Publications by authors named "Gary D Christian"

The current teaching and practice of analytical chemistry reflect the evolution of measurement science over time. Qualitative and quantitative measurements can be traced back to prebiblical times, have been important throughout human history, and today are key to the functioning of a modern society. This review is designed to provide a brief overview of the evolution of analytical science and a summary of the evolution, development, and growth of analytical chemistry in the United States, with emphasis on developments up to the mid-twentieth century.

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The Winter Conference on Flow Injection Analysis (WCFIA) began in 1989, and became the International Conference on Flow Injection Analysis, when merging with the Japanese Association for Flow Injection Analysis (JAFIA) in 1995. Talanta has published special issues on the conference since 1995. Beginning in 2013, accepted manuscripts are published in regular issues of Talanta, and a virtual special issue of all manuscripts is compiled for access online.

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Flow methods of analysis represent one of the most studied and practiced areas of analytical chemistry. Two major international conferences are regularly held devoted to these methods. The International Conference on Flow Analysis (FA) began in 1979, and the International Conference on Flow Injection Analysis (ICFIA) began in 1989, originally as the Winter Conference on Flow Injection Analysis (WCFIA).

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Guava leaf extract is utilized as an alternative natural reagent for quantification of iron. The flow injection technique enables the use of the extract in acetate buffer solution without the need of further purification. Some properties of the extract such as its stability and ability to form a colored complex with iron were studied.

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Thalassemia involves gene mutation that causes the production of an insufficient amount of normal structure globin chains while Hb variant involves gene mutation that causes the change in type or number of amino acid of the globin chain. It has been reported that some 200 million people worldwide had hemoglobinopathies of some sort. Attempts to develop effective and economical techniques for screening and analysis of thalassemia and Hb variants have become very important.

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A flow injection (FI) in-valve-mini-column packed with Chelex-100 resin is proposed for on-line sample pretreatment for some metal ions, namely, Cd(II), Pb(II) and Zn(II), prior to simultaneous determination using ion chromatography (IC). A solution containing a mixture of the cations was first passed through the in-valve-mini-column, followed by on-line elution. The eluate was then flowed further to an injection valve and was injected into an ion chromatograph.

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A sequential injection analysis (SIA) system is coupled with dynamic surface tension detection (DSTD) for the purpose of studying the interfacial properties of surface-active samples. DSTD is a novel analyzer based upon a growing drop method, utilizing a pressure sensor measurement of drop pressure. The pressure signal depends on the surface tension properties of sample solution drops that grow and detach at the end of a capillary tip.

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A novel Raman sensor using a liquid-core optical waveguide is reported, implementing a Teflon-AF 2400 tube filled with water. An aqueous analyte mixture of benzene, toluene and p-xylene was introduced using a 1000 microl sample loop to the liquid-core waveguide (LCW) sensor and the analytes were preconcentrated on the inside surface of the waveguide tubing. The analytes were then eluted from the waveguide using an acetonitrile-water solvent mixture injected via a 30 microl eluting solvent loop.

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Two sequential injection titration systems with spectrophotometric detection have been developed. The first system for determination of ascorbic acid was based on redox reaction between ascorbic acid and permanganate in an acidic medium and lead to a decrease in color intensity of permanganate, monitored at 525 nm. A linear dependence of peak area obtained with ascorbic acid concentration up to 1200 mg l(-1) was achieved.

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Simple sequential injection analysis systems with DSTD (SIA/DSTD) have been developed. One was employed for the study of the effects of the ion contents in solutions to the dynamic surface pressure of ionic surfactants. The results from the studies show the possibility for an alternative simple fast screening, but also a sensitive procedure for water quality determination.

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