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compounds and that the myo-inositol sample peak areas or heights
are within the range of the myo-inositol standard peak areas or
heights. The concentration of myo-inositol cannot be calculated if
there are interferences or if the separation is poor. The myo-inositol
retention time should be 11 to 13 min depending on the individual
analytical column.
(
a
)
Concentration of working standards
.
C
W
= W
×
1/0.05
×
1/10
×
A
1
/V
1
×
A
2
/V
2
= W
×
2
×
A
1
/V
1
×
A
2
/V
2
where C
W
is the concentration of the working standard solution in
milligrams per liter; W is the weight, in milligrams, of myo-inositol
standard weighed; 0.05 is the dilution volume of the stock standard
in liters; 1/10 is the intermediate standard dilution (10 to 100 mL);
A
1
is the aliquot of intermediate standard used, in milliliters; V
1
is
the dilution volume of the working standard in milliliters; A
2
is the
aliquot of working standard used, in milliliters, if applicable; and
V
2
is the dilution volume of the working standard in milliliters, if
applicable.
(
b
)
Preparation of standard curve.—
For each working standard
concentration, average the peak areas or heights from each
two consecutive sets of standards. Prepare a standard curve by
performing linear least squares (regression) on the concentrations
versus the averaged peak areas or heights. A standard curve must
have a correlation of at least 0.999 to be considered acceptable for
sample calculations.
At each working standard level, the peak areas or heights
of standards injected before and after a set of samples must not
increase or decrease by more than 7%.
(
c
)
Calculation of myo-inositol in samples
.—The concentration
of myo-inositol in a prepared sample is extrapolated from the
standard curve prepared above. From the diluted, prepared sample
concentration, the product concentration can be calculated:
C
p
= (C
d
×
D
1
)/S
where C
p
is the concentration of myo-inositol in the product sample
in milligrams per kilogram; C
d
is the concentration of myo-inositol
in the prepared sample in milligrams per liter; D
1
is the dilution
volume in milliliters; and S is the sample weight in grams.
Note
: For each set of samples, the control result must be within
three standard deviations of the control mean.
See
Figures
2011.18C
and
D
for typical standard and sample
chromatograms, respectively.
References:
J. AOAC Int . 95 , 937(2012)DOI: 10.5740/jaoacint.CS2011_18
J. AOAC Int.
(future issue)
AOAC SMPR 2011.007
J. AOAC Int . 95 , 295(2012)DOI: 10.5740/jaoac.int.11-0443
Posted: May 5, 2015
Candidates for 2016 Method of the Year
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