Methods to be Reviewed by OMB in 2016

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© 2015 AOAC INTERNATIONAL
( l) Sodium sulfate, anhydrous.—ACS reagent grade.
( m) Sodium hydrogen carbonate.—ACS reagent grade.
( n) Sulfuric acid.—Concentrated, ACS reagent grade.
( o) TBME.—Pesticide grade.
( p) 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride
(EDAC).—ACS reagent grade.
( q) 3-Nitroaniline.—ACS reagent grade.
Solutions.—
( a) 5 M hydrochloric acid (2000 mL) .—(Caution: Preparation
of solution should be performed inside a fume cupboard.) Into a
2000 mL volumetric flask add 800 mL deionized water. To this add
832 mL of 37–38% (12 M) concentrated hydrochloric acid. Mix
and allow to cool. Bring to volume with deionized water. Store at
room temperature.
( b) 0.2 M hydrochloric acid (2000 mL).—Into a 2000 mL
volumetric flask add 800 mL deionized water. To this add 80 mL of
5 M hydrochloric acid. Mix and allow to cool, and bring to volume
with deionized water. Store at room temperature.
( c) 2 M potassium hydroxide (2000 mL).—(Caution: Preparation
of solution should be performed inside a fume cupboard.) Place
1600 mL deionized water in a 2000 mL beaker and place on a
magnetic stirrer with follower. Weigh 224.4 g potassium hydroxide
into a 500 mL beaker. Add the potassium hydroxide, a few pellets
at a time, to the stirred solution. Do not allow the temperature to
rise above warm to the touch. When all the pellets have dissolved,
allow the solution to cool and then transfer quantitatively through
a glass funnel into a 2000 mL measuring cylinder and bring to
volume with deionized water. Store at room temperature.
( d) 20 mg/mL 3-nitroaniline (100 mL).—(Caution: Wear
gloves when working with this chemical.) Weigh 2.0 g aliquots of
3-nitroaniline into 100 mL Schott bottles and cap tightly. Store at
room temperature.
To one preweighed bottle of 3-nitroaniline add 100 mL
acetonitrile using a graduated measuring cylinder. This is sufficient
for two batches of 36 sample tubes. Prepare fresh daily.
(e) 100 mg/mL EDAC (25 mL).—(Caution : Exposure to
moisture degrades this reagent.) Preweigh 2.5 g aliquots of EDAC
into 50 mL polypropylene tubes and cap tightly. Store in a freezer
at or below –10°C in a desiccated container.
To one preweighed tube of EDAC add 25 mL deionized water.
Prepare fresh daily.
( f) TBME–n-hexane (70 + 30, v/v; 2000 mL).—Measure
1400 mL TBME into a 2000 mL Schott bottle and add 600 mL
n-hexane. Cap and mix. Store at room temperature.
( g) Sulfuric acid in water (25%, v/v; 2000 mL) .—(Caution:
Preparation of solution should be performed inside a fume
cupboard.) Add approximately 1200 mL deionized water to a 2 L
volumetric flask followed by slow addition of 500 mL sulfuric acid.
Mix and allow to cool to room temperature. Bring to 2 L volume
and store in a Schott bottle. Store at room temperature.
(h ) 0.05 M potassium dihydrogen phosphate, pH 2.3
(1000 mL).—Weigh 6.80 g potassium dihydrogen phosphate into
a 500 mL beaker. Add 300 mL deionized water to dissolve the
potassium dihydrogen phosphate and quantitatively transfer into
a 1 L Schott bottle. Add a further 300 mL deionized water to the
beaker to dissolve any remaining potassium dihydrogen phosphate,
quantitatively transfer into the Schott bottle, make up to 1 L. Cap,
mix, and adjust the pH to 2.3 ± 0.1 with concentrated phosphoric
acid. Store at room temperature.
(i) 0.1 M sodium hydrogen carbonate (1000 mL).—Weigh
8.40 g sodium hydrogen carbonate into a 500 mL beaker. Add
300 mL deionized water to dissolve the sodium hydrogen carbonate
and quantitatively transfer into a 1 L Schott bottle. Add a further
300 mL deionized water to the beaker to dissolve any remaining
sodium hydrogen carbonate, quantitatively transfer into the Schott
bottle, make up to 1 L, cap, and mix to ensure full solubility. Store
at room temperature.
(j) AG 1-X8 anion exchange resin.—Before use, soak the AG
1-X8 anion exchange resin in deionized water for 18–24 h, and
store in deionized water until use. Store in a refrigerator.
(k ) HPLC mobile phase A: 10 mM ammonium acetate in water
(1000 mL).—Weigh 0.77 g ammonium acetate into a 1 L Schott
bottle, followed by 1000 mL deionized water. Cap and mix to
ensure full solubility. Store at room temperature.
(l) HPLC mobile phase B: 10 mM ammonium acetate in 97%
acetonitrile (1000 mL).—Weigh 0.77 g ammonium acetate into
a 50 mL beaker. Use 30 mL deionized water to quantitatively
transfer to a 1 L Schott bottle. Stir to fully dissolve and add 970 mL
acetonitrile. Sonicate for 10 min to ensure full solubility. Store at
room temperature.
D. Standards
(a ) Primary standards.—Primary standards are stored in a
refrigerator between 2–8°C in the dark. Subsequent solutions
should be corrected for purity, moisture, and salt (if applicable).
Wear appropriate PPE when weighing out the primary material.
(1 )Analytes.—Sodium fluoroacetate (CAS No. 62-74-8).
(2 ) Internal standard.—13 C2D2 sodium fluoroacetate.
(b ) Secondary standards.—(1 ) Analytes.—Fluoroacetic acid
(1000 mg/L).—Weigh approximately 12.9 mg sodium fluoroacetate
into a calibrated 10 mLvolumetric flask.Add deionized water, make
to volume, and mix until solid is completely dissolved. Transfer to a
15 mL polypropylene screw cap test tube and cap tightly. Store in a
freezer at less than –10°C. Calculate exact concentration correcting
for purity, moisture (if applicable), and salt using Equation 1.
Table 2015.02B. Identification parameters for compounds analyzed as negative ions
Compound (3-nitroaniline
derivatives of analyte and
internal standard)
Expected retention
time, min Molecular ion (Q1) Product ion (Q3) Dwell, ms DP, V CE, eV CXP, V
2-Fluoro-3′ -nitroacetanilide 2.06 196.931 122.000 50 –120 –24 –17
196.931 146.900 50 –120 –22 –23
196.931 117.800 50 –120 –28 –17
1,2-13C-2,2-D-2-fluoro-3ʹ-
nitroacetanilide
2.06 201.001 134.900 50 –115 –30 –21
201.001 45.900 50 –115 –22 –23
Candidates for 2016 Method of the Year
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