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Advisory Committee on Health Effects of Endocrine Disruptors
The Supplement II to the Intermediary Report
1.2.4.2 |
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[Apparatus]
Liquid chromatograph/mass spectrometer (LC/MS): LC/MS capable of
selective ion monitoring (SIM) using an electrospraying ion
source. When a liquid chromatograph/tandem mass spectrometer
(LC/MS/MS) is used, perform multiple reaction monitoring (MRM).
[Sample preparation]
Place 100 ml water and 2 g sample5
in the essential oil distillator, add 3 ml hexane and 50 ng
internal standard (m-OP-d5), and reflux for an hour. Concentrate
the hexane layer obtained6
to dryness in a centrifugal evaporator7,
add 1 ml methanol, and dissolve ultrasonically to obtain the
sample solution.
[Operation]
Analysis by LC/MS
(i) LC/MS conditions (typical)
Column for analysis: C18 Reverse phase column, 2.0 mm i.d., 100
mm long, grain size 5 μm8
Column temperature: 40℃
Mobile phase for analysis: Water:acetonitrile (gradient elution
with 0.02% ammonium acetate9:
30:70 (8 min) -> 5:95 (10 min) -> 5:95 (20 min))
Flow rate of mobile phase: 0.2 ml/min
Quantity injected: 30 μl
Ionization: Electrospray ionization, negative mode
MS monitor ions: m/z = 219 (NP), m/z = 224 (m-OP-d5)
(ii) Qualitative and quantitative analysis
Confirm that the SIM peak (m/z = 219) permits separation of the
base line, and use the area of the peak for quantitation using
the internal standard. Construct a calibration curve over a
concentration range of 1 to 100 ppb. This range may be expanded
if samples of higher concentrations are to be analyzed.
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