Description

Levodopa arrives as a crystalline amino acid carrying a catechol ring, and most stockroom trouble with it comes from that ring rather than from the amino acid part. Zobacz również ten sam materiał w innej gramaturze: Löwenmähne / Igelsopran / Hericium Erinaceus < .

What kind of molecule is in the container?

An aromatic alpha-amino acid: a propanoic acid backbone bearing an amino group and a 3,4-dihydroxyphenyl substituent. The formula C9H11NO4 and the formula mass of 197.19 g/mol correspond to that single structure, while registry number 59-92-7 refers specifically to the L-enantiomer. Catechol and amino acid functions behave independently, which is why the compound is amphoteric and awkward to handle by analogy with either class alone.

Why does the solid darken with age?

Catechols oxidise. Atmospheric oxygen, light, alkaline pH and traces of iron or copper all push the ring towards quinone species, which then couple into coloured polymeric material. A portion that has turned grey or brown has not merely changed appearance; it now carries oxidation products that a chromatogram will resolve as extra peaks.

How does this batch differ from a technical grade?

Three things: an assay with the method named beside it, a declared water content, and a statement of chiral purity. Technical material may be a mixture of enantiomers or simply undeclared, and since the D-form is the antipode of what the registry number names, an undeclared portion is not strictly the same substance.

Which checks confirm identity?

Ultraviolet spectroscopy gives the catechol absorption pattern, mass spectrometry gives the molecular ion, and proton NMR resolves the aromatic and aliphatic regions cleanly. Chiral purity needs its own determination — optical rotation or a chiral column — because no achiral method distinguishes the two forms. Zobacz również ten sam materiał w innej gramaturze: Methylene Blue / METHYLENE BLUE. Purity ≥ 99.99% 1.

How should the container be stored and reopened?

Cool, dry, dark and tightly closed, ideally under an inert atmosphere where the vessel will be opened many times. Bring it to ambient temperature first, weigh promptly, then reseal; each opening admits both oxygen and moisture. Solutions are best made fresh and kept slightly acidic, since oxidation accelerates sharply as pH rises.

Does the melting behaviour tell you anything?

Less than it would for a simple organic solid. This material melts with decomposition, so what is recorded is a decomposition range rather than a sharp physical constant, and the value shifts with heating rate. Purity is judged far better by chromatography and water determination than by that thermal reading.

Identity rests on formula C9H11NO4, formula mass 197.19 g/mol and registry number 59-92-7.
The catechol ring is the reactive part; oxygen, light, alkali and metal traces are the adversaries.
Chiral purity demands a dedicated method and is never implied by an achiral assay.
Storage is cool, dry, dark and sealed, with solutions prepared fresh and kept acidic.
A decomposition range is not a purity criterion.

Materiały o zbliżonej charakterystyce

Literatura przedmiotu

Badania na zwierzętach i in vitro indeksowane w bazie PubMed; strona nie zawiera wskazówek dotyczących stosowania u ludzi.

Klawans HL Levodopa-induced myoclonus 1975, Archives of neurology. PMID 1079721
Nutt JG Pharmacokinetics and pharmacodynamics of levodopa 2008, Movement disorders : official journal of the. PMID 18781675
Nutt JG Levodopa: rational and irrational pharmacology 1994, Annals of neurology. PMID 8024259
Goetz CG Influence of COMT inhibition on levodopa pharmacology and therapy 1998, Neurology. PMID 9591519

Kwalifikacja odczynnika. Materiału nie wolno stosować u ludzi. Zastosowanie weterynaryjne jest równie wykluczone. Przeznaczenie: praca laboratoryjna i oznaczenia analityczne technikami HPLC i GC-MS. Poza kategorią produktów leczniczych i spożywczych.

Additional information

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