Table 1.

Structures of unconjugated, glycine- and taurine-conjugated bile acids and their optimum MS–MS parameters.

Bile acid	R1	R2	R3	R4	[M-H]-	MRM transitions	CE(V)
α-MCA	OH (β)	OH(α)	H	OH	407.2	407.2 → 407.2	20
β-MCA	OH (β)	OH (β)	H	OH	407.2	407.2 → 407.2	20
ω-MCA	OH (α)	OH (β)	H	OH	407.2	407.2 → 407.2	20
CA	H	OH (α)	OH	OH	407.2	407.2 → 407.2	20
CDCA	H	OH (α)	H	OH	391.2	391.2 → 391.2	20
DCA	H	H	OH	OH	391.2	391.2 → 391.2	20
UDCA	H	OH (β)	H	OH	391.2	391.2 → 391.2	20
GCA	H	OH (α)	OH	NHCH2CO2H	464.2	464.2 → 74.0	40
GCDCA	H	OH (α)	H	NHCH2CO2H	448.2	448.2 → 74.0	40
GDCA	H	H	OH	NHCH2CO2H	448.2	448.2 → 74.0	40
GUDCA	H	OH (β)	H	NHCH2CO2H	448.2	448.2 → 74.0	40
TMCA	OH (α)	OH (α)	H	NHCH2CH2SO3H	514.2	514.2 → 80.0	70
TCA	H	OH (α)	OH	NHCH2CH2SO3H	514.2	514.2 → 80.0	70
TCDCA	H	OH (α)	H	NHCH2CH2SO3H	498.2	498.2 → 80.0	70
TDCA	H	H	OH	NHCH2CH2SO3H	498.2	498.2 → 80.0	70
TUDCA	H	OH (β)	H	NHCH2CH2SO3H	498.2	498.2 → 80.0	70
TLCA	H	H	H	NHCH2CH2SO3H	482.2	482.2 → 80.0	70
IS					401.2	401.2 → 340.5	40

Backbone and side chain structures of the major BAs. CE: collision energy; IS (internal standard): cortisone acetate.