Transcript Hold time, storage, and sample container

HOLD TIME, STORAGE, AND SAMPLE CONTAINER CONSIDERATIONS
FOR ANALYTICAL METHODS TO DETERMINE HIGHLY FLUORINATED
COMPOUNDS IN ENVIRONMNTAL MATRICES
Mary A. Kaiser1, Million Woudneh2, Barbara S. Larsen1, Michael D. Aucoin3, Kelly A. Rinehimer3, and Richard Grace2
1 DuPont
Company, P.O.Box 80402, Wilmington, DE, 19880-0402; 2AXYS Analytical Services Ltd., 2045 Mills Road West, Sidney, B.C. V8L 5X2, Canada,
3URS
Corporation, Barley Mill Plaza 19, Wilmington, DE 19805 USA
ABSTRACT
A comprehensive panel of fluorotelomer alcohols, perfluorocarboxylic acids, and
perfluorinated sulfonates were stored in three types of storage containers:
polypropylene, high-density polyethylene (HDPE), and amber glass at common laboratory
storage conditions. Results were measured at intervals from 0 to 90 days to determine
hold time guidance and compatible container types. Results indicate that when stored in
appropriate containers and standard laboratory storage conditions, sample results are
not affected for periods up to 90 days. Amber glass or HDPE containers were
determined to be the best storage containers. Polypropylene containers were deemed
EXPERIMENTAL DESIGN
Fluorotelomer alcohols
Hold time study:
Matrix = methanol and filter
Container types = amber glass jar with polypropylene caps.
Hold time intervals = 0, 2, 7, 14, 28, 60 and 90 Days.
# of samples analyzed = 3 samples per hold time interval.
Storage temperature = -20oC
METHOD OUTLINE
to be incompatible with some perfluorinated carboxylic acids.
INTRODUCTION
Fluorotelomer alcohols, perfluorocarboxylic acids and perfluorinated sulfonates are
important highly fluorinated raw materials that have attracted considerable attention in
the last eight years. Many of these compounds have been found in a variety of
environmental matrices and have been reported in many locations. These compounds have
presented considerable analytical challenges. While considerable analytical work has
focused on providing increasingly reliable results, limited information is available on key
issues that affect sample results such as hold times, storage conditions and sample
containers.
USES OF HIGHLY FLUORINATED MATERIALS
Aerospace Materials
Hydraulic tubing
Wire & Cabling Flares
Health Care
Chemical
Processing
Valves, Lined
Piping, Tanks
Semiconductor Manufacture
Fire Fighting
Carpet & Textiles
MATERIALS
F(CF2)nCO2-
Perfluorocarboxylates
F(CF2)n CH2CH2OH
Fluorotelomer alcohols
F(CF2)n SO3-
Perfluoroalkyl sulfonates
•Note that there is a “perfluorinated” part and an organic
functional group.
•Very different physical-chemical properties from each
other.
EXPERIMENTAL DESIGN
Method validation for both perfluorinated acids and
fluorotelomer alcohols:
•two matrices
•three concentrations
•triplicate
•three different days
Perfluorinated acids
Hold time study:
Matrix = reagent water
Container types = polypropylene, amber glass, and highdensity polyethylene.
Hold time intervals = 0, 2, 7, 14, 28, 60 and 90 Days.
# of samples analyzed = 3 samples per hold time interval.
Storage temperature = 4oC
CONCLUSIONS
Fluorotelomer alcohols
Quantitative recovery achieved for 8:2 to 16:2
fluorotelomer alcohols spiked and stored in closed amber
glass jars.
Perfluorinated carboxylic and sulfonic acids
•Mean percent recovery values of all acid analytes were > 90%
after 60 days of storage in amber glass containers. Mean
percent recovery values of all acid analytes were > 80% after
90 days of storage in amber glass containers
•Mean percent recovery values of all acid analytes were > 70%
after 60 days of storage in HDPE containers. Mean percent
recovery values of all acid analytes were > 68% after 90 days
of storage in HDPE containers.
•Up to 28% PFUnA and 34% PFDoA were recovered from
polypropylene containers that were used for storing water
samples in contact with these perfluorinated acids.
Polypropylene containers are therefore not
suitable for sample collection for C11 and C12
perfluorocarboxylic acids.