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Cited by 3 publications
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Derivative spectroscopy is applied for the first time to the determination of alpha-and beta-acids in hops. The second derivative of the absorption spectrum provides adequate resolution for the simul taneous analysis of these compounds without any previous separation technique. The method is simple and rapid since the measurements are performed in a single scan. The results are comparable to those obtained by the ASBC photometric method and correlate well with the HPLC method (EBC).Key Words: Derivative spectroscopy, analysis method, hop products, spectrophotometry. IntroductionDerivative technique is becoming increasingly popular in analytical spectrophotometry as a resolution enhancement technique4 and as a background correction one31. It offers a convenient solution to a number of well defined analytical problems, such as resolution of multicornponent systems, sample turbidity or matrix background and enhancement of spectral details. This technique was first described by Hammond andPrice" in 1953, followed by the work of Morrison23 and French et al." Theoretical aspects have been discussed by several authors12-19-26-27 and a number of reviews concerning these aspects and the performance of the technique have been published7-24-25. Its usefulness has been demonstrated in biochemical3-14-15-31, pharmaceutical7, toxicological"' and inorganic analysis21- 22.3OAlthough UV-VIS spectrophotometry offers a very wide field of application for derivative spectroscopy, the derivative technique is perfectly general and can be applied to any other areas such as infrared spectra2", chromatography*-9 or densitometry28.In essence, derivative spectroscopy involves plotting the first, second or higher order derivatives of a spectrum with respect to wavelength. Usually this is obtained by an elec tronic RC or microcomputer device connected in series with the spectrophotometer, which computes the derivative with respect to time as the spectrum is scanned at constant speed (dMd)The "true" wavelength derivative is linearly related to the time derivative recorded, the magnitude of which is directly affected by scanning speed and spectral band width.The derivative process provides two general advantages: first, an effective enhancement of resolution, which can be useful to separate two or more components with overlapping spectra; second, a discrimination in favour of the sharpest features of a spectrum, used to eliminate interferences by broad band constituents. However, this process results in a decrease in the signal to noise ratio.Both advantages and disadvantages increase with the derivative order. Generally, the second derivative is more useful than the first ones.In this report, derivative spectrophotometry is applied for the first time to the analysis of alpha-and beta-acids in hops. The method developed allows the simultaneous determi nation of these compounds without the need for any separ ation technique and avoids the background absorption which is corrected in the ASBC method2 by means of a ternary spectrophotometric analy...
Derivative spectroscopy is applied for the first time to the determination of alpha-and beta-acids in hops. The second derivative of the absorption spectrum provides adequate resolution for the simul taneous analysis of these compounds without any previous separation technique. The method is simple and rapid since the measurements are performed in a single scan. The results are comparable to those obtained by the ASBC photometric method and correlate well with the HPLC method (EBC).Key Words: Derivative spectroscopy, analysis method, hop products, spectrophotometry. IntroductionDerivative technique is becoming increasingly popular in analytical spectrophotometry as a resolution enhancement technique4 and as a background correction one31. It offers a convenient solution to a number of well defined analytical problems, such as resolution of multicornponent systems, sample turbidity or matrix background and enhancement of spectral details. This technique was first described by Hammond andPrice" in 1953, followed by the work of Morrison23 and French et al." Theoretical aspects have been discussed by several authors12-19-26-27 and a number of reviews concerning these aspects and the performance of the technique have been published7-24-25. Its usefulness has been demonstrated in biochemical3-14-15-31, pharmaceutical7, toxicological"' and inorganic analysis21- 22.3OAlthough UV-VIS spectrophotometry offers a very wide field of application for derivative spectroscopy, the derivative technique is perfectly general and can be applied to any other areas such as infrared spectra2", chromatography*-9 or densitometry28.In essence, derivative spectroscopy involves plotting the first, second or higher order derivatives of a spectrum with respect to wavelength. Usually this is obtained by an elec tronic RC or microcomputer device connected in series with the spectrophotometer, which computes the derivative with respect to time as the spectrum is scanned at constant speed (dMd)The "true" wavelength derivative is linearly related to the time derivative recorded, the magnitude of which is directly affected by scanning speed and spectral band width.The derivative process provides two general advantages: first, an effective enhancement of resolution, which can be useful to separate two or more components with overlapping spectra; second, a discrimination in favour of the sharpest features of a spectrum, used to eliminate interferences by broad band constituents. However, this process results in a decrease in the signal to noise ratio.Both advantages and disadvantages increase with the derivative order. Generally, the second derivative is more useful than the first ones.In this report, derivative spectrophotometry is applied for the first time to the analysis of alpha-and beta-acids in hops. The method developed allows the simultaneous determi nation of these compounds without the need for any separ ation technique and avoids the background absorption which is corrected in the ASBC method2 by means of a ternary spectrophotometric analy...
Key Words:Thin-layer chromatography, HPTLC Qualitative and quantitative analysis Derivative spectra of analytes SummaryOne of the limitations due to lackof resolution for a given pair of analytes in TLC or HPTLC is the need to optimize the system. In practice this requires time, rerunning of the sample in different developing solvents, and a great deal of expertise on the part of the analyst.In our experience, application of first and second derivative recording techniques toHPTLC facilitates and speeds the whole process, permitting qualitative and quantitative assay of most unresolved spots. Consequently, we have now extended our instrumental capabilities to fourth derivative measurements. For this purpose, we have added a homemade electronic unit in series with the one previously used for first and second order derivatives. Thus, we have been able to evaluate the potential advantages of higher order derivatives for HPTLC analysis of unresolved components in various pharmaceutical products. A comparison of second and fourth order derivative measurements of seriously overlapping HWLC components in a sample of preservatives used in the pharmaceutical industry suggests that the lower order derivatives might be a better choice in view of the higher accuracy and precision of the corresponding data. This is supported by the results of other applications, such as the assay of a commercial colorant, and a syrup formulation. The observed lack of precision of fourth order measurements stems from the fact that although the second and higher order derivatives produce narrower bandwidths, thus contributing to improved resolution, the signal to noise ratio decreases and satellite peak interactions increase, thus rendering correct discrimination of the fine structural detail of overlapping components more difficult.
Rechnerunterstützte Befundung von Eiweißeiektrophoresen auf Celluloseacetatfolie
Zusammenfassung:In der klinisch-chemischen Routinediagnostik war eine effiziente rechnerunterstützte Befundung von Elektropherogrammen technologisch bislang nicht durchführbar. Der on-line Anschluß eines vollmechanisierten Elektrophoresegerätes an das Labordatensystem Deines zentralen Institutes für Klinische Chemie ermöglicht die Durchführung und Befundung von 300 Elektrophoresen pro Tag. Dabei werden nicht nur zusätzliche Informationen zum Patienten (bestimmte klinische Diagnosen, Vorwerte) und die quantitativen Veränderungen der Elektrophoresefraktionen, sondern auch Formveränderungen der Pherogrammkurve im Albumin-, ß-und -Globulin-Bereich in die Auswertung miteinbezogen. Dadurch können Doppelalbuminämien differenziert sowie transitorische Albuminverbreiterungen und monoklonale Gammopathien erkannt werden. Bei Veränderungen der quantitativen Ergebnisse einzelner Fraktionen und der Gesamteiweißkonzentration werden Hinweise bei Dysproteinämien, Mangel-und Defektproteinämien ausgegeben. Die Zuordnung der Pherogramnikonstellationen zu den medizinischen Befundmustern wird über eine Nummerncodierung der graduierten quantitativen Ergebnisse gesteuert. Das gewählte Vorgehen ist effizient und auf andere Gebiete übertragbar. Computer assisted interpretative reporting for serum protein electrophoresis on cellulose acetate filmSummary: Until a short time ago efficient Computer assisted reporting of electrophoretograms was not possible owing to the lack of appropriate technology. By integrating a fully mechanized electrophoresis System into the laboratofy dätä processing System of a centralized institute of clinical chemistry, the Separation and the Interpretation of results can be performed for 300 samples per day.The Interpretation is based üpoü available patient data (specified clinical diagnoses, previous results), calculated fractions and analysis of the electrophofetic curve in the area of albumin and the ß-and -globulin fraction. In this way it is possible to classify hereditary bisalbuminaemias and to detect transient bisalbuminaemias and monoclonal gammopathies, Piagnostic indications of specific dysproteinaemias and defect proteinaemias are printed on the report form if individual serum protein fractions and the total protein content are changed specifically. The resülts of the different electrophoretic fractions, the total protein and a set of possible alterations of the curve are nümerically coded according to the scaled biochemical ranges in five definite sections or to a decision matrix (alteration 'given' or 'not given'), respectively. The composed 'result patterns' are matched with preassigiied 'reference patterns' stored in the Computer file. The procedure is efficient and ädaptable to other areas of analysis.
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