22.0 Commonly used Environmental Analytical Terms
AA - Atomic Absorption. A methodology for the detection of metals. AA typically measures one element at one time. Flame AA - the sample is directly aspirated into a flame (often acetylene/oxygen); Graphite Furnace AA (GFAA) - the sample is electrically heated in a graphite chamber; Cold Vapor AA - the sample is introduced directly to the detector as a (cold) vapor (commonly used for mercury).
ABNs - Acid Base Neutrals. ABNs are also commonly referred to as BNAs or SVOCs. These are typically analyzed by method EPA 8270. (Note: as of this writing, the proper designation for this method is EPA 8270C. The current revision letter for this and other EPA methods will not be shown in this listing of terms. However, all analytical reports will reflect the current revision letter.)
Accuracy. Accuracy is a measure of how close a measurement is to the true value. (Also see precision).
Aliquot. A measured portion of a sample.
Analyte. The element or compound of interest.
BOD - Biological Oxygen Demand. A measure of the dissolved oxygen consumed by micro organisms over a specific time period (usually 5 days, designated as BOD5). BOD is a test of the polluting capacity of the water. A high BOD indicates that the water is high in pollutants (nutrients) that can support a high number of oxygen consuming organisms. As these micro organisms feed on the pollutants, they consume oxygen, thus depleting the water’s oxygen supply. This action will kill fish and other life that depends on the water’s dissolved oxygen.
BTEX - Benzene, Toluene, Ethylbenzene, and Xylene. These are major components of gasoline and indicators of light-hydrocarbon contamination, such as gasoline. These are typically measured by GC/PID or GC/MS.
BNAs. Base Neutral Acid extractable compounds. See ABNs.
Carbon range. Refers to the relative weight of petroleum hydrocarbons. It is based on the retention time of pure alkanes such as hexane, heptane, or octane. Pure straight chain hydrocarbons (alkanes) have retention times that increase regularly with the number of carbon atoms. These retention times are used to divide a chromatogram into carbon ranges. For example, C8-C10 refers to hydrocarbons with retention times (and hence relative weights) between those of octane (eight carbons) and decane (ten carbons).
The carbon ranges of some typical products are as follows: Gasoline (C4-C12), Jet Fuel (C4-C16), Kerosene & Fuel Oil #1 (C9-C16), Diesel #2 (C9-C20), Fuel Oil #2 (C11-C20), Fuel Oil #6, Bunker Fuel (C12-C32), Lube oil, motor oil (C18-C40/50), and Crude Oil (C4-C40/50).
CERCLA. Comprehensive Environmental Response, Compensation and Liability Act (also known as Superfund).
CFR - Code of Federal Regulations. Federal regulations established by law and published by the Government Printing Office.
CFU - colony forming units. Cfu is the unit used in bacteriological determinations. Example: 77 cfu per 100mL.
Chlorinated Hydrocarbons. These compounds are also referred to as Chlorinated Solvents or Purgeable Halocarbons. They are volatile compounds containing one or more chlorine atoms. These compounds are typically analyzed by GC/MS.
Chlorinated Solvents. See Chlorinated Hydrocarbons.
COD - Chemical Oxygen Demand. COD is used to measure the oxygen equivalent of organic matter content in a sample.
CWA. Clean Water Act. Regulates discharges into surface water. Also see NPDES.
Dissolved Metals. Metal concentrations determined in water after the sample has passed through a 0.45 micron filter.
Dissolved Solids. Disintegrated material contained in water. Excessive amounts make the water unfit for use.
Dissolved Oxygen (DO). Oxygen that is freely available is water. DO is essential to support desirable aquatic life.
DRO - Diesel Range Organics. DRO refers to the range of hydrocarbons that are detected in the range of approximately C12 to C28. Important: the presence of DROs does not necessarily mean that diesel fuel is present in the sample; rather, the presence of DRO indicates that hydrocarbons in the indicated carbon range were detected. These hydrocarbons could be from kerosene, fuel oil, or possibly pure product. DRO requires an extraction followed by GC/MS. The results are typically reported as a single value, such as mg/Kg; however, an examination of the chromatogram can help qualify the nature of the pollutant as a kerosine, pure product at C15, or some HC combination.
ECD - Electron Capture Detector. This GC detector is used for the analysis of chlorinated compounds such as pesticides and PCBs.
EPA 500 series - EPA drinking water methods.
EPA 600 series - EPA waste water methods.
EPA 8000 series - EPA solid waste, ground water or surface water methods. Some common EPA methods include 624 or 8260 for chlorinated and non chlorinated VOCs, and 625 or 8270 for chlorinated and non chlorinated Semi-Volatile Organic Compounds (SVOCs).
Fecal Coliform. An indicator of pollution and possible pathogen contamination.
FID - Flame Ionization Detector. This GC detector is applicable for most hydrocarbon analysis.
Gas Chromatography - GC. Gas chromatography separates compounds in a mixture. After the compounds are separated, they can be detected and then both qualified and quantified by the use of various detectors. Also refer to the references for these detectors: FID, PID, NPD, ECD and MS.
Graphite Furnace AA - GFAA. Used in trace metals analyses. Generally provides for lower levels of detection than AA or ICP. (Also see AA).
GRO - Gasoline Range Organics. GRO refers to hydrocarbons in the approximate range of C5 to C12 range. This method involves a purge and trap followed by GC/FID.
Headspace. Any area of a filled sample container that contains gas pockets.
Heavy Metals. Heavy metals typically pertains to metals with high atomic numbers, such as arsenic, cadmium, chromium, lead and mercury. However, if a client requests heavy metals analyses, Argus will call the client and confirm what metals are required.
Holding Time. This regulatory requirement indicates the time allowed between sample collection and sample analysis for properly preserved samples.
HPLC - High Pressure Liquid Chromatography. HPLC differs from Gas Chromatography in that it uses a liquid (solvent) as its carrier as opposed to a gas. HPLC is useful for analyzing polar compounds that are sensitive to high temperatures.
IC - Ion Chromatography. IC can be used for the detection of anions such as chloride, fluoride, sulphate, nitrite, and nitrate.
ICP - Inductively Coupled Plasma. ICP utilizes a high temperature plasma source for metals analysis. The sample is aspirated into the plasma. The metals of interest emit characteristic wave lengths that are collected and quantitated by the optics. In a simultaneous instrument, 20 or more metals can be analyzed at the same time.
ICP/MS - Inductively Coupled Plasma/Mass Spectrometry. For ultra low metal concentrations. This method utilizes an ICP as an ion source and a mass spectrometer as a detector.
Leachable. Describes the ability of toxic materials to be extracted from the soil by water in a natural environment.
LUFT. Leaking Underground Fuel Tanks.
LUFT 5 Heavy Metals. The metals commonly associated with LUFT problems are cadmium, chromium, nickel, lead, and zinc.
Matrix. The physical state of the sample (water, sludge, etc.).
MS - Mass Spectrometry. This GC detector typically provides excellent sensitivity, and the analysis is confirmed by the mass spectrum.
μg/L - micrograms per liter. A unit of measure used with liquids. Synonymous with ppb.
mg/kg - milligrams per kilogram. A unit of measure synonymous with ppm. It is normally used in conjunction with solid or soil samples.
mg/L - milligrams per liter. A unit of measure used with liquid samples. 1 mg/L is equivalent to 1 ppm.
ng/L - nanogram per liter. Equivalent to 1 ppt.
NPD - Nitrogen Phosphorous Detector. A GC detector used for N-P containing compounds, such as organophosphorus pesticides.
Nitrogen cycle. Refers to the series of analyses required to account for all nitrogen containing compounds (requires TKN, nitrate and nitrite). Nitrate and nitrite may be reported separately or as a total (nitrate plus nitrite). Ammonia can also be reported separately. TKN includes the total of ammonia plus organic nitrogen.
NPDES - National Pollutant discharge Elimination System. Prohibits the discharge of pollutants into US waters without a permit. Also see CWA
NTU - Nephelometric Turbidity Units. Used to measure the tubidity of water. Since turbidity measurements reported in NTU accounts only for scattered light, colored samples should not give positive interferences.
Organic Nitrogen. Organic nitrogen is defined as the difference between TKN and ammonia (TKN minus ammonia).
PCBs - polychlorinated biphenyls. Prior to being banned, PCBs were commonly used as transformers dielectrics. They are now considered a persistent and potentially carcinogenic pollutant.
PID - Photo Ionization Detector. This GC detector is used extensively for aromatic compounds such as benzene..
ppb - parts per billion. Refer to ug/L or ug/Kg.
ppm - parts per million. Refer to mg/L or mg/Kg.
ppt - parts per trillion.
Precision. A measure of the ability to reproduce an analytical result. Note: a result with excellent precision could have poor accuracy.
Preservatives. Chemical preservatives are added to samples to either prevent or slow the degradation of the target analyte.
Primary Drinking Water Standards. Specifies contaminant levels that, in the opinion of the EPA, have no adverse effects on humans.
Priority Pollutant Metals. Refers to a list of 13 metals defined by the U.S. Environmental Protection Agency which includes antimony (Sb), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), silver (Ag), thallium (Tl), and zinc (Zn).
Priority Pollutant Organics. Refers to the list of Volatile Organics, Semivolatile Organics, and Pesticides/PCBs defined by the US EPA. Also commonly referred to as Total Toxic Organics (TTOs).
Purge and Trap. This analytical technique is used for the analysis of volatile organic compounds. The analyte is purged from the sample by an inert gas, and then trapped on a sorbent column. After the purging is completed, the trapped analyte is released from the sorbent column by means of heat and transferred onto a GC for analysis.
Purgeable Halocarbons. These compounds are relatively insoluble in water and have boiling points below 200oC. These compounds have also been referred to as halogenated volatile organic compounds, chlorinated solvents or chlorinated halocarbons.
RCRA - Resource Conservation and Recovery Act. Pertains to hazardous substances.
Secondary Drinking Water Regulations. These are unenforceable regulations. They pertain to contaminants that may adversely affect water’s appearance and odor.
SIM. Selected ion monitoring. SIM sets the mass selective detector to repeatedly scan a few selected ions rather than a full spectrum. In the acquisition method (GC/MS SIM or Gas Chromatography/Mass Spectrometry using Selected Ion Monitoring), the selected ions can be changed to reflect the desired compound to be detected. The detector scans ions unique to the compound of interest.
Suspended solids. Particles that float on the surface or are suspended in liquids.
SVOCs - Semivolatile Organic Compounds. See ABNs.
TAL - Target Analyte List
TCL - Target Compound List
TCLP - Toxicity Characteristic Leachate Procedure. This procedure is used to characterize the mobility or leachability contaminants present in liquid and solid wastes. The TCLP is a sample preparation (extraction) that simulates the leaching action that could occur in an area such as a landfill. If the analysis of the extract results in a value for an analyte in excess of the regulatory requirement, then the tested material is considered a RCRA waste.
TCU - True Color Units. TCU are the units for measuring the color of a water sample. A TCU is defined as the amount of color (absorbed light) at a specific wavelength of light of a cobalt-platinate salt.
TDS - Total Dissolved Solids.
THE - Total Extractable Hydrocarbons. THE refers to hydrocarbons in the diesel/fuel oil range (approx. C10-C30). Also see DRO and TPH.
TEQ - Toxic Equivalents. It is a unit used as a means of normalizing the toxicity of a series of compounds relative to a single compound. TEQs are used in reporting dioxin results where 2,3,7,8-TCDD is assigned a TEQ of one and the other dioxin isomers are reported as their toxicity relative to 2,3,7,8-TCDD.
THMs - Trihalomethanes. THMs are a class of compounds with the chemical formula CHX3, where X is a halogen (chlorine and bromine are the most common). THMs are the by-products of chlorination of water supplies.
TIC - Tentatively Identified Compounds. Used for reporting detected analytes that are not included in the list of target compounds. The analyte identification is based on the mass spectral library, and the concentration is estimated.
TKN - Total Kjeldahl Nitrogen. Often erroneously referred as total nitrogen, TKN includes the summation of organic nitrogen compounds and ammonia; nitrates and nitrites are not included in TKN. The method was developed by Kjeldahl in 1883.
TOC --- Total Organic Carbon
TPH - Total Petroleum Hydrocarbons. TPH is a measure of the total amount of fuel present in a sample. Also refer to TPH-GRO and TPH-DRO.
TSS - Total Suspended Solids.
TTOs - Total Toxic Organics. See Priority Pollutant Organics.
VOAs - Volatile Organics. See VOCs.
VOCs - Volatile Organic Compounds.
VSS - Volatile Suspended Solids. VSS is the fraction of TSS that can be volatilized at 600 degrees Celsius. VSS can be used to approximate the organic fraction of TSS.
ZHE - Zero Headspace Extraction. This is the TCLP extraction method required for VOCs (Volatile Organic Compounds) in order to prevent target compound losses during the extraction process.