentoxide Spectrophotometry Heated reaction Reference material

"Spectrophotometric Flow Injection Analysis Of Silicates For Manganese"
Anal. Sci. 1987 Volume 3, Issue 3 Pages 251-255
K. OGUMA, K. NISHIYAMA and R. KURODA

Abstract: Powdered silicate rock (100 mg) was fused with anhydrous Li2CO3 - H3BO3 (1:1) at ~1000°C for 15 min. The melt was dissolved in 1 M HCl and diluted. Aliquots of sample solution were treated with HF and HClO4, the mixture was evaporated, the residue was moistened with HClO4 and the acid was evaporated. The residue was dissolved in 1 M HCl, the solution was applied to a column (7 cm x 8 mm) of cellulose phosphate (Whatman P-11) and Mn was eluted with 1 M HCl. An aliquot of the eluate and 1% aminoethanethiol hydrochloride were injected into 1 M HCl and water (carrier solution), respectively, and after mixing, the combined solution was mixed with 0.36 M formaldoxime in NH3 buffer solution (pH 10.5) and passed through a reaction coil in a water bath at 80°C. The absorbance was monitored at 452 nm. The flow injection manifold used is described (with diagram). The coefficient of variation (n = 10) were 0.8 and 0.33%, respectively, for 0.5 and 2 ppm of Mn. The sampling rate was 45 h-1.
Manganese Spectrophotometry Heated reaction

"Spectrophotometric Determination Of Silicon In Silicate Rocks By Flow Injection Analysis"
Anal. Sci. 1988 Volume 4, Issue 5 Pages 523-525
T. UCHIDA, K. YAMAMOTO, H. INOUE, I. KOJIMA, and C. IIDA

Abstract: A system is described and illustrated for flow injection spectrophotometric determination of Si. Powdered silicate rock (25 mg) is decomposed with 0.5 mL of HCl and 0.25 mL of HF by repeated (x3) heating and cooling for 1 and 5 min, respectively. After cooling and addition of 5 mL of 4% H3BO3 solution, the mixture is diluted with water. A 65 µL portion is injected into the carrier stream (0.6 M HCl, 2.45 mL min-1), which is then mixed with 3% (NH4)6Mo7O24 solution (2.45 mL min-1). The mixed solution then passes to a 200-cm reaction coil maintained at 45°C, and the absorbance is measured at 415 nm in a flow-through cell. The method is suitable for determination of 200 to 380 µg g-1 of Si. Results for determination of Si in 22 standard rock samples agreed with certified values. The coefficient of variation (n = 5) was 0.4%.
Silicon Sample preparation Spectrophotometry Heated reaction Reference material

"Atomic Absorption Spectrophotometric Determination Of Calcium Silicate Rocks By A Flow Injection Method"
Bunseki Kagaku 1983 Volume 32, Issue 7 Pages T79-T83
Kimura, H.;Oguma, K.;Kuroda, R.

Abstract: Powdered sample (~50 mg) was fused with 150 mg each of Li2CO3 and H3BO3, the fusion cake was dissolved in 1 M HCl to give 100 mL of solution, and a 120 µL portion was injected into a flow system linked to an AAS instrument for determination of Ca at 422.7 nm. To prevent interference from, e.g., Al, phosphate, silicate and SO42-, 130 µL of 2% La solution was mixed with the sample solution by the merging-zone technique. The coefficient of variation (n = 3) for 0.1 to 11% of CaO ranged from 0.3 to 2%, and 180 solution could be analyzed in 1 h. Results for 16 standard rocks agreed well with the certified values.
Calcium Spectrophotometry Sample preparation Interferences Merging zones Reference material

"Continuous Spectrophotometric Determination Of Calcium In Silicates By Flow Injection Analysis"
Bunseki Kagaku 1985 Volume 34, Issue 7 Pages T98-T103
Oguma, K.;Kato, Y.;Kuroda, R.

Abstract: The rock sample (100 mg) was fused with Li2CO3 (300 mg) and H3BO3 (300 mg), the melt was dissolved in 1 M HCl (to 100 ml), and a 1 mL aliquot of the solution was applied to a column of cellulose phosphate (to remove Fe(III) and other polyvalent cations). The Ca-containing fraction of the percolate was diluted to 25 mL and made 0.5 M in HCl, and a 311 µL portion of the solution was injected into the flow system. Calcium was determined, as a complex with o-cresolphthalein complexan, by spectrophotometry, with use of quinolin-8-ol as masking agent for Mg. The results obtained for 14 standard rocks were in good agreement with the reported values; for the determination of 1 to 2.5% and >3% of CaO, the coefficient of variation were 1 to 1.6% and 0.2 to 0.8%, respectively. The flow injection sampling rate was 40 h-1
Calcium Spectrophotometry 8-Hydroxyquinoline Cellulose Column Complexation Interferences Reference material

"Determination Of Sodium And Potassium In Silicates By Flow Injection Analysis/atomic Absorption Spectrometry"
Bunseki Kagaku 1987 Volume 36, Issue 12 Pages 851-855
Nara, T.;Oguma, K.;Kuroda, R.

Abstract: Two flow injection AAS systems are described (with diagrams). One is a split-flow system in which the sample is split into two flow channels leading to two AAS detectors, for Na and K, respectively, and reproducible splitting is achieved with use of a third channel. The other is a splitless-flow system consisting of two channels into which sample solution is introduced alternately. Silicate rock was fused with Li2CO3 - H3BO3 (1:1) and the melt was leached in 1 M HCl (1 mg mL-1 of silicate) and the solution was analyzed. Both systems allowed a sampling rate of 120 h-1. The coefficient of variation were 1% for Na and 0.5% for K for both systems.
Sodium Potassium Spectrophotometry

"Analytical Application Of FIA-AAS Combination For The Determination Of Heavy Metals In Environmental Samples"
Chem. Listy 1998 Volume 92, Issue 12 Pages 978-987
M. Foltin and T. Prochackova

Abstract: The examples of application of online FIA-AAS combination are presented for the trace heavy metals anal. of environmental and biological samples. The influence of various parts of flow injection system, e.g. type of flow, injection mode, separation and or pre-concentration cartridge, and detection mode on anal. signal is discussed.
Metals, heavy Spectrophotometry Spectrophotometry Precipitation Preconcentration Solid phase extraction

"Application Of Flow Injection Analysis To Silicate Rocks With Series Detectors"
Fenxi Huaxue 1990 Volume 18, Issue 2 Pages 117-120
Lin, S.L.;Shuai, Q.

Abstract: Silicate rocks and National Standard reference rock samples (0.2 g) are digested with 5 mL of HF solution and 1 mL of 9 M H2SO4 by heating. The mixture is evaporated to fumeless and the residue is dissolved in 5 mL of 6 M HCl. The solution is evaporated to dryness and the residue is dissolved in dilute HCl and diluted to 100 mL (final concentration. of 2% in HCl.). Titanium and P are determined by photometry and Mg and Na are determined by AAS. The series detectors were situated with the spectrophotometer at the upstream and the AAS instrument at the downstream end. Results agreed well with certified values.
Titanium Magnesium Sodium Phosphorus Sample preparation Spectrophotometry Spectrophotometry Reference material Dual detection

"Simultaneous Determination Of Trace Amounts Of Mercury, Cadmium And Zinc By Ion Chromatography Using M-tetrakis(4-sulfophenyl)porphyrin [TPPS4] As Post-column Derivatization Agent"
Gaodeng Xuexiao Huaxue Xuebao 1990 Volume 11, Issue 2 Pages 136-139
Yan, D.;Zhang, J.;Schwedt, G.

Abstract: The cited determination was carried out with use of TPPS4 as derivatization agent, 4-(2-pyridylazo)resorcinol in Na2B4O7 - NaOH buffer (pH 10.3 to 12) containing NaCl as the derivatization catalyst and tartaric acid - NaCl as mobile phase. A chemically bonded silica gel cation-exchanger was used as the stationary phase and the separation was completed in 10 min. The method was applied to the analysis of waste water, silicate and corn samples.
Mercury Cadmium Zinc HPIC Post-column derivatization Buffer pH Catalysis

"Flow Injection Analysis Of Silicate Rocks. 1. Flow Injection Analysis-AAS Determination Of Calcium In Diatomite"
Jilin Daxue Ziran Kexue Xuebao 1986 Volume 24, Issue 4 Pages 93-97
Wei Qingxun, Guo Yaxian, Liu Miao and Ben Yuezhi

Abstract: A pulse-free carrier stream was obtained for flow injection analysis (FIA) - atomic absorption spectrometry (AAS) by omitting the peristaltic pump and buffer applied. The pressure difference in the atomizer served as the driving force. Calcium was determined in diatomite by dissolving the sample with a HF-HNO3 mixture, using a lanthanum solution for eliminating the interferences, and AAS. The relative standard deviation is ≤2%.
Calcium Spectrophotometry Sample preparation Extraction

"Flow Injection Spectrophotometric Determination Of Cobalt In Silicate Rocks Employing Cobalt-nitroso-R Complex Retention On Activated Alumina Minicolumn"
Quim. Anal. 1996 Volume 15, Issue 2 Pages 135-139
Brasil, J.C.;Braga do Nascimento, P.V.;Santelli, R.E.

Abstract: Powdered silicate rock (1-1.25 g) was moistened with water and fumed with 1 mL 70% HClO4 and two 5 mL portions of 48% HF. The residue was dissolved in 5-10 mL acetic acid/sodium acetate buffer solution, adjusted to pH 4, treated with Tiron to complex Fe(III) and diluted to 50-100 mL with water. If turbidity persisted, the solution was filtered. The flow injection manifold allowed the prepared sample solution to be merged with a 0.5% solution of 1-nitroso-2-naphthol-3,6-disulfonic acid sodium salt; both flow rates were 0.88 ml/min. The resulting mixture was injected into a 1 M HClO4 carrier stream (0.7 ml/min) via a 500 µL sample loop and transported to a column (2.5 cm x 1.6 mm i.d.) packed with 50 µL activated alumina. The Co complex was eluted with 1 M H2SO4 (2.21 ml/min) and detected at 520 nm in a 1 cm optical path flow cell. Interference from Ni(II) and Cu(II) was eliminated by flushing the column for 80 s with carrier solution prior to elution of the Co(II) complex. The calibration graph was linear for 0.25-2 µg/ml Co, the detection limit was 50 ng/ml and the RSD for 0.25 and 1 µg/ml Co were 1.7% and 0.9%, respectively. Results for rock reference materials agreed with the certified values.
Cobalt Sample preparation Spectrophotometry Activated alumina Reference material Interferences Tiron

"Determination Of Silicon In Silicate Rocks By Flow Injection Analysis"
Yankuang Ceshi 1990 Volume 9, Issue 3 Pages 213-216
Zhang, X.;Lin, S.;Guo, T.

Abstract: Samples were fused with sodium carbonate and the melt was dissolved in boiling water. The solution was rapidly acidified, then adjusted to pH 13.3 before a 70 µL portion was mixed with 1.5% (NH4)2MoO4 in a reaction tube (130 cm or 80 cm length for silicon molybdenum yellow or silicon molybdenum blue, respectively) at 50°C. The absorbance was measured at 780 nm. There was no interference from P. The coefficient of variation for 25 µg mL-1 of Si was 1% (n = 11). The rapid and accurate method was used to determine SiO2 in four silicate rocks of national standard and one of local standard; the results agreed with certified values.
Silicon Sample preparation Spectrophotometry Reference material Heated reaction Interferences