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1122  Joseph et al. : J ournal of AOAC I nternational Vol. 98, No. 3, 2015

Table 2015.02A. Fortification of recovery samples

Volume, µL

Concn fluoroacetic acid, µg/kg

WS3 WS2 WS3

Tube No.

Name

1 a

Matrix standard 0 a

0 a

0 a

5 a

2 3 4 5 6 7

Recovery 1 0 0 40 Recovery 2 25 0 40 Recovery 3 125 0 40 Recovery 4 0 25 40 Recovery 5 0 125 40 Reagent blank 0 0 40

0

0.1 0.5

1 5 0

Figure 2015.02A. Sodium fluoroacetate.

( i )  Laboratory glassware .—Measuring cylinders, volumetric flasks, and beakers. ( j )  Multi-step dispenser with appropriate tips .—Eppendorf Stream or equivalent. ( k )  Nitrogen blow-down .—Capable of maintaining a temperature 40 ± 10°C. ( l )  pH meter . ( m )  Polypropylene SPE reservoirs .—10 mL, with adapters. ( n )  Positive displacement pipets .—25, 100, 250, and 1000 µL, with tips. ( o )  Refrigerator and freezer. ( p )  Resin chromatography column .—10 mL polypropylene (Bio-Rad). ( q )  Shaker .—Reciprocating bench top. ( r )  Ultrasonic bath . ( s )  Vacuum manifold for SPE cartridges.— With stopcocks. ( t )  Vortex mixer . ( u )  Water bath.— Maintained at 40 ± 2°C. Analytical instrumentation .— ( v )  LC-MS/MS instrument .—ABSciex 5500 QTRAP coupled with Agilent 1290 Series HPLC. ( w )  HPLC guard column .—Phenomenex Security C18, 4 × 2 mm. ( x )  HPLC column .—Agilent XDB-C18 100 × 4.6 mm, 1.8 μm. C. Reagents All reagents and chemicals must be of such a grade that they do not interfere with the analytical process. Chemicals .— ( a )  Acetone .—Pesticide grade. ( b )  Acetonitrile.— Pesticide grade. ( c )  AG 1-X8 resin .—100–200 mesh chloride form, ACS reagent grade. ( d )  Ammonium acetate .—ACS reagent grade. ( e )  Deionized water.— Laboratory purified, ≥18 ΩM.

a  The matrix standard is fortified at step F ( b )( 9 ).

( f )  Hydrochloric acid .—Concentrated, ACS reagent grade; 37–38%.

( g )  Methanol.— Pesticide grade. ( h )  n - Hexane .—Pesticide grade.

( i )  Phosphoric acid .—Concentrated, ACS reagent grade. ( j )  Potassium dihydrogen phosphate .—ACS reagent grade. ( k )  Potassium hydroxide.— ACS reagent grade. ( 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 ( a )  5Mhydrochloric acid (2000mL) .—( 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 hydrochloride (EDAC) .—ACS reagent grade. ( q )  3-Nitroaniline .—ACS reagent grade. Solutions.—

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

196.931 196.931 196.931 201.001 201.001

122.000 146.900 117.800 134.900 45.900

50 50 50 50 50

–120 –120 –120 –115 –115

–24 –22 –28 –30 –22

–17 –23 –17 –21 –23

1,2- 13 C-2,2-D-2-fluoro-3 ʹ - nitroacetanilide

2.06