A Branch of Ecological Services
Select one of the links below to display the method descriptions associated with RTI.
Tissue samples are prehomogenized using a food processor. A portion of the tissue sample (or sediment) is then freeze dried for determination of moisture content and ground to 100 mesh with a mill.Back to the Top
Preconcentration Digestion for Inductively Coupled Plasma Emission (ICP) Measurement
Using a CEM microwave oven, 0.5 g of freeze dried tissue is heated in a capped 120 mL Teflon vessel in the presence of 5 mL of Baker Instra-Analyzed nitric acid for three minutes at 120 watts, three minutes at 300 watts, and 35 minutes at 450 watts. The vessel contents are then allowed to cool and the cap is removed and rinsed carefully with 3 ml of HNO3 adding the rinsings to the vessels contents. The uncapped vessel is then returned to the microwave oven and heated until the vessel contents are less than 1 mL in volume. The contents are carefully rinsed with laboratory pure water into a 5 ml glass volumetric vessel and made to volume with additional laboratory pure water. The flask contents are then immediately transferred to a clean plastic centrigure or auto sampler tube and centrifuged for 1 minute to precipitate the suspended matter. The sample is now ready for ICP analysis.Back to the Top
Digest for ICP Measurement
Using a CEM microwave oven, 0.25 to 0.5 g. of freeze dried sample is heated in a capped 120 ml Teflon vessel in the presence of 5 ml of Baker Instra-Analyzed nitric acid for three minutes at 120 watts, three minutes at 300 watts, and fifteen minutes at 450 watts. The residue is then diluted to 50 ml with D.I. water.Back to the Top
Digestion for Graphite Furnace and Cold Vapor Atomic Absorption (GFAA) Measurement.
Using a CEM microwave oven, 0.25 to 0.5 g of freeze dried sample is heated in a capped 120 ml Teflon vessel in the presence of 5 ml of Baker Instra-Analyzed nitric acid for three minutes at 120 watts, three minutes at 300 watts, and fifteen minutes at 450 watts. The residue is then diluted to 50 ml with laboratory pure water.Back to the Top
Digestion for Hg Measurement by Cold Vapor Atomic Absorption (CVAA)
Some 0.25 to 0.5 g of tissue is refluxed for two hours in 10 ml HNO3 (Baker Instra-Analyzed) and diluted to 50 ml with 1% HCl.Back to the Top
ICP measurements are made using a Leeman Labs Plasma Spec I sequential or ES2000 simultaneous spectrometer.Back to the Top
Graphite Furnace Atomic Absorption (GFAA)
GFAA measurements are made using a Perkin-Elmer Zeeman 3030 or 4100ZL atomic absorption spectrometer.Back to the Top
Cold Vapor Atomic Absorption (CVAA)
Hg measurements are conducted using SnC14 as the reducing agent. A Leeman PS200 Hg Analyzer is employed.Back to the Top
Homogenization Following freeze drying samples
Homogenization Following freeze drying samples are ground to approximately 100 mesh using a mill.Back to the Top
Digestion for Inductively Coupled Plasma Emission (ICP) Measurement
Some 0.25 to 0.5 g of sediment is placed in a 120 ml Teflon microwave vessel. One ml each of HC1, HF, and HC104, and 10 ml HNO3 are added to the vessel. The vessel is then capped according to the manufacturer's instructions and heated in a CEM microwave oven for two minutes at 120 watts, three minutes at 180 watts, and ten minutes at 600 watts. The resulting residue is diluted to 100 ml with 5% HCl. This solution is then filtered through Whatman 41 filter paper prior to ICP measurement. An HF resistance torch tip is used for these digests during the ICP measurement.Back to the Top
Preconcentration Digestion for Inductively Coupled Plasma Emission (ICP) Measurement
Using a CEM microwave oven, 50 ml of water sample are heated in a capped 120 ml Teflon vessel in the presence of 5 ml of Baker Instra-Analyzed nitric acid for three minutes at 120 watts, three minutes at 300 watts, and 35 minutes at 450 watts. The vessel contents are then allowed to cool and the cap is removed and rinsed carefully with 3 ml of HNO3 adding the rinse to the vessel contents. The uncapped vessel is then returned to the microwave oven and heated until the vessel contents are less than 1 ml in volume. The contents are carefully rinsed with laboratory pure water into a 5 ml glass volumetric vessel and made to volume with additional laboratory pure water. The sample is now ready for ICP measurement.Back to the Top
Digestion for Graphite Furnace Atomic Absorption (GFAA) Measurement
Using a CEM microwave oven, 50 ml of water sample are heated in a capped 120 ml Teflon vessel in the presence of 5 ml of Baker Instra-Analyzed nitric acid for fifteen minutes at 300 watts. The sample is then diluted to 50 ml with laboratory pure water.Back to the Top
Digestion for Hg Measurement by Cold Vapor Atomic Absorption (CVAA)
Ten ml of water sample were refluxed for two hours in 10 ml HNO3 (Baker Instra-Analyzed) and diluted to 50 ml with 1% HCl.Back to the Top
Summary of EPA Method 3010 for wastewaters, etc.
A mixture of HNO3 and the material to be analyzed is refluxed in a covered Griffin beaker. This step is repeated with additional portions of HNO3 until the digestate is light in color or until its color is stabilized. After the digestate has been brought to a low volume, it is refluxed with HCl and brought up to volume. If the sample should go to dryness, it must be discarded and the sample reprepared.Back to the Top
Toxicity Characteristic Leaching Procedure (TCLP) analyses are performed according to EPA Method 1311, 40 CFR, Chapter 1 (7-1-91 Edition) Part.Back to the Top
Ultrasonic Extraction with IC Measurement.
0.5 g of sediment is sonicated in 30 mL of DI water for 30 minutes. The final volume of extract is adjusted to 50 mL with DI water. Anions are measured by ion chromatography.Back to the Top
IC MEASUREMENT OF WATER SAMPLES
Anions in water are measured by ion chromatography.Back to the Top
Determination of Radium - 226, 228
This method is applicable to determination of radium-226, 228 activity in aqueous solutions.
Radium isotopes are collected by co-precipitation with barium and lead sulfates from an alkaline citrate solution, and purified by re- precipitation from EDTA solution. Both radium-226 and radium-228 are collected in this manner. For radium-226 determination, radium is co-precipitated on barium sulfate and counted by alpha spectrometry. The Ra-226 yield is determined through initial addition of a Ba-133 tracer. Ra-228 is also co-precipitated on barium sulfate, then after a 36-hour ingrowth of neptunium 228 from radium-228, the actinium-228 is carried with yttrium, purified, precipitated as yttrium oxalate and beta counted. The Ra-228 yield is determined gravimetrically from the yttrium oxalate.
Samples containing barium in excess of 1 mg per aliquot may cause interference when counting the Ra-226 by alpha spectroscopy.
Performance studies of the EPA 904.0 method indicate that the presence of Sr-90 in the sample gives a positive bias to any measured radium- 228 activity because the Sr-90 is not completely separated from the Ac-228.Back to the Top
Determination of Strontium-90
This method is applicable to determination of strontium-90 activity in aqueous solutions and may be used in conjunction with sample preparation procedures which are designed to dissolve non-aqueous samples containing strontium-90 into an aqueous matrix.
Strontium-90 along with stable strontium carrier are precipitated from aqueous samples as insoluble carbonates. Interferences from calcium and other radionuclides are removed by one or more precipitations of the strontium carrier as strontium nitrate. Barium and radium are removed as chromate. The yttrium-90 daughter of strontium-90 is removed from the initial sample by a hydroxide precipitation step. The yttrium-90 daughter is permitted to grow in again and is then separated with stable yttrium carrier as hydroxide and finally precipitated as the oxalate and beta counted. The strontium-90 concentration is determined by the yttrium-90 activity.
Samples that contain significant amounts of stable strontium may cause errors in the recovery of the added strontium carrier. Hard waters containing large quantities of calcium which will precipitate with the strontium in the initial carbonate precipitation may cause errors in the strontium recovery. Repeated precipitations of the strontium nitrate will minimize this interference but may not eliminate it.Back to the Top
Total organic carbon (TOC)
Total organic carbon (TOC) analyses are performed according to EPA Method 9060 "Text Methods for Evaluating Solid Waste: Physical/Chemical Methods; SW-846 3rd Ed. 1986.
Measurement of the TOC as CO2 is performed by IR using a Dohrman DC-80 TOC analyzer. Analyses will be performed either in-house or though purchase order agreement with Chemical and Environmental Technology, Inc. (Gary, NC).Back to the Top
Analysis by Ion Selective Electrode.Back to the Top
Cr(VI) by IC-PCR - Hexavalent Chromium
Cr(VI) by IC-PCR - Hexavalent Chromium is separated from other anions and cations by ion chromatography followed by post column reaction with diphenyl carbazide (DPC). The Cr(VI)-DPC complex is measured colorimetrically at 530 nm.Back to the Top
Hexavalent Chromium species are extracted from 10 grams of soil using 100 mL 0.1N NaOH for 30 minutes using ultrasonication. After filtering 100 mL the resulting mixture, the filterate is suitable for det ermination of Cr(VI) by ion chromatography (IC-PCR).Back to the Top
Method for Total Cyanide Analysis in Soil/Sediment Cyanide, Total (in Sediments)
Method 335.2 CLP.M (Titrimetric; Manual Spectrophotometric; Semi-Automated Spectrophotometric)
SCOPE AND APPLICATION
This method is applicable to the determination of cyanide in sediments and other solids. The detection limit is dependent upon the weight of sample taken for analysis.
SUMMARY OF METHOD
The cyanide as hydrocyanic acid (HCN) is released from cyanide complexes by means of reflux-distillation operation and absorbed in a scrubber containing sodium hydroxide solution. The cyanide ion in the absorbing solution is then determined by volumetric filtration or colorimetrically.
In the colorimetric measurement the cyanide is converted to cyanogen chloride, CNCl, by reaction with chloramine-T at a pH less than 8 without hydrolyzing to the cyanate. After the reaction is complete, color is formed on the addition of pyridine-pyrazolone or pyridine- barbituric acid regent. The absorbance is read at 620 nm when using pyridine-pyrazolone and at 578 nm when using pyridine-barbituric acid. To obtain colors of comparable intensity, it is essential to have the same salt content in both the sample and the standards.Back to the Top
Methods for Determination of Grain Size
Grain size analysis will be performed to determine the relative proportion of the different grain sizes of unconsolidated soils or sediments. The general classification of grain sizes includes gravel (grain size > 2mm), sand (grain size between 0.0625 mm and 22 mm), silt (grain size between 0.0039 mm and 0.0625 mm) and clay (grain size fractions will be dependent on the nature of the sample. If the sample contains very little silt and clay, it will be dried, weighed, and sieved through a stacked column of sieves of the desired mesh sizes with the bottom sieve having a mesh size of 0.0625 mm (U.S. Standard Sieve Mesh No. 230). The material caught in the collection pan will represent the size fraction <0.0625 mm or the silt-clay fraction. If the sample contains a significant silt-clay fraction, it will be moistened with a dispersing agent and wet-sieved. Again, the material caught in the collection pan represents the silt-clay fraction. Pipette analysis will be used to determine the relative proportion of silt to clay; the silt- clay fraction is dispersed in 1000 mL of distilled water containing dispersant. After the water and sample are vigorously agitated, measured volumes will be pipetted from the container at specified time intervals at a measured withdrawal depth. Since settling velocity is proportional to the square of the particle diameter, the particle size diameter can be computed given the parameters of time and depth. The pipetted samples are then dried and weighed to determine the weight percent fraction of the total sample.Back to the Top
Nitric Acid Digestion of Blood and Soft Tissues
Nitric Acid Digestion of Blood and Soft Tissues at 85 C Using a Water Bath Followed by Microwave Concentration
PURPOSE: This procedure is a wet chemical digestion procedure for biological samples using nitric acid. Digestion is accomplished using concentrated nitric acid and heating in a water bath. The resulting digest is suitable for the atomic spectroscopic determination of nitric acid soluble metals.
INSTRUMENT DESCRIPTION: See operator's manual for a complete and detailed description of the water bath (1). The basic instrument features are presented here for the water bath and digestion system.
1. Water bath - Model No. 1235 PC by VWR Company. Hz = 50/60; Volts 120 phase single. Watts 600, Serial No. 1100493 - Located in Room 220A, Building 6.
2. CEM MDS-2000 Microwave Digestion System.
PROCEDURE: The following procedure describes preparation of biological materials for the atomic spectroscopic determination of copper and other metals.
1. Precleaning of 15 mL centrifuge tubes. After the normal nitric acid wash and deionized water rinse of the centrifuge tubes used for digestion, soak each tube for 30 minutes with 25% nitric acid. Discard this solution and rinse three (3) times with deionized water.
2. Digestion of Biological Samples. An aliquot of wet tissue (0.1 grams to 1.5 grams) is weighed into a graduated 15 mL plastic centrifuge tube. Two (2) mL of concentrated nitric acid (Baker Instra-analyzed Reagent for trace metals analysis, 70.0-71.0% HNO3) are added to each tube. The tubes are capped tightly and are placed into plastic racks and the racks are placed in the water bath at a water temperature of 85 C + 2 C for 45 minutes. Be sure that the bath water level is at least up to the level of the sample digestion solutions in each centrifuge tube. Cool and remove the caps, add 1 mL of hydrogen peroxide and reheat for an additional 15 minutes. Cool and place in a CEM MDS-2000 microwave oven. With caps removed, heat the rack of samples at 20-40% power (120-240 watts) CAREFULLY until 0.5 mL of residue remains. All samples are then brought up to the 5 mL mark on the centrifuge tubes with deionized water and mixed well. If other measurements are needed the final volume may need to be increased. Documentany other volumes used on the digestion sheet.
3. Calibration. At least monthly, monitor the bath temperature with an NIST traceable thermometer that reads between approximately 20 and 100 C. The temperature should be within 2 C of the temperature display on the bath. If not, adjust the bath thermostat until 85 + 2 C is reached, according to the operators' manual.Back to the Top
FAT IN FOODS CHLOROFORM-METHENOL EXTRACTION METHOD
Method is applicable to composite foods and foods for which methods of analysis for fat or lipids are not specified. Method is for lipids, not for fats (triglycerides and other ether-soluble materials).
JAOAC 66, 927 (1983).Back to the Top
Perchloric Acid Digestion Procedure
1. Weigh 0.25 grams of sample directly into a glass 50 mL florence flash.
2. Add 4 ml of Instra analyzed nitric acid 70.0-71.0% to each flask.
3. Place the flasks in a rack and microwave for 5 minutes at 75% power.
4. Remove the rack from the microwave and allow to cool completely in the fume hood.
5. Add 2.5 ml of perchloric acid to each flask.
6. Place the rack of flasks in the microwave and heat gently to dense white fumes. Take the sample volume down very carefully to approximately 1 ml.
7. Remove the rack of flasks from the microwave and place in the fume hood. Allow to cool completely.
8. Quantitatively transfer the contents of each flask to a 15 ml plastic centrifuge tube. Bring all samples to a final volume of 14 ml with deionized water.Back to the Top
MEASUREMENT BY ICP-MS
MEASUREMENT BY ICP-MSBack to the Top
Nitric Acid Digestion of Water Sample at 85 C Using a Water Bath
1. Place 44-45 ml of the water sample in a 50 ml polypropylene centrifuge tube.
2. Add 5 ml of Baker Instra-analyzed HNO3.
3. Heat samples in a water bath at 85 C for 1 hour.
4. Dilute to 50 ml volume with DI water.Back to the Top
HYDRIDE GENERATION WITH ICP MEASUREMENT
HYDRIDE GENERATION WITH ICP MEASUREMENTBack to the Top
MERCURY IN LIQUID WASTE (MANUAL COLD-VAPOR TECHNIQUE) EPA SW846, METHOD 7470
1.0 SCOPE AND APPLICATION
1.1 Method 7470 is a cold-vapor atomic absorption procedure approved for determining the concentration of mercury in mobility- procedure extracts, aqueous wastes, and ground waters. (Method 7470 can also be used for analyzing certain solid and sludge-type wastes; however, Method 7471 is usually the method of choice for these waste types.) All samples must be subjected to an appropriate dissolution step prior to analysis.
2.0 SUMMARY OF METHOD
2.1 Prior to analysis, the liquid samples must be prepared according to the procedure discussed in this method.
2.2 Method 7470, a cold-vapor atomic absorption technique, is based on the absorption of radiation at 253.7-nm by mercury vapor. The mercury is reduced to the elemental state and aerated from solution in a closed system. The
2.3 The typical detection limit for this method is 0.0002 mg/L.Back to the Top
AOAC Method 942.05 for % Ash
One gram of sample is weighed into a porcelain crucible and placed in a muffle furnace at 600 C for 2 hours. The crucible is then placed in a desiccator, cooled, and weighed.Back to the Top
The Elemental Analyzer EA1108
The Elemental Analyzer EA1108 (Figure 1) is an instrument designed for the micro, semi-micro and macro determination of total carbon, hydrogen, nitrogen, sulphur and oxygen (C, H, N, S, O) present in a wide range of organic and inorganic samples such as: organic chemicals, pharmaceuticals, fine chemicals, fuels, gasolines, oils, coal, coke, graphite, metal powders, steel, nitrides, carbides, polymers, rubbers, catalysts, soils and sediments, ceramics, carbon fibers and many others.
The original analytical method is based on the complete and instantaneous oxidation of the sample by "flash combustion" which converts all organic and inorganic substances into combustion products. The resulting combustion gases pass through a reduction furnace and are swept into the chromatographic column by the carrier gas (helium) where they are separated and detected by a thermal conductivity detector (TCD) which gives an output signal proportional to the concentration of the individual components of the mixture.Back to the Top
Flame Atomic Absorption
Flame Atomic Absorption -- Perkin Elmer 603Back to the Top
Approximately 70mg of sample is placed in a 7ml teflon digestion vessel with 3ml of 3M nitric acid. The vessel is tightly capped and placed in a 90 C drying oven for 1 hour. The sample is then diluted to an appropriate volume with deionized water.Back to the Top
N. Fofonoff and R. Millard -- "Algorithms for Calculation of Fundatmental Properties of Seawater" from UNESCO Technical Papers in Marine Science, No 44.Back to the Top
Extraction of methylmercury. The sample was treated with 10 ml of 5 mol/l HCI to liberate methylmercury (plus any other organomercury species), which was then extracted into 3 x 20 ml aliquots of toluene. The combined toluene aliquots was diluted to 100 ml with toluene. This solution was amenable to gas chromatography. For the other techniques which accept only aqueous samples, methylmercury was extracted from the toluene solution with a cysteine acetate solution, 4/1 v/v. To prepare the cysteine acetate solution, 0.5 g of cysteine hydrochloride monohydrate, 0.34 g of sodium acetate and 6.25 g of anhydrous sodium sulphate was dissolved in 50 ml of DDW.
Cold vapor atomic absorption spectrometry. Digestion: EPA method 7470 (nitric, sulfuric acids permangante, persulfate). After digestion the resulting solution was then subjected to CVAAS. An automated mercury analyzer, the Leeman Labs PS200, was used for measurement. The reducing agent was a solution of stannous chloride and hydroxylamine hydrochloride (2/1).
Marine Biological Reference Materials for Methylmercury: Analytical Methodologies Used in Certification. Fresenius Z Anal. Chem. (1989) 333:641-644.Back to the Top
Total Kjeldahl Nitrogen (as N) (TKN): EPA Method 351.3
Summary of method: The sample is heated in the presence of conc. sulfuric acid, K2SO4 and CuSO4 and evaporated until SO3 fumes are obtained and the solution becomes colorless or pale yellow. The residue is cooled, diluted, and is treated and made alkaline with a hydroxide-thiosulfate solution. The ammonia is distilled and determined by titration.Back to the Top
Determination of Inorganic Anions by Ion Chromatography: EPA Method 300.0
Summary of method: A small volume of sample, typically 2 to 3 ml, is introduced in to an ion chromatograph. The anions of interest are separated and measured using a system comprised of a guard column, analytical column, suppressor device, and conductivity detector.Back to the Top
Total Phosphorus (as P) - EPA Method 365.3
Ammonium molybdate and antimony potassium tartrate are added to the sample in an acid medium to form an antimony-phospho-molybdate complex. This complex is reduced to an intensely blue colored complex by ascorbic acid. The color is proportional to the phosphorus concentration. Since only orthophosphate forms a blue color in this test, sulfuric acid and ammonium persulfate are added to convert polyphosphates and organic phosphorus compounds to the orthophosphate form.Back to the Top
Determination of Sulfide as Hydrogen Sulfide By Gas Phase Molecular AS
This is a molecular absorption method which uses a sharp-line irradiation source for the determination of sulfide in water and sludge samples. Sulfide is transformed into hydrogen sulfide by adding sulfuric acid and then the absorption of H2S is measured at 196.0 nm using the selenium atomic line.Back to the Top
Approximately 0.02 grams of the sample was transferred into a 50 mL beaker. 10 mLs of acetonitrile with 0.1% acetic acid was added to the beaker. The beaker was covered with parafilm and placed in the ultrasonic bath for approximately 30 minutes. The contents of the beaker was transferred into a centrifuge tube. The sample was then centrifuged for 20 minutes at about 2000 rpm. The supernatant was decanted into the sample cup and analyzed for Sn by GFAA with a calibration curve generated by standards made from tributyltin chloride.Back to the Top
Preparation: Weigh sample to nearest 0.01 mg. Weigh the sample directly into a sample boat tared on electronic balance. The weight is automatically transferred to SC432 database. Cover the sample with V2O6 combustion accelerator as called for by sample type. Place liquids in a capsule and crimp.
Instrument: LECO SC 432DR Sulfur Analyzer
Calibration: Three conditioners of 4-12 mg Cystine. One each of NIST traceable sulphanilic acid at 18, 15, 12, 9, 6, and 3 mg, plus 50 mg of NIST non-fat milk powder for initial calibration. Calibration is generated internally using a quadratic regressed curve.
Control: 6-1625 Cystine (26.69% S)
Determination: Combustion in O2 atmosphere at 1350 +/- 50 C. An infrared detector quantitates the resulting SO2.
Detection limit: 1 %.
Precision and Accuracy:RSD RE
1.56 % -0.20%
Calculations: Internal, quadratic regression.
References: Leco Sulfur Analyzer Systems Manual: 602-500, Version 1.0
ASTM D4239-83, Sulfur in the Analysis Sample of Coal and Coke Using High Temperature Tube Furnace Combustion Methods, Method C: Annual Book of ASTM Methods, Vol. 05:05, 1992.
ASTM D 1552-95: Test Method for Sulfur in Petroleum Products (High- Temperature Method); Annual Book of ASTM Methods, Vol. 05:01, 1997.Back to the Top
An aliquot of acid is added to a fixed weight of waste in a closed system. The generated gas is swept into a scrubber and the sulfide is then quantified using Method 9034 which is a titrimetric procedure.Back to the Top
Total Dissolved Solids
A well mixed water sample is filtered through a standard glass fiber filter and the filtrate is evaporated in a weighed dish and dried to a constant weight at 180 C. The increase in dish weight represents the total dissolved solids.Back to the Top
Total Suspended Solids
A well mised water sample is filtered through a weighed standard glass fiber filter and the residue retained on the filter is dried to a constant weight at 103 to 105 C. The increase in weight of the filter represents the total suspended solids.Back to the Top
Mercury in Solids and Solutions by Thermal Decomposition, Amalgamation, and Atomic Absorption (EPA Method 7473)
Approximately 0.25 g of sample is introduced into a Milestone DMA-80 Mercury Analyzer. The sample is dried, then chemically decomposed at 750oC under an oxygen atmosphere, liberating the mercury content in the sample. The mercury vapor is then collected selectively on a gold amalgam surface. The amalgamator is then rapidly heated to 800oC and the oxygen flow carries the mercury vapor though an absorption cell where the Hg absorbance (as a function of Hg concentration) is measured at 253.7nm. The detection limit for sediments and tissues is approximately 0.01 æg/g.Back to the Top