Abderhalden's drying pistol is a piece of

laboratory glassware Laboratory glassware refers to a variety of equipment used in scientific work, and traditionally made of glass. Glass can be blown, bent, cut, molded, and formed into many sizes and shapes, and is therefore common in chemistry, biology, and anal ...

used to free samples from traces of water, or other impurities. It is called a "pistol" because of its resemblance to the firearm. Its use has declined due to modern hotplate technology and vacuum pumps. The apparatus was first described in a book edited by

Emil Abderhalden Emil Abderhalden (9 March 1877 – 5 August 1950) was a Swiss biochemist and physiologist. His main findings, though disputed already in the 1910s, were not finally rejected until the late 1990s. Whether his misleading findings were based on f ...

. The drying pistol allows the sample to be dried at elevated

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...

; this is especially preferred when storage in a

desiccator Desiccators are sealable enclosures containing desiccants used for preserving moisture-sensitive items such as cobalt chloride paper for another use. A common use for desiccators is to protect chemicals which are hygroscopic or which react with w ...

at room temperature does not give satisfactory results.

Operation

The drying pistol consists of two concentric barrels; the inner is connected to a

vacuum A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or " void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often di ...

source via a trap. The outer barrel is connected at the bottom to a

round bottom flask Round-bottom flasks (also called round-bottomed flasks or RB flasks) are types of Laboratory flask, flasks having spherical bottoms used as laboratory glassware, mostly for chemistry, chemical or biochemistry, biochemical work. They are typicall ...

, and a condenser. To operate the drying pistol, a sample is placed within the inner barrel, and the barrel is evacuated. The round bottom flask, filled with an appropriate solvent, is heated to a boil. Hot vapors warm the inner barrel; losses are avoided with the condenser. By choosing the appropriate solvent, the temperature at which the sample is dried can be selected. The trap is filled with an appropriate material: water is removed with

phosphorus pentoxide Phosphorus pentoxide is a chemical compound with molecular formula P4 O10 (with its common name derived from its empirical formula, P2O5). This white crystalline solid is the anhydride of phosphoric acid. It is a powerful desiccant and dehydra ...

, acidic gases by

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 atmosph ...

or sodium hydroxide, and organic solvents by thin pieces of paraffin. However, use of these agents has been shown to have little efficacy. Generally, the main impurity to be removed is water.{{cite book , last1=Chai , first1=Christina Li Lin , last2=Armarego , first2=W. L. F. , title=Purification of laboratory chemicals , publisher=Butterworth-Heinemann , location=Oxford , year=2003 , pages=25–26 , isbn=0-7506-7571-3 , url = https://books.google.com/books?id=SYzm1tx2z3QC&pg=PA25 , format =

Google Books Google Books (previously known as Google Book Search, Google Print, and by its code-name Project Ocean) is a service from Google Inc. that searches the full text of books and magazines that Google has scanned, converted to text using optical ...

excerpt This set-up allows the desiccation of heat-sensitive compounds under relatively mild conditions. Removing these trace impurities is especially important to give good results for

elemental analysis Elemental analysis is a process where a sample of some material (e.g., soil, waste or drinking water, bodily fluids, minerals, chemical compounds) is analyzed for its elemental and sometimes isotopic composition. Elemental analysis can be qualita ...

and

gravimetric analysis Gravimetric analysis describes a set of methods used in analytical chemistry for the quantitative determination of an analyte (the ion being analyzed) based on its mass. The principle of this type of analysis is that once an ion's mass has been ...

References

Laboratory glassware