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Mottier:

J

ournal of

AOAC I

nternational

V

ol.

98, N

o

. 4, 2015 

1133

(

a

) 

Linearity

.—Linearity was verified over the 0–2 area ratio

range, corresponding to 0–0.8 ng sodium fluoroacetate (0.4 ng

IS) injected on-column. The calibration follows a linear model

with R

2

> 0.99 and relative standard deviation of the average of

response factors <15%.

(

b

) 

LOQ

.—LOQ is 1 µg/kg for infant formulae. This

concentration corresponds to the lowest fortification level

considered during validation.

(

c

) 

Recovery, repeatability, and intermediate reproducibility

precisions

.—Precision data are described in Table

2015.03G

.All

performance data fulfilled SANCO/12571/2013 requirements,

i.e., both CV(r) and CV(iR) ≤ 20% and recoveries within the

70–120% range. Exception was recovery for a milk-based

formula at the 1 µg/kg fortification level (134%). A small peak

was observed at the transition reaction used for quantification

in the related unfortified sample extract, meaning that sodium

fluoroacetate might be present at a concentration well below the

quantification capability of this method. This may explain this

higher recovery value.

J. Internal Control Plan

QC samples (certified,

P

-test, in-house reference samples,

or spiked samples) must be regularly included and analyzed in

duplicate.

Spiked experiment

.—Spike the test portion with 20 µL (for

powdered matrices) or 100 µL (for liquid matrices) of standard

working solution 0.05 µg/mL,

C

(

d

), at the same time as the

IS is added,

E

(

a

). This corresponds to 10 µg/kg spiking level.

Calculate the recovery rate (Rec) of the spiked sample using the

following equation:

100

Re

×

=

Spiked

N

T

c

ρ

ρ

ρ

where ρ

T

is the total concentration of sodium fluoroacetate

measured in the spiked sample in micrograms per kg. ρ

N

is

the native concentration of sodium fluoroacetate measured

Table 2015.03D. Typical MS parameters for the analysis of

sodium fluoroacetate

Parameter

Applied Biosystems Sciex 5500

Ionization type

Electrospray (ESI)

Polarity

Negative ionization

Spray voltage

–4500 V

Source block temperature

500°C

Gas

Curtain gas: 30 psi

Ion source gas 1 (GS1): 40 psi

Ion source gas 2 (GS2): 40 psi

Source position adjustments

Vertical micrometer value: 5.0

Horizontal micrometer value: 5.0

Electrode protusion: 1.0 mm

Collision energy (CE)

–15

Entrance potential (EP)

–10 V

Collision exit potential (CXP)

–9 V

Declustering potential (DP)

–45 V

CAD gas pressure (MRM)

Medium (6)

Resolution

High on each quadrupole

Scan time (for each transition)

100 ms

Table 2015.03E

. 

Transition reactions monitored for the analysis of sodium fluoroacetate (as its fluoroacetate anion) and its

corresponding IS and peak area ratios along with their limit of acceptance according to CD 2002/657/EC (1)

Transition reactions (

m/z

) used for

Peak area ratio ± limit, %

Quantification

Analyte confirmation

Fluoroacetate

77.0

33.0

a

77.0

57.0

a

0.80

±

20

13

C

2

-Fluoroacetate (IS)

79.0

34.0

79.0

59.0

0.68

±

20

a

 m/z

57 corresponds to the loss of hydrofluoric acid [M-HF]

-

and

m/z

33 to the loss of carbone dioxide [M-CO

2

]

-

.

Table 2015.03F. Samples considered for the validation

(SPIFAN kit)

Infant formulae

Batch

Manufacturer (USA)

Milk-based

K16NTAV PBM Nutritionals

Soy-based

E10NWZC PBM Nutritionals

Partially hydrolyzed milk-based 410057652Z

Nestlé

Partially hydrolyzed soy-based 410457651Z

Nestlé

High-fat nutritional

00729RF00 Abbott Nutrition

High-protein nutritional

00730RF00 Abbott Nutrition

Table 2015.03G. Performance characteristics

Sample

Recovery, %

a

CV(r), %

CV(iR), %

1 µg/kg

10 µg/kg

1 µg/kg

10 µg/kg

1 µg/kg 10 µg/kg

Milk-based formula

134

105

6

3

11

4

Soy-based formula

117

103

6

2

8

3

Partially Hydrolyzed milk-based formula

111

108

4

5

9

4

Partially hydrolyzed soy-based formula

116

103

9

2

8

2

High-fat nutritional formula

112

101

4

3

7

4

High-protein nutritional formula

96

99

4

2

6

2

a

 Recovery data for sodium fluoroacetate were calculated from values obtained under intermediate reproducibility conditions.

252