Changes in Field Treatment Protocols and Bottle Types for Whole-Water Samples Collected for Total Ammonium plus Organic Nitrogen and Total Phosphorus Determinations
Date: Wed, 25 Nov 1998 11:34:53 -0500
From: Nana Snow
Reply-To: "Nana L Snow, Secretary (OA), Reston, VA "
To: "E - All WRD Employees"
CC: " WRD Archive File, "
Subject: OWQ 99.004--Changes in Field Treatment Protocols and Bottle Types for
In Reply Refer To:
Mail Stop 412 November 25, 1998
OFFICE OF WATER QUALITY TECHNICAL MEMORANDUM NO. 99.04
Subject: Changes in Field Treatment Protocols and Bottle Types for
Whole-Water Samples Collected for Total Ammonium plus
Organic Nitrogen and Total Phosphorus Determinations
This technical memorandum pertains to changes, effective January 1,
1999, in field-treatment protocols and bottle types for whole-water
samples collected for determining ammonium (see definitions) plus
organic nitrogen (Kjeldahl nitrogen) and phosphorus. Specifically, it
announces that,
1. Whole-water samples collected for these analyses will be
preserved with sulfuric acid at collection sites, and
2. Translucent ("plain"), polyethylene bottles will be used to
collect, ship, and store these samples rather than the brown ones
formerly specified.
As a consequence of these changes, RCA and RCC sample designators (see
Table 1) will be discontinued and replaced by a new WCA (Whole-water,
Chilled, Acidified) sample designator (see table 2) on January 1, 1999.
Table 3 shows bottle-type changes for affected analyses. Note that
National Water Quality Laboratory (NWQL) codes and NWIS (National Water
Information System) parameter and method codes for affected analyses
remain unchanged.
Between January 1, 1999 and February 28, 1999, RCC samples inadvertently
sent to the NWQL will be preserved with sulfuric acid and designated as
WCA samples prior to analyses at no charge to the customer. After this
grace period, all RCC bottles received at the NWQL will be returned at
submitters' expense or discarded.
Table 1. Excerpt from the current NWQL catalog showing sample
designations, container sizes, container types, and treatment protocols
that will be discontinued December 31, 1998
[mL, milliliter; oz, ounce; deg C, degree Celsius; RCA, raw chilled
acidified; RCC, raw chilled]
_______________________________________________________________________
Sample Container Container Treatment and preservation
designation size type
_______________________________________________________________________
RCA 125 mL Brown Use unfiltered sample to
(4 oz) polyethylene rinse bottles, acidify with
bottle H2S04, chill and maintain at
4 deg C; ship immediately.
RCC 125 mL Brown Use unfiltered sample to
(4 oz) polyethylene rinse bottles, chill, and
bottle maintain at 4 deg C; ship
immediately.
_______________________________________________________________________
Table 2. Entry to the NWQL catalog, effective January 1, 1999, showing
new sample designation, container size, container type, and treatment
protocol for whole-water nutrient samples
[WCA, whole-water, chilled, acidified; mL, milliliter; oz, ounce; deg
C, degree Celsius]
______________________________________________________________________
Sample Container Container Treatment and preservation
designation size type
_______________________________________________________________________
WCA 125 mL Plain Use unfiltered sample to
(4 oz) (translucent) bottles, acidify with 1 mL
polyethylene of 4.5 normal (N) H2S04,
bottle chill and maintain at 4 deg
C; ship immediately.
____________________________________________________________________
Table 3. Discontinued and replacement bottle types for
nutrient determinations in whole-water nutrient samples.
[ASF, automated-segmented flow; WWR, whole-water recoverable]
_______________________________________________________________________
Lab NWIS Procedure name Required bottle type
code Parameter Before After
(method) 1/1/99 12/31/98
codes
_______________________________________________________________________
1982 00665 (F) Colorimetry, ASF, acid RCC WCA
persulfate digestion, low-
level phosphorus, as P, WWR
1984 00665 (D) Colorimetry, ASF, micro- RCC WCA
Kjeldahl digestion,
phosphorus, as P, WWR
1986 00625 (D) Colorimetry, ASF, micro- RCC WCA
Kjeldahl digestion, ammonia
+ organic nitrogen, as N, WWR
1993 00665 (E) Colorimetry, ASF, micro- RCA WCA
Kjeldahl digestion, phosphorus,
as P, WWR, acidified
1995 00625 (E) Colorimetry, ASF, micro- RCA WCA
Kjeldahl digestion, ammonia +
organic nitrogen, as N, WWR,
acidified
_______________________________________________________________________
Process WCA bottles at collection sites as follows:
1. Field rinse the translucent, 125-mL polyethylene bottles with
three 10- to 15-mL volumes of well-mixed, whole water dispensed from
churn or cone splitters. Then fill bottles to the level of their
shoulders (approximately 120 mL).
2. Add 1 mL of sulfuric acid preservative to each WCA bottle and
secure the cap.
3. Immediately shake or swirl the bottle to mix the sulfuric acid
preservative with the sample.
4. Pack processed sample bottles in ice and ship them with next-day
priority to the NWQL for analyses.
Required field supplies, available from the USGS Quality of Water
Service Unit (QWSU) in Ocala, Florida, are tabulated below.
_______________________________________________________________________
QWSU Item Description Quantity
Number
_______________________________________________________________________
407FLD Bottle, Poly., Plain, 4 oz (125 mL) Case (100)
406FLD Bottle, Poly., Plain, 4 oz (125 mL) Case (500)
26FLD Bottle Cap, Plastic, 28 mm Box (900)
417FLD Bottle Cap, Plastic, 28 mm Pack (100)
438FLD Vial (PP), H2SO4, 4.5 N (1:7), 1 mL, Box (24)
Whole Water (WCA) Nutrient Preservative
_______________________________________________________________________
RATIONALE FOR CHANGES
On October 1, 1994, the USGS discontinued the practice of adding
mercuric chloride to samples collected for nutrient analysis (U.S.
Geological Survey Office of Water Quality Technical Memorandum No.
94.16, 1994). The decision to discontinue this practice was based on
preliminary analysis data from the USGS nutrient preservation experiment
(Patton and Truitt, 1995). Additional statistical analysis of these
data (Patton and Gilroy, in press) suggested that for some whole-water
samples containing high (1.5 to 5.5 mg of NH4-N/L) initial ammonium
concentrations, sulfuric acid or mercury (II) preservative was necessary
to ensure stability of the ammonium fraction of Kjeldahl nitrogen during
30-day storage at 4°C. The cause of this instability is unknown, but
may be rationalized by the assumption of high biological activity in
affected samples. Sulfuric acid preservative was selected in preference
to mercury (II) preservative for stabilizing whole-water nutrient
samples during storage because of its comparable effectiveness and lower
toxicity. Patton and Gilroy (in press), upon which these changes are
based, received Director's approval on June 24, 1998, and is accessible
in its entirety as an Acrobat PDF document from the NWQL home page
(http://wwwnwql.cr.usgs.gov/).
The primary reason for the change to a translucent container for WCA
samples is to enable laboratory analysts to estimate the quantity and
settling rate of suspended solids in whole-water samples by visual
inspection prior to analysis. With this change, the analysts' ability
to obtain representative subsamples for whole-water digest preparation
will improve. An added, anticipated benefit of using different bottles
for collection and storage of dissolved and whole-water nutrient samples
is reduced potential for collection-site and laboratory bottle mix-ups.
The new WCA designation was established to emphasize that a specific
sulfuric acid concentration (1 mL of 4.5 N H2SO4 per 125-mL container)
is now required.
Because our data have shown that 30-day storage stability of filtered
nutrient species is not improved by sulfuric acid amendment (Patton and
Gilroy, in press), this memo has no direct effect on field treatment
protocols or bottle types for filtered nutrient samples. However,
acidification of filtered nutrient samples is required by some U.S.
Environmental Protection Agency (USEPA) protocols. When filtered
nutrient samples are collected in compliance with USEPA protocols, it is
recommended that the WCA preservative (1 mL of 4.5 N H2SO4 per 125 mL of
sample) be added to FCA (filtered, chilled, acidified) samples. Use of
this preservative in all acidified nutrient samples will provide the
NWQL with a known and consistent analytical matrix, which in turn should
improve the analytical data quality.
DEFINITIONS
Ammonium. As discussed in Office of Water Quality Technical Memorandum
93.12, the long-established and prevailing convention of reporting the
sum of ammonium (NH4+) and solvated ammonia (NH3 {aq}) as "ammonia" is
misleading and confusing, because ammonium is the overwhelmingly
predominant species in most unpolluted natural water systems and in
Kjeldahl nitrogen digests. In an effort to achieve and promote
technical correctness, this memo uses ammonium to describe the analyte
reported as ammonia in the NWQL SPiN database.
Analyte. As used in this memo, analyte is the substance being
identified and measured in an analytical determination.
REFERENCES
Patton, C.J., and Gilroy, E.J., in press, U.S. Geological Survey
nutrient preservation experiment—Experimental design, statistical
analysis, and interpretation of analytical results: U.S. Geological
Survey Water-Resources Investigations Report 98-4118.
Patton, C.J., and Truitt, E.P., 1995, U.S. Geological Survey nutrient
preservation experiment—Nutrient concentration data for surface-,
ground-, and municipal-supply water samples: U.S. Geological Survey
Open-File Report 95-141, 140 p.
U.S. Geological Survey, 1994, New preservation techniques nutrient
samples: Office of Water Quality Technical Memorandum No. 94.16,
accessed September 30, 1998, at URL
http://water.usgs.gov/admin/memo/QW/qw94.16.
U.S. Geological Survey, 1998, Reporting level changes for volatile
organic compounds (Schedules 2020/2021), Inductively Coupled Plasma-
Atomic Emission Spectrometry (ICP-AES), Ammonia plus Organic Nitrogen
and Phosphorus (micro-Kjeldahl) in Water Methods at the National Water
Quality Laboratory: National Water Quality Laboratory Technical
Memorandum No. 98.07, accessed September 30, 1998, at URL
http://nwql.usgs.gov/Public/tech_memos/nwql.98-07.html.
Janice R. Ward
Acting Chief, Office of Water Quality
Distribution: All WRD Employees
Contact: Charles J. Patton, Methods Research and Development
Program 303/467-8084; email: cjpatton@usgs.gov
This memorandum does not supersede any other Office of Water Quality
Memorandum.
Key Words: Nutrients, Whole-Water Samples, RCA, RCC, WCA, Preservative