Refer to p.59


Column : Wakopak® Wakosil-Ⅱ 5SIL-AQ
      (2.0 mm × 150 mm)
Eluent : CH3CN/10 mM HCOONH2 (pH 4.0)=90/10 (v/v)
Flow Rate : 0.2 mL/min. at 40℃
Injection : 5 μL, 0.1 ng/mL each
Detection : LC/MS(ESI),
Positive mode & Negative mode


ESI-TOF-MS
TOF MS
Ion Spray Voltage

Ion Source Gas 1
Ion Source Gas 2
Curtain Gas
Temperature
Declustering Potential
Focusing Potential
Declustering Potential 2

(Min.) 50 (Max.) 300
4000 V (pos)
−3500 V (Neg)
50
50
20
300℃
30
150
15

Sample: (1) Isocyanuric Acid (Neg: 128); (2) Ammelide (Pos: 129); (3) Melamine (Pos:127); (4) Ammeline (Pos: 126)



Refer to p.9

Sample B (blank): 5 μg of I.S. (melamine-13C3-15N3) and 25 mL of 50% CH3CN aqueous solution are added to 5 g of sample.
Sample S (sample for recovery test): Melamine reference standard, 5 g of I.S. (melamine-13C3-15N3) and 25 mL of 50% CH3CN aqueous solution are added to 5 μg of sample.
After homogenization, the sample is centrifuged (3000 rpm, 5 min), and the obtained supernatant is used as an extract.

Column conditioning:
       Column①:CH3OH 5 mL,50% CH3CN 5 mL
       Column②:CH3OH 5 mL,H2O 5 mL

Results of measurement of recovery of added melamine
Melamine Average recovery
I.S. (milk powder) 57%
Reference Standard (milk powder) 105%
I.S. (milk) 72%
Reference Standard (milk) 97%
(I.S.: Corrected for melamine-13C3-15N3)

The content of melamine can be measured in conformity with the requirement “the recovery shall be 70 to 120%, and, when the internal standard is used, the recovery of the internal standard shall be 40% or more.”


Reference : Notice Shoku-An-Kan No. 1002003,
       October 2, 2008,Ministry of Health,
       Labour and Welfare




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