Joint International Conference on Long-term Experiments ...

lamps; if available, a thin layer plate densitometer with fluorescent capability,
excitation wavelength 365 nm and emission wavelength > 400 nm.
d) TLC plate sprayer – Kontes, K-422540
e) Blender – waring, equipped with 1 L jar and lied
f) Filter paper – Whatman 2V folded circles, 24 cm
g) Vials – 5 mL, conical, tapered inside, with Teflon-lined screw cap
Reagents
a) Solvents – reagent grade acetonitrile, hexane, methylene chloride, benzene, methanol,
acetic acid, and anhydrous ethyl ether. (Caution: Benzene is a suspected carcinogen.
Use necessary safety measures when handling this chemical)
b) Silicone DC-200 – 12 500 centistokes
c) Silicone-ether spray – silicone-anhydrous ether (18 + 82). If weighing silicone is more
convenient, 1g = 1mL
d) Potassium chloride solution – dissolve 4g KCl in 100 mL water
e) Aluminium chloride solution – Dissolve 15 g AlCl, in ethanol and dilute to 100mL
f) Calcium chloride – anhydrous, granular (8mesh). Prepare in advance CaCl2 –water (1 +
2, w/v). Hasten solution by placing in ultrasonic bath. Remove slight cloudiness by
filtering through Whatman 2V paper
g) Curpic carbonate, Cu (II) – Reagent grade powder
h) Diatomaceous earth – Hyflo Super- Cel
i) Sterigmatocystin standards – Stock standard – Prepare according to sec. 26.133.
Working standard – Dilute stock standard to ca ng/ μL benzene
j) Boiling chips – Si C. Float off fines and extraneous particles with water, wash with
acetone, and dry.
Extraction
Weigh 36 G composited sample into 1L Waring blender jar. Add 170 mL acetonitrile and
30 mL KCl solution; secure lid and blend 3 min at high speed. Decant extract through
Whatman 2V paper. Transfer 50 mL filtrate to 250 mL separatory funnel, add 50 Ml CaCl2
solution, vigorously shake ca 30 s, and let stand until layers separate; separation usually
occurs within 5 min.
Discard bottom layer. Remove excess water from inside the stem of the separatory
funnel by drying with laboratory wiping tissue, such as Kimwipes. Place a small wad of
glass wool into the stem of the separatory funnel to serve as a filter and drain the remaining
phase into a second separatory funnel. Add 50 Ml water to remaining phase and mix. Add
50 mL hexane, vigourously shake about 1 min, and let layers separate. Transfer bottom
layer to another 250 mL separatory funnel. Extract, using 50 and 25 mL portions of
methylene chloride, by shaking first extraction 1 min and second extraction 10 s. Again,
complete separation usually occurs within 5 min. Collect methylene chloride extracts
separately and save for column chromatography.
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