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10.4 Spectrophotometer Calibration Quality Control. Calculate the least squares slope of the calibration curve. The line must pass through the origin or through a point no further from the origin than ±2 percent of the recorder full scale. Multiply the corrected peak height by the reciprocal of the least squares slope to determine the distance each calibration point lies from the theoretical calibration line. The difference between the calculated concentration values and the actual concentrations (e.g., 1, 3, 5, 8, and 10 mg As for the high-level procedure) must be less than 7 percent for all standards.
Note: For instruments equipped with direct concentration readout devices, preparation of a standard curve will not be necessary. In all cases, follow calibration and operational procedures in the manufacturers' instruction manual.
11.0 Analytical Procedure
11.1 Sample Loss Check. Prior to analysis, check the liquid level in Containers Number 2 and Number 4. Note on the analytical data sheet whether leakage occurred during transport. If a noticeable amount of leakage occurred, either void the sample or take steps, subject to the approval of the Administrator, to adjust the final results.
11.2 Sample Preparation.
11.2.1 Container Number 1 (Filter). Place the filter and loose particulate matter in a 150 ml beaker. Also, add the filtered solid material from Container Number 2 (see Section 11.2.2). Add 50 ml of 0.1 N NaOH. Then stir and warm on a hot plate at low heat (do not boil) for about 15 minutes. Add 10 ml of concentrated HNO3, bring to a boil, then simmer for about 15 minutes. Filter the solution through a glass fiber filter. Wash with hot water, and catch the filtrate in a clean 150 ml beaker. Boil the filtrate, and evaporate to dryness. Cool, add 5 ml of 50 percent HNO3, and then warm and stir. Allow to cool. Transfer to a 50-ml volumetric flask, dilute to volume with water, and mix well.
11.2.2 Container Number 2 (Probe Wash).
11.2.2.1 Filter (using a glass fiber filter) the contents of Container Number 2 into a 200 ml volumetric flask. Combine the filtered (solid) material with the contents of Container Number 1 (Filter).
11.2.2.2 Dilute the filtrate to exactly 200 ml with water. Then pipet 50 ml into a 150 ml beaker. Add 10 ml of concentrated HNO3, bring to a boil, and evaporate to dryness. Allow to cool, add 5 ml of 50 percent HNO3, and then warm and stir. Allow the solution to cool, transfer to a 50-ml volumetric flask, dilute to volume with water, and mix well.
11.2.3 Container Number 4 (Impinger Solution). Transfer the contents of Container Number 4 to a 500 ml volumetric flask, and dilute to exactly 500-ml with water. Pipet 50 ml of the solution into a 150-ml beaker. Add 10 ml of concentrated HNO3, bring to a boil, and evaporate to dryness. Allow to cool, add 5 ml of 50 percent HNO3, and then warm and stir. Allow the solution to cool, transfer to a 50-ml volumetric flask, dilute to volume with water, and mix well.
11.2.4 Filter Blank. Cut each filter into strips, and treat each filter individually as directed in Section 11.2.1, beginning with the sentence, “Add 50 ml of 0.1 N NaOH.”
11.2.5 Sodium Hydroxide and Water Blanks. Treat separately 50 ml of 0.1 N NaOH and 50 ml water, as directed under Section 11.2.3, beginning with the sentence, “Pipet 50 ml of the solution into a 150-ml beaker.”
11.3 Spectrophotometer Preparation. Turn on the power; set the wavelength, slit width, and lamp current. Adjust the background corrector as instructed by the manufacturer's manual for the particular atomic absorption spectrophotometer. Adjust the burner and flame characteristics as necessary.
11.4 Analysis. Calibrate the analytical equipment and develop a calibration curve as outlined in Sections 10.2 through 10.4.
11.4.1 Arsenic Samples. Analyze an appropriately sized aliquot of each diluted sample (from Sections 11.2.1 through 11.2.3) until two consecutive peak heights agree within 3 percent of their average value. If applicable, follow the procedures outlined in Section 11.4.1.1. If the sample concentration falls outside the range of the calibration curve, make an appropriate dilution with 0.8 N HNO3 so that the final concentration falls within the range of the curve. Using the calibration curve, determine the arsenic concentration in each sample fraction.
Note: Because instruments vary between manufacturers, no detailed operating instructions will be given here. Instead, the instrument manufacturer's detailed operating instructions should be followed.
11.4.1.1 Arsenic Determination at Low Concentration. The lower limit of flame AAS is 10 µg As/ml. If the arsenic concentration of any sample is at a lower level, use the graphite furnace or vapor generator which is available as an accessory component. Flame, graphite furnace, or vapor generators may be used for samples whose concentrations are between 10 and 30 µg/ml. Follow the manufacturer's instructions in the use of such equipment.
11.4.1.1.1 Vapor Generator Procedure. Place a sample containing between 0 and 5 µg of arsenic in the reaction tube, and dilute to 15 ml with water. Since there is some trial and error involved in this procedure, it may be necessary to screen the samples by conventional atomic absorption until an approximate concentration is determined. After determining the approximate concentration, adjust the volume of the sample accordingly. Pipet 15 ml of concentrated HCl into each tube. Add 1 ml of 30 percent KI solution. Place the reaction tube into a 50 °C (120 °F) water bath for 5 minutes. Cool to room temperature. Connect the reaction tube to the vapor generator assembly. When the instrument response has returned to baseline, inject 5.0 ml of 5 percent NaBH4, and integrate the resulting spectrophotometer signal over a 30-second time period.
11.4.1.1.2 Graphite Furnace Procedure. Dilute the digested sample so that a 5 ml aliquot contains less than 1.5 µg of arsenic. Pipet 5 ml of this digested solution into a 10-ml volumetric flask. Add 1 ml of the 1 percent nickel nitrate solution, 0.5 ml of 50 percent HNO3, and 1 ml of the 3 percent hydrogen peroxide and dilute to 10 ml with water. The sample is now ready for analysis.
11.4.1.2 Run a blank (0.8 N HNO3) and standard at least after every five samples to check the spectrophotometer calibration. The peak height of the blank must pass through a point no further from the origin than ±2 percent of the recorder full scale. The difference between the measured concentration of the standard (the product of the corrected average peak height and the reciprocal of the least squares slope) and the actual concentration of the standard must be less than 7 percent, or recalibration of the analyzer is required.
11.4.1.3 Determine the arsenic concentration in the filter blank (i.e., the average of the two blank values from each lot).
11.4.2 Container Number 3 (Silica Gel). This step may be conducted in the field. Weigh the spent silica gel (or silica gel plus impinger) to the nearest 0.5 g; record this weight.
11.5 Check for matrix effects on the arsenic results. Same as Method 12, Section 11.5.
11.6 Audit Sample Analysis.
11.6.1 When the method is used to analyze samples to demonstrate compliance with a source emission regulation, a set of EPA audit samples must be analyzed, subject to availability.
11.6.2 Concurrently analyze the audit samples and the compliance samples in the same manner to evaluate the technique of the analyst and the standards preparation.
Note: It is recommended that known quality control samples be analyzed prior to the compliance and audit sample analyses to optimize the system accuracy and precision. These quality control samples may be obtained by contacting the appropriate EPA regional Office or the responsible enforcement authority.
11.6.3 The same analyst, analytical reagents, and analytical system shall be used for the compliance samples and the EPA audit samples. If this condition is met, duplicate auditing of subsequent compliance analyses for the same enforcement agency within a 30-day period is waived. An audit sample set may not be used to validate different sets of compliance samples under the jurisdiction of separate enforcement agencies, unless prior arrangements have been made with both enforcement agencies.
11.7 Audit Sample Results.
11.7.1 Calculate the audit sample concentrations in g/m3 and submit results using the instructions provided with the audit samples.
11.7.2 Report the results of the audit samples and the compliance determination samples along with their identification numbers, and the analyst's name to the responsible enforcement authority. Include this information with reports of any subsequent compliance analyses for the same enforcement authority during the 30-day period.
11.7.3 The concentrations of the audit samples obtained by the analyst shall agree within 10 percent of the actual concentrations. If the 10 percent specification is not met, reanalyze the compliance and audit samples, and include initial and reanalysis values in the test report.
11.7.4 Failure to meet the 10 percent specification may require retests until the audit problems are resolved. However, if the audit results do not affect the compliance or noncompliance status of the affected facility, the Administrator may waive the reanalysis requirement, further audits, or retests and accept the results of the compliance test. While steps are being taken to resolve audit analysis problems, the Administrator may also choose to use the data to determine the compliance or noncompliance status of the affected facility.
12.0 Data Analysis and Calculations
12.1 Nomenclature.
Bws = Water in the gas stream, proportion by volume.
Ca = Concentration of arsenic as read from the standard curve, µg/ml.
Cc = Actual audit concentration, g/m 3 .
Cd = Determined audit concentration, g/m 3 .
Cs = Arsenic concentration in stack gas, dry basis, converted to standard conditions, g/dsm 3 (gr/dscf).
Ea = Arsenic mass emission rate, g/hr (lb/hr).
Fd = Dilution factor (equals 1 if the sample has not been diluted).
I = Percent of isokinetic sampling.
mbi = Total mass of all four impingers and contents before sampling, g.
mfi = Total mass of all four impingers and contents after sampling, g.
mn = Total mass of arsenic collected in a specific part of the sampling train, µg.
mt = Total mass of arsenic collected in the sampling train, µg.
Tm = Absolute average dry gas meter temperature (see Figure 108–2), °K (°R).
Vm = Volume of gas sample as measured by the dry gas meter, dry basis, m 3 (ft 3 ).
Vm(std) = Volume of gas sample as measured by the dry gas meter, corrected to standard conditions, m 3 (ft 3 ).
Vn = Volume of solution in which the arsenic is contained, ml.
Vw(std) = Volume of water vapor collected in the sampling train, corrected to standard conditions, m 3 (ft 3 ).
?H = Average pressure differential across the orifice meter (see Figure 108–2), mm H2O (in. H2O).
12.2 Average Dry Gas Meter Temperatures (Tm) and Average Orifice Pressure Drop (?H). See data sheet (Figure 108–2).
12.3 Dry Gas Volume. Using data from this test, calculate Vm(std) according to the procedures outlined in Method 5, Section 12.3.
12.4 Volume of Water Vapor.
Where:
K2 = 0.001334 m 3 /g for metric units.
= 0.047012 ft 3 /g for English units.
12.5 Moisture Content.
12.6 Amount of Arsenic Collected.
12.6.1 Calculate the amount of arsenic collected in each part of the sampling train, as follows:
12.6.2 Calculate the total amount of arsenic collected in the sampling train as follows:
12.7 Calculate the arsenic concentration in the stack gas (dry basis, adjusted to standard conditions) as follows:
Where:
K3 = 10-6 g/µg for metric units
= 1.54 × 10-5 gr/µg for English units
12.8 Stack Gas Velocity and Volumetric Flow Rate. Calculate the average stack gas velocity and volumetric flow rate using data obtained in this method and the equations in Sections 12.2 and 12.3 of Method 2.
12.9 Pollutant Mass Rate. Calculate the arsenic mass emission rate as follows:
12.10 Isokinetic Variation. Same as Method 5, Section 12.11.
13.0 Method Performance
13.1 Sensitivity. The lower limit of flame AAS 10 µg As/ml. The analytical procedure includes provisions for the use of a graphite furnace or vapor generator for samples with a lower arsenic concentration.
14.0 Pollution Prevention. [Reserved]
15.0 Waste Management. [Reserved]
16.0 References.
Same as References 1 through 9 of Method 5, Section 17.0, with the addition of the following:
1. Perkin Elmer Corporation. Analytical Methods for Atomic Absorption Spectrophotometry. 303–0152. Norwalk, Connecticut. September 1976. pp. 5–6.
2. Standard Specification for Reagent Water. In: Annual Book of American Society for Testing and Materials Standards. Part 31: Water, Atmospheric Analysis. American Society for Testing and Materials. Philadelphia, PA. 1974. pp. 40–42.
3. Stack Sampling Safety Manual (Draft). U.S. Environmental Protection Agency, Office of Air Quality Planning and Standard, Research Triangle Park, NC. September 1978.
17.0 Tables, Diagrams, Flowcharts, and Validation Data
View or download PDF
View or download PDF
Method 108A—Determination of Arsenic Content in Ore Samples From Nonferrous Smelters
Note: This method does not include all of the specifications (e.g., equipment and supplies) and procedures (e.g., sampling and analytical) essential to its performance. Some material is incorporated by reference from other methods in appendix A to 40 CFR part 60. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of Method 12.
1.0 Scope and Application
1.1 Analytes.
------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Arsenic compounds as arsenic 7440-38-2........ Lower limit 10
(As). µg/ml or less.
------------------------------------------------------------------------
1.2 Applicability. This method applies to the determination of inorganic As content of process ore and reverberatory matte samples from nonferrous smelters and other sources as specified in an applicable subpart of the regulations.
1.3 Data Quality Objectives. Adherence to the requirements of this method will enhance the quality of the data obtained from air pollutant sampling methods.
2.0 Summary of Method
Arsenic bound in ore samples is liberated by acid digestion and analyzed by flame atomic absorption spectrophotometry (AAS).
3.0 Definitions [Reserved]
4.0 Interferences
Analysis for As by flame AAS is sensitive to the chemical composition and to the physical properties (e.g., viscosity, pH) of the sample. The analytical procedure includes a check for matrix effects (section 11.5).
5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method may not address all of the safety problems associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to performing this test method.
5.2 Corrosive Reagents. The following reagents are hazardous. Personal protective equipment and safe procedures that prevent chemical splashes are recommended. If contact occurs, immediately flush with copious amounts of water for at least 15 minutes. Remove clothing under shower and decontaminate. Treat residual chemical burns as thermal burns.
5.2.1 Hydrochloric Acid (HCl). Highly corrosive liquid with toxic vapors. Vapors are highly irritating to eyes, skin, nose, and lungs, causing severe damage. May cause bronchitis, pneumonia, or edema of lungs. Exposure to concentrations of 0.13 to 0.2 percent can be lethal to humans in a few minutes. Provide ventilation to limit exposure. Reacts with metals, producing hydrogen gas.
5.2.2 Hydrofluoric Acid (HF). Highly corrosive to eyes, skin, nose, throat, and lungs. Reaction to exposure may be delayed by 24 hours or more. Provide ventilation to limit exposure.
5.2.3 Hydrogen Peroxide (H2O2). Very harmful to eyes. 30% H2O2 can burn skin, nose, and lungs.
5.2.4 Nitric Acid (HNO3). Highly corrosive to eyes, skin, nose, and lungs. Vapors are highly toxic and can cause bronchitis, pneumonia, or edema of lungs. Reaction to inhalation may be delayed as long as 30 hours and still be fatal. Provide ventilation to limit exposure. Strong oxidizer. Hazardous reaction may occur with organic materials such as solvents.
5.2.5 Sodium Hydroxide (NaOH). Causes severe damage to eyes and skin. Inhalation causes irritation to nose, throat, and lungs. Reacts exothermically with limited amounts of water.
6.0 Equipment and Supplies
6.1 Sample Collection and Preparation. The following items are required for sample collection and preparation:
6.1.1 Parr Acid Digestion Bomb. Stainless steel with vapor-tight Teflon cup and cover.
6.1.2 Volumetric Pipets. 2- and 5-ml sizes.
6.1.3 Volumetric Flask. 50-ml polypropylene with screw caps, (one needed per standard).
6.1.4 Funnel. Polyethylene or polypropylene.
6.1.5 Oven. Capable of maintaining a temperature of approximately 105 °C (221 °F).
6.1.6 Analytical Balance. To measure to within 0.1 mg.
6.2 Analysis. The following items are required for analysis:
6.2.1 Spectrophotometer and Recorder. Equipped with an electrodeless discharge lamp and a background corrector to measure absorbance at 193.7 nm. For measuring samples having less than 10 µg As/ml, use a graphite furnace or vapor generator accessory. The recorder shall match the output of the spectrophotometer.
6.2.2 Volumetric Flasks. Class A, 50-ml (one needed per sample and blank), 500-ml, and 1-liter.
6.2.3 Volumetric Pipets. Class A, 1-, 5-, 10-, and 25-ml sizes.
7.0 Reagents and Standards.
Unless otherwise indicated, it is intended that all reagents conform to the specifications established by the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available; otherwise, use the best available grade.
7.1 Sample Collection and Preparation. The following reagents are required for sample collection and preparation:
7.1.1 Water. Deionized distilled to meet ASTM D 1193–77 or 91 Type 3 (incorporated by reference—See §61.18). When high concentrations of organic matter are not expected to be present, the KMnO4 test for oxidizable organic matter may be omitted. Use in all dilutions requiring water.
7.1.2 Nitric Acid Concentrated.
7.1.3 Nitric Acid, 0.5 N. In a 1-liter volumetric flask containing water, add 32 ml of concentrated HNO3 and dilute to volume with water.
7.1.4 Hydrofluoric Acid, Concentrated.
7.1.5 Potassium Chloride (KCl) Solution, 10 percent weight by volume (W/V). Dissolve 10 g KCl in water, add 3 ml concentrated HNO3, and dilute to 100 ml.
7.1.6 Filter. Teflon filters, 3-micron porosity, 47-mm size. (Available from Millipore Co., type FS, Catalog Number FSLW04700.)
7.1.7 Sodium Borohydride (NaBH4), 5 Percent (W/V). Dissolve 50.0 g of NaBH4 in about 500 ml of 0.1 N NaOH in a 1-liter volumetric flask. Then, dilute to exactly 1.0 liter with 0.1 N NaOH.
7.1.8 Nickel Nitrate, 5 Percent Ni (W/V). Dissolve 24.780 g of nickel nitrate hexahydrate [Ni(NO3)2 6H2O] in water in a 100-ml volumetric flask, and dilute to 100 ml with water.
7.1.9 Nickel Nitrate, 1 Percent Ni (W/V). Pipet 20 ml of 5 percent nickel nitrate solution into a 100-ml volumetric flask, and dilute to 100 ml with water.
7.2 Analysis. The following reagents and standards are required for analysis:
7.2.1 Water. Same as in Section 7.1.1.
7.2.2 Sodium Hydroxide, 0.1 N. Dissolve 2.00 g of NaOH in water in a 500-ml volumetric flask. Dilute to volume with water.
7.2.3 Nitric Acid, 0.5 N. Same as in Section 7.1.3.
7.2.4 Potassium Chloride Solution, 10 percent. Same as in Section 7.1.5.
7.2.5 Hydrochloric Acid, Concentrated.
7.2.6 Potassium Iodide (KI), 30 Percent (W/V). Dissolve 300 g of KI in about 500 ml of water in a 1-liter volumetric flask. Then, dilute to exactly 1.0 liter with water.
7.2.7 Hydrogen Peroxide, 3 Percent by Volume. Pipet 50 ml of 30 percent H2O2 into a 500-ml volumetric flask, and dilute to exactly 500 ml with water.
7.2.8 Stock Arsenic Standard, 1 mg As/ml. Dissolve 1.3203 g of primary grade As2O3 in 20 ml of 0.1 N NaOH. Slowly add 30 ml of concentrated HNO3, and heat in an oven at 105 °C (221 °F) for 2 hours. Allow to cool, and dilute to 1 liter with deionized distilled water.
7.2.9 Nitrous Oxide. Suitable quality for AAS analysis.
7.2.10 Acetylene. Suitable quality for AAS analysis.
7.2.11 Quality Assurance Audit Samples. When making compliance determinations, and upon availability, audit samples may be obtained from the appropriate EPA regional Office or from the responsible enforcement authority.
Note: The responsible enforcement authority should be notified at least 30 days prior to the test date to allow sufficient time for sample delivery.
8.0 Sample Collection, Preservation, Transport, and Storage
8.1 Sample Collection. A sample that is representative of the ore lot to be tested must be taken prior to analysis. (A portion of the samples routinely collected for metals analysis may be used provided the sample is representative of the ore being tested.)
8.2 Sample Preparation. The sample must be ground into a finely pulverized state.
9.0 Quality Control
------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
10.2.......................... Spectrophotometer Ensure linearity of
calibration. spectrophotometer
response to
standards.
11.5.......................... Check for matrix Eliminate matrix
effects. effects
11.6.......................... Audit sample Evaluate analyst's
analysis. technique and
standards
preparation.
------------------------------------------------------------------------
10.0 Calibration and Standardizations
Note: Maintain a laboratory log of all calibrations.
10.1 Preparation of Standard Solutions. Pipet 1, 5, 10, and 25 ml of the stock As solution into separate 100-ml volumetric flasks. Add 10 ml KCl solution and dilute to the mark with 0.5 N HNO3. This will give standard concentrations of 10, 50, 100, and 250 µg As/ml. For low-level arsenic samples that require the use of a graphite furnace or vapor generator, follow the procedures in Section 11.3:1. Dilute 10 ml of KCl solution to 100 ml with 0.5 N HNO3 and use as a reagent blank.
10.2 Calibration Curve. Analyze the reagent blank and each standard solution according to the procedures outlined in Section 11.3. Repeat this procedure on each standard solution until two consecutive peaks agree within 3 percent of their average value. Subtract the average peak height (or peak area) of the blank—which must be less than 2 percent of recorder full scale—from the averaged peak heights of each standard solution. If the blank absorbance is greater than 2 percent of full-scale, the probable cause is Hg contamination of a reagent or carry-over of As from a previous sample. Prepare the calibration curve by plotting the corrected peak height of each standard solution versus the corresponding final total As weight in the solution.
10.3 Spectrophotometer Calibration Quality Control. Calculate the least squares slope of the calibration curve. The line must pass through the origin or through a point no further from the origin than ±2 percent of the recorder full scale. Multiply the corrected peak height by the reciprocal of the least squares slope to determine the distance each calibration point lies from the theoretical calibration line. The difference between the calculated concentration values and the actual concentrations must be less than 7 percent for all standards.
Note: For instruments equipped with direct concentration readout devices, preparation of a standard curve will not be necessary. In all cases, follow calibration and operational procedures in the manufacturer's instruction manual.
11.0 Analytical Procedure
11.1 Sample Preparation. Weigh 50 to 500 mg of finely pulverized sample to the nearest 0.1 mg. Transfer the sample into the Teflon cup of the digestion bomb, and add 2 ml each of concentrated HNO3 and HF. Seal the bomb immediately to prevent the loss of any volatile arsenic compounds that may form. Heat in an oven at 105 °C (221 °F) for 2 hours. Remove the bomb from the oven and allow to cool. Using a Teflon filter, quantitatively filter the digested sample into a 50-ml polypropylene volumetric flask. Rinse the bomb three times with small portions of 0.5 N HNO3, and filter the rinses into the flask. Add 5 ml of KCl solution to the flask, and dilute to 50 ml with 0.5 N HNO3.
11.2 Spectrophotometer Preparation.
11.2.1 Turn on the power; set the wavelength, slit width, and lamp current. Adjust the background corrector as instructed by the manufacturer's manual for the particular atomic absorption spectrophotometer. Adjust the burner and flame characteristics as necessary.
11.2.2 Develop a spectrophotometer calibration curve as outlined in Sections 10.2 and 10.3.
11.3 Arsenic Determination. Analyze an appropriately sized aliquot of each diluted sample (from Section 11.1) until two consecutive peak heights agree within 3 percent of their average value. If applicable, follow the procedures outlined in Section 11.3.1. If the sample concentration falls outside the range of the calibration curve, make an appropriate dilution with 0.5 N HNO3 so that the final concentration falls within the range of the curve. Using the calibration curve, determine the As concentration in each sample.
Note: Because instruments vary between manufacturers, no detailed operating instructions will be given here. Instead, the instrument manufacturer's detailed operating instructions should be followed.
11.3.1 Arsenic Determination at Low Concentration. The lower limit of flame AAS is 10 µg As/ml. If the arsenic concentration of any sample is at a lower level, use the vapor generator or graphite furnace which is available as an accessory component. Flame, graphite furnace, or vapor generators may be used for samples whose concentrations are between 10 and 30 µg/ml. Follow the manufacturer's instructions in the use of such equipment.
11.3.1.1 Vapor Generator Procedure. Place a sample containing between 0 and 5 µg of arsenic in the reaction tube, and dilute to 15 ml with water. Since there is some trial and error involved in this procedure, it may be necessary to screen the samples by conventional AAS until an approximate concentration is determined. After determining the approximate concentration, adjust the volume of the sample accordingly. Pipet 15 ml of concentrated HCl into each tube. Add 1 ml of 30 percent KI solution. Place the reaction tube into a 50 °C (120 °F) water bath for 5 minutes. Cool to room temperature. Connect the reaction tube to the vapor generator assembly. When the instrument response has returned to baseline, inject 5.0 ml of 5 percent NaBH4 and integrate the resulting spectrophotometer signal over a 30-second time period.
11.3.1.2 Graphite Furnace Procedure. Pipet 5 ml of the digested solution into a 10-ml volumetric flask. Add 1 ml of the 1 percent nickel nitrate solution, 0.5 ml of 50 percent HNO3, and 1 ml of the 3 percent H2O2, and dilute to 10 ml with water. The sample is now ready to inject in the furnace for analysis.
11.4 Run a blank and standard at least after every five samples to check the spectrophotometer calibration. The peak height of the blank must pass through a point no further from the origin than ±2 percent of the recorder full scale. The difference between the measured concentration of the standard (the product of the corrected average peak height and the reciprocal of the least squares slope) and the actual concentration of the standard must be less than 7 percent, or recalibration of the analyzer is required.
11.5 Mandatory Check for Matrix Effects on the Arsenic Results. Same as Method 12, Section 11.5.
11.6 Audit Sample Analysis.
11.6.1 When the method is used to analyze samples to demonstrate compliance with a source emission regulation, a set of EPA audit samples must be analyzed, subject to availability.
11.6.2 Concurrently analyze the audit samples and the compliance samples in the same manner to evaluate the technique of the analyst and the standards preparation.
Note: It is recommended that known quality control samples be analyzed prior to the compliance and audit sample analyses to optimize the system accuracy and precision. These quality control samples may be obtained by contacting the appropriate EPA regional Office or the responsible enforcement authority.
11.6.3 The same analyst, analytical reagents, and analytical system shall be used for the compliance samples and the EPA audit samples. If this condition is met, duplicate auditing of subsequent compliance analyses for the same enforcement agency within a 30-day period is waived. An audit sample set may not be used to validate different sets of compliance samples under the jurisdiction of separate enforcement agencies, unless prior arrangements have been made with both enforcement agencies.
11.7 Audit Sample Results.
11.7.1 Calculate the audit sample concentrations in g/m 3 and submit results using the instructions provided with the audit samples.
11.7.2 Report the results of the audit samples and the compliance determination samples along with their identification numbers, and the analyst's name to the responsible enforcement authority. Include this information with reports of any subsequent compliance analyses for the same enforcement authority during the 30-day period.
11.7.3 The concentrations of the audit samples obtained by the analyst shall agree within 10 percent of the actual concentrations. If the 10 percent specification is not met, reanalyze the compliance and audit samples, and include initial and reanalysis values in the test report.
11.7.4 Failure to meet the 10 percent specification may require retests until the audit problems are resolved. However, if the audit results do not affect the compliance or noncompliance status of the affected facility, the Administrator may waive the reanalysis requirement, further audits, or retests and accept the results of the compliance test. While steps are being taken to resolve audit analysis problems, the Administrator may also choose to use the data to determine the compliance or noncompliance status of the affected facility.
12.0 Data Analysis and Calculations
12.1 Calculate the percent arsenic in the ore sample as follows:
Where:
Ca = Concentration of As as read from the standard curve, µg/ml.
Fd = Dilution factor (equals to 1 if the sample has not been diluted).
W = Weight of ore sample analyzed, mg.
5 = (50 ml sample “ 100)/(10 3 µg/mg).
13.0 Method Performance
13.1 Sensitivity. The lower limit of flame AAS is 10 µg As/ml. The analytical procedure includes provisions for the use of a graphite furnace or vapor generator for samples with a lower arsenic concentration.
14.0 Pollution Prevention. [Reserved]
15.0 Waste Management. [Reserved]
16.0 References
Same as References 1 through 9 of Section 17.0 of Method 5, with the addition of the following:
1. Perkin Elmer Corporation. Analytical Methods of Atomic Absorption Spectrophotometry. 303–0152. Norwalk, Connecticut. September 1976. pp 5–6.
2. Ringwald, D. Arsenic Determination on Process Materials from ASARCO's Copper Smelter in Tacoma, Washington. Unpublished Report. Prepared for Emission Measurement Branch, Emission Standards and Engineering Division, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina. August 1980. 35 pp.
3. Stack Sampling Safety Manual (Draft). U.S. Environmental Protection Agency, Office of Air Quality Planning and Standard, Research Triangle Park, NC. September 1978.
17.0 Tables, Diagrams, Flowcharts, and Validation Data. [Reserved]
Method 108B—Determination of Arsenic Content in Ore Samples From Nonferrous Smelters
Note: This method does not include all of the specifications (e.g., equipment and supplies) and procedures (e.g., sampling and analytical) essential to its performance. Some material is incorporated by reference from other methods in this appendix and in appendix A to 40 CFR part 60. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of at least the following additional test methods: Method 12 and Method 108A.
1.0 Scope and Application
1.1 Analytes.
------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Arsenic compounds as arsenic 7440-38-2........ Lower limit 10
(As). µg/ml.
------------------------------------------------------------------------
1.2 Applicability. This method applies to the determination of inorganic As content of process ore and reverberatory matte samples from nonferrous smelters and other sources as specified in an applicable subpart of the regulations. Samples resulting in an analytical concentration greater than 10 µg As/ml may be analyzed by this method. For lower level arsenic samples, Method 108C should be used.
1.3 Data Quality Objectives. Adherence to the requirements of this method will enhance the quality of the data obtained from air pollutant sampling methods.
2.0 Summary of Method
Arsenic bound in ore samples is liberated by acid digestion and analyzed by flame atomic absorption spectrophotometry (AAS).
3.0 Definitions [Reserved]
4.0 Interferences
Analysis for As by flame AAS is sensitive to the chemical composition and to the physical properties (e.g., viscosity, pH) of the sample. The analytical procedure includes a check for matrix effects (Section 11.4).
5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method may not address all of the safety problems associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to performing this test method.
5.2 Corrosive Reagents. The following reagents are hazardous. Personal protective equipment and safe procedures that prevent chemical splashes are recommended. If contact occurs, immediately flush with copious amounts of water for at least 15 minutes. Remove clothing under shower and decontaminate. Treat residual chemical burns as thermal burns.
5.2.1 Hydrochloric acid (HCl). Highly corrosive liquid with toxic vapors. Vapors are highly irritating to eyes, skin, nose, and lungs, causing severe damage. May cause bronchitis, pneumonia, or edema of lungs. Exposure to concentrations of 0.13 to 0.2 percent can be lethal to humans in a few minutes. Provide ventilation to limit exposure. Reacts with metals, producing hydrogen gas.
5.2.2 Hydrofluoric Acid (HF). Highly corrosive to eyes, skin, nose, throat, and lungs. Reaction to exposure may be delayed by 24 hours or more. Provide ventilation to limit exposure.
5.2.3 Nitric Acid (HNO3). Highly corrosive to eyes, skin, nose, and lungs. Vapors are highly toxic and can cause bronchitis, pneumonia, or edema of lungs. Reaction to inhalation may be delayed as long as 30 hours and still be fatal. Provide ventilation to limit exposure. Strong oxidizer. Hazardous reaction may occur with organic materials such as solvents.
5.2.4 Perchloric Acid (HClO4). Corrosive to eyes, skin, nose, and throat. Provide ventilation to limit exposure. Very strong oxidizer. Keep separate from water and oxidizable materials to prevent vigorous evolution of heat, spontaneous combustion, or explosion. Heat solutions containing HClO4 only in hoods specifically designed for HClO4.
6.0 Equipment and Supplies
6.1 Sample Preparation. The following items are required for sample preparation:
6.1.1 Teflon Beakers. 150-ml.
6.1.2 Graduated Pipets. 5-ml disposable.
6.1.3 Graduated Cylinder. 50-ml.
6.1.4 Volumetric Flask. 100-ml.
6.1.5 Analytical Balance. To measure within 0.1 mg.
6.1.6 Hot Plate.
6.1.7 Perchloric Acid Fume Hood.
6.2 Analysis. The following items are required for analysis:
6.2.1 Spectrophotometer. Equipped with an electrodeless discharge lamp and a background corrector to measure absorbance at 193.7 nm.
6.2.2 Beaker and Watch Glass. 400-ml.
6.2.3 Volumetric Flask. 1-liter.
6.2.4 Volumetric Pipets. 1-, 5-, 10-, and 25-ml.
7.0 Reagents and Standards
Unless otherwise indicated, it is intended that all reagents conform to the specifications established by the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available; otherwise, use the best available grade.
7.1 Sample Preparation. The following reagents are required for sample preparation:
7.1.1 Water. Deionized distilled to meet ASTM D 1193–77 or 91 Type 3 (incorporated by reference—see §61.18).
7.1.2 Nitric Acid, Concentrated.
7.1.3 Hydrofluoric Acid, Concentrated.
7.1.4 Perchloric Acid, 70 Percent.
7.1.5 Hydrochloric Acid, Concentrated.
7.2 Analysis. The following reagents and standards are required for analysis:
7.2.1 Water. Same as in Section 7.1.1.
7.2.2 Stock Arsenic Standard, 1.0 mg As/ml. Dissolve 1.3203 g of primary grade As203 [dried at 105 °C (221 °F)] in a 400-ml beaker with 10 ml of HNO3 and 5 ml of HCl. Cover with a watch glass, and heat gently until dissolution is complete. Add 10 ml of HNO3 and 25 ml of HClO4, evaporate to strong fumes of HClO4, and reduce to about 20 ml volume. Cool, add 100 ml of water and 100 ml of HCl, and transfer quantitatively to a 1-liter volumetric flask. Dilute to volume with water and mix.
7.2.3 Acetylene. Suitable quality for AAS analysis.
7.2.4 Air. Suitable quality for AAS analysis.
7.2.5 Quality Assurance Audit Samples. Same as in Method 108A, Section 7.2.11.
8.0 Sample Collection, Preservation, Transport, and Storage
Same as in Method 108A, Sections 8.1 and 8.2.
9.0 Quality Control
------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
10.2.......................... Spectrophotometer Ensure linearity of
calibration. spectrophotometer
response to
standards.
11.4.......................... Check for matrix Eliminate matrix
effects. effects.
11.5.......................... Audit sample Evaluate analyst's
analysis. technique and
standards
preparation.
------------------------------------------------------------------------
10.0 Calibration and Standardization
Note: Maintain a laboratory log of all calibrations.
10.1 Preparation of Standard Solutions. Pipet 1, 5, 10, and 25 ml of the stock As solution into separate 100-ml volumetric flasks. Add 2 ml of HClO4, 10 ml of HCl, and dilute to the mark with water. This will provide standard concentrations of 10, 50, 100, and 250 µg As/ml.
10.2 Calibration Curve and Spectrophotometer Calibration Quality Control. Same as Method 108A, Sections 10.2 and 10.3
11.0 Analytical Procedure
11.1 Sample Preparation. Weigh 100 to 1000 mg of finely pulverized sample to the nearest 0.1 mg. Transfer the sample to a 150-ml Teflon beaker. Dissolve the sample by adding 15 ml of HNO3, 10 ml of HCl, 10 ml of HF, and 10 ml of HClO4 in the exact order as described, and let stand for 10 minutes. In a HClO4 fume hood, heat on a hot plate until 2–3 ml of HClO4 remain, then cool. Add 20 ml of water and 10 ml of HCl. Cover and warm until the soluble salts are in solution. Cool, and transfer quantitatively to a 100-ml volumetric flask. Dilute to the mark with water.
11.2 Spectrophotometer Preparation. Same as in Method 108A, Section 11.2.
11.3 Arsenic Determination. If the sample concentration falls outside the range of the calibration curve, make an appropriate dilution with 2 percent HClO4/10 percent HCl (prepared by diluting 2 ml concentrated HClO4 and 10 ml concentrated HCl to 100 ml with water) so that the final concentration falls within the range of the curve. Using the calibration curve, determine the As concentration in each sample.
Note: Because instruments vary between manufacturers, no detailed operating instructions will be given here. Instead, the instrument manufacturer's detailed operating instructions should be followed.
Run a blank and standard at least after every five samples to check the spectrophotometer calibration. The peak height of the blank must pass through a point no further from the origin than ±2 percent of the recorder full scale. The difference between the measured concentration of the standard (the product of the corrected average peak height and the reciprocal of the least squares slope) and the actual concentration of the standard must be less than 7 percent, or recalibration of the analyzer is required.
11.4 Mandatory Check for Matrix Effects on the Arsenic Results. Same as Method 12, Section 11.5.
11.5 Audit Sample Analysis. Same as in Method 108A, Section 11.6.
12.0 Data Analysis and Calculations
Same as in Method 108A, Section 12.0.
13.0 Method Performance
13.1 Sensitivity. The lower limit of flame AAS is 10 µg As/ml.
14.0 Pollution Prevention [Reserved]
15.0 Waste Management [Reserved]
16.0 References
Same as in Method 108A, Section 16.0.
17.0 Tables, Diagrams, Flowcharts, and Validation Data [Reserved]
Method 108C—Determination of Arsenic Content in Ore Samples From Nonferrous Smelters (Molybdenum Blue Photometric Procedure)
Note: This method does not include all of the specifications (e.g., equipment and supplies) and procedures (e.g., sampling and analytical) essential to its performance. Some material is incorporated by reference from other methods in this part. Therefore, to obtain reliable results, persons using this method should have a thorough knowledge of at least Method 108A.
1.0 Scope and Application
1.1 Analytes.
------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Arsenic compounds as arsenic 7440-38-2........ Lower limit 0.0002
(As). percent As by
weight.
------------------------------------------------------------------------
1.2 Applicability. This method applies to the determination of inorganic As content of process ore and reverberatory matte samples from nonferrous smelters and other sources as specified in an applicable subpart of the regulations.
1.3 Data Quality Objectives. Adherence to the requirements of this method will enhance the quality of the data obtained from air pollutant sampling methods.
2.0 Summary of Method
Arsenic bound in ore samples is liberated by acid digestion and analyzed by the molybdenum blue photometric procedure.
3.0 Definitions. [Reserved]
4.0 Interferences. [Reserved]
5.0 Safety
5.1 Disclaimer. This method may involve hazardous materials, operations, and equipment. This test method may not address all of the safety problems associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to performing this test method.
5.2 Corrosive Reagents. The following reagents are hazardous. Personal protective equipment and safe procedures that prevent chemical splashes are recommended. If contact occurs, immediately flush with copious amounts of water for at least 15 minutes. Remove clothing under shower and decontaminate. Treat residual chemical burns as thermal burns.
5.2.1 Hydrochloric Acid (HCl). Highly corrosive liquid with toxic vapors. Vapors are highly irritating to eyes, skin, nose, and lungs, causing severe damage. May cause bronchitis, pneumonia, or edema of lungs. Exposure to concentrations of 0.13 to 0.2 percent can be lethal to humans in a few minutes. Provide ventilation to limit exposure. Reacts with metals, producing hydrogen gas.
5.2.2 Hydrofluoric Acid (HF). Highly corrosive to eyes, skin, nose, throat, and lungs. Reaction to exposure may be delayed by 24 hours or more. Provide ventilation to limit exposure.
5.2.3 Nitric Acid (HNO4). Highly corrosive to eyes, skin, nose, and lungs. Vapors are highly toxic and can cause bronchitis, pneumonia, or edema of lungs. Reaction to inhalation may be delayed as long as 30 hours and still be fatal. Provide ventilation to limit exposure. Strong oxidizer. Hazardous reaction may occur with organic materials such as solvents.
5.2.4 Perchloric Acid (HClO4). Corrosive to eyes, skin, nose, and throat. Provide ventilation to limit exposure. Very strong oxidizer. Keep separate from water and oxidizable materials to prevent vigorous evolution of heat, spontaneous combustion, or explosion. Heat solutions containing HClO4 only in hoods specifically designed for HClO4.
5.2.5 Sulfuric acid (H2SO4). Rapidly destructive to body tissue. Will cause third degree burns. Eye damage may result in blindness. Inhalation may be fatal from spasm of the larynx, usually within 30 minutes. May cause lung tissue damage with edema. 3 mg/m 3 will cause lung damage in uninitiated. 1 mg/m 3 for 8 hours will cause lung damage or, in higher concentrations, death. Provide ventilation to limit inhalation. Reacts violently with metals and organics.
6.0 Equipment and Supplies
6.1 Sample Preparation. The following items are required for sample preparation:
6.1.1 Analytical Balance. To measure to within 0.1 mg.
6.1.2 Erlenmeyer Flask. 300-ml.
6.1.3 Hot Plate.
6.1.4 Distillation Apparatus. No. 6, in ASTM E 50–82, 86, or 90 (Reapproved 1995)(incorporated by reference—see §61.18); detailed in Figure 108C–1.
6.1.5 Graduated Cylinder. 50-ml.
6.1.6 Perchloric Acid Fume Hood.
6.2 Analysis. The following items are required for analysis:
6.2.1 Spectrophotometer. Capable of measuring at 660 nm.
6.2.2 Volumetric Flasks. 50- and 100-ml.
7.0 Reagents and Standards
Unless otherwise indicated, it is intended that all reagents conform to the specifications established by the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available; otherwise, use the best available grade.
7.1 Sample Preparation. The following reagents are required for sample preparation:
7.1.1 Water. Deionized distilled to meet ASTM D 1193–77 or 91 Type 3 (incorporated by reference—see §61.18). When high concentrations of organic matter are not expected to be present, the KMnO4 test for oxidizable organic matter may be omitted. Use in all dilutions requiring water.
7.1.2 Nitric Acid, Concentrated.
7.1.3 Hydrofluoric Acid, Concentrated.
7.1.4 Sulfuric Acid, Concentrated.
7.1.5 Perchloric Acid, 70 Percent.
7.1.6 Hydrochloric Acid, Concentrated.
7.1.7 Dilute Hydrochloric Acid. Add one part concentrated HCl to nine parts water.
7.1.8 Hydrazine Sulfate ((NH2)2·H2SO4).
7.1.9 Potassium Bromide (KBr).
7.1.10 Bromine Water, Saturated.
7.2 Analysis. The following reagents and standards are required for analysis:
7.2.1 Water. Same as in Section 7.1.1.
7.2.2 Methyl Orange Solution, 1 g/liter.
7.2.3 Ammonium Molybdate Solution, 5 g/liter. Dissolve 0.5 g (NH4)Mo7O24·4H2O in water in a 100-ml volumetric flask, and dilute to the mark. This solution must be freshly prepared.
7.2.4 Standard Arsenic Solution, 10 µg As/ml. Dissolve 0.13203 g of As2O3 in 100 ml HCl in a 1-liter volumetric flask. Add 200 ml of water, cool, dilute to the mark with water, and mix. Transfer 100 ml of this solution to a 1-liter volumetric flask, add 40 ml HCl, cool, dilute to the mark, and mix.
7.2.5 Hydrazine Sulfate Solution, 1 g/liter. Dissolve 0.1 g of [(NH2)2·H2SO4] in water, and dilute to 100 ml in a volumetric flask. This solution must be freshly prepared.
7.2.6 Potassium Bromate (KBrO3) Solution, 0.03 Percent Weight by Volume (W/V). Dissolve 0.3 g KBrO3 in water, and dilute to 1 liter with water. (continued)