Table 1. Operating conditions to HPLC-MS/MS

Parameters			Conditions
HPLC	Flow rate		0.45 mL/min
	Column		C18 150x2.1 mm, 2.7 μm
	Column temperature		40°C
	Mobile phase		Isocratic 5 mM ammonium acetate/MeOH (5/95)
	Injection volume		1 μL
MS/MS	Interface		ESI
	Nebulizing gas flow		3 L/min
	Heating gas flow		10 L/min
	Interface temperature		300°C
	DL temperature		250°C
	Heat block temperature		400°C
	Vitamin D2	Precursor ion	397.30
		Product ion	107.1, 105.1, 91.0
	Vitamin D3	Precursor ion	385.10
		Product ion	107.1, 105.1, 79.1