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Analysis of Vitamin D
2
and Vitamin D
3
by LC-MS/MS in Milk
Powders, Infant Formulas, and Adult Nutritionals
Page 8 of 10
1000
10
1.0 x
SS SILD
SILIS
D3conc
3
D3conc
u
where:
SILIS
D3conc
= concentration of SIL d6-vitamin D
3
in internal standard (
units
: ng mL
-1
)
SILD
3
SS
D3conc
= concentration of SIL d6-vitamin D
3
in stock standard (
units
: μg mL
-1
)
1000 = concentration conversion factor (
units
: μg mL
-1
to ng mL
-1
)
Concentration of non-labelled vitamin D
2
in purity standard
NLD
2
PS
:
10000
x
1%
1cm
max)
abs(
λ
2
D2conc
2
E
PS NLD
PS NLD
where:
NLD
2
PS
D2conc
= concentration of vitamin D
2
in purity standard (
units
: μg mL
-1
)
NLD
2
PS
abs(
λ
max)
= UV absorbance of purity standard at 265 nm (
units
: none)
= extinction coefficient for vitamin D
2
in ethanol [461] (
units
: dL g
-1
cm
-1
)
10000 = concentration conversion factor (
units
: g dL
-1
to μg mL
-1
)
Concentration of non-labelled vitamin D
3
in purity standard
NLD
3
PS
:
10000
x
1%
1cm
max)
abs(
λ
3
D3conc
3
E
PS NLD
PS NLD
where:
NLD
3
PS
D3conc
= concentration of vitamin D
3
in purity standard (
units
: μg mL
-1
)
NLD
3
PS
abs(
λ
max)
= UV absorbance of purity standard at 265 nm (
units
: none)
= extinction coefficient for vitamin D
3
in ethanol [485] (
units
: dL g
-1
cm
-1
)
10000 = concentration conversion factor (
units
: g dL
-1
to μg mL
-1
)
Concentration of non-labelled vitamin D
2
in working standard
NLWS
:
1000
10
1.0 x
PS NLD
NLWS
D2conc
2
D2conc
u
where:
NLWS
D2conc
= concentration of vitamin D
2
in working standard (
units
: ng mL
-1
)
NLD
2
PS
D2conc
= concentration of vitamin D
2
in purity standard (
units
: μg mL
-1
)
1000 = concentration conversion factor (
units
: μg mL
-1
to ng mL
-1
)
Concentration of non-labelled vitamin D
3
in working standard
NLWS
:
1000
10
1.0 x
PS NLD
NLWS
D3conc
3
D3conc
u
where:
NLWS
D3conc
= concentration of vitamin D
3
in working standard (
units
: ng mL
-1
)
NLD
3
PS
D3conc
= concentration of vitamin D
3
in purity standard (
units
: μg mL
-1
)
1000 = concentration conversion factor (
units
: μg mL
-1
to ng mL
-1
)
Concentration of vitamin D
2
and vitamin D
3
in calibration standards
CS1–5
:
25
0.01 x
NLWS
CS1
D2conc
D2conc
25
0.01 x
NLWS
CS1
D3conc
D3conc
25
0.05 x
NLWS
CS2
D2conc
D2conc
25
0.05 x
NLWS
CS2
D3conc
D3conc
1%
1cm
E
1%
1cm
E
VitD-18 (February 2016)
FOR ERP USE ONLY
DO NOT DISTRIBUTE