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. Author manuscript; available in PMC: 2019 May 14.
Published in final edited form as: Anal Chem. 2009 Jun 1;81(11):4349–4355. doi: 10.1021/ac9001707

Table 1.

Linear Equations of Disaccharides Based on a Fixed Amount of the Corresponding Isotopically Labeled Internal Standardsa

disaccharides linear equations correlation coefficients
 0S Y = 0.125X + 0.242 R2 = 0.999
 NS Y = 0.128X + 0.244 R2 = 0.999
 6S Y = 0.131X – 0.123 R2 = 0.997
 2S Y = 0.127X – 0.216 R2 = 0.992
 NS6S Y = 0.138X – 0.172 R2 = 0.997
 NS2S Y = 0.128X – 0.212 R2 = 0.987
 2S6S Y = 0.131X – 0.271 R2 = 0.995
 TriS Y = 0.131X + 0.145 R2 = 0.998
a

A mixture of all of the isotopically labeled disaccharides, each in a fixed amount (15 ng), was analyzed by LC–MS five times in the presence of a mixture of the eight unlabeled disaccharides in five different amounts (2, 5,10, 20, and 50 ng). The ratio of the intensity of the ion corresponding to each unlabeled disaccharide to the ion corresponding to the identical isotopically labeled disaccharide (Y) was plotted as a function of the amount of unlabeled disaccharide (X).