AOAC SPIFAN ERP & Working Group Method Reviews (July 10, 2019)
in purity standard (μg/mL); and 1000 = concentration conversion factor (μg/mL to ng/mL). (i) Concentrations of vitamin D 2 and vitamin D 3 in CS1–CS5. — = × CS1 NLWS 0.01 25 Dconcn Dconcn
SILD SS
λ
=
×
3 abs( max)
10000
SILD SS
3 D3concn
1 cm 1%
E
where SILD 3
SS
= concentration of d6 -vitamin D 3
in the stock
D3concn
standard (μg/mL); SILD 3 standard at 265 nm (cm −1 ); E 1cm conversion factor (g/dL to μg/mL). (c) Concentration of SIL vitamin D 2 SS abs(λ max) vitamin D 3
= UV absorbance of the stock 1% = extinction coefficient for
0.05
=
×
in ethanol (485 dL/g·cm); and 10000 = concentration
CS2
NLWS
Dconcn
Dconcn
25
in SILIS. —
0.25
=
×
CS3
NLWS
Dconcn
Dconcn
25
× × 1.0 10
=
SILIS
SILD SS
1000
D2concn
2 D2concn
0.5
=
×
CS4
NLWS
Dconcn
Dconcn
25
where SILIS
= concentration of d6 -vitamin D 2
in the internal
D2concn
standard (ng/mL); SILD 2 = concentration of d6 -vitamin D 2 in the stock standard (μg/mL); and 1000 = concentration conversion factor (μg/mL to ng/mL). (d) Concentration of SIL vitamin D 3 in SILIS. — = × × SILIS SILD SS 1.0 10 1000 D3concn 3 D3concn = concentration of d6 -vitamin D 3 in the stock standard (μg/mL); and 1000 = concentration conversion factor (μg/mL to ng/mL). (e) Concentration of nonlabeled vitamin D 2 in NLD 2 PS. — = × λ 10000 NLD PS NLD PS E 2 D2concn 2 abs( max) 1 cm 1% where NLD 2 PSD 2concn = concentration of vitamin D 2 in the purity standard (μg/mL); NLD 2 PS abs(λ max) = UV absorbance of the purity standard at 265 nm (cm −1 ); E 1 cm 1% is the extinction coefficient for vitamin D 2 in ethanol (461 dL/g·cm); and 10 000 is the concentration conversion factor (g/dL to μg/mL). (f) Concentration of nonlabeled vitamin D 3 in NLD 3 PS. — = × λ 10000 NLD PS NLD PS E 3 D3concn 3 abs( max) 1 cm 1% where NLD 3 PS D3concn = concentration of vitamin D 3 in the purity standard (μg/mL); NLD 3 PS abs(λ max) = UV absorbance of the purity standard at 265 nm (cm −1 ); E 1 cm 1% = extinction coefficient for vitamin D 3 in ethanol (485 dL/g·cm); and 10 000 = concentration conversion factor (g/dL to μg/mL). (g) Concentration of nonlabeled vitamin D 2 in NLWS. — = × × NLWS NLD PS 1.0 10 1000 D2concn 2 D2concn = concentration of vitamin D 2 in the purity standard (μg/mL); and 1000 = concentration conversion factor (μg/mL to ng/mL). (h) Concentration of nonlabeled vitamin D 3 in NLWS. — = × × NLWS NLD PS 1.0 10 1000 D3concn 3 D3concn SS D2concn where SILIS D3concn = concentration of d6 -vitamin D 3 in the internal standard (ng/mL); SILD 3 SS D3concn where NLWS D2concn = concentration of vitamin D 2 in the working standard (ng/mL); NLD 2 PS D2concn
1.25
=
×
CS5
NLWS
Dconcn
Dconcn
25
where CS1–CS5
= concentration of vitamin D 2
or vitamin D 3
Dconcn
= concentration of vitamin D 2
in the CSs (ng/mL); and NLWS
Dconcn
in the working standard (ng/mL).
or vitamin D 3
(j) Concentrations of SIL d6-vitamin D 2
and d6-vitamin D 3
in
CS1–CS5. —
0.25
− = Dconcn
×
CS1 5
SILIS
Dconcn
25
where CS1–CS5 vitamin D 3 d6 -vitamin D 2
= concentration of d6 -vitamin D 2
or d6 -
Dconcn
in the CSs (ng/mL); and SILIS
= concentration of
Dconcn
or d6 -vitamin D 3
in the internal standard (ng/mL).
(k) Mass of powder in slurried sample. —
D
= +
´
mass
S
A
mass
mass
(D W )
mass
mass
where S mass = mass of powder in the slurried sample (g); D mass = mass of the dry powder used to make the slurry (g) W mass water used to make the slurry (g); and A mass slurried sample used in the analysis (g). (l) Determine the linear regression curve y = m·x + c (using the least-squares method) for the ratio of peak areas (nonlabeled vitamin D/SIL d6 -vitamin D) versus the ratio of concentrations (nonlabeled vitamin D/SIL d6 -vitamin D) for five CSs with the y -intercept forced through zero. (m) The concentration (w/w) of vitamin D 2 or vitamin D 3 in dry powders is calculated as = mass of = mass of the aliquot of
SILIS
PA
SILIS
100
=
×
×
×
alqt
NLD
Dconcn
Result D
PA
L
S
1000
SILD
mass
where Result D = vitamin D 2
or vitamin D 3
concentration in the or vitamin D 3 or d6 -vitamin D 3 in
NLD = peak area of vitamin D 2 = peak area of d6 -vitamin D 2
sample (μg/hg); PA
the sample; PA
SILD
= concentration of d6 -vitamin D 2
or d6 -
in the sample; SILISD
concn
vitamin D 3 in the SILIS (ng/mL); L = slope of the calibration curve; alqt = volume of the SILIS aliquot spiked into the sample (0.5 mL); S mass = mass of the sample (g); 1000 = concentration conversion factor (ng/g to μg/g); and 100 = concentration conversion factor (μg/g to μg/hg). (n) The concentration (w/v) of vitamin D 2 or vitamin D 3 in ready-to-feed (RTF) liquids is calculated as SILIS
where NLWS
= concentration of vitamin D 3
in working
D3concn
PS
= concentration of vitamin D 3
standard (ng/mL); NLD 3
D3concn
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