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11.3.2 Process all LRBs, LFBs, LSSMBs and LFSSMs using the sample collection
devices is Section 8.1.
11.3.3 Prepare the sample for analysis by pipetting 5 mL into an autosampler vial, or
other suitable single use vial. Dilution of the sample may be required if the
sample concentration is suspected to exceed the upper calibration standard. Add
50 µL of the 100 µg/L IS-FS (Sect. 7.2.1.2), cap the vial and invert several times
to mix. If using a commercially available IS solution, calculate the volume
necessary to achieve a 1.0 µg Cl 18 O 4
-
/L final IS concentration in the sample.
NOTE: A 1% dilution error introduced by the addition of the IS is considered
insignificant. It is permissible to use a different IS concentration; however, the
analyst must be aware that ionization suppression of the native ClO 4
-
may occur
if the IS concentration is too high.
11.4 SAMPLE ANALYSIS
11.4.1 Establish optimal operating conditions for the IC-ESI/MS instrumentation to be
used. Operating conditions may vary depending on instrumentation. The
analyst is responsible for determining optimal conditions for their
instrumentation. The configuration of Figure 1 and the operating conditions of
Table 1 were used to generate the data presented in this method.
11.4.2 Establish a valid Initial Calibration following the procedures outlined in
Section 10.3 or confirm that the calibration is still valid by analyzing the
required CCCs as described in Section 10.4.
11.4.3 Inject aliquots of field samples and QC samples under the same instrumental
conditions used for the Initial Calibration (a 200 µL sample size was used in
collection of data for the method). A sample Analysis Batch is presented in
Table 3.
NOTE: If not using an autosampler, use a syringe to withdraw the sample from
the sample vial. Place the injection valve in the Load position and manually
load the sample loop. The loop size must be the same loop size that was used to
calibrate the instrument. Flush the loop with at least three loop volumes of
sample.
11.4.4 At the conclusion of data acquisition, use the same data acquisition method that
was used for the Initial Calibration to identify peaks in the chromatogram. Use
the data acquisition method to determine the relative retention times and
integrate the peak areas of the monitored ions (m/z 99, 101, and 107).
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