337 / 471
(
i
)
Visiprep 5-port flask vacuum manifold
.—RS-SUPELCO 57101-U (Sigma-Aldrich Shanghai Trading Co.,
Ltd).
See
Figure
2014.09B
or equivalent.
(
j
)
Variable volume pipet
.--10 μL, 200 μL, and 1 mL.
(
k
)
Balance
.--Capable of accurately measuring weights from 0.05 to 100 g within ±0.01 g.
F. Extraction and Cleanup Procedure
(
a
)
Sample extraction
.—(
1
) Weigh 5 g dry tea powder (accurate to 0.01 g) into an 80 mL centrifuge tube.
(
2
) Add 15 mL acetonitrile.
(
3
) Homogenize at 13500 r/min for 1 min.
(
4
) Centrifuge at 2879 ×
g
for 5 min at room temperature.
(
5
) Transfer the supernatant into a pear-shaped flask.
(
6
) Reextract the sample with 15 mL acetonitrile, homogenize, centrifuge, and combine the supernatants
from the two extractions.
(
7
) Concentrate the extract to approximately 1 mL in a rotary evaporator (or TurboVap) in a 40°C water
bath.
(
8
) Place a pear-shaped flask in the vacuum manifold.
(
9
) Mount a Cleanert TPT cartridge onto the manifold.
(
10
) Add anhydrous sodium sulfate (approximately 2 cm) onto the Cleanert TPT packing material.
(
11
) Add 10 mL acetonitrile-toluene (3 + 1, v/v) to activate the cartridge.
(
12
) Stop the flow-through the cartridge when the liquid level in the cartridge barrel has just reached the
top of the sodium sulphate packing.
(
13
) Discard the waste solution collected in the pear-shaped flask and replace with a clean pear-shaped
flask.
(
b
)
SPE cleanup
.--(
1
) Load the concentrated extract from
F
(
a
)(
7
) into the conditioned Cleanert TPT
cartridge collecting the eluate into the clean pear-shaped flask.
(
2
) Rinse the pear-shaped flask that contained the concentrated extract with 3 × 2 mL acetonitrile-
toluene (3 + 1, v/v).
(
3
) Load the rinse into the cartridge when the level of the loading solution in the cartridge reaches the
top of the anhydrous sodium sulfate packing.
Candidates for 2016 Method of the Year
277