Spot Extraction Research Articles

Hazardous Peak Concentrations of Hydrogen Sulfide Gas Related to the Sewage Purification Process

The concentration of hydrogen sulfide in the atmosphere of a sewage purification plant in Norway was studied. Continuous measurements over several 3-week periods showed that the concentrations generally were lower than 2 ppm, but peak concentrations over 100 ppm were discovered. Rapid onset and decline characterized these peak concentrations, which occurred at regular intervals. Through evaluation of the time pattern of these peaks compared with plant operations, a specific process was identified as the likely causative factor of the spikes. Through simple remedial actions the hydrogen sulfide concentration associated with this activity was reduced from above 100 ppm to less than 2 ppm. Olfactory fatigue to hydrogen sulfide and strong offensive odors from other compounds in the sewage makes smell ineffective for signaling high concentrations. Peak concentrations may therefore pass unnoticed unless detected with continuous measuring equipment. The risk for exposure may be reduced by enclosing processes and through the use of spot extraction ventilation in areas with compacted anaerobic waste material.

Determination of mefloquine in blood, filter paper-absorbed blood and urine by 9-fluorenylmethyl chloroformate derivatization followed by liquid chromatography with fluorescence detection

We describe a method for determination of mefloquine (MQ) in 100-microliters samples of urine, whole blood, and capillary blood collected on filter paper; quantification is by liquid chromatography with fluorescence detection at 475 nm of the 9-fluorenylmethyleneoxycarbonyl derivative. Whole blood and urine samples were prepared by extraction of MQ and internal standard from aqueous base with methyl tert.-butyl ether (MTBE), separation and evaporation of the MTBE layer, and derivatization using a solution of 9-fluorenylmethyl chloroformate in acetonitrile. Filter paper spots were immersed for 16 h in 0.1 M hydrochloric acid, followed by extraction with MTBE from aqueous sodium carbonate. The separated and evaporated organic layer was treated with the derivatizing solution. An aliquot was injected onto a high-performance liquid chromatography system using a C18 reversed-phase column and acetonitrile-water (72:28) mobile phase for filter paper spot extracts as for whole blood and urine extracts. The method has a limit of determination in blood, blood spots, and urine of 50 ng/ml with 100 microliters sample size (coefficient of variation = 16%). Linearity and precision (within-day and between-day) for the method are good. The MQ derivative was isolated and characterized spectroscopically. Values for MQ concentrations in filter paper blood spots compared favorably with values found in corresponding whole blood samples analyzed by a published method.

Temperature-Driven Segmentation for Autonomous Anti-Tank Weapons

In this paper we discuss a simple temperature-driven segmentation technique that can be used for autonomous terminal guidance of anti-tank munitions. A ratio between two images from different IR bands is taken to form an emissivity independent image that is a function of temperature only. Size and temperature discrimination can then be used to find hot spots of interest. Candidate targets are segmented from the image about the points of interest using an.algorithm that finds all regions in multi-region objects and does not require a priori intensity information. Size and gross shape features are used to determine if the segmented objects are to be classified as targets. The key to this approach is the initial hot spot extraction. The temperature dependent ratio image allows quick and confident screening of the entire field of view, so that only the regions of interest require further processing. The described techniques effectively found tanks in the presence of common battlefield clutter when used with synthetic IR imagery provided by Georgia Tech Research Institute. The simplicity, effectiveness and potential speed of this technique make it ideal for autonomous guidance of expendable anti-tank weapons, especially where only low resolution IR imagery is available.

GELLAB: A computer system for 2D gel electrophoresis analysis I. Segmentation of spots and system preliminaries

GELLAB is a computerized analysis system for two-dimensional gel electrophoresis images. It is particularly concerned with tools for the automation of comparisons among multiple gels rather than simple gel-pair analyses. Interrogation of and experimentation with the spot data base may then be performed in order to extract measurements on particular spots within the set of gels. In the case of gels partitioned into multiple classes, it is possible to search for spots in the spot data base having statistically significant differences between classes. This first paper deals with: (1) some gel properties which bear on image acquisition and image analysis, (2) the broad image acquisition environment, beyond mere scanning, such as auxiliary data, standarization and calibration, and (3) segmentation as a means of spot extraction and characterization. Our segmentation algorithm is based on problem domain heuristics and particularly on properties of the second derivative. It is therefore largely shape and density independent. The segmenter, as the other GELLAB programs, is written in SAIL and runs on either a DECSYSTEM-10 or -20.

Infrared Microsampling by Diffuse Reflectance Fourier Transform Spectrometry

It is shown that diffuse reflectance techniques enable increased sensitivity to be obtained for infrared microsampling compared with the use of KBr micropellets. When nonabsorbing matrices, such as KCl, are used, detection limits of less than 10 ng of samples are observed. Samples absorbed on graphitized substrates, which have a fairly strong general absorption but few intense absorption bands, may also be studied but at somewhat reduced sensitivity. Diffuse reflectance infrared Fourier transform spectrometry does not appear to be particularly useful for studying adsorbates on silica gel, which is not only a strong infrared absorber but also has a surface which is so active that small changes in the surface structure can change the spectrum significantly. Extraction of sample spots from thin layer chromatography plates followed by deposition onto KCl yields much better results than in situ measurements.

Combined thin-layer and gas-liquid chromatographic identification of tricyclic antidepressants in urine

A combined thin-layer and gas-liquid chromatographic (TLC-GLC) procedure for determination of tricyclic antidepressant drugs in urine is described. GLC on 1.5% OV-17 was utilized to analyze basic urine extracts directly for the tricyclics and to confirm the identify of spots extracted from thin-layer chromatograms, and TLC was used to confirm the results of these GLC screens. Lower limits of sensitivity for the thin-layer spot extraction procedure were found to range from 2 μg/ml for amitriptyline and imipramine to 10 μg/ml for desipramine and nortriptyline. Turn-around-times for the GLC tricyclic screens were usually less than 1 h. The finding that nortriptyline and desipramine were chemically altered under various extraction conditions was used as a means of confirming the identity of these drugs, and the identity of these chemically altered derivatives was discussed with reference to their low resolution mass spectra.

Solvent for extraction of L-fucose spots from paper chromatograms

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolvent for extraction of L-fucose spots from paper chromatogramsBipin R. MehtaCite this: Anal. Chem. 1976, 48, 13, 2035–2036Publication Date (Print):November 1, 1976Publication History Published online1 May 2002Published inissue 1 November 1976https://doi.org/10.1021/ac50007a061RIGHTS & PERMISSIONSArticle Views23Altmetric-Citations1LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (298 KB) Get e-Alerts Get e-Alerts

Analyse von Polyphenylgemischen mit der Dünnschichtchromatographie

A quantitative analysis of mixtures of polyphenyls can be achieved by Chromatographic separation on thin-layers of alumina G using n-heptane as the mobile phase, extraction of the separated spots by n-heptane or methylene chloride and spectrophotometric determination of the extracted compounds. © 1964 Springer-Verlag.

Extraction of Ninhydrin-Developed Spots from Paper Chromatograms and Determination of Amino Acids

(1957). Extraction of Ninhydrin-Developed Spots from Paper Chromatograms and Determination of Amino Acids. Proceedings. Annual meeting - American Society of Brewing Chemists: Vol. 15, Proceedings of the Annual Meeting 1957, pp. 60-65.