Basic HTML Version
Appendix C
5/20/2009
9
8
SAMPLE COLLECTION, PRESERVATION, AND STORAGE
8.1 Water collected for DOC and/or DIC should be filtered through a
Whatman GF/F glass fiber filter (nominal pore size 0.7
µ
m), or equivalent.
8.2 Water collected for DOC should be frozen at -20
°
C, or acidified with 2N
HCl to a pH of ≤2. Water collected for DIC should not be acidified. The
sample container should be either borosilicate glass or Teflon. Plastic
containers may be used if well cleaned and aged. Freshwater samples
should be frozen in Teflon or plastic to prevent breakage.
8.3 Frozen DOC and/or DIC samples may be stored longer than 28 days. It
has been shown that frozen QCS samples up to a year old still fall well
within the control limits.
8.4 DOC samples acidified with 2N HCL should be frozen, as above, or
refrigerated at 4
°
C for no longer than 28 days.
8.5 DIC samples stored at 4
°
C should be analyzed within 28 days.
9
QUALITY CONTROL
9.1 The laboratory is required to operate a formal quality control (QC)
program. The minimum requirements of this program consist of an initial
demonstration of laboratory capability and the continued analysis of
laboratory instrument blanks and calibration standard material, analyzed
as samples, as a continuing check on performance. The laboratory is
required to maintain performance records that define the quality of data
generated.
9.2
Initial Demonstration of Capability
9.2.1
The initial demonstration of capability (DOC) – is used to
characterize instrument performance (MDLs) and
laboratory performance (analysis of QC samples) prior to
the analyses conducted by this procedure.
9.2.2
Quality Control Sample (QCS/SRM) – When using this
procedure, a quality control sample is required to be
analyzed at the beginning and end of the run, to verify data
quality and acceptable instrument performance. If the
determined concentrations are not within
±
10% of the
certified values, performance of the determinative step of
the method is unacceptable. The source of the problem
must be identified and corrected before either proceeding
with the initial determination of MDLs or continuing with
analyses.
9.2.3
Method Detection Limits (MDLs) – MDLs should be
established for DOC and DIC using a low level ambient
water sample. To determine the MDL values, analyzed
seven replicate aliquots of water. Perform all calculations
defined in the procedure (Section 10) and report the