HPLC-DAD analysis

COMPOSITION OF THE MOBILE PHASE USED FOR THE HPLC-DAD ANALYSIS... 

A similar heterogeneous photocatalytic system was applied for the study of the decomposition of the anthraquinone dye, Acid blue 25 (AB25). The chemical structure of the dye and those of the first intermediates tentatively identified by HPLC-MS are shown in Fig. 3.55. RP-HPLC-DAD analysis of AB25 was carried out in a C4 column (250 X 4 mm i.d. particle size 5 //m) at ambient temperature. The isocratic mobile phase was composed of ACN (solvent A)-water (pH adjusted to 4.5 with acetic acid and ammonium acetate) (42 58, v/v). 

Table 5.1 Characterization of ginsenoside content and composition across products through HPLC-DAD analysis...

This is the first attempt to examine family-held ginseng landraces that have been in cultivation for several decades. Clearly, there is evidence of variation between these landraces. Although HPLC-DAD analysis clearly quantified ginsenoside levels and showed variability, it did not present unique characteristics that would rapidly identify each landrace. Currenfiy, Nuclear Magnetic Resonance (NMR) methods are... 

Determination of captan and its metabolites in grape, must and wine by GC-MS and HPLC-DAD analysis (Angioni et al., 2003)... 

Table 8.6 Instrumental setting for HPLC-DAD analysis of residual sulphur on grapes.

When the graphite electrodes are arced into a hydrocarbon solvent like -hexane, as described in the experimental section, although the main reaction product consists predominantly of a mixture of polyynes, it is possible to detect other byproducts by HPLC-DAD analysis. These byproducts are not found when graphite electrodes are arced in liquid nitrogen or are present in extremely small trace amounts when the arc is made in certain solvents like methanol, ethanol or water (see Table 8.1). 

Completely opposite results to those discussed in the case of -hexane and benzene have been observed in the case of alcohols like methanol and ethanol (Table 8.1). When methanol or ethanol were used as the solvent for arcing with Ti electrodes, the formation of carbon black derived from solvent carbonization was reduced to a minimum. Simultaneously, the HPLC DAD analysis revealed the complete absence of any polyynes in these oxygenated solvents. Instead, only PAHs were detected, but in trace amounts (Table 8.1). Among the PAHs detected in methanol, biphenyl, naphthalene, acenaphthalene, phenanthrene, and anthracene were easily identified, based both on their retention times and on their peculiar UV spectral pattern in comparison with the spectral pattern of authentic reference compounds. Perylene and fluoranthene were also reasonably identified, based on the retention times and the reasonable matches of reference UV spectra. In any case, the PAHs formed under these conditions were present in at least two orders of magnitude lower concentration than the polyynes formed by arcing the graphite electrodes in methanol. Moreover, PAH formation in methanol was considerably lower than the trace amounts produced in n-hexane. 

The HPLC-DAD analysis revealed the presence of the following polyynes C4H2, C6H2, C8H2, and C10H2. Polyyne C-xIL was by far the most abundant product. 

ROMANI A, MINUNNI M, MULINACCI N, PINELLI P and VINCIERI E F (2000), Comparison among differential pulse voltammetry, amperometrie biosensor, and HPLC/DAD analysis for polyphenol determination , J... 

Arapitsas P, Turner C (2008) Pressurized solvent extraction and monolithic column-HPLC/ DAD analysis of anthocyanins in red cabbage. Talanta 74(5) 1218-1223... 

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