Hardware manual

Technical Information 6
Agilent 7500 Series ICP-MS Hardware Manual 6-9
solvents attack PP. Since PP is a plastic type material, wetability is not as good
as for the QZ and PG. When a PP spray chamber is not in use, it must be kept
in an acid bath to maintain wetability. A 5%(v/v) HNO
3
bath is recommended.
Teflon (PFA)
This PFA spray chamber is the standard spray chamber for the inert sample
introduction kit, and is used when aspirating hydrofluoric acid.
[Reference] Pyrex Glass (PG)
It can be used for acids and organic solvents, but not for HF or strong alkaline
solutions. Pyrex glass contains % levels of Na, B, Al and Ca, which are leached
out in acids. Therefore, it is difficult to avoid contamination from this spray
chamber when low ppt levels of these elements are analyzed.
ICP Torch
The Agilent 7500 employs a Fassel type torch, which is the most common torch
design and used for almost all ICP instruments. There are three Ar gas lines:
plasma gas, auxiliary gas, and carrier gas. The plasma gas flow is tangentially
introduced into the outer sheath of the torch at about 15 L/min. Its role is to
cool the torch itself and to sustain the plasma. The auxiliary gas is also
tangentially introduced into the middle sheath of the torch at about 1 L/min.
Its role is to push the plasma forward in order to avoid melting the sample
injector tip. The carrier gas is introduced into the center of the torch through
the injector.
In the case of the Agilent 7500, the standard torch is a one- piece design and is
made of quartz. The inner diameter of the injector is 2.5 mm. For HF solutions,
a platinum (or sapphire) injector is used as the inert introduction system. The
injector is removable and a demountable torch is used.
The optimal carrier and make- up gas flows depend on the diameter of the
injector; about 1.2 L/min for φ2.5 mm and about 1 L/min for φ2.0 mm, when an
aqueous sample is analyzed.