This powerpoint presentation begins by presenting research objectives that include the following: evaluate the impact of not strictly following U.S. Environmental Protection Agency (USEPA)
guidelines for preservation and storage of synthetic organics;
evaluate the impact of extended storage at
room temperature on analyte stability,
e.g. simulate long transit times;
evaluate impact of eliminating "dangerous
goods" from preservation, e.g. facilitate international transport; and,
eliminate dual stage preservation,
e.g. de-chlorination followed by acidification. Reasons for evaluating alternatives include the following: there are inconsistencies between various
500 series methods for the same analyte;
two-stage preservation for disinfected
samples is a source of field errors; for international projects, sending acids is
sometimes prohibited, Keep It Simple; and,
the World Health Organization (WHO) regulates some analytes that are not
covered in USEPA regulations and there is
no literature data on preservation. Observations on pesticide/SOC analysis
and degradation with 525 scheme include the following:
under refrigeration, almost all target analytes are
stable for 28 days when acidified;
however, without acidification but with refrigeration,
almost all target analytes are stable for at least 7 days;
without refrigeration there are significant differences
by compound class with acidification vs neutral pH, and
is also somewhat matrix dependent; and,
for some compounds acidification enhances
degradation whereas de-chlorination does not. Significant observations from Part
One studies indicate:
cyanazine unstable if acidified, but
dechlorination is acceptable (contrary to 525);
heptachlor is relatively stable without
acidification (more stable than with acid);
diazinon is relatively stable without acidification; and, a few USEPA regulated analytes show significant
degradation when preserved per method
requirements. Studies in process and recommendations include the following:
527 Preservation in Matrices (as was done
with 525 options in part 1);
evaluation of Room Temperature Storage
with 527;
develop Triage Scheme for Data
Interpretation Based on Findings;
it appears clear that USEPA can move away
from two-stage preservation; and, USEPA can also
clarify existing options. Includes table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.4 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 39 |
| Published : | 11/01/2008 |
