A Simple and Rapid LC-MS/MS Method for Quantification of Total Daidzein, Genistein, and Equol in Human Urine

Table 2

Comparison of the efficiency of conjugate hydrolysis between method 1 and method 2.

Method name	Daidzein glucuronide (m/z: 429/253	Genistein glucuronide (m/z: 445/269)	Equol glucuronide (m/z: 417/241)	Daidzein monosulfate (m/z: 333/253)	Genistein monosulfate (m/z: 349/269)	Equol monosulfate (m/z: 321/241)
Method 1	−	−	−	+	+	+
Method 2	−	−	−	−	−	−

Method 1 is the original method and does not result in complete hydrolysis of isoflavone and equol sulfates. Method 2 is the new method reported here which efficiently hydrolyses all the isoflavone and equol phase-2 conjugates including the sulfates. + denotes presence of compound after hydrolysis (i.e., not fully hydrolysed) and − denotes fully hydrolysed (i.e., no detectable conjugates observed after hydrolysis).