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Last Updated:
Friday, October 03, 2008
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| MISCELLANEOUS TESTING |
A) Acute Fish Toxicity
- Basic acute fish toxicity screen (pass / fail) & definitive (numerical concentration for 50% mortality, LC50) testing are now performed by MAI. Fathead minnow, Sheepshead minnow & Rainbow Trout static renewal & non-renewal testing of effluent & receiving waters as well as the testing of water & 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 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, S2O7‾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.
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