- Basic acute fish toxicity screen (pass / fail) & definitive
(numerical concentration for 50% mortality, LC50) testing are now
performed by MAI. Fathead minnows are used for hazardous classification. Effluent
testing is conducted on Fathead minnows & Rainbow Trout in fresh water
& Sheepshead minnows in salt
water. Static renewal & non-renewal testing of effluent &
receiving waters as well as the testing of liquid & solids for 96 hour
hazardous waste classification are available.
- The effluent or receiving water screen test consists of a
laboratory control & the sample & its duplicate (effluent) or 4
replicates (receiving water) at 100% concentration (undiluted). The
definitive test consists of a laboratory control & the sample &
duplicate at 5 concentrations, normally 6.25%, 12.5%, 25%, 50% & 100%.
10 fish are present per tank per concentration. Variations exit in terms
of test duration, continuous flow through versus static state of the water,
& renewal versus non-renewal of the water. MAI only performs static
testing, but offer the following variations: 96 hour static non-renewal,
48 hour static non-renewal, 96 hour renewal-3x24h, & 96 hour
renewal-1x48h. ELAP says that 96 hour renewal-1x48h screen is the most
common variant in California.
- Hazardous waste LC50 testing consists of a laboratory control
& the sample & its duplicate at 3 different concentrations, 250
mg/L, 500 mg/L & 750 mg/L. 10 fish are present per tank per
concentration.
- The duration of the tests are generally 96 or 48 hours. Initial
& final conductivity, pH, DO, hardness, total alkalinity &
residual chlorine (when needed) are measured & pH, DO, temperature
& fish mortality are determined on a daily basis. Ammonia can be determined
for an additional charge. LC50 is statistically calculated for the
definitive effluent test & the hazardous waste classification test.
All data as well as a qualitative pass / fail screen evaluation are
reported.
- Fish toxicity testing requires coordination between the client
& the lab. Fish are ordered by the lab one to two days in advance of
testing. All samples must be shipped “on ice”, effluent volumes are fairly
large, up to 10L, requiring a medium to large cooler, & effluent has a
36 hour hold time. MAI should be notified in advance of sampling to ensure
hold time compliance. The type of water, whether effluent, receiving, or
for hazardous classification must be specified.
- Fish are living organisms & can die during transit, storage or
testing without apparent reason. If greater than 10% of the control fish
die the test is nullified. This will result in a certain small number of
aborted tests, necessitating re-sampling. We will strive to minimize this
occurrence; however, any re-sampling costs are the responsibility of the
client.
- Our goal is to provide results in 6 business days at routine
pricing.
B) Bench Studies
- We have performed several bench studies assessing ozonation
by-products of natural aquifers simulated using coeval soil borings &
groundwater.
- Client specifies conditions, such as water: soil ratios, dose,
chemical constituents of interest. Various ORCs (oxidant release
compounds) can be used, for example MnO4-, H2O2,
S2O8-2, O3.
- Custom large volume reaction vessels allow multiple fluid
withdrawals without significantly effecting experimental water: soil
ratios.
- We provide a detailed report, complete with chemical reactions,
experimental data, bench & analytical QC & data interpretation.
- MAI is responsible for the data from start to finish. By-products
& water quality parameters can exhibit very complex behavior, largely
controlled by experimental & analytical technique, & MAI’s
oversite for this kind of data is crucial. The relationship between ORC
dose & contaminant decrease is much simpler & in this context MAI
can provide chemical analyses on client provided fluids without
experimental oversite.
C) Preparative Clean Up
- Hydrocarbon fuels & oils, metabolites, biological or food
matrix & elemental sulfur are common chromatography interferents.
Without clean-up, dilution is required, & the loss of analyte
sensitivity may render the data unusable.
- Various types of clean-ups are available from MAI, including GPC
(Gel Permeation Chromatography), bench column chromatography,
in-a-vial sorption, & chemical
treatment.
- Automated clean-up methods are being developed in-house that will
allow more diverse, complex & reproducible procedures.
- Clean-up techniques are best applied to retricted target groups
because the specific chemical affinity of the target analytes is the key
to the separation process. ‘Basket’ methods such as EPA 8270 have no
useful clean-up procedure whereas restricted chemical groups such as PCBs,
PNAs and dioxins have very effective clean-ups.
- GPC (EPA 3660) is applied to matrices containing biological (cell
material, peptides, proteins, triglycerides, fats/oils) interferents
and/or elemental sulfur & combines size exclusion & affinity
chromatography. It is not sufficient by itself to clean up natural
matrices but can be a useful starting point, especially for time
integrated SPMD samples.
- Bench column chromatography (EPA 3600) primarily uses silica gel,
alumina or florisil as sorbents in affinity chromatography & requires
skilled chemists, well developed techniques & accompanying QC data for
effective use.
- Examples of our laboratory separations using bench column
chromatography are:
Aliphatic
hydrocarbons (C6-C36) from aromatic hydrocarbons (C6-C36) (TPHCWG)
Unsaturated
chlorinated compounds from saturated chlorinated compounds
PCBs from
hydrocarbons
Polar oxygen
& nitrogen bearing compounds from non-polar compounds
- In-a-vial clean-up, typified by EPA 418.1, is more effective than
is generally believed, although the choice of solvent is important. An MAI
study demonstrated that it is as effective as bench column chromatography
in separating short (C8) & long chain (C27) mono-alcohols from pure
hydrocarbons when using hexane as the solvent, & it is less subject to
error.
- Chemical treatments, such as water washing to separate water
soluble from water-insoluble compounds, or acid-permanganate clean-up of
PCBs in oils, are generally less effective than bench column
chromatography but are inexpensive & have situational applications.
- MAI can perform customer specifed clean-up procedures or develop
custom clean-up procedures upon request.