User manual

52 Bio-inert Quaternary Pump User Manual
4 Using the Pump
Solvent Information
PEEK
PEEK (Polyether-Ether Ketones) combines excellent properties regarding
biocompatibility, chemical resistance, mechanical and thermal stability and is
therefore the material of choice for biochemical instrumentation. It is stable in
the specified pH range and inert to many common solvents. There is still a
number of known incompatibilities to chemicals like chloroform, methylene
chloride, THF, DMSO, strong acids (nitric acid > 10 %, sulphuric acid > 10 %,
sulfonic acids, trichloroacetic acid), halogenes or aequous halogene solutions,
phenol and derivatives (cresols, salicylic acid etc.).
When used above room temperature, it is sensitive to bases and various
organic solvents, which can cause PEEK to swell. As normal PEEK capillaries
are very sensitive to high pressure especially under such conditions, Agilent
uses stainless-steel cladded PEEK capillaries in order to keep the flow path
free of steel and to ensure pressure stability to at least 600 bar. In case of
doubt, please consult common literature about the chemical compatibility of
PEEK.
Titanium
Titanium is highly resistant to oxidizing acids (e.g. nitric, perchloric and
hypochlorous acid) over a wide range of concentrations and temperatures,
which is due to a thin oxide layer on the surface, which is stabilized by
oxidizing compounds. Reducing acids (e.g. hydrochloric, sulfuric and
phosphoric acid) can slightly corrode titanium, which increases with acid
concentration and temperature. For example the corrosion rate of 3 % HCl
(about pH 0.1) at room temperature is about 13 µm/year. At room
temperature, titanium is resistant to concentrations of about 5 % sulfuric acid
(about pH 0.3). The addition of nitric acid to hydrochloric or sulfuric acids
significantly reduces corrosion rates. Titanium is subject to corrosion in
anhydrous methanol, which can be avoided by adding a small amount of water
(about 3 %). Slight corrosion is possible with ammonia > 10 %.
Fused silica
Fused silica is inert against all common solvents and acids except hydrofluoric
acid. It is corroded by strong bases and should not be used above pH 12 at
room temperature. The corrosion of flow cell windows can negatively affect
measurement results. For a pH larger than 12, the use of flow cells with
sapphire windows is recommended.