United States
Environmental Protection
Agency
Office of Ground Water
and Drinking Water
Technical
Support Division
EPA-814-K-93-001
September 1993
EPA Labcert Bulletin
Welcome Back to the
Labcert Bulletin
INo, you weren't dropped from the list.
Changing government regulations have
interfered with our efforts to publish this
bulletin in a more timely manner. In this issue
we discuss items of current interest to the
certification community. If you have ideas
about other areas of certification you would
like to see covered, please call or write to the
editors. We have included a FAX sheet to
update our mailing list or to add or update
your name to our mailing list. Feel free to
use it as needed or call one of the editors.
Ed Click 513 569-7939
Mary Ann Feige 513 569-7944
Carol Madding 513 569-7402
26 W. Martin Luther King Dr.
Cincinnati, OH 45268
In This Issue-
Analytical Methods
Proposed Rule 1
Method Recommendations ... 2
Mercuric Chloride 2
Nitrite .2
Simple Quality Control for the
Membrane Filter Technique ... 3
Compositing Guidance .4
A Better Way to Use
Diazomethane 5
Fax Sheet . . 5
Improper Interpretation 8
Analytical Methods--
Proposed Rule and Method
Recommendations
A roposed Rule— EPA is preparing an
Analytical Methods Federal Register Notice,
which will be proposed in 1993. EPA will
propose to update 89 chemical or
microbiological methods to versions that are
in the most current manuals published by
ASTM, EPA and Standard Methods.
The rule will propose to expand the
analytical scope of five methods. Ten new
methods will be proposed, and several older
methods will be proposed for gradual
withdrawal. The latter include packed-column
GC methods, and inorganic chemical methods
which have not been updated since 1979.
Please Note — In an article about using SPE
disks, written by Craig Markell in the April
1993 issue of Varian's SPE Environmental
Newsletter, it was stated, "If you are using
525.1 for compliance purposes and are
concerned about deviating from the recipe, we
have been told that alternate elution solvents
ARE ACCEPTABLE AS LONG AS QA/QC
REQUIREMENTS ARE MET." This is
incorrect. EPA wishes to grant flexibility to
analysts but this flexibility extends only to
changes which are not chemical in nature
(i.e., chromatography columns/programs,
detectors, etc.) as long as QA/QC
requirements can be met. EPA does not
allow an analyst to substitute alternate elution
solvents since this is a change in the chemistry
of the method.
An updated method, 525.2, will be
proposed in the above mentioned Analytical
Labcert Bulletin is printed on recycled paper.
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Methods notice. The method contains data
which demonstrates that the sequence of ethyl
acetate and methylene chloride to elute SPE
disks is critical to obtain acceptable results.
Additionally, EPA does not recommend the
use of acetone as an extraction solvent in any
drinking water method.
Recommended Methods— Readers have
asked for guidance on using appropriate
methods to measure analyles for which there
are no MCLs or monitoring requirements.
Although EPA only promulgates methods for
contaminants regulated under tbe Safe
Drinking Water Act, the Agency encourages
use of these methods for other analytes of
interest, provided they are specifically listed in
the analytical scope of the method.
New Trihalomethane Methods- Or August
3, 1993 (58 FR 41344) EPA promulgated two
additional methods for the analysis of total
trihalomethanes. The rule, which was
effective September 2, 1993, promulgated
EPA Methods 502.2 and 524.2 for THMs.
EPA believes the following guidance will help
laboratories correctly preserve and analyze
samples for compliance monitoring i nder 40
CFR 141.30.
Laboratories must carefully follow the
dechlorination procedure described in each
method, especially the order in which reagents
are added to the sample. The methods allow
analysts to choose among four reagents
(ammonium chloride, ascorbic acid, sodium
sulfite or sodium thiosulfate) to dechlorinate
a water sample. However, EPA strongly
recommends sodium thiosulfate, since EPA
has the most performance data \\ith this
chemical. The exception is that ascorbic acid
should be used when SO2 may be an
interference with a mass spectrometer. All
dechlorinated VOC samples must be ; cidified
immediately, as directed in the method.
Comments— If you have any questions or
operating experiences that you wish to
communicate, please write to editors of the
Labcert bulletin.
Mercuric Chloride
1 he use of mercuric chloride as a preserva-
tive has been required in various U.S. EPA
methods. Concerns relating to the
environmental hazards and the costs
associated with the disposal of this biocide
have prompted the Office of Ground Water
and Drinking Water (OGWDW) to issue new
guidance on the subject.
A memo from Mike Conlon, Director,
Drinking Water Standards Division, dated
March 25, 1993, removes the requirement that
mercuric chloride be used as a preservative
for compliance monitoring samples unless
there is evidence of biological degradation in
any specific sample or sample set.
This should provide relief to the many
laboratories that were having difficulties
dealing with mercuric chloride. However, it
may be prudent to analyze at least one
sample set with and without mercuric chloride
to prove that no biological degradation occurs
in the matrix.
For further information please call Baldev
Bathija at 202-260-3040.
Nitrite
W e have received numerous calls regarding
the requirement to analyze for nitrite,
glyphosate, and cyanide in water that has
been chlorinated. The presence of chlorine
oxidizes nitrite and glyphosate and converts
cyanide to cyanogen chloride. For glyphosate
and cyanide, states can negotiate susceptibility
waivers with their regions for systems that can
demonstrate a chlorine residual. Nitrite is an
acute contaminant, so no waivers are allowed.
However, if the nitrite or nitrite plus nitrate
concentration in the initial analysis is less
than 1/2 MCL of nitrite (0.5 mg/L),
continued monitoring frequency is established
by the state.
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Simple Quality Control for
the Membrane Filter
Technique
In microbiological analysis of water, quality
control (QC) procedures recommended for
the membrane filter (MF) technique
commonly involve the use of laboratory
maintained or commercially available freeze
dried bacteriological cultures or bacterial
disks. These pure cultures must be
reconstituted and diluted until a volume
containing 20 to 80 organisms is obtained.
This volume is then filtered arid the
membranes, media, and procedure are
evaluated. Both positive and negative
bacterial controls are analyzed in duplicate
assays. This procedure is time consuming and
labor intensive, particularly when performed
by a laboratory that analyzes large numbers of
samples. Also, since most water laboratories
do not routinely need to make dilutions,
errors can occur.
A direct inoculation (spot test) is suggested
as a simple, rapid QC procedure of media,
membranes, and incubation conditions. The
test involves little additional effort other than
preparing a few additional plates for each
batch of media and using appropriate pure
cultures. A positive and negative control can
be easily tested with each membrane filtration
series. For example, in the total coliform
technique with M-Endo media, the spot test
procedure involves aseptically placing a sterile
MF on the selected medium. The petn plate,
containing the MF on the medium, is divided
into two areas using a marking pencil.
Alternatively, two individual MF's and two
medium-containing plates may be used, one
for each control organism. Escherichia coji,
(positive) and Pseudomonas alcaligenes,
(negative) cultures could be used as controls.
Using a sterile loop, needle, or applicator
stick, a portion of the positive control culture
is spotted on the MF five or six times in
different places. Likewise, a negative culture
can be placed on the other half of the MF or
another plate. These QC plates are incubated
under the same time and temperature
conditions as the standard test procedure.
The sample analysis plates and the QC
plates are read at the same time and
recorded. The MF area on the QC plate
inoculated with the positive culture produces
growth in the spotted areas with the
characteristic reaction for that organism on
that specific medium. In the total coliform
test, for example, the positive E.coli culture
produces red colonies with metallic green
sheen. The negative control shows no growth
or, if growth occurs on the medium, the
organism produces uncharacteristic target
colonies.
The spot test procedure is ideal for the QC
of a two step, two media technique. After
checking the QC on the first medium, the
spot test MF is lifted from the first medium
and placed on the second following the two
step test procedure for the samples. The QC
controls are then tested along with the
samples for the final reading. For example, in
the two step procedure for total coliforms and
E. coli, after the spot tested MF is checked
for sheen, the test MF is lifted off the M-
Endo medium and placed on Nutrient Agar
with MUG (NA-MUG), incubated for four
additional hours, and then inspected for
fluorescence on the NA-MUG, typical of E..
coli. This method not only provides QC of
the media and MF's, but also of the
incubation times and temperature.
This spot test QC procedure was found to
be most helpful in a recent water quality MF
study in which samples were analyzed for
Clostridium. A good QC procedure was
critical because the medium was difficult to
prepare from basic ingredients, required
anaerobic incubation conditions, and the
isolation of few Clostridium were expected.
By using a spot test QC plate with a pure
culture of Clostridium perfringens (positive
control) and a negative control in each
anaerobic jar incubated, it was assured that
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Clostridium. if present, would grow on the
medium under the test conditions.
The spot test QC procedure can he used
directly on an agar medium surface if a two
step media evaluation is not needed md the
MF need not be tested. In this case the spot
inoculum is placed directly on the agar
surface, and after incubation, typical color
characteristic growth colonies can be observed
on the agar as the positive control, and no
growth or uncharacteristic growth colonies are
seen on the negative control. However, it is
essential that the agar surface is dry, as any
moisture on the agar might cause the spot
inoculation to spread over the entire surface
and the positive and negative control cultures
could not be separated from each other.
For further information please call Lois
Shadix at 513-569-7864.
Compositing Guidance
most contaminants, states may reduce
the total number of samples which must be
analyzed by allowing the use of compositing.
(THMs and fluoride samples may not be
composited for compliance monitoring
purposes.) Composite samples from a
maximum of five sampling points are allowed,
provided that the laboratory can, using the
prescribed method, achieve a detection limit
for the contaminant that is less than one-fifth
of the maximum contaminant level (MCL).
The samples must be composited in the
laboratory and the composite analyzed within
appropriate holding times. If any
contaminant is detected, a follow-up sample
must be analyzed within 14 days fron each
sampling point included in the composite.
The detect triggers for each class of
contaminant are listed below. If available,
duplicates of the original sample taken from
each sampling point used in the composite
(holding times must not be exceeded), may be
used for the analyses instead of resampling.
The duplicates must be analyzed and the
results reported to the state within 14 days of
collection.
If the population served by the system is
more than 3,300 persons, then compositing
may only be permitted by the state at
sampling points within a single system. In
systems serving less than or equal to 3,300
persons, the state may permit compositing
among different systems.
For economic reasons, if you anticipate the
presence of a contaminant near the detect
limit, it may be prudent to forgo compositing,
or at least collect duplicate samples for
possible individual analyses. The economics
of compositing in these cases must be
carefully weighed.
ORGANICS
VOLATILE ORGANICS
Currently, there are 18 regulated VOCs. A
VOC is considered detected if the
concentration in the composite sample is
equal to or greater than 0.0005 mg/L.
When compositing VOC samples, special
precautions must be taken to minimize
volatilization losses. Composite cool (4 C)
samples only and always maintain zero
headspace in the syringe. If purging a 5 mL
sample, pour 5 mL (or equal larger volumes,
depending on the number of samples being
composited) of each sample to a 25 mL glass
syringe, mix well, and draw out a 5 mL
aliquot for analysis. Because it may be
difficult to pour exactly 5 mL of each sample
into one syringe and measure perfectly, you
may choose to pour one mL of each sample
into each of five syringes and introduce each
of these directly into the sparger. If purging
25 mL, introduce 5 mL (or equal larger
volumes) of each sample into a syringe by
pouring the sample. As above, you may
choose to pour 5 mL of each sample into five
syringes and add these directly to the sparger.
To avoid losses, VOC samples should never
be drawn up into the syringe, they should' be
poured.
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OTHER ORGANICS
Organics other than volatiles are considered
detected if the concentrations are greater than
or equal to the regulatory detection limits in
Table 1.
When using liquid-liquid extraction to
extract these contaminants, shake the sample,
and using one graduated cylinder, transfer
equal volumes of each sample (to make one
liter), into a separatory funnel. Because the
contaminants may adhere to the sides of the
(Continued on Page 7)
A Better Way To Use
Diazomethane
Uiazomethane, used to esterify analytes in
methods 515.1 and 552, is a hazardous
material and must be handled with care.
Method 515.1 offers two means to prepare
and use diazomethane when esterifying
samples. Method 552 allows only one.
In the first technique, the gaseous
technique, the extract is esterified by directly
passing the nitrogen gas, laden with
diazomethane, directly into the sample. This
technique produces less consistent results than
the one described below.
The other more uniform and safer
technique is the generation of a small volume
of diazomethane into a vial of Methyl tert-
Butyl Ether (MtBE). The analyst suspends a
small (5 mL) screw capped vial in a beaker of
water so that the screw cap is above the
surface (we use rubber bands for this). Fill
the vial with MtBE and place this in a freezer
until the water in the beaker is frozen.
Use only the amount of reagents needed
and generate diazomethane directly into the
MtBE in the vial. This should be prepared
on the day needed. Return the vial in the
beaker to the freezer until the time of
esterification. (The solution may be kept in
the freezer and used as much as 48 hours
later, but this is not a recommended pi act ice.)
When ready to esterify the samples, remove
the vial from the freezer and place in a hood.
Add 250 to 500 pL of the cold solution to
each sample and ensure that a persistent pale
yellow color remains. (If this does not occur,
add successive 50 /zL aliquots until the yellow
color remains.) The yellow indicates an
excess of diazomethane is available for
esterification of the analytes. Equal and
consistent esterification between samples and
standards will be achieved in this manner.
The diazomethane must remain in contact
with the sample for exactly 20 minutes in
method 552 and 30 minutes in method 515.1.
When the esterification is completed for all
samples, the excess diazomethane is reduced
in the samples and in the vial with the
addition of 0.2 gin of silica gel per sample.
Add silica gel to the vial until the yellow color
disappears. Allow the nitrogen gas to evolve
from the sample before removing portions for
injection into the GC.
FAX IT TO US
Please add/change (circle one) my name to
the Labcert Bulletin mailing list.
Company
Address
Telephone
Fax#
Fax to: Grace Zile
USEPA - TSD
26 W. M.L.King Drive
Cincinnati, OH 45268
FAX 513-569-7191
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TABLE 1 MDLs and MCLs for Other Organics (in mg/L)
Contaminant
Alachlor
Atrazine
Benzo[a]pyrene
Carbofuran
Chlordane
Dalapon
Dibromochloropropane (DBCP)
Di(2-ethylhexyl)adipate
Di(2-ethy Ihexyl )pthalate
Dinoseb
Diquat
2,4-D
Endothall
Endrin
Ethylene dibromide (EDB)
Glyphosatc
Heptachlor
Heptachlor epoxide
Hexachlorobenzene
Hexachlorocyclopentadiene
Lindanc
Methoxyclilor
Oxamyl
Pic lo ram
PCBs (as dccachlorobiphenyl)
Pentachloroplicnol
Simazine
Toxaphcnc2
Dioxin
2,4,5-TP (Silvcx)
Regulation
Detect
.0002
.0001
.00002
.0004
.000;i
.001
.00002
.0006
.0006
.0002
.0004
.000!
.009
.00001
.00001
.006
.00004
.00002
.0001
.000;
.00002
.000,
.002
.000
.000.
.00004
.00007
.001
.OOOi '00005
.000.:
Lowest
MDL1
.00002
.00013
.00004
.0015
.00014
.0013
.00001
.0005
.00008
.0002
.00044
.0002
.011
.000015
.00001
.006
.00001
.000015
.000002
.0001
.000003
.00005
.002
.00014
.0001
.00008
.00008
.001
.00008
MCL
.002
.003
.0002
.04
.002
.2
.0002
.4
.006
.007
.02
.07
.1
.002
.00005
.7
.0004
.0002
.001
.05
.0002
.04
"i
.5
.0005
.001
.004
.003
.00000003
.05
MCL/5
.0004
.0006
.00004
.008
.0004
.04
.00004
.08
.0012
.0014
.004
.014
.02
.0004
.00001
.14
.00008
.00004
.0002
.01
.00004
.008
.04
.1
.0001
.0002
.0008
.0006
.000000006
.01
'This is the lowest published MDL of any regulated method. 1 abonttories may composite
which is at least l/5th of the MCL can be reached.
•laboratories may composite no more than 3 samples for toxaphene because lowest MDL
five samples only if a detection limit
is 1/3 of MCL.
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Compositing Guidance
(Continued from page 5)
glass sample container and cylinder, it is necessary to rinse each sample bottle and the
cylinder with the extracting solvent and add this to the aliquot being extracted. So, discard
the remaining sample, rinse each empty bottle with a portion of the extraction solvent, rinse
the graduate, and put all solvent portions into the separatory funnel. Rinsing each sample
container in this manner may result in a high bias, but it is necessary in order to assure
recovery of all of the contaminants. An alternative procedure would be to collect a smaller
size sample (260 mL for instance) when you know your are going to composite. Extract and
continue according to the EPA Method directions.
For liquid-solid extraction, combine equal volumes of each sample (for a total volume of
1 L) in the 2-L separatory funnel as described in the method. Extract the sample through
the cartridge or disk in the in.inner described in the method. The method requires the
sample bottle to be rinsed with solvent in order to collect contaminants that may adhere to
the glass. When compositing, it is necessary to rinse each sample bottle with elution solvent.
Since a small solvent volume is used for extraction, rinse each sample container sequentially
with the entire solvent volume.
INORGANICS
An inorganic contaminant is considered detected if the concentration of any contaminant
in the composite sample is greater than or equal to one-fifth the MCL. (This is assuming
five samples have been composited.) If an inorganic contaminant is detected in the
composite, the follow up sample only has to be analyzed for the contaminants that were
detected in the composite sample. Except for Method 204.2 for selenium and Method 279.2
for thallium, all method MDLs are low enough to reach 1/5 of the MCL. MCLs, in mg/L,
are:
ANALYTE-
Antimony
Asbestos
Barium
Beryllium
Cadmium
Chromium
Copper
Cyanide
MCL
006
7 MFL
2
,004
005
.1
1.3*
2
/5 MCL
.0012
< .4 MFL
.4
.0012
.001
.02
.64
.04
ANALYTE
Lead
M e re u ry
Nickel
Nitrate
Nitrite
Selenium
Thallium
MCL
.015*
.002
.1
10 (as N)
1 .0 (as N)
.05
.002
1/5 MCL
.003
.0004
.02
2
2
.01
.0004
* Action Level
SPECIAL ASBESTOS GUIDANCE
States may allow systems to Composite up to five samples. Sample compositing must be
done in the laboratory on samples which are less than 48 hours old or have been individually
ozone/UV treated in their original sample containers. Samples should be sonicated and
equal amounts withdrawn to make up the composite. It may also be prudent to filter an
aliquot of each individual sample for analysis in case the composite sample concentration
exceeds 1/5 of the MCL (1.4 MFL > lO^m long). If this is not done, the original samples
can only be filtered if they are less than 48 hours old and have been resonicated. If the
sample is more than 48 hours old it must be treated with ozone/UV and resonicated.
•tfll.S. GOVERNMENT PRINTING OFFICE: 1993 - 750 002/X0300
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Improper Interpretation
Ivecently (2/19/93), a Regional certification official sent a copy of a SUPELCO
flyer to us concerning purge and trap analyses. On page four of that flyer it
states,"Although EPA methods specify purge traps, provisions for best available
technology (BAT) allow the selection of traps (and analytical columns) that offer
improved performance." This statement contains some truth but also a lot of
misunderstanding.
BAT stands for Best Available Technology and refers to treatment technologies
used by water treatment plants to remove a regulated contaminant from the drinking
water supplied to its customers. BAT does not, in any rule that the Agency has
promulgated, refer to drinking water analytical methodology.
All EPA purge and trap methods are very specific in the detail and description of
the traps that MUST be used when determining regulated contaminants in drinking
water. This section of the method is part of the extraction of volatile contaminants
from drinking water and as such is considered part of the chemistry of the method.
This is also true for the purge volume and purge time. In order to use a method for
compliance monitoring of drinking waters, the analyst must not change the chemistry of
the method.
Changes, other than chemical changes, are allowed as long as the QA/QC
requirements are met to the satisfaction of the certifying authority. This would, as
the flyer properly states, allow the use of a chromatographic column (for separation
and identification) other than that specified in the method if all QA/QC conditions
could still be met. Other detectors or chromatgraphic conditions can also be varied
as long as all QA/QC conditions can be met.
We hope this clarifies the situation.
The Editors
United States Bulk Rate
Environmental Protection OGWDW-TSD Postage^jFees Paid
Agency Cincinnati, OH 45268 Postage no. G-35
Official Business, Penalty for Private Use
$300
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