PROGRAM AND PLANS: New Custom Analysis Schedule (172) for Blanks
In Reply Refer To: January 3, 1994
Mail Stop 412
OFFICE OF WATER QUALITY TECHNICAL MEMORANDUM NO. 94.06
Subject: PROGRAM AND PLANS: New Custom Analysis Schedule (172) for
Blanks
PURPOSE OF THIS MEMORANDUM
A new custom analysis schedule -- Schedule 172 -- is now available at the
National Water Quality Laboratory (NWQL) to produce quality control (QC)
data to support the new protocol for low level inorganic analyses. This
memorandum describes (1) the types of blank samples covered by Schedule 172,
(2) analyses covered by the schedule, (3) cost and sample turnaround time,
(4) sample tracking, (5) reporting results, and (6) supplies.
SAMPLES COVERED
Schedule 172 was developed to provide QC data on appropriately preserved
deionized water field sampling and processing blanks and for blanks used to
monitor possible contamination in preservatives and other supplies. The
objective is to provide very low-level data so project personnel can identify
(and subsequently remove) contamination arising from equipment, supplies,
field methods, and field conditions. Samples can include (1) equipment or
supply blanks, (2) field blanks, and (3) samples from deionizing units in
Field Service Units. Blanks analyzed for major cations and trace metals must
be preserved with ultrapure nitric acid. Blanks for nutrients must be
preserved with mercuric chloride. Schedule 172 is not suitable for the
analysis of environmental water matrices. Therefore, you can not use this
schedule for the analysis of environmental samples.
ANALYSES COVERED
Schedule 172 has been developed specifically for analyzing sample blanks for
major cations, trace elements, and nutrients at low concentration levels.
Major cations will be determined by Inductively Coupled Plasma-Optical
Emission Spectrometry (ICP-OES). Results will be reported to the method
detection limits (MDLs). Therefore, the concentrations reported will be lower
than those from the current ICP-OES method.
Trace elements will be determined using Inductively Coupled Plasma-Mass
Spectrometry (ICP-MS). Results will be reported to the MDLs, which are lower
than those from the current ICP-MS method (see Methods of Analysis by the U.S.
Geological Survey National Water Quality Laboratory - Determination of Metals
in Water by Inductively Coupled Plasma-Mass Spectrometry, Lynda M. Faires,
U.S. Geological Survey, Open-File Report 92-634).
Nutrients will be determined by low-level automated-segmented flow (ASF), and
results will be given following the usual method reporting criteria (MDLs).
Schedule 172 analytes and the MDLs are tabulated in Table 1.
ANALYSIS COST AND SAMPLE TURNAROUND TIME
The cost of Schedule 172 will be $225 per sample.
The turnaround time will be 2 weeks from sample login at the NWQL to the time
at which the data are available for retrieval. Blank samples to be determined
under Schedule 172 will be analyzed on Thursday and/or Friday each week. This
will improve analysis efficiency, ensure quick sample turn-around times, and
improve sample tracking. With this analysis schedule in mind, you can better
coordinate sample shipment.
SAMPLE TRACKING
Field personnel must submit the Analytical Services Request (ASR) form with
the following statement in the comment field "Attn. Ed Zayhowski - FIELD
COLLECTION & PROCESSING BLANKS, LOW LEVEL ANALYSES". We recommend that
appropriate codes be used for storing the QC data in NWIS-I (see Branch of
Quality Assurance Memos 90.03 and 92.01). These include a sample medium code
(for example Q), sample type (2 for blanks), and the 99100 and 99101 codes to
identify the type and source of the blank water.
REPORTING OF RESULTS
The analytical results from Schedule 172 will be available through conventional
means (NWIS-I). The data will be assigned new method characters with specific
significant figures that in-turn will ensure the standard rounding routines
are not used. Results that are less than the MDLs will be reported as '<' the
MDL value. The data results from Schedule 172 may be stored in your local
NWIS-I database. However, the data must NOT be released to WATSTORE because
the methods are not approved. This means that the NWIS-I option to "FLAG
APPROVED SAMPLES" must be used to flag these samples with a "Z" (local-Use
Data) in the data base.
SUPPLIES*
All supplies can be obtained from the Ocala Quality Water Service Unit (QWSU).
These supplies and costs are:
Item Quantity Cost
________________________________________________________
Preservatives
Ultrex nitric acid in
borosilicate ampules for
major cations/trace elements box of 24 $125.00
Ultrex nitric acid in
Teflon vials for major
cations/trace elements each 20.00
Mercuric chloride ampules
for nutrients box of 24 42.00
Bottles
Acid rinsed, 250 mL, natural
(clear) polyethylene bottles
and caps for major cations/ box of 15 6.00
trace elements box of 225 85.00
125 mL, amber, polyethylene box of 100 16.00
bottles for nutrients box of 660 62.00
_________________________________________________________
* NO other preservatives or bottles can be substituted.
Initially, borosilicate glass ampules of Ultrex nitric acid will be available
for the low-level protocol. During a series of tests at the NWQL, the current
lot of these ampules has been found to contain measurable levels of aluminum,
barium, boron, calcium, chromium, magnesium, silica, and sodium. Similar
results were found for ampules of three other types of glass. Furthermore,
based on an industry survey, it appears likely that these contaminants will
always be present at some level whenever glass ampules are used to hold the
acid. To assist District personnel in the quantification of contaminants, all
acid preservatives for the low-level protocol will be shipped with a
certificate of analysis indicating the measured levels of each element in
selected ampules from each ordered lot. The certificate will assist in
interpretation of blank and environmental data, and should help reduce the
occurrence of false positives.
While the measured levels of contamination from the ampules are low, the
observed concentrations will cause some false positives in environmental data.
Therefore, Teflon vials of Ultrex nitric acid will be made available (probably
beginning in March) for projects that require or wish to use a contaminant-free
acid preservative. A certificate of analysis will also be shipped with the
vials. However, initial tests show that the concentration of each analyte is
below the MDL. The Teflon vials are expected to cost approximately $20.00 per
vial, with a $4.00 refundable deposit that will be reimbursed upon return of
the vial. A mechanism for returning vials will be developed by the Ocala QWSU.
The Office of Water Quality (OWQ) will work with the NWQL and the Ocala QWSU
to streamline the process for obtaining and returning the vials. We will also
seek ways to reduce the cost.
Please contact Kathy Fitzgerald, OWQ, concerning questions about whether to
use ampules or vials on individual projects.
REMINDERS
1. Schedule 172 is ONLY available for the analysis of deionized water blanks.
2. Results from Schedule 172 are NOT to be entered into the WATSTORE system.
David A. Rickert
Chief, Office of Water Quality
Attachment not included: Sample ASR Form
This memorandum does not supersede any previous Office of Water Quality
Technical Memorandum.
Key Words: Analytical schedule, blanks, contamination, trace elements
Distribution: A, B, S, FO, PO, AH
Table 1. Method Detection Limits for Schedule 172*
_________________________________
ICP-OES
Analyte MDL, mg/L
B 0.002
Ca 0.002
Fe 0.003
Mg 0.001
Na 0.025
SiO2 0.02
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_________________________________
ICP-MS
Analyte MDL, ug/L
Ag 0.2
Al 0.3
Ba 0.2
Be 0.2
Cd 0.3
Co 0.2
Cr 0.2
Cu 0.2
Mn 0.1
Mo 0.2
Ni 0.5
Pb 0.3
Sb 0.2
Sr 0.1
Tl 0.1
U 0.2
Zn 0.5
__________________________________
__________________________________
ASF
Analyte MDL, mg/L
Ammonia (N) 0.002
Nitrite (N) 0.001
Nitrite + Nitrate (N) 0.005
Phosphate (P) 0.001
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*The MDL is the concentration that can be reported at the 99% confidence
level. It is calculated from the measured analytical precision at an analyte
concentration 1 to 5 times the estimated instrument detection limit following
the procedure outlined in the Code of Federal Regulation 40 CFR 136 Appendix B,
p. 537-539.