High performance liquid chromatography coupled with photodiode array detector (HPLC-DAD) has been reported to quantify isolated flavonoids or these compounds in complex biological matrices, such as Chinese herbal drugs and products from factories. This work was designed, therefore, to develop an HPLC-DAD system to separate quercetin, luteolin and apigenin and to quantify them in extractive solu...

During the high-performance liquid chromatographic (HPLC) analysis of o-phthaldialdehyde (OPA)-derivatized amino acids such as arginine and homoarginine, we observed that the response of the fluorescence detection (FLD) system is decreased when the photodiode array detection (DAD) system (located before the FLD system) was simultaneously switched on. The decrease in the FLD response, i.e., the ...

An automated, qualitative screening HPLC method for the identification of basic compounds in urine has been established. A 1-ml volume of urine was extracted by on-line extraction and separated on two coupled strong cation-exchange columns under isocratic conditions. The use of the photodiode-array detector (DAD, = 190370 nm) gave access to a library of > 2600 toxicologically relevant compounds...

Melatonina, tirosol e hidroxitirosol son sustancias bioactivas cuya presencia se ha descrito en el vino baja concentración, lo que representa un reto para su análisis. El presente trabajo plantea la puesta a punto de método determinación, mediante cromatografía líquida alta eficacia acoplada detección por espectrofotometría diodos y espectrometría masas (HPLC-DAD-MS) aplicación posterior anális...

Cuscuta chinensis and Cuscuta australis, the two botanical sources of the Chinese herbal medicine Tu-Si-Zi, were distinguished from each other based on qualitative and quantitative chemical analysis. By HPLC‑DAD‑MS, a total of 36 compounds were characterized from these two Cuscuta species, including 14 flavonoids, 17 quinic acid derivatives, and 5 lignans. In addition, HPLC‑UV was applied to de...