Chapter 6 methods, 1 introduction to methods, 1 sensitivity – INFICON HAPSITE Smart Plus Chemical Identification System User Manual
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HAPSITE Smart Plus Operating Manual
Chapter 6
Methods
6.1 Introduction to Methods
The versatility of the HAPSITE lies in the variety of methods available. The
HAPSITE can be run in Analyze (GC/MS) mode or Survey (MS only mode) and
uses various sampling accessories to extend its capabilities. The accessories
include the Concentrator, the Headspace Sampling System and the SituProbe.
This chapter describes the various sampling methods.
6.1.1 Sensitivity
The sensitivity of the HAPSITE is dependent on the configuration and sampling
mode chosen. The Survey Mode is the least sensitive, requiring levels of greater
than 10 ppm (parts per million) for detectability. The Sample Loop with the probe is
able to detect levels in the low ppm to high ppb (parts per billion) ranges. With a
Concentrator installed and using the probe, the HAPSITE can detect low ppb to
high ppt (parts per trillion) levels. The Sample Loop with the Headspace Sampling
System detects down to 5 to 10 ppb and will detect even lower with the
Concentrator installed.
6.2 Survey Method
Survey is used to quickly screen a location for volatile compounds. The sample is
drawn in through the probe and sent directly to the Mass Spectrometer. It bypasses
the GC to provide a quick response. The Survey mode of sample collection is also
referred to as MIMS (Membrane Interface Mass Spectrometry).
There are two ways the Survey Methods can provide tentative identification of
compounds. They can either extract target mass spectra from the MS response or
search the total MS response against the AMDIS or NIST library. Survey Methods,
when run from the HAPSITE, also provide an indication of the concentrations of
VOCs based on the response of the TIC (Total Ion Count). The LCD of the
HAPSITE provides a real time plot of response vs. sampling time. Survey Methods
can be Selected Ion Monitoring (SIM) or Full Scan methods. The sensitivity of a
Survey method in full scan will be approximately 10 ppm or greater. A Survey SIM
method gives an improved level of sensitivity compared to a Full Scan method.
NOTE: These sensitivity ranges should be viewed as general guidelines, as the
sensitivity of individual compounds can vary.