© 2012 AOAC INTERNATIONAL
C. Chemicals and Solvents
(
a
)
Acetic acid
.—Glacial, ACS.
(
b
)
Chloroform
.—High-purity, HPLC grade.
(
c
)
Diethyl ether
.—Anhydrous, HPLC grade.
(
d
)
Drierite (desiccant)
.—Anhydrous calcium sulfate, 8 mesh.
(
e
)
Helium
.—Zero grade or equivalent.
(
f
)
Hexane
.—HPLC grade.
(
g
)
Hydrochloric acid
.—Concentrated (36–38%), ACS.
(
h
)
Distilled or deionized laboratory water.
(
i
)
Methanol
.—HPLC grade.
(
j
)
Myo-inositol
.—USP reference standard, official lot; store
desiccated.
See
standard label for purity.
(
k
)
Sodium acetate trihydrate or sodium acetate
.—Anhydrous,
ACS.
(
l
)
Sodium chloride.
(
m
)
Sodium hydroxide
.—50% (w/w), low carbonate form.
D. Preparation of Reagents and Standard Solutions
All solutions can be scaled up or down for convenience provided
good laboratory practices are observed. Solutions can be stored at
2–30°C in tight, inert containers otherwise noted.
(
a
)
Myo-inositol stock standard solution (approximately
2000 mg/L).—
Accurately weigh approximately 0.100 g myo-
inositol and quantitatively transfer to a 50 mL volumetric flask.
Dilute to volume with water. Mix well. Store refrigerated.
Expiration: 3 months.
(
b
)
Myo-inositol intermediate standard solution (approximately
200 mg/L).—
Dilute 10.0 mL stock standard to 100 mL with
laboratory water and mix well. Discard after use.
(
c
)
Myo-inositol working standard solutions (approximately 4,
2, 1, 0.5, 0.2, and 0.05 mg/L).—
Dilute 2.0, 1.0, and 0.5 mL myo-
inositol intermediate standard to 100 mL with laboratory water (4,
2, and 1 mg/L). Dilute 0.5 mL myo-inositol intermediate standard
to 200 mL with laboratory water (0.5 mg/L). Dilute 4 and 1 mL
of the 0.5 mg/L myo-inositol working standard to 10 mL with
laboratory water (0.2 and 0.05 mg/L). Expiration: 2 weeks.
(
d
)
Hydrochloric acid, 0.5%.—
Add 1.25 mL concentrated
hydrochloric acid to approximately 200 mL water in a 250 mL
volumetric flask. Dilute to volume with water and mix well.
Expiration: 6 months.
(
e
)
Sodium chloride, 1 N.—
Dissolve 5.8 g sodium chloride and
dilute to 100 mL with water. Expiration: 1 month.
(
f
)
Sodium hydroxide, 0.12% or 30 mM (Pump 1).—
Quickly
weigh 4.8 (±0.1) g of 50% sodium hydroxide into a 2000 mL
volumetric flask containing approximately 1900 mL water. (
Note
:
It is important that the sodium hydroxide does not absorb carbon
dioxide from the air.) Swirl to mix well. Dilute to volume with
water and mix well. Expiration: 1 month.
(
g
)
Sodium hydroxide,
34
.0% or
750 m1
M (Pump 2).—
Quickly
weigh 1
62
0 (±3) g of 50% sodium hydroxide into a 2000 mL
volumetric flask containing approximately 1900 mL water. (
Note
:
It is important that the sodium hydroxide does not absorb carbon
dioxide from the air.) Swirl to mix well. Dilute to volume with
water and mix well. Expiration: 1 month.
(
h
)
6% Metaphosphoric acid.—
Weigh 6.0 g metaphosphoric
acid into a 100 mL volumetric flask. Dissolve and dilute to volume
with laboratory water. Mix well. Store refrigerated. Expiration:
1 week.
