1, perform initial tests to determine appropriate GC conditions that

provide good resolution and minimum analysis time for the compounds of interest. 6.1.3 Preparation of Presurvey Samples. If the samples were collected on an adsorbent, extract the sample as recommended by the manufacturer for removal of the compounds with a solvent suitable to the type of GC analysis. Prepare other samples in an appropriate manner. 6.1.4 Presurvey Sample Analysis. Before analysis, heat the presurvey sample to the duct temperature to vaporize any condensed material. Analyze the samples by the GC procedure, and compare the retention times against those of the calibration samples that contain the components expected to be in the stream. If any compounds cannot be identified with certainty by this procedure, identify them by other means such as GC/mass spectroscopy (GC/MS) or GC/infrared techniques. A GC/MS system is recommended. Use the GC conditions determined by the procedure of Section 6.1.2 for the first injection. Vary the GC parameters during subsequent injections to determine the optimum settings. Once the optimum settings have been determined, perform repeat injections of the sample to determine the retention time of each compound. To inject a sample, draw sample through the loop at a constant rate (100 ml/min for 30 seconds). Be careful not to pressurize the gas in the loop. Turn off the pump and allow the gas in the sample loop to come to ambient pressure. Activate the sample valve, and record injection time, loop temperature, column temperature, carrier flow rate, chart speed, and attenuator setting. Calculate the retention time of each peak using the distance from injection to the peak maximum divided by the chart speed. Retention times should be repeatable within 0.5 seconds. If the concentrations are too high for appropriate detector response, a smaller sample loop or dilutions may be used for gas samples, and, for liquid samples, dilution with solvent is appropriate. Use the standard curves (Section 6.3) to obtain an estimate of the concentrations. Identify all peaks by comparing the known retention times of compounds expected to be in the retention times of peaks in the sample. Identify any remaining unidentified peaks which have areas larger than 5 percent of the total using a GC/MS, or estimation of possible compounds by their retention times compared to known compounds, with confirmation by further GC analysis. 6.2 Calibration Standards. Prepare or obtain enough calibration standards so that there are three different concentrations of each organic compound expected to be measured in the source sample. For each organic compound, select those concentrations that bracket the concentrations expected in the source samples. A calibration standard may contain more than one organic compound. If available, commercial cylinder gases may be used if their concentrations have been certified by direct analysis. If samples are collected in adsorbent tubes (charcoal, XAD-2, Tenax, etc.), prepare or obtain standards in the same solvent used for the sample extraction procedure. Refer to Section 7.4.3. Verify the stability of all standards for the time periods they are used. If gas standards are prepared in the laboratory, use one or more of the following EMTIC M-18 EMTIC NSPS Test Method Page 5 purged and filled with duct gases, open the stopcock to the grab flask until the pressure in the flask reaches duct pressure. Close off the stopcock, and remove the probe from the duct. Remove the tee from the flask and tape the stopcocks to prevent leaks during shipment. Measure and record the duct temperature and pressure. 5.3.1.2 Purged Flask Procedure. Attach one end of the sampling flask to a rubber suction bulb. Attach the other end to a 6-mm OD glass probe as described in Section 5.3.1.1. Place the filter end of the probe at the centroid of the duct, or at a point no closer to the walls than 1 m, and apply suction with the bulb to completely purge the probe and flask. After the flask has been purged, close off the stopcock near the suction bulb, and then close off the stopcock near the probe. Remove the probe from the duct, and disconnect both the probe and suction bulb. Tape the stopcocks to prevent leakage during shipment. Measure and record the duct temperature and pressure. 5.3.2 Flexible Bag Procedure. Tedlar or aluminized Mylar bags can also be used to obtain the presurvey sample. Use new bags, and leak check them before field use. In addition, check the bag before use for contamination by filling it with nitrogen or air, and analyzing the gas by GC at high sensitivity. Experience indicates that it is desirable to allow the inert gas to remain in the bag about 24 hours or longer to check for desorption of organics from the bag. Follow the leak-check and sample collection procedures given in Section 7.1. 5.3.3 Determination of Moisture Content. For combustion or water- controlled processes, obtain the moisture content from plant personnel or by measurement during the presurvey. If the source is below 59°C, measure the wet bulb and dry bulb temperatures, and calculate the moisture content using a psychrometric chart. At higher temperatures, use Method 4 to determine the moisture content. 5.4 Determination of Static Pressure. Obtain the static pressure from the plant personnel or measurement. If a type S pitot tube and an inclined manometer are used, take care to align the pitot tube 90° from the direction of the flow. Disconnect one of the tubes to the manometer, and read the static pressure; note whether the reading is positive or negative. 5.5 Collection of Presurvey Samples with Adsorption Tube. Follow Section 7.4 for presurvey sampling. 6. ANALYSIS DEVELOPMENT 6.1 Selection of GC Parameters. 6.1.1 Column Choice. Based on the initial contact with plant personnel concerning the plant process and the anticipated emissions, choose a column that. provides good resolution and rapid analysis time. The choice of an appropriate column can be aided by a literature search, contact with manufacturers of GC columns, and discussion with personnel at the emission source. Most column manufacturers keep excellent records on their products. Their technical service departments may be able to recommend appropriate columns and detector type for separating the anticipated compounds, and they may be able to provide information on interferences, optimum operating conditions, and column limitations. Plants with analytical laboratories may be able to provide information on their EMTIC M-18 EMTIC NSPS Test Method Page 4 5.2 Reagents. 5.2.1 Water. Deionized distilled. 5.2.2 Methylene Dichloride. 5.2.3 Calibration Gases. A series of standards prepared for every compound of interest. 5.2.4 Organic Compound Solutions. Pure (99.9 percent), or a S pure as can reasonably be obtained, liquid samples of all the organic compounds needed to prepare calibration standards. 5.2.5 Extraction Solvents. For extraction of adsorbent tube samples in preparation for analysis. 5.2.6 Fuel. As recommended by the manufacturer for operation of the GC. 5.2.7 Carrier Gas. Hydrocarbon free, as recommended by the manufacturer for operation of the detector and compatibility with the column. 5.2.8 Zero Gas. Hydrocarbon free air or nitrogen, to be used for dilutions, blank preparation, and standard preparation. 5.3 Sampling. 5.3.1 Collection of Samples with Glass Sampling Flasks. Presurvey samples can be collected in precleaned 250-ml double-ended glass sampling flasks. Teflon stopcocks, without grease, are preferred. Flasks should be cleaned as follows: Remove the stopcocks from both ends of the flasks, and wipe the parts to remove any grease. Clean the stopcocks, barrels, and receivers with methylene dichloride. Clean all glass ports with a soap solution, then rinse with tap and deionized distilled water. Place the flask in a cool glass annealing furnace, and apply heat up to 500°C. Maintain at this temperature for 1 hours. After this time period, shut off and open the furnace to allow the flask to cool. Grease the stopcocks with stopcock grease, and return them to the flask receivers. Purge the assembly with high- purity nitrogen for 2 to 5 minutes. Close off the stopcocks after purging to maintain a slight positive nitrogen pressure. Secure the stopcocks with tape. Presurvey samples can be obtained either by drawing the gases into the previously evacuated flask or by drawing the gases into and purging the flask with a rubber suction bulb. 5.3.1.1 Evacuated Flask Procedure. Use a high-vacuum pump to evacuate the flask to the capacity of the pump; then close off the stopcock leading to the pump. Attach a 6-mm outside diameter (OD) glass tee to the flask inlet with a short piece of Teflon tubing. Select a 6-mm OD borosilicate sampling probe, enlarged at one end to a 12-mm OD and of sufficient length to reach the centroid of the duct to be sampled. Insert a glass wool plug in the enlarged end of the probe to remove particulate matter. Attach the other end of the probe to the tee with a short piece of Teflon tubing. Connect a rubber suction bulb to the third leg of the tee. Place the filter end of the probe at the centroid of the duct, and purge the probe with the rubber suction bulb. After the probe is completely EMTIC M-18 EMTIC NSPS Test Method Page 3 constitute endorsement by the U.S. Environmental Protection Agency.) Diameter and length determined by connection requirements of cylinder regulators and the GC. Additional tubing is necessary to connect the GC sample loop to the sample. 5.1.2 Gas Chromatograph. GC with suitable detector, columns, temperature-controlled sample loop and valve assembly, and temperature programmable oven, if necessary. The GC shall achieve sensitivity requirements for the compounds under study. 5.1.3 Pump. Capable of pumping 100 ml/min. For flushing sample loop. 5.1.4 Flow Meter. To measure flow rates. 5.1.5 Regulators. Used on gas cylinders for GC and for cylinder standards. 5.1.6 Recorder. Recorder with linear strip chart is minimum acceptable. Integrator (optional) is recommended. 5.1.7 Syringes. 0.5-ml, 1.0- and 10-microliter size, calibrated, maximum accuracy (gas tight) for preparing calibration standards. Other appropriate sizes can be used. 5.1.8 Tubing Fittings. To plumb GC and gas cylinders. 5.1.9 Septums. For syringe injections. 5.1.10 Glass Jars. If necessary, clean, colored glass jars with Teflon-lined lids for condensate sample collection. Size depends on volume of condensate. 5.1.11 Soap Film Flowmeter. To determine flow rates. 5.1.12 Tedlar Bags. 10- and 50-liter capacity, for preparation of standards. 5.1.13 Dry Gas Meter with Temperature and Pressure Gauges. Accurate to ± 2 percent, for preparation of gas standards. 5.1.14 Midget Impinger/Hot Plate Assembly. For preparation of gas standards. 5.1.15 Sample Flasks. For presurvey samples, must have gas-tight seals. 5.1.16 Adsorption Tubes. If necessary, blank tubes filled with necessary adsorbent (charcoal, Tenax, XAD-2, etc.) for presurvey samples. 5.1.17 Personnel Sampling Pump. Calibrated, for collecting adsorbent tube presurvey samples. 5.1.18 Dilution System. Calibrated, the dilution system is to be constructed following the specifications of an acceptable method. 5.1.19 Sample Probes. Pyrex or stainless steel, of sufficient length to reach centroid of stack, or a point no closer to the walls than 1 m. 5.1.20 Barometer. To measure barometric pressure. EMTIC M-18 EMTIC NSPS Test Method Page 2 2.2 Sensitivity. The sensitivity limit for a compound is defined as the minimum detectable concentration of that compound, or the concentration that produces a signal-to-noise ratio of three to one. The minimum detectable concentration is determined during the presurvey calibration for each compound. 3. PRECISION AND ACCURACY Gas chromatographic techniques typically provide a precision of 5 to 10 percent relative standard deviation (RSD), but an experienced GC operator with a reliable instrument can readily achieve 5 percent RSD. For this method, the following combined GC/operator values are required. (a) Precision. Duplicate analyses are within 5 percent of their mean value. (b) Accuracy. Analysis results of prepared audit samples are within 10 percent of preparation values. (c) Recovery. After developing an appropriate sampling and analytical system for the pollutants of interest, conduct the procedure in Section 7.6. Conduct the appropriate recovery study in Section 7.6 at each sampling point where the method is being applied. Submit the data and results of the recovery procedure with the reporting of results under Section 7.5. 4. INTERFERENCES 4.1 Resolution interferences that may occur can be eliminated by appropriate GC column and detector choice or by shifting the retention times through changes in the column flow rate and the use of temperature programming. 4.2 The analytical system is demonstrated to be essentially free from contaminants by periodically analyzing blanks that consist of hydrocarbon-free air or nitrogen. 4.3 Sample cross-contamination that occurs when high-level and low-level samples or standards are analyzed alternately, is best dealt with by thorough purging of the GC sample loop between samples. 4.4 To assure consistent detector response, calibration gases are contained in dry air. To adjust gaseous organic concentrations when water vapor is present in the sample, water vapor concentrations are determined for those samples, and a correction factor is applied. 5. PRESURVEY AND PRESURVEY SAMPLING Perform a presurvey for each source to be tested. Refer to Figure 18-1. Some of the information can be collected from literature surveys and source personnel. Collect gas samples that can be analyzed to confirm the identities and approximate concentrations of the organic emissions. 5.1 Apparatus. This apparatus list also applies to Sections 6 and 7. 5.1.1 Teflon Tubing. (Mention of trade names or specific products does not EMISSION MEASUREMENT TECHNICAL INFORMATION CENTER NSPS TEST METHOD Method 18 - Measurement of Gaseous Organic Compound Emissions by Gas Chromatography INTRODUCTION This method should not be attempted by persons unfamiliar with the performance characteristics of gas chromatography, nor by those persons who are unfamiliar with source sampling. Particular care should be exercised in the area of safety concerning choice of equipment and operation in potentially explosive atmospheres. 1. APPLICABILITY AND PRINCIPLE 1.1 Applicability. 1.1.1 This method applies to the analysis of approximately 90 percent of the total gaseous organics emitted from an industrial source. It does not include techniques to identify and measure trace amounts of organic compounds, such as those found in building air and fugitive emission sources. 1.1.2 This method will not determine compounds that (1) are polymeric (high molecular weight), (2) can polymerize before analysis, or (3) have very low vapor pressures at stack or instrument conditions. 1.2 Principle. The major organic components of a gas mixture are separated by gas chromatography (GC) and individually quantified by flame ionization, photoionization, electron capture, or other appropriate detection principles. The retention times of each separated component are compared with those of known compounds under identical conditions. Therefore, the analyst confirms the identity and approximate concentrations of the organic emission components beforehand. With this information, the analyst then prepares or purchases commercially available standard mixtures to calibrate the GC under conditions identical to those of the samples. The analyst also determines the need for sample dilution to avoid detector saturation, gas stream filtration to eliminate particulate matter, and prevention of moisture condensation. 2. RANGE AND SENSITIVITY 2.1 Range. The lower range of this method is determined by the sampling system; adsorbents may be used to concentrate the sample, thus lowering the limit of detection below the 1 part per million (ppm) typically achievable with direct interface or bag sampling. The upper limit is governed by GC detector saturation or column overloading; the upper range can be extended by dilution of sample with an inert gas or by using smaller volume gas sampling loops. The upper limit can also be governed by condensation of higher boiling compounds. EMTIC M-18 Prepared by Emission Measurement Center Technical Support Division, OAQPS, EPA APÉNDICE A MÉTODO 18 DEL 40 CRF PARTE 60 EMTIC M-18 EMTIC NSPS Test Method Page 41 2. Field Analysis Data - Calibration Gas Run No. Time Components Area Attenuation A x A Factor Conc. (ppm) Run No. Time Components Area Attenuation A x A Factor Conc. (ppm) Run No. Time Components Area Attenuation A x A Factor Conc. (ppm) Figure 18-11 (continued). Field analysis data sheets. EMTIC M-18 EMTIC NSPS Test Method Page 42 Vent Rowmeter TC TC Readout Readout or Stack Controller Needle Wall Valve 1/4in SS Tubing Charocal Absorber Heated Tellon e Pump Insulation <<<<<<<<<<<<< Line ToGC Instrument Vein Glass Tubing Wool Heated Gas Temperature Sampling Valve Controller Carrier in InGC Figure 18-12. Direct Interface Sampling System. EMTIC M-18 EMTIC NSPS Test Method Page 43 Vent to Charcoal Adsorbers 101 1001 Quick Connects To Gas Sample Valve Heated Line From Probe Quick Connect Source 150 cc/Min 150 coMn Gas Pump Pump Pump 1.5 L/Mn Flowmaters (On Cutside of Box) 3-Way Valves in 1001 Position Check Valve Cuick Comeds Flow Rate For Calibration of 1350 coMin Heated Boxal 120 or Source Temperature Figure 18-13. Schematic Diagram of the Heated Box Required for Dilution of Sample Gas. EMTIC M-18 EMTIC NSPS Test M. hod Page 44 Gaseous Organic Sampling and Analysis Check List (Respond with initials or number as appropriate) 1. Presurvey data Date A. Grab sample collected B. Grab sample analyzed for composition Method GC GC/MS Other C. GC-FID analysis performed 2. Laboratory calibration data A. Calibration curves prepared Number of components Number of concentrations/ component (3 required) B. Audit samples (optional) Analysis completed Verified for concentration OK obtained for field work 3. Sampling procedures A. Method Bag sample Direct interface Dilution interface B. Number of samples collected 4. Field Analysis A. Total hydrocarbon analysis performed B. Calibration curve prepared Number of components Number of concentrations per component (3 required) Gaseous Organic Sampling and Analysis Data APÉNDICE A MÉTODO 21 DEL 40 CRF PARTE 60 EMTIC M-18 EMTIC NSPS Test Method Page 45 Plant Date Location Source Source Source sample_1 sample_2 sample_3 1. General information Source temperature (°C) Probe temperature (°C) Ambient temperature (°C) Atmospheric pressure (mm Hg) Source pressure (mm Hg) Sampling rate (ml/min) Sample loop volume (ml) Sample loop temperature (°C) Sample collection time (24-hr basis) Column temperature Initial (°C) Program rate (°C/min) Final (°C) Carrier gas flow rate (ml/min) Detector temperature (°C) Chart speed (cm/min) Dilution gas flow rate (ml/min) Diluent gas used (symbol) Dilution ratio Performed by (signature): Date: Figure 18-14. Sampling and analysis sheet. EMISSION MEASUREMENT TECHNICAL INFORMATION CENTER NSPS TEST METHOD (EMTIC M-21, 2/9/93) Method 21 - Determination of Volatile Organic Compound Leaks 1. APPLICABILITY AND PRINCIPLE 1.1 Applicability. This method applies to the determination of volatile organic compound (VOC) leaks from process equipment. These sources include, but are not limited to, valves, flanges and other connections, pumps and compressors, pressure relief devices, process drains, open-ended valves, pump and compressor seal system degassing vents, accumulator vessel vents, agitator seals, and access door seals. 1.2 Principle. A portable instrument is used to detect VOC leaks from individual sources. The instrument detector type is not specified, but it must meet the specifications and performance criteria contained in Section 3. A leak definition concentration based on a reference compound is specified in each applicable regulation. This procedure is intended to locate and classify leaks only, and is not to be used as a direct measure of mass emission rate from individual sources. 2. DEFINITIONS 2.1 Leak Definition Concentration. The local VOC concentration at the surface of a leak source that indicates that a VOC emission (leak) is present, The leak definition is an instrument meter reading based on a reference compound. 2.2 Reference Compound. The VOC species selected as an instrument calibration basis for specification of the leak definition concentration. (For example, if a leak definition concentration is 10,000 ppm as methane, then any source emission that results in a local concentration that yields a meter reading of 10,000 on an instrument meter calibrated with methane would be classified as a leak. In this example, the leak definition is 10,000 ppm, and the reference compound is methane.) 2.3 Calibration Gas. The VOC compound used to adjust the instrument meter reading to a known value. The calibration gas is usually the reference compound at a known concentration approximately equal to the leak definition concentration. 2.4 No Detectable Emission. The total VOC concentration at the surface of a leak source that indicates that a VOC emission (leak) is not present. Since background VOC concentrations may exist, and to account for instrument drift and imperfect reproducibility, a difference between the source surface concentration and the local ambient concentration is determined. A difference based on the meter readings of less than a concentration corresponding to the minimum readability specification indicates that a VOC emission (leak) is not present. (For example, if the leak definition in a regulation is 10,000 ppm, then the allowable increase is surface concentration versus local ambient concentration would be 500 ppm based on the instrument meter readings.) 2.5 Response Factor. The ratio of the known concentration of a VOC compound to the observed meter reading when measured using an instrument calibrated with the reference compound specified in the applicable regulation. 2.6 Calibration Precision. The degree of agreement between measurements of the same known value, expressed as the relative percentage of the average difference between the meter readings and the known concentration to the known concentration. 2.7 Response Time. The time interval from a step change in VOC concentration at the input of the sampling system to the time at which 90 percent of the corresponding final value is reached as displayed on the instrument readout meter. 3. APPARATUS 3.1 Monitoring Instrument. 3.1.1 Specifications a. The VOC instrument detector shall respond to the compounds being processed. Detector types which may meet this requirement include, but are not limited to, catalytic oxidation, flame ionization, infrared absorption, and photoionization. b. The instrument shall be capable of measuring the leak definition concentration specified in the regulation. C. The scale of the instrument meter shall be readable to + or - 5 percent of the specified leak definition concentration. d. The instrument shall be equipped with a pump so that a continuous sample is provided to the detector. The nominal sample flow rate shall be 0.1 to 3.0 liters per minute. e. The instrument shall be intrinsically safe for operation in explosive atmospheres as defined by the applicable U.S.A. standards (e.g., National Electrical Code by the National Fire Prevention Association). f. The instrument shall be equipped with a probe or probe extension for sampling not to exceed 1/4 in. in outside diameter, with a single end opening for admission of sample. 3.1.2 Performance Criteria. a. The instrument response factors for the individual compounds to be measured must be less than 10. b. The instrument response time must be equal to or less than 30 seconds. The response time must be determined for the instrument configuration to be used during testing. C. The calibration precision must be equal to or less than 10 percent of the calibration gas value. d. The evaluation procedure for each parameter is given in