74 
5.3.7.2 Linearity 
s- and mPCA: 
• ECNI: Linearity was very good within two orders of magnitude (1-100 ng/pl). 
Regression coefficients were always >0.99 (seven measuring points) Figure 3 shows 
an example of the linear range for a sPCA congener group. 
• CH4/CH2CI2-NICI: Linearity was very good within two orders of magnitude (1-100 
ng/pl, r 2 >0.998, six measuring points). 
• EI-MS/MS: Linearity was very good within two orders of magnitude (ion trap: 2- 
100 ng/pl, r 2 >0.998, six measuring points; triple quadrupole: 0.2-100 ng/pl). 
Concentration [ng/pl] 
Figure 8: Linear range of ECNI for the sPCA congener group C13CI6H22 from a sPCA mixture with 
55.5 % chlorine content. Linearity could be obtained within 1-100 ng/pl. The most abundant isotope 
signal of the [M-HCl]"ion was recorded. 
Chlordanes: 
• ECNI: Linearity was very good within 1-6 pg/pl to ca. 5600 pg/pl (r 2 >0.99, 8-10 
measuring points).