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

Organic compound

Classification: Organic compound

Citations 7

"Rapid Determination Of Chemical Oxygen Demand By A Semi-automated Method Based On Microwave Sample Digestion, Chromium(VI) Organic Solvent Extraction And Flame Atomic Absorption Spectrometry"
Anal. Chim. Acta 1998 Volume 372, Issue 3 Pages 399-409
Angel Cuesta, José L. Todolí*, Juan Mora and Antonio Canals

Abstract: In the present work, a new flow injection analysis (FIA) manifold for the rapid determination of COD is presented and evaluated. The FIA manifold combines sample digestion by means of an oxidant solution (i.e., potassium dichromate and mercury sulfate) and an acid solution (sulfuric acid and silver sulfate) in a domestic microwave oven with the liquid-liquid extraction of Cr(VI) with tri-Bu phosphate (TBP). Finally, the remaining (non-reduced) Cr(VI) is determined in the organic phase by atomic absorption spectrometry. The digestion of the organic matter is carried out in the stopped-flow mode. Potassium hydrogenphthalate has been used for optimization of the method and as a standard to check its performance. The optimized conditions (oxidation) are: digestion time, 7 min; acid concentration, 67% (v/v). The optimized conditions for the extraction of the remaining Cr(VI) are: acid concentration, ≥30% (v/v); TBP, 1 mL. The proposed method has been successfully applied, with the exception of pyridine, to several organic compounds and waters. A semi-micro method has been used for comparison. The application range extends from 40 to 12,000 mg O2/L, whereas the lowest limits of detection and quantification are 13.5 and 45 mg O2/L, respectively. Following this method, the interference of Cl- can be compensated for at least up to 10,000 mg L-1 Cl-. Up to nine samples per h can be analyzed.
Chemical oxygen demand Sample preparation Spectrophotometry Microwave Online digestion Solvent extraction Stopped-flow Optimization Interferences

"Determination Of Formaldehyde In Reagents And Beverages Using Flow Injection"
Analyst 1994 Volume 119, Issue 6 Pages 1413-1416
Hironori Tsuchiya, Shigeru Ohtani, Kuniaki Yamada, Mioko Akagiri, Nobuhiko Takagi and Masaru Sato

Abstract: Organic solvents and water were analyzed immediately after distillation or after opening new bottles, and also after standing for 1 month. Alcoholic beverages were analyzed directly. Fruit juice was centrifuged, the supernatant solution filtered and the filtrate analyzed. Cigarette smoke was collected in phosphate buffer and the solution analyzed. A 50-100 µL portion of the sample solution was injected into a carrier stream (0.8 ml/min) of acetonitrile/0.1 M phosphate buffer of pH 2 (1:4) and the solution was passed through a column (10 cm x 4.6 mm i.d.) of NS-Gel C18 (5 µm) before being mixed with a second stream (0.5 ml/min) of a 60 mM 4-amino-3-penten-2-one solution in acetonitrile. The mixture was transported to a mixing coil kept at 60°C and the fluorescence intensity was measured at 510 nm (excitation at 410 nm). A diagram of the manifold used is given. The calibration graph was linear from 0.5-100 nmol/ml of formaldehyde. The RSD (n = 6) was 0.26%. Recoveries were quantitative. The throughput was 12 samples/h.
Formaldehyde Fluorescence Heated reaction C18

"Determination Of Trace Metals In Volatile Organic Solvents Using Inductively Coupled Plasma Atomic-emission Spectrometry And Inductively Coupled Plasma Mass Spectrometry"
J. Anal. At. Spectrom. 1992 Volume 7, Issue 1 Pages 23-28
Steve J. Hill, James Hartley and Les Ebdon

Abstract: A desolvation system is described to facilitate the introduction of volatile organic solvents in plasmas which utilizes Peltier coolers to reduce the temperature of an Al heat sink interface placed between the heated spray chamber and the plasma torch (details given). The system was applied in the determination of trace metals in ethyl ether under optimum conditions (tabulated) by ICP-AES and ICP-MS. Results were more sensitive than those using a conventionally-cooled mini-spray chamber, with detection limits in the low- to sub µg L-1 range. Flow injection techniques were also used to reduce the amount of volatile organic solvent entering the plasma. In addition to achieving an enhancement in plasma stability, it was found that smaller sample loops (50 µL) facilitated faster flow rates, resulting in better-shaped transient peaks and reduced memory effects. A desolvation system has been designed to help facilitate the introduction of volatile organic solvents into inductively coupled plasmas. The system utilizes Peltier coolers to reduce the temperature of an interface placed between a heated spray chamber and the plasma torch. The interface consists of a drilled aluminum block that acts as a heat sink and through which pass glass cooling tubes. The Peltier coolers are mounted around the block, sandwiched between the block itself and a series of copper cooling plates. The optimum conditions necessary for the determination of trace amounts of metals in di-Et ether are discussed and the results obtained using these conditions compared with those obtained using a conventionally cooled mini-spray chamber. Detection limits, using the system in conjunction with continuous nebulization, were found to be in the low to sub µg L-1 range for inductively coupled plasma mass spectrometry. Flow injection techniques have also been used to reduce the amt. of volatile organic solvent entering the plasma. In this instance the volatile solvent (di-Et ether) was carried in a stream of less volatile solvent (2-ethoxyethanol) to the plasma. The effects of varying the sample loop volume have been investigated, and the results compared with those obtained using continuous-flow nebulization. The results indicated that, in addition to achieving an enhancement in plasma stability, smaller sample loops (50 µL) facilitate faster flow rates, which result in better shaped transient peaks and reduced memory effects.
Mass spectrometry Spectrophotometry Interface Organic solvent Optimization Method comparison

"Spectrophotometric Determination Of Water By Flow Injection Analysis Using Conventional And Pyridine-free Two-component Karl-Fischer Reagents"
Anal. Chem. 1985 Volume 57, Issue 13 Pages 2571-2575
Ingrid Nordin-Andersson and Anders Cedergren

Abstract: The cited flow injection method was evaluated by using a large number of organic solvents with refractive indices ranging from 1.32 to 1.50 at 20°C. The conventional Karl Fischer reagent and three commercial two-component pyridine-free reagents (Merck, ReAquant and Hydranal) were used. The mean deviation between flow injection and coulometric values was 0.0014% (v/v) of water. Triethylamine gave rise to increased interference effects, while less influence from ketal-forming samples was found for the two-component reagents. The latter effect was not noticed for Hydranal.
Water Karl Fischer analysis Spectrophotometry Interferences Method comparison

"A Microbioreactor Based On Interfacial Polymerisation And Application To Flow Injection Analysis Of Glucose"
Sens. Actuat. B 1996 Volume 34, Issue 1-3 Pages 422-428
Muntak Son, Frank Peddie*, Dennis Mulcahy, David Davey and Malcolm R. Haskard

Abstract: A bioreactor chamber was created by anisotropic etching of a Si wafer. The chamber was attached to a microelectronic sensor using epoxy resin. A biocatalyst, e.g., an enzyme, a combination of enzymes or intact viable cells, could then be contained within the chamber by an ultra-thin nylon membrane (preparation details given). The membrane was tightly sealed to the Si wafer surface by pretreating the wafer with a silylating reagent by dipping into dry toluene containing 10% γ-aminopropyl triethoxysilane and refluxing for 24 h. The membrane was then created by interfacial polymerization. The nylon membrane could then be covalently linked to the wafer surface by appropriate selection of aqueous and organic phase constituents. The microbioreactor was successfully used as a glucose sensor within a flow injection cell; results indicate that many other applications are feasible.
Glucose Sensor Nylon

"Determination Of Water In Organic Solvents By The Karl Fischer Method Under Flow Injection Conditions"
Chem. Tech. 1987 Volume 39, Issue 1 Pages 25-28
Muller, H.;Seelisch, J.;Kirsch, D.

Abstract: A flow-injection procedure for the determination of water by using Karl Fischer reagents and spectrophotometric indication is described. Water contents (0.05%(v/v) water) in alcohols and ketones can be determined at a rate of 120 samples/h with good precision (relative standard deviation ~1%). The method was calibrated against the Karl Fischer method with dead-stop indication and a good correlation was obtained between the two methods. (SFS)
Water Karl Fischer analysis Method comparison

"Advances In Analytical Chemistry In 1995"
J. Anal. Chem. 1997 Volume 52, Issue 2 Pages 178-189
M. M. Buzlanova

Abstract: Research in analytical chemistry carried out in Russia during 1995 is described. The discussion is divided into subject areas including standardization of analytical methods, automation and use of computers, sample preparation, individual techniques (e.g. MS, XRF, FIA) and sample type (e.g., environmental materials, organic compounds, high-purity compounds and noble metals). Advances in analytical instrumentation are described and future trends in analytical chemistry are outlined.
Review