Abstract: Method of identification and quantitative analysis of carboxylic acid(s) in a sample by mass spectrometry using stable isotope labeled internal standard is provided. Said internal standard is prepared by reaction of an authentic sample of said carboxylic acid with a stable isotope labeled reagent, and is added to a sample containing said carboxylic acid. Said carboxylic acid in said sample is then quantitatively converted to a chemical compound of identical structure, except the stable isotope atoms, as that of said internal standard using a non-labeled reagent. Said sample is then extracted and the extract is analyzed by mass spectrometry. Identification and quantification of said carboxylic acid are made from a plot of ion ratio of said converted carboxylic acid to said internal standard versus carboxylic acid concentration.

Abstract: A heated vibrating foot massaging device for reducing tension in the feet of a user. The heated vibrating foot massaging device includes a base member having a plurality of wall members for pivotally supporting an elongate semi-circularly shaped massage unit. The massage unit incorporates both a vibrator assembly and a heater unit coupled to heating elements thereby providing both oscillatory and thermal comfort. A plurality of pressure points are positioned on the exterior surface for therapeudic action.