PubMed · 16645003
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Joseph C McDonald. 2006. On changes and passings.. https://doi.org/10.1093/rpd%2Fncl037
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The concentrations of the polymethoxylated flavones (PMFs) in peels of selected citrus cultivars grown in Jamaica and Mexico were determined. The PMFs were extracted from sun-dried citrus peels with reagent-grade methanol. Analyses were carried out by reverse-phase HPLC and UV detection. The column used was a C(18) 5 microm (150 x 4.6 mm) Discovery column. Elution was in the gradient mode, using a ternary mobile phase. The results showed that all the citrus cultivars used contained at least three of the six major PMFs quantified. Ortanique peel contained the highest quantity of PMFs (34,393 +/- 272 ppm), followed by tangerine (28,389 +/- 343 ppm) and Mexican sweet orange (sample 1; 21,627 +/- 494 ppm). The major PMFs, i.e. sinensetin, nobiletin, tangeretin, heptamethoxyflavone, tetramethylscutellarein and hexamethyl-o-quercetagetin, present in the peels of 20 citrus cultivars, was quantified. The results were compared with those of Florida citrus peels. A large amount of citrus peels and byproducts are produced in the Caribbean which could provide a cheap and convenient source of PMFs.
A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of camboginol in the extract of fruit rinds of Garcinia cambogia has been developed. Separation was achieved isocratically on an RP C(18) column using a solvent system consisting of a mixture of acetonitrile-water (9:1) and methanol-acetic acid (99.5:0.5) in the ratio of 30:70 as mobile phase at a flow rate of 0.4 mL/min. A multiple reaction monitoring (MRM) method was developed for quantification of camboginol in the fruit rinds extract of G. cambogia using MRM transitions of m/z 601.4 --> m/z 176.7 and m/z 601.4 --> m/z 448.9, respectively. The calibration curve based on peak area against concentration was linear up to 50 ng/mL with a detection limit of 0.5 ng/mL. The method showed satisfactory reproducibility with a coefficient of variation of less than 6%. The method was successfully applied for quantification of camboginol in different Garcinia extracts.
Electrospray ionisation mass spectrometry (ESI-MS) is used for the qualitative and quantitative study of ion binding to interfaces. The ESI-MS measurements are carried out in aqueous solutions of sodium dodecyl sulphate (SDS) in the presence of NaCl, NH(4)ClO(4) , KCl, or Mg(ClO(4))(2) . The effect of the electrolyte concentration on the fractions, y(cation(+) ), of the DS(-) monomers bound to the cations is shown. Moreover, the binding stability of different cations with DS(-) monomers is determined versus the electrolyte concentration. This stability and the y(Na(+) ) values (the Na(+) ions derived from SDS), estimated in the presence of a given electrolyte, are quantitatively correlated with the electrolyte cation effect on the water structure. We also present calibration curves from which the molar concentrations of the sodium ions (derived from SDS) and of the other cations (derived from the electrolyte), bound to the SDS-micelle surface at a given electrolyte concentration, can be obtained. Besides, specific ion effects (Hofmeister effects) are considered for 1:1 electrolytes.