Page 19 - Shimadzu Journal vol.7 Issue1

Environmental Analysis

Fig. 11 Accuracy data for EPA 537, ASTM D7979, and ISO 21675 (20 ng/L)

Fig. 11 shows the recovery of a 20 nanograms per liter (ng/L) Recovery for each analyte is well within the recommended 70 –
standard. The ASTM and EPA data are single laboratory (SSI) data 130%. Data shows that all three methods, each with a different
extracted from reagent water. The ISO data are multiple laboratory calibration model, produce comparable results. Fig. 12 shows the
data from a river water matrix. precision of a 20 nanograms per liter (ng/L) standard. The ASTM and
EPA data are single laboratory (SSI) data extracted from reagent water.
The ISO data are multiple laboratory data from a river water matrix.

Fig. 12 Accuracy data for EPA 537, ASTM D7979, and ISO 21675 (20 ng/L)

The better precision of the ISO method is indicative of the isotope instrument to reach equivalent detection limits as obtained by more
dilution calibration model, however, each method precision is well sensitive instruments using the ASTM method. Lower concentrations
within the required 30 % Relative Standard Deviation (RSD). Isotope are possible using the SPE methods and sensitive LCMS instruments,
dilution is not necessary or allowed by the ASTM method. such as the Shimadzu LCMS-8050 and LCMS-8060, however,
Each of the above methods has different instrument sensitivity laboratories need to be cautious because PFAS is a common
requirements. Because the EPA and ISO methods extract samples laboratory contaminant. Figure 13 shows the different Shimadzu
using SPE, there is a concentration factor enabling a less sensitive LCMS instruments in relation to their sensitivity.

19