Drug substances HPLC data

As a characterization technique, UV absorption can be used as an important piece of confirmatory evidence for a proposed structure. Simple rules for the prediction of absorption maxima for structures can be found in introductory texts.19 More advanced techniques for the uses of HPLC-DAD have been previously presented.20 Often, HPLC-DAD data are used to show that an impurity or degradant is similar (electronically) to the drug substance by virtue of the same chromophore.21... 

Chemists and statisticians use the term mixture in different ways. To a chemist, any combination of several substances is a mixture. In more formal statistical terms, however, a mixture involves a series of factors whose total is a constant sum this property is often called closure and will be discussed in completely different contexts in the area of scaling data prior to principal components analysis (Chapter 4, Section 4.3.6.5 and Chapter 6, Section 6.2.3.1). Hence in statistics (and chemometrics) a solvent system in HPLC or a blend of components in products such as paints, drugs or food is considered a mixture, as each component can be expressed as a proportion and the total adds up to 1 or 100%. The response could be a chromatographic separation, the taste of a foodstuff or physical properties of a manufactured material. Often the aim of experimentation is to find an optimum blend of components that tastes best, or provide die best chromatographic separation, or die material diat is most durable. 

HPLC of Alkaloids from Khat HPLC can be used to identify the drugs present in this controlled substance, with resolution of cathinone, norpseudoephedrine and norephedrine being achieved on silica gel (as the stationary phase), with a mobile phase consisting of 1,2-dichloroethane/methanol/acetic acid/diethylamine/water (800 200 10 5 5, by volume), employing UV detection at 257 nm [7]. This method has also been used to quantify the drug components present in these samples. However, retention time data were not provided in this paper. 

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