Protein samples containing ionic surfactants such as sodium dodecyl sulfate (SDS) can be analyzed by matrixassisted laser desorption/ionization mass spectrometry, contrary to what is currently accepted. SDS at varying concentrations was added to four polypeptide samples. As expected, a decrease in the signal was observed for increasing concentrations of SDS up to 0.1% (w/v), at which no signal was observed for three of the analytes. However, a recovery of the signals of all the analytes was observed at concentrations of SDS above 0.3%, with useful spectra at concentrations as high as 10%. The SDS concentration at which signal recovery starts is always the same, regardless of the type and the concentration of the analyte. Another two surfactants 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) and octylphenolpoly(ethylene glycol ether)10 (Triton X-100) were also tested. The trend for signal variation with CHAPS addition is similar to that for SDS addition, but for Triton X-100, the signal always diminishes with increasing surfactant concentration. For protein samples containing surfactants with anionic groups, addition of more surfactant allows the acquisition of useful mass spectrometric data.

The results of a survey of 28 over-the-counter tablet preparations of isoflavones extracted from soy and 2 with black cohosh that are available in Portuguese pharmacies are presented. All were remedies for hot flushes and post-menopause related problems. Their isoflavone content was analysed by HPLC/DAD and LC/MS-MS. The results show that the isoflavonoids in soy extracts sold by the pharmaceutical companies in Portugal are mainly daidzin, glycitin and genistin.

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