Instrumental Analytical Chemistry Research Articles

Analog Spectrophotometers in the Digital Age: Data Acquisition on a Budget

In this article we describe how to employ an inexpensive analog-to-digital converter and a user interface to Microsoft Excel to make a useful computerized spectrophotometer. Readily available types of data loggers, Vernier LabPro and digital multimeters with an RS-232 interface, were utilized. The proposed design does not compromise the quality of the measurements. The conversion of the data to the Microsoft Excel format makes it a convenient tool for a wide range of data processing applications. The software can operate in Windows 9x/NT/2000/XP environments that are familiar to most chemistry students. The infrared and UV–vis instruments were used for various laboratory experiments in instrumental analytical chemistry and in organic chemistry laboratories.

Progress and future of instrumental analytical chemistry applied to the environment

The recent trends in the development of environmental analysis are reviewed with emphasis on the progress of extraction techniques, of methods of analysis of pesticide residues in food, of the search for chemical and biological agents released into the environment, and of analytical instrumentation. A variety of new sorbents have been synthesized for the extraction and concentration of pollutants, including general purpose adsorbents (e.g., porous polystyrene/divinylbenzene resins) and polymers imprinted for specific compounds. New, faster, more selective and sensitive methods have been developed to improve analytical performance, e.g., synthetic fibers in the air pollution, stirbars coated with polymethylsiloxane. Bidimensional gas chromatography has brought a considerable leap in separation power and sensitivity. Finally the combination of open tubular columns and miniaturized quadrupole mass spectrometer allows the rapid identification of viral agents or a wide variety of chemicals.

Sensors and analytical chemistry

Instrumental analytical chemistry and chemical sensors, especially biosensors have made remarkable progress in the last decade. With respect to the analytical chemical performance characteristics the sensitivities could be increased drastically. However, the very important comparability of trace and ultra-trace analytical data produced in different laboratories has not been improved to the same degree. The analytical chemical performance characteristics of chemical and biochemical sensors must be judged with those facts in mind when they are validated using such traditional instrumental reference methods. Biosensors based on immune-chemical principles are more versatile in allowing nearly every analyte to be determined and are therefore chosen for this progress report. A recently developed calibration free optical single-use “immuno-chip” is described. This low-cost chip is based on an evanescence field fluorescence detection. The same technique and can also be used for a real-time recording of DNA hybridisation and dissociation events. Multi-analyte devices and DNA-arrays based on this technological platform were developed using a fast kinetic evaluation method. This offers certain advantages to methods detecting only the endpoint of a molecular association reaction especially concerning the detection of mismatches (SNP detection). Finally, a novel and relatively simple micro-electrochemical method based on a microelectrode array in combination with receptor-functionalized magnetic latex beads and an indicating redox system is described which bears in it an alternative to atomic force microscope binding forces measurements. Depending of the numer of individually addressable microelectrodes this method allows the simultaneous study of several hundred to thousands of molecule–molecule interactions within seconds. In addition, a single molecule detection and nearly unlimited multi-analyte, ultra-trace immuno-chemical sensing capabilities seem possible.

Scientometric analysis of nature, the journal

300,000 reports inNature during the 1869–1998 period have been reviewed. The distribution of articles by subfields was determined. Additional sources of information were several journals on analytical chemistry and papers at the Pittsburg conference series during 1950–1999. The methodology used is based on the analysis of the average age of employed instruments. The agreement between scientometric data from various sources of information depends on the development stage of the field of science. Calculated and measured scientometric curves were compared. One of the key trends in the development of basic sciences, namely, the increase of articles dealing with instrumental analytical chemistry, inNature is revealed.

A 19F NMR Study of Enzyme Activity

This basic enzyme activity laboratory experiment demonstrates how 19F NMR can be used in biochemical studies and presents the advantages of 19F NMR over 1H NMR for studies of this nature. N-Trifluoroacetylglycine was selected as a commercially available model fluorine-tagged substrate that readily undergoes acylase I-catalyzed hydrolysis to produce trifluoroacetic acid and glycine. Progress of the reaction was monitored by following conversion of the trifluoroacetyl moiety peak of N-trifluoroacetylglycine to trifluoroacetic acid. The extent of hydrolysis was determined by comparing integrated ratios of the two 19F NMR peaks. A plot of percent hydrolysis versus enzyme concentration was used to calculate unit activity of the enzyme. This is a viable laboratory experiment for junior/senior-level courses in instrumental analytical chemistry, biochemistry, molecular biology, or spectroscopy.

Sedimentary Derivatives of Green Sulphur Bacteria as a Molecular Proxy for the Assessment of Euxinic Conditions in the Photic Zone

Organic matter burried in sediments contains a multitude of palaeoceanographic and palaeoclimatic signals. With the major developments in instrumental analytical chemistry in the last 20 years, the decoding of these signals has become possible and molecular fossils have become an important tool in the assessment of palaeoenvironments. For instance, the determination of the number of double bonds in sedimentary long-chain ketones derived from coccolithophorid algae is now a widely applied technique in palaeoceanography to determine past sea-surface temperatures (Brassell, 1993). In this paper we will demonstrate the use of molecular fossils derived from the carotenoid isorenieratene to assess photic zone euxinia in ancient depositional environments. As an example the redox state of the North Atlantic Ocean during the Cenomanian/Turonian (C/T) anoxic event will be evaluated.

Improvements in the Atomic Fluorescence Detection of Mercury

A new optical detector box for a commercially available detector for the atomic fluorescence detection of mercury was redesigned and tested. After optimisation of the new set-up the limit of detection was improved 13 fold. It was not feasible to use a hydrogen argon diffusion flame for the speciation of mercury, because of strong fluorescence signal quenching. +Permanent address: CNR, Institute of Instrumental Analytical Chemistry, Via Risorgimento 35, Pisa, Italy.

Detection of Sulphur Compounds with an Alkali Flame Ionization Detector

Journal Article Detection of Sulphur Compounds with an Alkali Flame Ionization Detector Get access M. Dressler, M. Dressler Search for other works by this author on: Oxford Academic PubMed Google Scholar J. Janák J. Janák Institute of Instrumental Analytical Chemistry, Czechoslovak Academy of Science, Brno, Czechoslovakia Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Chromatographic Science, Volume 7, Issue 7, July 1969, Pages 451–452, https://doi.org/10.1093/chromsci/7.7.451 Published: 01 July 1969 Article history Received: 07 October 1968 Published: 01 July 1969