New concepts in densitometry

Bethke, H.; Frei, R.W.

doi:10.1016/s0021-9673(01)97922-1

Cited by 26 publications

(2 citation statements)

References 3 publications

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“…Particularly for curvilinear response curves, the intercept may be only a mathematical parameter of the regression expression for the extrapolated linear dynamic range of interest (Figure 1 in Ref. 25). In such a case, the zero concentration response value is analytically immaterial.…”

Section: Theoreticalmentioning

confidence: 99%

“…It is only fair to point out, however, as this paper will show, that in either case, under certain fortuitous circumstances involving the sample and standard responses, no computational error in the result may, in fact, exist. Intercepts in response curves are often encountered with positive or negative values almost always of the algebraic sign as predictable from the type of measured signal: positivefluorometry (3,20), spectrophotometry (22,23), spectrofluorodensitometry or spectrophotodensitometry (3,7,25); negative-polarography (4), GLC (19), HPLC (6,24). It is the purpose of this paper to evaluate both qualitatively and quantitatively the bias error caused by an SPEC calculation from an assumed linear response curve through zero for the case where the true response curve is a straight line with a significant intercept.…”

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confidence: 99%

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Potential error in single-point-ratio calculations based on linear calibration curves with a significant intercept

Cardone¹,

Palermo²,

Sybrandt³

1980

Anal. Chem.

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Calculations based on a single-point standard linear calibration curve which has a finite intercept are a potential source of bias error. The error has been shown to be a function of magnitude of the slope and intercept, and the magnitude of the difference in the standard and sample responses. For maximum accuracy, the ratio of the difference in responses to the standard response should be the lowest possible. For any response curve, a reliable calculation of the percent error resulting from making a single-point-ratio calculation (SPRC) where a finite intercept exists is shown so that a decision as to its proper use or non-use may be made. In most cases, even when an analytically significant intercept is found in a linear calibration curve, the SPRC technique may stili be employed by calculating the sample signal to standard signal, S,/S, ratio range for an acceptable % error bias range. This calculation of the S,/S, ratio constitutes a trade-off between the use of a single standard and a shortened linear dynamic range with its possibility of more reanalyses against the use of the entire linear dynamic range with its mandatory requirement of more standards but the lesser possibility of reanalyses.

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Section: Theoreticalmentioning

confidence: 99%

mentioning

confidence: 99%

Potential error in single-point-ratio calculations based on linear calibration curves with a significant intercept

Cardone¹,

Palermo²,

Sybrandt³

1980

Anal. Chem.

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Über die Bestimmung des Metamizols und seines Hydrolyseproduktes durch quantitative Auswertung von Dünnschichtchromatogrammen

Ebel

Rost

1978

Archiv der Pharmazie

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Ebel und RostArch. Pharm. 4-Methylphenyl-bis-(4-trimethylsilyl-phen yl)-methan (6d)SC: El; leicht gelbliche, amorphe, zahe Mass mit Rf = 0,67 (El Metamizol and its degradation product, 4-methylaminophenazone, were determined by TLC and in situ measurement of their reflectances. In metamizol solutions, used for injections, hydrolysis reaches 3.6 to 4.0 %. This degradation is independent of the storage time.

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Bestimmung von Ephedrin in Arzneimitteln durch quantitative Dünnschichtchromatographie

Ebel

Rost

1979

Archiv der Pharmazie

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Arch. Pharm. 100 Ebel un d R 0 s t am Rotationsverdampfer entfernt. Der olige Ruckstand wird erneut in trockenem Ether gelost und Petrolether bis zur Triibung zugegeben. Das Cemisch wird mehrere Std unter R u c k f l d geruhrt und dann einige Std bei 0' stehen gelassen. Nach Absaugen des Bodenkorpers unter Stickstoff wird aus Chloroform-Methanol ( 2 0 : l ) urnkristallisicrt. Ausb. = 50 %fur 9a, 10-20 %fur 9b-d. Wu danken Fraulein E. Munhort sowie Herrn A. Gisser fur ihre geschickte Mitarbeit bei d i e s n Experimenten. 1 H. Hahn und S. Rebsdat (Hoechst AG), DT-OS 1 768 171, sowie US.-Patent 3 926 989, C. Die direkte Remissionsmessung von Ephedrin nach d c Trennung ist bei einem Gehalt von mehr als 2 @ pro Fleck moglich. Nach Reaktion mit Ninhydrin liegt die Erfassungsgrenze bei etwa 50 ng pro Fleck. In beiden Fallen liegt die Genauigkeit der Bestimmungsmethode in der GroiJenordnung von 2,5-5 8 (ale relative Standardabweichung); bedingt durch den relativ hohen Gehalt bei der diekten Vermessung odcr durch die notwendige Farbreaktion. @ Verlag Chemie, CmbH, Weinheim 1379 I k i der Irnidazolsynthese aus crRromketoncn und Formirninoethylestcr in fliissigem Ammoniak werden a-alkylsubstituierte Hutterslure-Amide als Nebenprodukte erhalten, deren Entstchen einer I.hvorskii-UinlagerunR zugeschrieben wird. Die isolierten Verbindungen wurden NMR-spektroskopisch untersucht. NMR Spectroscopy of Heterocycles. VI: Favorskii Rearrangement of a-Bromo-p-methoxy KetonesDuring Imidazole Cyclisation in Liquid Ammonia.During irnidazole synthesis with a-brorno ketones and formiminic ethyl ester in liquid ammonia a-alkylbutyric amidcs were obtained as by-products. 'Ihcir formation is attributed to a Eboorskii rearrangement. The compounds were investigated by NMR spectroscopy..-

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New concepts in densitometry

Cited by 26 publications

References 3 publications

Potential error in single-point-ratio calculations based on linear calibration curves with a significant intercept

Potential error in single-point-ratio calculations based on linear calibration curves with a significant intercept

Über die Bestimmung des Metamizols und seines Hydrolyseproduktes durch quantitative Auswertung von Dünnschichtchromatogrammen

Bestimmung von Ephedrin in Arzneimitteln durch quantitative Dünnschichtchromatographie

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