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CS
, µg/mL =
WS
× (
V
WS
/25)
where
WS
= concentration of nucleotide in working standard
(μg/mL);
V
WS
= volume of working standard in calibration standard
(mL); and 25 = total volume of calibration standard (mL).
(
g
) Determine the linear regression curve for the ratio of peaks
areas (nucleotide/TMP;
y
-axis) vs the ratio of concentrations
(nucleotide/TMP;
x
-axis) for calibration standards and calculate
the slope with the
y
-intercept forced through 0.
(
h
) Interpolate the nucleotide contents in unknown samples
from this calibration curve.
(
1
)
For powders
.—
Nucleotide, mg/hg =
1000
100 )
( 1
×
×
××
S
SI
SI
SI
TN
W
V C
L A
A
(
2
)
For ready-to-feed liquids
.—
Nucleotide, mg/dL =
1000
100 )
( 1
×
×
××
S
SI
SI
SI
TN
V
V C
L A
A
where
A
NT
= nucleotide peak area in sample;
A
IS
= TMP peak area
in sample;
L
= linear regression slope of calibration curve;
C
IS
=
concentration of internal standard added to sample (µg/mL);
V
IS
= volume of internal standard added to sample (mL);
W
S
= weight
of sample (g); 1000 = mass conversion of result (µg to mg);
V
S
=
volume of sample (mL); and 100 = mass or volume conversion of
result (g to hg or mL to dL).
J. Data Handling
Report results in mg/hg or mg/dL to 1 decimal place.
References:
J. AOAC Int
.
93
, 966(2010)
J. AOAC Int. 95 , 599(2012)DOI: 10.5740/jaoacint.CS2011_20
AOAC SMPR 2011.008
J. AOAC Int . 95 , 296(2012)DOI: 10.5740/jaoac.int.11-0453
Anal. Bioanal. Chem
.
405
, 5311(2013)
Posted: February 6, 2015
Candidates for 2016 Method of the Year
356