Nujol is a brand of mineral oil by Plough Inc., cas number 8012-95-1, and density 0.838 g/mL at 25 °C, used in
infrared spectroscopy
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or function ...
. It is a heavy
paraffin Paraffin may refer to:
Substances
* Paraffin wax, a white or colorless soft solid that is used as a lubricant and for other applications
* Liquid paraffin (drug), a very highly refined mineral oil used in cosmetics and for medical purposes
* Alkane ...
oil so it is chemically
inert and has a relatively uncomplicated
IR spectrum, with major peaks between 2950-2800, 1465-1450, and 1380–1300 cm
−1.
The empirical formula of Nujol is hard to determine exactly because it is a mixture but it is essentially the alkane formula where ''n'' is very large.
To obtain an IR spectrum of a solid, a sample is combined with Nujol in a
mortar and pestle
Mortar and pestle is a set of two simple tools used from the Stone Age to the present day to prepare ingredients or substances by crushing and grinding them into a fine paste or powder in the kitchen, laboratory, and pharmacy. The ''mortar'' () ...
or some other device to make a
mull
Mull may refer to:
Places
*Isle of Mull, a Scottish island in the Inner Hebrides
** Sound of Mull, between the Isle of Mull and the rest of Scotland
* Mount Mull, Antarctica
*Mull Hill, Isle of Man
* Mull, Arkansas, a place along Arkansas Highway ...
(a very thick
suspension
Suspension or suspended may refer to:
Science and engineering
* Suspension (topology), in mathematics
* Suspension (dynamical systems), in mathematics
* Suspension of a ring, in mathematics
* Suspension (chemistry), small solid particles suspend ...
), and is usually sandwiched between
potassium
Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...
- or
sodium chloride
Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g ...
plates before being placed in the spectrometer. For very reactive samples, the layer of Nujol can provide a protective coating, preventing sample decomposition during acquisition of the IR spectrum. When preparing the sample it is important to keep the sample from being saturated with Nujol, this will result in erroneous spectra since the Nujol peaks will dominate, silencing the actual sample's peaks.
References
External links
MSDS data sheetCAS Number for Nujol
Hydrocarbon solvents
Infrared spectroscopy
Alkanes
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