A Microseparatory Funnel
tory funnel provides results equivalent to that obtained in 1min. usine a senturn-sealed test tube (2) . . or loueer times using an open test tube and vortex formation by drumming with the fineers. Results usuallv are suoerior to extraction using the "Guirting" technique(7). u
Martin Hulce Creighton University Omaha. NE 68178
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Liquid-liquid extractions of volumes greater than 10 mL can be carried out with separatory funnels. Smaller volumes are extracted by mixing of the two phases in vials or test tubes (1-4). Shaking small volumes in a vial or test tube sealed with a screw cap, cork, or septum mixes the two phases very well, but leakage around the closure, and contamination by the cap liner, cork, or rubber of the septum are problems. In addition, heat transfer from the hands to the vial or test tube can cause significant solvent vaporization and result in reduced sample recovery and purity. A convenient separatory funnel of appropriate size minimizes these problems. The construction of microseparatory funnel for extractions 2-6 mL in total volume is shown in the figure. A straigbtforward modification of the Williamson chromatography column (51, it consists of a 10-mm NMR tube pressure cap (Aldrich 211,808-71, a 10-mm 0.d. x 7.5-mm i.d. x 200-mm glass tube (Kontes 420166-0001), a 7.5-mm to male Luer slip tip adapter (Kontes 4201680000). and a one-wav SYring; stopcock (KO&S 420163-45001. The asMicroseparatory funnel consisting sembled microseparatory of (a) 10-mm NMR tube pressure funnel has a volume of cap; (b) 10-mm 0.d. x 7.5-mm i.d. x about 8 mL. Extractions 200-mm glass tube; (c) 7.5-mm to using this funnel are for part identical to male Luer slip tip adapter, and (d) th, t, syringe stopcock. those with larger scale devices. The funnel should be held only at the cap and stopcock while shaking to minimize heat transfer from the hands to the funnel and prevent pressure buildup caused by vaporization of volatile solvents. It also should be vented frequently, either by periodic removal of the pressure cap or through the stopcock, taking care to tap it with a finger fwst in order to clear it of any liquid. The separate phases can be removed as in usual separatory funnel technique (6), or with a 9-in. Pasteur pipet. Typically (see below), a 1-minextraction with this microsepara-
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vpical Procedure Transfer a solution of 106.3me (0.8 mmol) of 2-nitmoheno1 in 1.5 mL of 5%aqueous ~ a rto)the~ microseparahy funnel usine0.5 mLof H.O. Add sufficient ice-cold 1 M HCI solution dropwise with 'haking until the aqueous layer is acidic accordine to DHDaDer. Extract the resulting susvension using the; 1.6& aiiquots of ether, periodicky venting the funnel through the stopcock after tapping the stopcock with an index finger to free it of any droplets of liquid. Separate the ether layers, removing each via pipet, and combine them in a 13- x 100-mm test tube containing anhydrous Na2S04.Transfer the combined ether portions to a tared 10-mL flask using 0.5 mL of ether to wash the Na2SOc and evaporate the ether. A 94.6 mg (0.7 mmol, 89%)quantity of 2-nitrophenol is returned. Literature Cited
New York, 1989, pp 75-78. 5. Wihmso", KL. MocmamlmamlondMimosmlr O g ~ n i c E ' ~ ~ ~ m ~ 8 ; HTmin%on, eath: 1989, p 6. 6. Zubriek, J. W The Ogonic C k m Lob Svruivd Mmud, 2nd ed, Why: New York 1988, pp 126128. 7. Wilmr, C. F., Jr Eqxrimntol OgonicCkmishy:ASmnil-Smk&p-h;MdIan: NewY0rk. 1988,pp9041.
Rapid Cleaning of Porcelain Crucibles Mono M. Singh, KC. Swallow, Ronald M. Pike, and Zvi Szafran Merrimack College N. Andover, MA01845
In our microscale chemistry laboratories, we use 1-mL porcelain crucibles for multiple gravimetric determinations. Often these crucibles become badly stained and cannot be cleaned even by treating them with aqua regia. We have found that the following simple method cleans these crucibles easily and rapidly. Put 14 NaOH pellets into a stained crucible and cover them with 0.14.5 g of anhydrous Na2COs.Using a Bunsen burner, heat the crucible slowly at first and then strongly to melt the mixture. ARer the initial frothing, the melt will settle down. During this process, tilt the crucible to cover the stained oortion with the melt. After heating for 2 6 min, remove'the crucible from the heat, cool it a d rinse it thorouehlv with distilled water. Then immerse it in a beaker contakng 3 M HzS04 solution to remove the last traces of the baaic melt from inside the crucible. Finally, rinse thoroughly with distilled water. Use a test tube brush, if necessary, to remove all the stains from the crucible. Five to 10 microcrucibles can be cleaned at one time.
Volume 70 Number 2 February 1993
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