Solvent Purification

Solvent Purification Methods

UV-transparent solvents are essential for spectroscopy below 300 nm. Classical methods of purifying solvents for UV spectroscopy are very timeconsuming and complex. This is not the case when using adsorption filtration. UV-transparent solvents can be quickly and easily prepared from solvents of ordinary analytical purity. Moreover, they are less sensitive to air and thus more stable.

Purification of Hydrocarbon Solvents

A sample of 300 ml analytical grade n-hexane or pre-purified (by shaking with sulfuric acid to remove alkenes or olefines) technical grade cyclohexane is simply filtered without suction through a column (25 mm I.D. and 250 mm height) filled with 150 g Alumina Basic, Act. I (Cat.# 15640). The filtrate is anhydrous and can immediately be used.

Technical grade cyclohexane, which is not pre-purified, can easily be purified by filtering through a combined Silica Gel, Active, 60 Å, 63-200 μm/Alumina Basic, Act. I column. A column (25 mm I.D. and 400 mm height) is first filled with 100 g Alumina Basic, Act. I (Cat.# 15640) and on top of this,100 g of Silica Gel, Active, 60 Å, 63-200 μm (Cat.# 10840) is added. Then the crude cyclohexane is dripped through. Purified cyclohexane is anhydrous.

Purification of Organic Solvents

Depending on the kind of impurities, which depends on the origin and the nature of the solvent, the solvent can be filtered through a column filled with Silica Gel, Active, 60 Å, 63-200 μm, Alumina (Acid, Neutral or Basic), Act. I, or a combination of the two with the alumina section of the column above the silica gel section of the column. The following table gives recommendations on the amount and type of adsorbent to be used as well as the solvent yield and obtained purity.

Solvent Alumina, Acid,
Act. I, Cat. #15600
Alumina, Neutral,
Act. I, Cat. #15740
Alumina, Basic,
Act. I, Cat. #15640
Silica Gel, Active, 60Å, 63-200um
Cat. #10840
Solvent Yield (mL) 50% Trans.
at nm
(4cm cuvette)
n-Pentane 40g 250 217
40g 55 217
n-Hexane 40g 250 218
40g 50
Cyclohexane 40g 700 233
40g 80 234
n-Heptane 40g 500 224
40g 70 232
Isooctane 40g 40g 250 226
40g 1600 224
40g 255 255
40g 255 255
Carbon Tetrachloride 40g 80 280
40g 4000 276
Chloroform DAB6 40g 340
40g 100
Nitromethane 40g 40 402
Dimethyl Sulfoxide 40g 170 326
Pyridine 40g 30 321
40g 35 332
40g 30
20g 20g 25 316
Solvent Purification Methods hydrocarbon organic