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Labcert Bulletin
EPA-815-N-99-002a, April 1999
We're Back
In this issue you will find tables, tables, tables. The
first table lists the long awaited errata for the Fourth
Edition of the Lab Cert Manual. We discussed these last
year and have finalized them. Next are two tables with
information on providers who have requested NIST
accreditation to supply drinking water PEs for the
certification program. One table includes names,
addresses, etc., and the second table charts the
proficiency testing program designations for which they
have applied.
|
In This Issue
-
Lab Cert Web Page
-
4th Edition Lab Cert Manual Errata
-
Contact Information for Proficiency Test Providers that
Applied to NIST for Accreditation
-
Criteria Acceptance for Proficiency
|
If there are certification topics you would like to see discussed,
please call, write, fax or e-mail the editors.
Ed Glick 513-569-7939,
glick.ed@epa.gov
Carol Madding 513-569-7402, madding.caroline@epa.gov
26 W. Martin Luther King Dr.
Cincinnati, OH 45268
FAX: 513-569-7191
The New Millennia
With the approaching new era we too have taken the steps to propel
ourselves into the twenty first century (hopefully not screaming). We
wish to welcome you to our web page on laboratory certification at
www.epa.gov/safewater/standards.html. If you visit,
you'll find interesting things about drinking water regulations as
well as a page for lab certification. On our page is the "Manual for
the Certification of Laboratories Analyzing Drinking Water," the
errata sheets, past issues of the Labcert Bulletin and this issue.
Hope you enjoy your visit and please comment as you feel is needed.
Two other websights that you may find helpful are
www.epa.gov/ow/resources/wpeval.html, where the PT
provider applicants and areas for which they have applied are listed,
and
www.gpo.gov/su_docs/aces/aces140.html
,where
you can find the drinking water regulations.
4th Edition Lab Cert Manual Errata
Chapter IV Chemistry
|
Page
|
Section
|
Change
|
Reason
|
|
IV-2
|
4.3.1
|
Change "be free from interferences" to "contain less than two
times the MDL"
|
Clarification
|
|
IV-3
|
6.2
|
Change 4C to 4C +/- 2C
|
To make practical
|
|
IV-4
|
7.1.4
|
Change "verified each day they are used" to "verified at
least annually"
|
Previous statement was impractical.
|
|
IV-5
|
7.2.1
|
Change last sentence to read: "A laboratory should not be
certified for an analyte that it fails repeatedly. (See p
III-7 & 8)"
|
It is not the intention of this regulation to allow a
laboratory to be certified for an analyte that it fails
consistently.
|
|
IV-5
|
7.2.4
|
Insert after first sentence, "on a daily basis. Where the
determinative time is extensive such as for Methods
508/508.1, 515.1, 524.2, 525.2, etc. and the instrumentation
is very stable,"
|
Clarification
|
|
IV-5
|
7.2.4
|
Insert before the last sentence: "The concentration of the
standard should vary from day to day across the range of
analyte concentrations being measured." For some methods an
initial conditioning shot needs to be made to deactivate
active sites that may have developed overnight. The blank may
or may not be appropriate depending on the method.
|
It is important to know the curve is correct for all
concentrations being measured.
Clarification
|
|
IV-6
|
7.2.7
Second paragraph
|
change FRB to LFB
|
Consistency with preceding paragraph.
|
|
IV-6
|
7.2.8
|
Change second sentence to read: "It is recommended that an
IDC be performed by each analyst."
Add: "It is also recommended that an IDC be performed for
each instrument."
|
It is not necessary for an analyst to do numerous IDCs of the
same method on similar instruments.
|
|
IV-6
|
7.2.9
|
Add reference: "EPA SW 846 Test Methods for Evaluating Solid
Waste Physical/Chemical Methods, Third Edition" after the
mention of EPA Method 8081
|
Gives publication name
|
|
IV-7
|
7.2.12
|
Insert after the first sentence: "The LFBs should be analyzed
across the range of analyte concentrations being measured."
|
It is important to know the curve is correct for all
concentrations being measured.
|
|
IV-8
|
8.2
|
Insert after the second sentence: "Changes in ownership,
mergers or closures of laboratories do not eliminate these
requirements."
|
These procedures need to be followed during these
circumstances.
|
|
IV-25
|
Table IV-7 Nitrate/Nitrite
|
See Method 300, Section 8
|
What is in the table is in the regulation. However, these
preservation techniques are incorrect. The techniques listed
in EPA Method 300 are correct and will be in MUFRN II.
|
|
IV-25
|
Table IV-7 o-Phosphate
|
delete: "filter immediately"
|
Drinking water samples do not have to be filtered, but if
using method 300.0, it would be wise to filter the sample or
you might clog the instrument filter.
|
|
IV-47
|
Checklist
|
delete
"Excitation at 340nm" & "detection at >308" Replace
with: "Absorption at 257nm & 308nm
|
Diquat is absorbed at 308nm and paraquat is absorbed at 257nm
|
Chapter V. Critical Elements for Microbiology
|
Page
|
Section
|
Change
|
Reason
|
|
V-2
|
3.1.5
|
Change to read: "Buffers should be discarded upon the
expiration date."
|
Buffers are not discarded before the expiration date.
|
|
V-3
|
3.6.3
|
Delete "or ampule"
|
Ampule will explode
|
|
V-4
|
3.11.5
|
The lot number for membrane filters and the date received
should be recorded. Add: "Assure that membrane filters are
not brittle nor distorted." Insert as second sentence: "Have
available manufacturer's specification/certification sheet."
|
Explanation for recording date.
Sentence inserted requires documentation of quality
control of membranes.
|
|
V-4
|
3.11.6
|
Insert "Forceps"
"Forceps should be blunt, smooth tipped without corrugations
on the inner sides of tips."
|
Moved from previously proposed 3.18 insertion to "Membrane
Filter Equipment," more appropriate location.
|
|
V-5
|
3.14
|
Delete title "Culture tubes and Closures" and replace with
3.16 Glassware and Plasticware" Renumber 3.14.
|
Clarification and improved organization
|
|
V-5
|
3.14.1
|
Delete. Replace with 3.16.1 and 3.16.2, and renumber as
3.14.1 and 3.14.2
|
3.14.1 is repeated in 3.16.1. 3.14 and 3.16 belong under
"Glassware and Plasticware"
|
|
V-5
|
3.14.2
|
Change to 3.14.3
|
|
|
V-5
|
3.14.3
|
Change to 3.14.4
|
|
|
V-5
|
3.17
|
Change to 3.16
|
|
|
V-7
|
4.3.2
|
Change "Ratio of growth rate 0.8:3.0." to "Ratio of growth
rate 0.8 to 3.0."
|
Clarification
|
|
V-7
|
4.3.2
|
Footnote 3. Change to read: "See Standard Methods, Section
9020B. This bacteriological quality test is not needed for
laboratories that meet the criteria for Types I and II
reagent water, as defined in Standard Methods, Section 1080."
|
Clarification of statement. Delete reference to ASTM Type I
and II reagent waters. Insert Type II waters and reference to
Standard Methods (not ASTM) types.
|
|
V-9
|
5.2.5
|
Change 3rd sentence to read: "If no sheen colonies
are observed, verify up to five red questionable sheen or
non-sheen atypical colonies per sample."
|
Clarification
|
|
V-9
|
5.2.5
|
Change 1st sentence to read, "All sheen colonies
up to a maximum of five must be verified..."
|
Clarification
|
|
V-9
|
5.3.2.2
|
Insert at start of second sentence: "Optionally, ... '
|
Clarification
|
|
V-10
|
5.3.5
|
Insert at end of sentence "... and a fecal coliform/ E.
coli test must be conducted."
|
Consistent with 5.4.4
|
|
V-12
|
5.6.6
|
Change third sentence to read: "If the medium changes from
yellow to a magenta color, the sample must be reported as
total coliform positive"
|
Correction in interpretation of test result
|
|
V-13
|
5.6.8
|
Line 6, change to read "...ensure that the specified
incubation period at that temperature is followed (see 5.6.5
and 5.6.6)." Add at end: "Alternatively, pre-warm the sample.
Avoid overcrowding the incubator."
|
Clarification
|
|
V-13
|
5.7.2.5
|
Change first sentence to read: "In accordance with paragraph
5.1.7.4... "
|
Correction of cross reference
|
|
V-14
|
5.9.1
|
Change reference in first sentence to: "141.74(a)(1)"
|
Correction of reference
|
|
V-15
|
5.9.4
|
Insert in second sentence after (44-46C) "...plate count
(tryptone glucose yeast) agar..."
|
Clarification
|
|
V-15
|
5.9.7
|
Change "darkfield" to "dark field"
|
Grammar
|
|
V-16
|
6.3
|
Delete "Source water samples must be held at <10C (see
Standard Methods, Section 9060B).
|
Not in regulations
|
|
V-18
|
8.3.5
|
After parenthesis, change to read "a negative result must be
tagged as an invalid sample."
|
Clarification
|
|
Checklist
|
|
V-21
|
3.1
|
Insert: QC Commercial buffer solutions dated upon receipt,
and when opened. Buffers discarded upon expiration date.
|
Item inadvertently left out of checklist. Consistent with
3.1.5.
|
|
V-23
|
4th block
|
delete "or ampule"
|
Consistent with text
|
|
V-24
|
3.11
|
Change to be consistent with 3.11.5 and 3.11.6 in text
|
Consistent with text
|
|
V-24
|
3.14
|
Change to respond with chapter changes, deleting 3.16 and
changing 3.17 to 3.16.
|
Consistent with text
|
|
V-27
|
4.3
|
Change "0.8:3.0" to "0.8 to 3.0"
|
Consistent with text
|
|
V-30
|
7th block
|
Change to be consistent with 5.2.5
|
Consistent with text
|
|
V-31
|
5.3
|
Insert second sentence after item beginning "Refrigerated
sterile MTF ..." to read: "Media discarded if evaporation
exceeds 10% of original volume."
|
Consistent with 5.3.2.4
|
|
V-31
|
10th block
|
add "and a fecal coliform/E. Coli test conducted"
|
Consistent with 5.3.5
|
|
V-39
|
6.3
|
Delete: "(... required for source water)
|
Not in regulations
|
|
V-41
|
2nd block
|
after parenthesis change to read "negative sample tagged as
an invalid sample
|
Consistent with text at 8.3.5
|
|
Microbiology Laboratory Analysis Review Checklist
|
|
H-21
|
pH meter
|
Change to: "Commercial buffer solutions dated upon receipt
and when opened. Buffers discarded upon expiration date."
|
Consistent with text at 3.1.5
|
|
H-23
|
|
Delete statement about confirmation of E.coli in EC
Mug
|
Consistency
|
Chapter VI Radiologicals
|
Page
|
Section
|
Change
|
Reason
|
|
VI-2
|
3.1.2
|
Add "natural uranium" to list of analytes
|
You can do natural uranium using this system, but other
methods are better
|
|
VI-6
|
8.4.6
|
Add "sample volume"
|
You need to know the volume to do DL calculations
|
|
H-6
|
2.4
|
Add liquid scintillation counters and alpha spectrometry
systems.
|
Now allowed by the regulations
|
|
H-25
|
Checklist
|
Add "radioactive materials license"
|
Need to check that the lab has one
|
|
H-28
|
checklist
line 7
|
Delete "field and"
|
Field blank analysis is not part of the instrument
performance check.
|
|
H-28
|
checklist
line 12
|
Add "system" after detector
|
It is the whole system that must meet DL requirements
|
Contact Information for Proficiency Test Providers Who Applied
To NIST for Accredidation
By the January 1999 Deadline
|
Entity
|
Address
|
Key Contact
|
Phone Number/Fax Number
|
EMAIL
|
|
Absolute Standards, Inc.
|
PO Box 5585
Hamden, CT 06518
|
Stephen J. Arpie
|
1-800-368-1131
1-800-410-2577 (fax)
|
AbsoluteStandards.com
|
|
AccuStandard
|
125 Market Street
New Haven, CT 06513
|
John Yamusas
|
1-203-786-5290 (ext.101)
1-203-786-5287 (fax)
|
jy@accustandard.com
|
|
Analytical Standards, Inc.
|
6331 Emerson Avenue
Parkersburg, WV 26101
|
Frederick Anderson
|
1-304-422-4274 or
1-800-Audit44
1-304-422-4761 (fax)
|
asi@marietta.edu
|
|
APG
|
2730 Washington Blvd.
Belpre, OH 45714
|
Tom Coyner
|
1-614-423-4200 or
1-800-272-4442
740-423-5588 (fax)
|
APG@citynet.net
|
|
CHRISOPE Technologies, A Division of Remel
|
LabProficiency
3941 Ryan St.
Lake Charles, LA 70605
|
Jody D. Moss
|
1-800-256-4376 (ex 236)
1-318-479-1006 (fax)
|
JLDMoss@aol.com
|
|
Environmental Resource Associates
|
5540 Marshall St.
Arvada, CO. 80002
|
Chuck Wibby
|
1-800-372-0122
1-303-421-0159 (fax)
|
qcstds@aol.com
|
|
Microcheck, Inc.
|
PO Box 456
Northfield, VT 05663
|
Carrie Pontbriand
|
1-802-485-6600 @ext. 26
1-802-485-6100 (fax)
|
microcheck@microcheck.com
|
|
New York State
|
Environmental Laboratory Approval Program
NYSDoH, Wadsworth Center
P.O. Box 509
Albany, NY 12201
|
Matthew Caruso
|
1-518-485-5570
1-518-485-5568 (fax)
|
caruso@wadsworth.org
|
|
Protocol Analytical Supplies
|
472 Lincoln Blvd
Middlesex, NJ 08846
|
William H. Hahn
|
1-732-627-0500
1-732-627-0979 (fax)
|
bhahn@prostds.com
|
|
R.T. Corporation/NSI Environmental Solutions
|
P.O. Box 1346
Laramie, WY 82073
|
Bob Rucinski
|
1-307-742-5452 or
1-800-576-5690
1-307-745-7936 FAX
|
RT-Corp@RT-Corp.com
|
|
SPEX CERTIPREP
|
203 Norcross Ave.
Metuchen, N.J. 08840
|
Vanaja Sivakumar
|
1-732-549-7144 (ex.418)
1-732-494-1747 FAX
|
VSivakumar@spexcsp.com
|
|
ULTRA Scientfic
|
250 Smith St.
N.Kingstown, RI 02852
|
Edward Martz
|
1-401-294-9400
1-401-295-2330 FAX
|
emartz@ultrasci.com
|
All 12 of these applicants voluntarily submitted their name to EPA
and understand that their names will be released to the public upon
request as well as posted on the EPA, Office of Water Web page.
Applying for accreditation does not imply or ensure that an
organization will become NVLAP accredited. A list of those
organizations that do receive NVLAP accreditation to be PT study
providers will be posted on the NVLAB Web page in June or July 1999.
|
Water Supply (WS) Proficiency Testing Program
Designations
Included in Designated Organization's NIST NVLAP
PPT Application (January 1999)
|
|
NVLAP Code
|
USEPA Designation
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
12
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
20/U01
|
WSCHEM Trace Metals
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U02
|
WSCHEM Sodium
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U03
|
WSCHEM Nitrate, Nitrite, Fluoride, and Orthophosphate
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U04
|
WSCHEM Bromate, Bromide, Chlorate, and Chlorite
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U05
|
WSCHEM Sulfate
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U06
|
WSCHEM Residual Free Chlorine
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U07
|
WSCHEM Cyanide
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U08
|
WSCHEM Asbestos
|
|
X
|
X
|
|
|
|
|
X
|
|
X
|
|
|
|
20/U09
|
WSCHEM Volatile Organic Compounds (VOCs) Group I
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
X
|
X
|
|
20/U10
|
WSCHEM Volatile Organic Compounds (VOCs) Group II
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
X
|
X
|
|
20/U11
|
WSCHEM Insecticides (Pesticides)
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
|
X
|
|
20/U12
|
WSCHEM Herbicides
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
|
X
|
|
20/U13
|
WSCHEM Carbamate Pesticides
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
|
X
|
|
20/U14
|
WSCHEM Polycyclic Aromatic Hydrocarbons
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
X
|
X
|
|
20/U15
|
WSCHEM Polychlorinated Biphenyls (PCBs/Aroclors)
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
|
X
|
|
20/U16
|
WSCHEM Toxaphene and Chlordane
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
|
X
|
|
20/U17
|
WSCHEM Dioxin (2,3,7,8-TCDD)
|
X
|
X
|
X
|
X
|
|
|
|
X
|
X
|
X
|
|
X
|
|
20/U18
|
WSCHEM Adipate and Phthalate Esters
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
X
|
X
|
|
20/U19
|
WSCHEM Haloacetic Acids
|
X
|
X
|
X
|
X
|
|
X
|
|
|
X
|
X
|
|
X
|
|
20/U20
|
WSCHEM Chloral Hydrate
|
X
|
X
|
X
|
X
|
|
X
|
|
|
|
X
|
|
X
|
|
20/U21
|
WSCHEM Total Organic Carbon (TOC)
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U22
|
WSCHEM Alkalinity (as CaCO3)
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U23
|
WSCHEM Calcium Hardness (as CaCO3)
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U24
|
WSCHEM Total Filterable Residue
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U25
|
WSCHEM pH
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U26
|
WSCHEM Turbidity
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U27
|
WSMICRO Coliform (Presence/Absence)
|
X
|
|
X
|
|
X
|
X
|
X
|
X
|
|
X
|
|
|
|
Water Pollution (WP) Proficiency Testing Program
Designations
Included in Designated Organization's NIST NVLAP
PPT Application (January 1999)
|
|
NVLAP Code
|
USEPA Designation
|
1
|
2
|
3
|
4
|
5
|
6
|
7
|
8
|
9
|
10
|
11
|
12
|
|
20/U28
|
WPCHEM Trace Metals
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U29
|
WPCHEM Minerals : Calcium, Magnesium, Potassium, and Sodium
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U30
|
WPCHEM Minerals: Chloride, Fluoride, and Sulfate
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U31
|
WPCHEM/DMRQACHEM Nutrients
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U32
|
WPCHEM/DMRQACHEM Total Residual Chlorine
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U33
|
WPCHEM/DMRQACHEM Cyanide
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U34
|
WPCHEM Volatile Halocarbon Compounds
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
X
|
X
|
|
20/U35
|
WPCHEM Volatile Aromatic Compounds
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
X
|
X
|
|
20/U36
|
WPCHEM Chlorinated Pesticides
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
|
X
|
|
20/U37
|
WPCHEM Chlordane
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
|
X
|
|
20/U38
|
WPCHEM Polychlorinated Biphenyls (PCBs as Aroclors) in Water
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
|
X
|
|
20/U39
|
WPCHEM Polychlorinated Biphenyls (PCBs as Aroclors) in Oil
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
X
|
X
|
|
X
|
|
20/U40
|
WPCHEM Total Phenolics
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U41
|
WPCHEM Demands
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U42
|
WPCHEM Total Alkalinity (as CaCO3)
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U43
|
WPCHEM Total Hardness (as CaCO3)
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U44
|
WPCHEM Total Dissolved Solids
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U45
|
WPCHEM/DMRQACHEM Non-Filterable Residue
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U46
|
WPCHEM/DMRQACHEM Oil and Grease
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U47
|
WPCHEM/DMRQACHEM pH
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
|
20/U48
|
WPCHEM Specific Conductance
|
X
|
X
|
X
|
X
|
|
X
|
|
X
|
|
X
|
X
|
X
|
1. = Absolute Standards, Inc.
2. = Accustandard
3. = Analytical Standards, Inc.
4. = Analytical Products Group, Inc. (APG)
5. = CHRISTOPE Technologies, A Division of Remel
6. = Environmental Resource Associates (ERA)
7. = Microscheck, Inc.
8. = New York State
9. = Protocol analytical supplies
10. = R.T. Corporation/NSI Environmental Solutions
11. = SPEX CERTIPREP
12. = ULTRA Scientific
Acceptance Criteria for Proficiency Testing (PT) Samples
We have recently been apprised of the need for clarification
regarding the acceptance criteria to be used on PT samples.
Depending on the contaminant, your PT provider must use the fixed
limits (stated as ± percentages) as written in the Code of
Federal Regulations or the statistical algorithms (stated as
regression equations) that NERL-Ci has generated. These algorithms are
presented in the document entitled "National Standards for Water
Proficiency Testing Studies - Criteria Document."
The NERL statistical limits were derived using past data from
performance evaluation (PE)
studies and, provide more accurate criteria than could be generated
by smaller studies of similiar design to the NERL-Ci PEs. It is the
responsibility of your PT provider to verify that the limits used are
appropriate for their samples.
Any of the twelve providers listed on page 5 already have these
statistical algorithms. Other providers may obtain a copy of the
Criteria Document by contacting Mr. Raymond Wesselman at the following
address:
U.S. EPA
National Exposure Research Laboratory
Ecological Exposure Research Division
Cincinnati, Ohio 45268
or by calling 513-569-7325.
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