TABLE 1

Mass spectrometric data obtained on timolol and timolol metabolites M1 to M4

Compound	m/z	Identification	Measured Accurate Mass	Calculated Accurate Mass	Labile Protons
			Da
Timolol	317.15	[M + H]⁺ = [C₁₃H₂₄O₃N₄S + H]⁺	317.1647	317.1652	2
	261.1	[M + H - C₄H₈]⁺	261.1014	261.1021
	244.1	[M + H - C₄H₁₁N]⁺	244.0775	244.0756
	188.1	[M + H - C₇H₁₄NOH]⁺	188.0527	188.0493
M1	333.15	[M + H]⁺ = [C₁₃H₂₄O₄N₄S + H]⁺	333.1596	333.1596	3
	315.13	[M + H - H₂O]⁺	*
	259.1	[M + H - H₂O - C₄H₈]⁺	259.0867	259.0865
	242.1	[M + H - H₂O - C₄H₁₁N]⁺	*
	186.0	[M + H - H₂O - C₇H₁₄NOH]⁺	186.0371	186.0337
M2	335.15	[M + H]⁺ = [C₁₃H₂₆O₄N₄S + H]⁺	335.1741	335.1753	3 or 4
	279.1	[M + H - C₄H₈]⁺	279.1132	279.1127
	206.1	[M + H - C₇H₁₄NOH]⁺	206.0637	206.0599
M3	349.15	[M + H]⁺ = [C₁₃H₂₄O₅N₄S + H]⁺	349.1566	349.1545	4
	293.1	[M + H - C₄H₈]⁺	*
	220.1	[M + H - C₇H₁₄NOH]⁺	220.0437	220.0392
M4	315.15	[M + H]⁺ = [C₁₃H₂₂O₃N₄S + H]⁺	315.1450	315.1491	2
	259.1	[M + H - C₄H₈]⁺	*
	186.0	[M + H - C₇H₁₄NOH]⁺	*