TECHNICAL NOTE
Concentration Estimation Equationfor HAPSITE Smart Plus™

The approximate concentration of an analyte of interest thatwas not collected using a quantitative method can becalculated by comparing the analyte response to theHAPSITE internal standard response. Every HAPSITE Smart
Plus GC/MS analysis automatically adds 0.4 mL (0.24second equivalent) of 5 ppm bromopentafluorobenzene(BPFB) from the internal standard canister to the collectedsample.

The HAPSITE detector response to this analyte is presumed
to be similar to that of BPFB. The maximum normalization
number of an analyte is defined as the highest value of themost dominant mass fragment at the apex of the peak.
The maximum normalization number of BPFB and theanalyte are used to obtain the ratio between the twochemicals. The known quantity of BPFB and the sample
collection time are combined with this ratio to estimate theanalyte concentration as shown in (1). Two examples follow.

Maximum Normalization
 Concentration of BPFB    Volume BPFB # of Analyte----------------------------------------------------------------  ---------------------------------------------------------------------------------------------------------------------- =Sample Collection TimeMaximum Normalization# of BPFB (mass 117)
Example 1: Default method Air_Tri-Bed_PPM_Standard
collects the sample for 3 seconds. The maximum
normalization number obtained for the analyte chlorobenzene
is 1,345,376 for mass 112. (See Figure 1.)

Approximate
Concentrationof Analyte(1)

The maximum normalization number for BPFB in the sameanalysis is 695,046 for mass 117. This information can besubstituted into (1) as shown in (2). The concentration oftrichloroethylene is estimated to be approximately 0.8 ppm.

1,345,376 (mass 112) 5 ppm  0.24 s----------------------------------------------------------  --------------------------------------- = 0.774 ppm  0.8 ppm
695,046 (mass 117)
3s(2)Figure 1 Normalization Numbers

Normalization
112 : 1,345,376

chlorobenzene

Normalization
117 : 695,046

bromopentafluorobenzene (BPFB)

1 of 2

Concentration Estimation Equation for HAPSITE Smart Plus™

2 of 2

Example 2: Default method Air_Tri-Bed_PPB_Standard
collects a sample for 60 seconds. The maximum
normalization number for the analyte toluene is 968,159 formass 91. The maximum normalization number for BPFB in
the same analysis is 800,400 for mass 117. (See Figure 2.)

A BPFB concentration of 5,000 ppb (5 ppm = 5,000 ppb) isused to calculate analyte concentration in ppb. Substitute theinformation into (1), as shown in (3). The concentration oftoluene is estimated to be approximately 24 ppb.

968, 159 (mass 91) 5,000 ppb  0.24 sec-------------------------------------------------------  ------------------------------------------------------- = 24.19 ppb  24 ppb
800, 400 (mass 117)
60 secFigure 2 Normalization Numbers

Normalization
117 : 800,400

Normalization
91 : 968,159

toluenebromopentafluorobenzene (BPFB)

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