Hardware manual

6-6 Agilent 7500 Series ICP-MS Hardware Manual
6 Technical Information
Another possible problem is leakage of the Ar gas line and sample line; if the
O- rings for the sample tube are not tightened enough, air leaks will occur
(Figure 127). This will often be indicated by a higher signal for N, N
2
and ArN
at m/z 14, 28 and 54, respectively, higher sensitivity for lighter masses and
lower sensitivity for heavier masses.
Figure 127 Cross-Section of Concentric Nebulizer
Micro Flow Nebulizer
This nebulizer is similar to the concentric nebulizer except for the diameter of
the capillary and the gap for the Ar gas, which is smaller than that of the
concentric nebulizer. This nebulizer consists of only PFA. The sample is
introduced by self- aspiration.
This nebulizer has the following unique features:
• The sample uptake rate is 50 to 150 µL/min but it gives almost the same
sensitivity as the CN, CF, and BN. It allows analysis of ultra trace levels in
small volumes of a sample, such as impurities in silicon wafers.
• The range of the carrier gas flow rate is 0.4 to 1.1 L/min.
• As the sample is introduced by self- aspiration, the sample uptake rate is
changed by the carrier gas flow rate.
• As this nebulizer consists of only PFA, it is used for various types of
samples such as strong acid, strong base, and organic solvent. However, a
strong base may negatively affect the torch.
Since the sample uptake rate is low and the diameter of the capillary and the
gap for the Ar gas are very small, take care when handling it. For ultra trace
levels analysis, it is recommended that the nebulizer is used for ultra low- level
samples only. If particles are included in the sample or argon gas, it may cause
nebulizer to clog.
Refer to the “Agilent Micro Flow Nebulizer, Nebulizer Installation Guide” in
detail.
Capilary
Possible Air Liaks