Glassware
(9. Consumables continued)
9.18
Beaker, 50 mL
FB100050
9.19
Fisherbrand laboratory
9653630
bottle, 250 mL
9.20
Erlenmeyer Flask, 100 mL
9653520
9.21
Fisherbrand test tubes
14-958D
9.22
Funnel, 55mm
14353D
9.23
Glass tubes
14957E
9.24
Measuring cyclinder, 100 mL
FB56449
9.25
Measuring cyclinder, 1000 mL
FB 56453
9.26
Pasteur pipette
136786A
9.27
Round flask 50 mL, NS 29/32
9011835
Fisher Scientific Germany
9.28
Separator funnel, 250 mL
9203325
9.29
Separator funnel, 500 mL
9203328
9.30
Volumetric flask, 10 mL
FB40110
9.31
Volumetric flask, 25 mL
10200A
10. Procedure
10.1 Saponification
10.1.1
Accurately weigh the homogenized sample (ca. 2 g)
into a 250 mL Duran Bottle
10.1.2
Add 50 µL of PAH internal standard solution to
the sample
10.1.3
Vortex the mixture for 10 s and wait 10 min for
equilibration
10.1.4
Add 200 mL of MeOH/KOH solution
10.1.5
Put samples into an ultrasonic bath for 30 min at
60 °C for saponification
10.1.6
Cool sample
10.2 Extraction
10.2.1
Filter saponified sample through glass wool into a
500 mL separating funnel
10.2.2
Add 100 mL of hexane to the sample and shake
for 3 min
10.2.3
Transfer the hexane layer into a 100 mL
Erlenmeyer flask
10.2.4
Repeat the extraction (10.2.2) one more time
10.2.5
Combine hexane layers in a separator funnel
10.2.6
Wash hexane layer by shaking with 50 mL of
MeOH/H
2
O solution for 1 min
10.2.7
Repeat washing step (10.2.6) two more times
10.2.8
Evaporate to 1 mL under vacuum (220 mbar/50 °C)
10.3 Clean-up
10.3.1
Condition the SPE-Cartridge with 3 mL of hexane
10.3.2
Apply the extract to the cartridge and elute into
an evaporator glass tube with 5 mL of hexane
10.3.3
Evaporate at 40 °C to dryness using a blow-down
apparatus under a gentle stream of nitrogen
10.3.4
Reconstitute in 180 µL of cyclohexane plus 20 µL
of injection standard
10.4 Analysis
10.4.1
GC operating conditions
GC analysis was performed on a Thermo Scientific
TRACE GC Ultra
™
system (Thermo Fisher Scientific,
Waltham, MA USA). The GC conditions were as follows:
Column: Thermo Scientific TR-50MS 30 m
Column ID: 0.25 mm, 0.25 µm film capillary column
Injection mode: splitless with a 5 mm injection port liner
Injection port temperature: 270 °C
Flow rate: 1.2 mL/min
Split flow: “On”, flow: 25 mL/min
Splitless time: 1 min
SSL carrier method mode: constant flow
Initial value: “On” with 1.2 mL/min
Initial time: 1 min
Gas saver flow: 15 mL/min
Gas saver time: 3 min
Vacuum compensation: “On”
Transfer line temperature: 270 °C
Oven Temperature: 60 °C for 1 min, then programmed at
12 °C/min to 210 °C, then 8 °C/min to
340 °C with 5 min hold time
10.4.2
Mass spectrometric conditions
MS analysis is carried out using a Thermo Scientific TSQ
Quantum
™
XLS triple quadrupole mass spectrometer
(Thermo Fisher Scientific, Waltham, MA USA). A satisfactory
tune of the mass spectrometer is achieved when the detector
is set at
m/z
300 or less and the three FC 43 (calibration
gas) ions (69, 219, and 502) are at least half the height
of their respective windows and the ions at 502 and 503
are resolved. The MS conditions were as follows:
Ionization mode: EI positive ion
Ion volume: closed EI
Emission current: 50 uA
Ion source temperature: 250 °C
Scan type: Full scan in range
m/z
45-650 and SRM
Scan width: 0.15 for SRM
Scan time 0.2 s for full scan and 0.05 for SRM
Peak width: Q1, 0.7 Da; Q3, 0.7 Da FWHM
Collision gas (Ar) pressure: 0.5 mTorr
The mass spectrometer is programmed to be able to
simultaneously monitor the hydrocarbon profile in scanning
full scan (FS) GC-MS and quantify the presence of PAHs
by MS/MS within a single chromatographic run. Eight
segments are programmed each with two simultaneous
scan events. One scan event is used to monitor the aliphatic
hydrocarbon profile throughout the whole chromatographic
run (i.e. in all segments), while SRM traces are set up for
the target PAHs in the other scan event. The program of
segments of SRM events (#1) is shown in Table 1.
Setting of scan event #2 for hydrocarbon profiling was
kept constant in all segments:
Scan type: FS in range 45-650
m/z
Scan time: 0.2 s
FWHM: 0.7 Da
Collision gas pressure: 0.5
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