nitrogen. Contact with water generates hydrogen fluoride gas
which is highly toxic. Store at 4
C (see Note 3).
3. Pyridine, analytic grade. Store at room temperature (see
Note 3).
4. Retention time index standard mixture: fatty acids methyl
esters (FAMES). All must be of standard grade for GC: Esters
included are methylcaprylate, methyl pelargonate, methylcaprate, methyllaurate, methylmyristate, methylpalmitate, methylstearate, methyleicosanoate, methyldocosanoate, lignoceric
acid methylester, methylhexacosanoate, methyloctacosanoate,
and triacontanoic acid methylester. The esters are dissolved in
CHCl 3 at a final concentration of 0.8 μL/mL for liquid;
0.4 mg/mL for solid standards. Mix all well, aliquot into
glass vials, and store at À20
C.
5. 1.1 mL Screw Top Tapered Vial—Clear Gold Grade.
6. Shaker (950 rpm).
2.2.3 GC-TOF-MS
1. Autosampler system.
2. Capillary column MDN-35, 30 m  0.32 mm, 0.25 μm film
thickness.
3. Conical single taper split/splitless liner.
4. Gas chromatograph, split and splitless injector with electronic
pressure control up to 150 psi.
5. Helium 5.0 carrier gas.
6. Pegasus Tof mass analyzer and corresponding software.
2.3 LC-MS
2.3.1 Sampling and
Extraction
1. Round-bottom-shaped 2 mL tube.
2. Round-bottom-shaped 1.5 mL tube.
3. Zirconia bead (3 mm ϕ).
4. Internal standard.
5. Methanol (MeOH) ULC/MS grade. Caution: Methanol is
toxic and should be handled under the fume hood.
6. Distilled water ULC/MS grade.
7. Extraction buffer (mixture of methanol:distilled water, 8:2
(v/v) containing internal standard).
2.3.2 LC-MS Analysis
1. LC-MS system with the operation software provided by MS
manufacturer.
2. Glass vial.
3. Screw cap for glass vial.
4. Distilled water ULC/MS grade.
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Si Wu et al.
which is highly toxic. Store at 4
C (see Note 3).
3. Pyridine, analytic grade. Store at room temperature (see
Note 3).
4. Retention time index standard mixture: fatty acids methyl
esters (FAMES). All must be of standard grade for GC: Esters
included are methylcaprylate, methyl pelargonate, methylcaprate, methyllaurate, methylmyristate, methylpalmitate, methylstearate, methyleicosanoate, methyldocosanoate, lignoceric
acid methylester, methylhexacosanoate, methyloctacosanoate,
and triacontanoic acid methylester. The esters are dissolved in
CHCl 3 at a final concentration of 0.8 μL/mL for liquid;
0.4 mg/mL for solid standards. Mix all well, aliquot into
glass vials, and store at À20
C.
5. 1.1 mL Screw Top Tapered Vial—Clear Gold Grade.
6. Shaker (950 rpm).
2.2.3 GC-TOF-MS
1. Autosampler system.
2. Capillary column MDN-35, 30 m  0.32 mm, 0.25 μm film
thickness.
3. Conical single taper split/splitless liner.
4. Gas chromatograph, split and splitless injector with electronic
pressure control up to 150 psi.
5. Helium 5.0 carrier gas.
6. Pegasus Tof mass analyzer and corresponding software.
2.3 LC-MS
2.3.1 Sampling and
Extraction
1. Round-bottom-shaped 2 mL tube.
2. Round-bottom-shaped 1.5 mL tube.
3. Zirconia bead (3 mm ϕ).
4. Internal standard.
5. Methanol (MeOH) ULC/MS grade. Caution: Methanol is
toxic and should be handled under the fume hood.
6. Distilled water ULC/MS grade.
7. Extraction buffer (mixture of methanol:distilled water, 8:2
(v/v) containing internal standard).
2.3.2 LC-MS Analysis
1. LC-MS system with the operation software provided by MS
manufacturer.
2. Glass vial.
3. Screw cap for glass vial.
4. Distilled water ULC/MS grade.
396
Si Wu et al.