Field Analytical MethodsField Analytical Methods

Considerations for Field Analytical Considerations for Field Analytical MethodsMethods

Which parameters are anticipated to occur at the site?Which parameters are anticipated to occur at the site?• What media will be analyzed?What media will be analyzed?• What concentrations are expected?What concentrations are expected?• Is there matrix interference? (High concentrations of Is there matrix interference? (High concentrations of

one constituent can mask other constituents.)one constituent can mask other constituents.)• Will my methods work under these conditions? (i.e. Will my methods work under these conditions? (i.e.

Color of sample may prevent colorimetric methods Color of sample may prevent colorimetric methods from working.)from working.)

• Cost? How does the field analytical method compare Cost? How does the field analytical method compare to a laboratory or remote laboratory analysis?to a laboratory or remote laboratory analysis?

Additional ConsiderationsAdditional Considerations

• in situin situ – the measurement is taken in – the measurement is taken in place without a sample being collected.place without a sample being collected.– no error associated with sample collectionno error associated with sample collection– possible error from environmentpossible error from environment

• ex situex situ – measurement taken in a – measurement taken in a sample that has been collected. sample that has been collected. – sampling error and biassampling error and bias

pHpH

pH= –log H+pH= –log H+• Can be measured Can be measured

using pH meter and using pH meter and probe, or using a field probe, or using a field test kit. The probe and test kit. The probe and meter is easy to use meter is easy to use and accurate if and accurate if calibrated. calibrated.

• The pH meter needs to The pH meter needs to be calibrated. Most be calibrated. Most models automatically models automatically adjust for temperature, adjust for temperature, but some may require but some may require additional calibration. additional calibration.

ConductivityConductivity

• Conductivity is a measure of Conductivity is a measure of the ability of water to pass an the ability of water to pass an electrical current. It is electrical current. It is affected by the presence affected by the presence inorganic cations and anions. inorganic cations and anions. Conductivity is affected by Conductivity is affected by temperature. Increase in temperature. Increase in temperature increases temperature increases conductivity. Conductivity is conductivity. Conductivity is generally reported at 25° C. generally reported at 25° C.

• Conductivity is mainly Conductivity is mainly affected by the geology of the affected by the geology of the area, although discharges area, although discharges could increase conductivity. could increase conductivity.

• Conductivity is measured in Conductivity is measured in microsiemens per centimeter. microsiemens per centimeter.

Dissolved OxygenDissolved Oxygen

DO concentrations are influenced by water DO concentrations are influenced by water temperature, atmospheric pressure, the rate temperature, atmospheric pressure, the rate of photosynthesis, the degree of light of photosynthesis, the degree of light penetration (turbidity), the degree of penetration (turbidity), the degree of turbulence or wave action, and the amount of turbulence or wave action, and the amount of oxygen used by the respiration and decay of oxygen used by the respiration and decay of organic matter. organic matter.

• Can be measured using titration or using a Can be measured using titration or using a meter and probe. The meter and probe is meter and probe. The meter and probe is easy and quick to use. Since DO does depend easy and quick to use. Since DO does depend on atmospheric pressure, a barometer or on atmospheric pressure, a barometer or altimeter may be required in addition to your altimeter may be required in addition to your meter. meter.

AlkalinityAlkalinity

• Alkalinity is the quantitative Alkalinity is the quantitative capacity of a water or water capacity of a water or water solution to neutralize an acid. solution to neutralize an acid. It is expressed in terms of its It is expressed in terms of its calcium carbonate calcium carbonate equivalent.equivalent.

• Alkalinity is measured by Alkalinity is measured by titration. A 0.02N solution of titration. A 0.02N solution of NH2SO4 is titrated into the NH2SO4 is titrated into the sample until the pH is equal sample until the pH is equal to 4.5. A colorimetric to 4.5. A colorimetric indicator or a pH meter and indicator or a pH meter and probe may be used. A probe may be used. A stronger solution may be stronger solution may be used if the alkalinity is very used if the alkalinity is very high. high.

ColorimetricColorimetric

• Reagent test kits are Reagent test kits are self-contained. self-contained.

• Highly potableHighly potable

• InexpensiveInexpensive

• Often no sample Often no sample preparation required.preparation required.

• Available for a wide Available for a wide range of analytesrange of analytes

• Limited training Limited training needed.needed.

What Does it Mean?What Does it Mean?

• Qualitative – is the constituent present? Qualitative – is the constituent present? – Based on color change. Based on color change.

• Quantitative – how much of the Quantitative – how much of the constituent is present?constituent is present?

• Based on color intensity.Based on color intensity.– Compared to color chart or photograph.Compared to color chart or photograph.– Subject to bias regarding color interpretation.Subject to bias regarding color interpretation.– Accuracy may be questionable – maybe semi-Accuracy may be questionable – maybe semi-

quantitative data.quantitative data.

ImmunoassayImmunoassay

A measure of immune A measure of immune system response to system response to an analyte. an analyte.

Uses antigen in an Uses antigen in an enzyme conjugate.enzyme conjugate.

• Enzyme Enzyme immunoassay.immunoassay.

• Radioimmunoassay.Radioimmunoassay.• Fluorescent Fluorescent

immunoassay.immunoassay.• Enzyme-Linked Enzyme-Linked

Immunoabsorbant Immunoabsorbant Assay (ELISA)Assay (ELISA)

ImmunoassayImmunoassay

• Widely used in food and health-care industry.Widely used in food and health-care industry.• In the environmental industry, provide semi-In the environmental industry, provide semi-

quantitative and quantitative data for a wide quantitative and quantitative data for a wide range of organic and inorganic compounds in soil range of organic and inorganic compounds in soil and water.and water.

• Commonly used for gasoline, diesel, jet fuel, Commonly used for gasoline, diesel, jet fuel, BTEX, PAH, PCP, pesticides and herbicides, BTEX, PAH, PCP, pesticides and herbicides, explosives and propellants, PCBs, etc.explosives and propellants, PCBs, etc.

• Used to measure lighter aromatic petroleum Used to measure lighter aromatic petroleum fractions, which cause immune system responses. fractions, which cause immune system responses. (Not used for heavy petroleum or degraded (Not used for heavy petroleum or degraded petroleum).petroleum).

Application to Environmental Application to Environmental SciencesSciences

• ELISA is most commonly used.ELISA is most commonly used.

• Can be optimized for speed, Can be optimized for speed, sensitivity, and selectivity.sensitivity, and selectivity.

• Long shelf life.Long shelf life.

• Does not require the use of Does not require the use of radioactive materials.radioactive materials.

Advantages:Advantages:

• Speed of analysis.Speed of analysis.• PortabilityPortability• Ease of UseEase of Use• Relatively low cost per sample.Relatively low cost per sample.• Methods available for a wide range of Methods available for a wide range of

contaminants.contaminants.• EPA SW846 methods for PCP, 2,4D, PCBs, Dioxen, EPA SW846 methods for PCP, 2,4D, PCBs, Dioxen,

TPH, PAHs, Toxaphane, Chlorodane, DDT, RDX, TPH, PAHs, Toxaphane, Chlorodane, DDT, RDX, TCE, Triazine as atrazine, Mercury.TCE, Triazine as atrazine, Mercury.

• Low detection limits (ppb for water, ppm for soils)Low detection limits (ppb for water, ppm for soils)

Disadvantages:Disadvantages:

• You must correctly identify the analyte You must correctly identify the analyte or family of analytes of interest at the or family of analytes of interest at the site because the kits are contaminant site because the kits are contaminant specific. specific.

• Similar compounds may cause “cross-Similar compounds may cause “cross-reactivity”.reactivity”.

• Many sample reagents highly sensitive Many sample reagents highly sensitive to direct sunlight and temperature.to direct sunlight and temperature.

• Sample reagents expire.Sample reagents expire.

X-Ray Fluorescence (XRF)X-Ray Fluorescence (XRF)

• Used where trace metal concentration is Used where trace metal concentration is concerned. concerned.

• Radioisotope source and detector.Radioisotope source and detector.• Miniature X-ray tube source. Miniature X-ray tube source. • Can be used Can be used in situ in situ or or ex situex situ. . • In situIn situ – rapid screening of soils in place. – rapid screening of soils in place.

Count times are low so detection limits are Count times are low so detection limits are higher.higher.

• Ex situEx situ – sample is analyzed. Count times – sample is analyzed. Count times are longer so detection limits are lower.are longer so detection limits are lower.

Gas Chromatograph (GC)Gas Chromatograph (GC)

• Widely used for the analysis of Widely used for the analysis of organic compounds in air, soil gas, organic compounds in air, soil gas, soil, and water samples.soil, and water samples.

• Can be combined with Mass Can be combined with Mass Spectrometer for definitive Spectrometer for definitive identification of complex compounds. identification of complex compounds.

QUESTIONS?QUESTIONS?