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Sample collection and Preservation Information – UCMR3 methods.
Method 522 – 1,4 Dioxane
8. SAMPLE COLLECTION, PRESERVATION, AND STORAGE
8.1 SAMPLE PRESERVATIVES – Preservation reagents, listed in the table below, are
added to each sample at the time of sample collection. Sodium sulfite must be
added first and may be placed as a dry material in the sample bottles prior to
shipment to the field. Aqueous solutions of sodium sulfite may not be added to
sample bottles prior to shipment to the collection site because these solutions are
unstable and cannot be relied upon to completely dechlorinate the samples.
Sodium bisulfate is added only after the sodium sulfite has been dissolved in the
aqueous sample. See Section 8.2.2 and 8.2.3 for complete instructions.
Compound Amount
Purpose
Sodium sulfite 50 mg/L
Reduce chlorine/chloramine residual
Sodium bisulfate 1 g/L (approx)
Microbial inhibitor
8.2 SAMPLE COLLECTION
8.2.1 Open the tap and allow the system to flush until the water temperature has
stabilized (approximately three to five min). Collect samples from the flowing
system.
8.2.2 Fill sample bottles, taking care not to flush out the sample dechlorination
reagent. Samples do not need to be collected headspace free.
8.2.3 After collecting the sample, cap the bottle and agitate by hand until the
sodium sulfite is dissolved. Add enough sodium bisulfate such that the final
concentration will be 1 g/L. Cap the bottle and mix until dissolved. Unless field
verification of pH is to be performed, keep the sample sealed until just prior to
extraction.
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8.2.4 Field verification of pH 4 (optional). It is anticipated that 1 g/L of sodium
bisulfate will be sufficient to acidify most samples to < pH 4. If there is reason to
suspect that more may be needed, the pH can be verified with narrow range pH
paper at the time of sample collection. After acidification and mixing, pour a
small amount of sample over a strip of the pH paper (do not dip the strip in the
sample). Read the result as instructed on the pH paper package. If the pH is ≥ 4,
add additional sodium bisulfate until pH < 4 is obtained. Seal the bottle, and keep
the sample sealed until extraction.
METHOD 539 – HORMONES (FIELD BLANK REQUIRED)
8. SAMPLE COLLECTION, PRESERVATION, AND STORAGE
8.1 SAMPLE BOTTLE PREPARATION
8.1.1 SAMPLE CONTAINERS – One-liter amber glass bottles with PTFE-lined screw
caps and sufficient capacity to allow subsequent preparation of all required
sample and QC aliquots.
NOTE: Smaller sample volumes (e.g., 500-mL) can be collected if the laboratory
demonstrates acceptable performance in meeting the required MRLs (Sect. 9.2.4)
using the smaller sample volume. The amount of added preservatives and
surrogate/analyte fortification levels should be adjusted accordingly. 539-13
8.1.2 ADDITION OF PRESERVATIVES – Preservation reagents, listed in the table
below, are added to each sample bottle prior to shipment to the field (or prior to
sample collection).
Compound
Sodium thiosulfate
Amount
80 mg/L
2mercaptopyridine1-oxide, sodium salt
65 mg/L
Purpose
Removes free
chlorine
Microbial inhibitor
8.2 SAMPLE COLLECTION – Grab samples must be collected in accordance with
conventional sampling practices. Fill sample bottles taking care not to flush out
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the preservatives. Because the method analytes are not volatile, it is not
necessary to ensure that the sample bottles are completely headspace-free.
8.2.1 SAMPLING FROM A TAP – When sampling from a cold water tap, remove the
aerator, open the tap, and allow the system to flush until the water temperature
has stabilized (approximately five minutes). Invert the bottles several times to mix
the sample with the preservation reagents.
Field Blanks – EPA is requiring the collection of field blank samples for UCMR3
and, to minimize the potential issue of field blank and sample contamination,
advises the sampler and the laboratory personnel to wear nitrile gloves when
collecting or handling samples for hormones. Reagent water is shipped by
laboratory with preservatives along with empty bottles. During sampling, the
reagent bottle is poured into the empty, unpreserved bottle and capped. This is
shipped back to laboratory along with samples and labeled Field Blank.
It is advisable to also wear a dusk mask during sampling of hormones to reduce
the risk of breath contaminating samples.
8.3 SAMPLE SHIPMENT AND STORAGE – Samples must be chilled during shipment
and must not exceed 10 °C during the first 48 hours after collection. Samples must
be confirmed to be at or below 10 °C when they are received at the laboratory. In
the laboratory, samples must be stored at or below 6 °C and protected from light
until analysis. Samples must not be frozen.
8.4 SAMPLE HOLDING TIMES – Results of the sample storage stability study (Table
9) indicated that all compounds listed in the method have adequate stability for
28 days when collected, preserved, shipped and stored as described in Sections
8.1 – 8.3. Therefore, samples should be extracted as soon as possible, but must be
extracted within 28 days. Extracts must be stored at 0 °C or less and analyzed
within 28 days after extraction. The extract storage stability study data are
presented in Table 10.
METHOD 524.3 – VOLATILE ORGANICS (FIELD BLANK REQUIRED)
8.1 SAMPLE COLLECTION
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8.1.1 Prior to shipment to the field, maleic and ascorbic acid must be added to
each sample bottle. Cap the vials tightly to avoid spillage of the preservation
reagents. If using a 40-mL vial, add 25 mg of ascorbic acid and 200 mg of maleic
acid. If other collection volumes are used, adjust the amount of the preservation
reagents so that the final concentrations of ascorbic and maleic acid in the sample
containers are 0.625g/L and 5 g/L, respectively. Using narrow-range pH paper,
periodically verify that sample pH is ~2 for each sample source.
8.1.2 If a sample foams vigorously when added to a VOA vial containing maleic
and ascorbic acids, discard the sample. Collect another sample for that location,
but do not add the method preservatives. Document these samples as “not
acidified.” Unpreserved samples must be analyzed within 24 hours of collection.
8.1.3 If sampling only for the THMs, you may preserve samples with sodium
thiosulfate. Add 3 mg to each 40-mL VOA vial prior to sample collection. Do not
add ascorbic or maleic acid when employing this preservation option.
NOTE: If the residual chlorine is likely to be present at greater than 5 mg/L, a
determination of the chlorine concentration may be necessary. Add an additional
25mg of ascorbic acid or 3 mg of sodium thiosulfate per each 5 mg/L of residual
chlorine for each 40-mL of sample.
8.1.4 Grab samples must be collected in accordance with standard sampling
practices. When sampling from a cold water tap, remove the aerator, open the
tap and allow the system to flush until the water temperature has stabilized
(approximately 3 to 5 minutes). Fill sample bottles to overflowing, but take care
not to flush out the rapidly dissolving solid preservatives. No air bubbles should
pass through the sample as the bottle is filled, or be trapped in the sample when
the bottle is sealed.
8.1.5 When sampling from an open body of water, fill a beaker with water
collected from a representative area. Use this bulk sample to generate individual
samples and Field Duplicates as needed.
Trip blanks (field blanks) must accompany samples from lab to field and back to
lab. Do not open containers in the field.
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METHOD 537- PERFLUORONATED COMPOUNDS (FIELD BLANK REQUIRED)
8. SAMPLE COLLECTION, PRESERVATION, AND STORAGE
8.1 SAMPLE BOTTLE PREPARATION
8.1.1 Samples must be collected in a 250-mL polypropylene bottle fitted with a
polypropylene screw-cap.
8.1.2 The preservation reagent, listed in the table below, is added to each sample
bottle as a solid prior to shipment to the field (or prior to sample collection).
Compound
Amount
Purpose
Trizma
5.0 g/L
buffering reagent and
removes free chlorine
8.2 SAMPLE COLLECTION
8.2.1 The sample handler must wash their hands before sampling and wear nitrile
gloves while filling and sealing the sample bottles. PFAA contamination during
sampling can occur from a number of common sources, such as food packaging
and certain foods and beverages. Proper hand washing and wearing nitrile gloves
will aid in minimizing this type of accidental contamination of the samples.
8.2.2 Open the tap and allow the system to flush until the water temperature has
stabilized (approximately 3 to 5 min). Collect samples from the flowing system.
8.2.3 Fill sample bottles, taking care not to flush out the sample preservation
reagent. Samples do not need to be collected headspace free.
8.2.4 After collecting the sample, cap the bottle and agitate by hand until
preservative is dissolved. Keep the sample sealed from time of collection until
extraction.
8.3 FIELD REAGENT BLANKS (FRB)
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8.3.1 A FRB must be handled along with each sample set. The sample set is
composed of samples collected from the same sample site and at the same time.
At the laboratory, fill the field blank sample bottle with reagent water and
preservatives, seal, and ship to the sampling site along with the sample bottles.
For each FRB shipped, an empty sample bottle (no preservatives) must also be
shipped. At the sampling site, the sampler must open the shipped FRB and pour
the preserved reagent water into the empty shipped sample bottle, seal and label
this bottle as the FRB. The FRB is shipped back to the laboratory along with the
samples and analyzed to ensure that PFAAs were not introduced into the sample
during sample collection/handling.
8.3.2 The same batch of preservative must be used for the FRBs as for the field
samples.
8.3.3 The reagent water used for the FRBs must be initially analyzed for method
analytes as a LRB and must meet the LRB criteria in Section 9.3.1 prior to use.
This requirement will ensure samples are not being discarded due to
contaminated reagent water rather than contamination during sampling.
8.4 SAMPLE SHIPMENT AND STORAGE
Samples must be chilled during shipment and must not exceed 10 °C during the
first 48 hours after collection. Sample temperature must be confirmed to be at or
below 10 °C when the samples are received at the laboratory. Samples stored in
the lab must be held at or below 6 °C until extraction, but should not be frozen.
NOTE: Samples that are significantly above 10° C, at the time of collection, may
need to be iced or refrigerated for a period of time, in order to chill them prior to
shipping. This will allow them to be shipped with sufficient ice to meet the
above requirements.
8.5 SAMPLE AND EXTRACT HOLDING TIMES – Results of the sample storage
stability study (Table 10) indicated that all compounds listed in this method have
adequate stability for 14 days when collected, preserved, shipped and stored as
described in Sections 8.1, 8.2, and 8.4. Therefore, water samples should be
extracted as soon as possible but must be extracted within 14 days. Extracts must
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be stored at room temperature and analyzed within 28 days after extraction. The
extract storage stability study data are presented in Table 11.
METHOD 300.1 – CHLORATE
8.0 Sample Collection, Preservation and Storage
8.1 Samples should be collected in plastic or glass bottles. All bottles must be
thoroughly cleaned and rinsed with reagent water. Volume collected should be
sufficient to insure a representative sample, allow for replicate analysis, if
required, and minimize waste disposal.
8.3 Sample preservation and holding times for the anions that can be determined
by this method are as follows:
PART B : Inorganic Disinfection By-products
Analyte
Preservation
Holding Time
Chlorate
28 days
50 mg/L EDA (0.5 mL to
1L)
8.4 When collecting a sample from a treatment plant employing chlorine
dioxide, the sample must be sparged with an inert gas (helium, argon, nitrogen)
prior to addition of the EDA preservative at time of sample collection.
8.6 EDA is primarily used as a preservative for chlorite. Chlorite is susceptible to
degradation both through catalytic reactions with dissolved iron salts and
reactivity towards free chlorine which exists as hypochlorous acid/hypochlorite
ion in most drinking water as a residual disinfectant. EDA serves a dual purpose as
a preservative for chlorite by chelating iron as well as any other catalytically
destructive metal cations and removing hypochlorous acid/hypochlorite ion by
forming an organochloroamine. EDA preservation of chlorite also preserves the
integrity of chlorate which can increase in unpreserved samples as a result of
chlorite degradation.
METHOD 200.8 – METALS (FIELD BLANK REQUIRED)
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8.0 SAMPLE COLLECTION, PRESERVATION, AND STORAGE
8.3 For the determination of total recoverable elements in aqueous samples,
samples are not filtered, but acidified with (1+1) nitric acid to pH <2 (normally, 3
mL of (1+1) acid per liter of sample is sufficient for most ambient and drinking
water samples). Preservation may be done at the time of collection, however, to
avoid the hazards of strong acids in the field, transport restrictions, and possible
contamination it is recommended that the samples be returned to the laboratory
within two weeks of collection and acid preserved upon receipt in the laboratory.
8.5 For aqueous samples, a field blank should be prepared and analyzed as
required by the data user. Use the same container and acid as used in sample
collection. Open field blank container and close. No transfer required.
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METHOD 218.7 – CHROMIUM 6+
8. SAMPLE COLLECTION, PRESERVATION AND STORAGE
8.1 ADDITION OF PRESERVATIVE –The samples are preserved with a combined
buffer/dechlorinating reagent. Either the liquid formulation or the solid
formulation of the preservative described in the following sections may be used.
Only one preservative formulation should be used (liquid or solid) to prepare the
sample bottles.
8.1.1. LIQUID FORMULATION - NH4OH/(NH4)2SO4 –
8.1.2. SOLID FORMULATION - CO3-2/HCO3-/(NH4)2SO4 –
8.2 SAMPLE COLLECTION – Open the tap and allow the system to flush for
approximately 5 minutes. Fill sample bottles with 100-mL of sample, taking care
not to flush out the preservative. Invert the bottle several times to mix the sample
with the preservative.
8.3 SAMPLE SHIPMENT AND STORAGE – Storage stability studies have
demonstrated that samples are stable for at least 14 days at both ambient
temperature (25 °C) and chilled temperature (6 °C). If the anticipated shipping
conditions would expose the samples to temperature extremes, samples may be
chilled during shipment. Standard quality control practices should be put in place
to confirm that the shipping conditions do not adversely affect sample stability. A
laboratory fortified sample that is shipped with the sample kit can aid in making
this determination. Upon sample receipt, measure the free chlorine and sample
pH. The free chlorine concentration must be less than 0.1 mg/L and the pH must
be >8 for the sample to be valid. In the laboratory, it is recommended that the
samples are stored at or below 6 °C until analysis.
8.4 SAMPLE HOLDING TIMES – Results of the sample storage stability study (Table
7) indicate that Cr(VI) is stable for at least 14 days when collected, preserved,
shipped and stored as described in Sections 8.1 to 8.3. Samples should be
analyzed as soon as possible, but must be analyzed within 14 days.
FOR METHODS WITH FIELD BLANKS – YOU NEED A SEPARATE FIELD BLANK FOR
EACH SAMPLE SITE!