定价： 819元 / 折扣价： 697 元

定价： 260元 / 折扣价： 221 元 加购物车

1.1 This specification establishes the requirements for hard-drawn, seamless capillary tube made from Copper Alloy UNS Nos. C10800, C12000, or C12200.1.2 This tube is commonly supplied in straight lengths intended for restrictor applications such as metering lines for liquids and gases where close control over smoothness and diameter of the bore is required to insure uniform flow characteristics between tubes.1.3 Units—The values stated in inch pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

5.1 The multidimensional approach permits all of the trace impurities to be well separated from the main vinyl chloride peak, thereby improving quantitative accuracy over established packed column methods.5.2 The minimum detection limit (MDL) for all components of interest has been shown to be well below 500 ppb for this test method.1.1 This is a general-purpose capillary-based test method for the determination of trace level impurities in high-purity vinyl chloride. This test method uses serially coupled capillary PLOT columns in conjunction with the multidimensional techniques of column switching and cryogenic trapping to permit the complete separation of the 11 key vinyl chloride impurities in a single 25-min run.NOTE 1: There is no known ISO equivalent to this standard.1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in Section 8.1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

4.1 This test method determines the purity of isophorone, as well as the concentration of various potential impurities, several of which are critical in the application of these solvents.1.1 This test method covers the determination of the purity of isophorone. This method also determines the impurities of the material in concentration level less than 0.5 mass %, which may include mesityl oxide (MSO), mesityl oxide-isomer, mesitylene, trimethyl cyclohexenone (TMCH), phorone, phorone-isomer, xylitone, and tetralone.1.2 Water cannot be determined by this test method and shall be measured by other appropriate ASTM procedure. The result is used to normalize the chromatographic data determined by this test method.1.3 For purposes of determining conformance of an observed or a calculated value using this test method to relevant specifications, test result(s) shall be rounded off “to the nearest unit” in the last right-hand digit used in expressing the specification limit, in accordance with the rounding-off method of Practice E29.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and to determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 515元 / 折扣价： 438 元 加购物车

5.1 The viscosity at 60 °C [140 °F] characterizes flow behavior and may be used for specification requirements for cutback asphalt and asphalt binders.NOTE 3: The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone does not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.1.1 This test method covers procedures for the determination of the apparent viscosity of asphalt binder by vacuum capillary viscometers at 60 °C [140 °F]. It is applicable to materials having viscosities in the range from 0.0036 to over 20 000 Pa·s [0.036 to over 200 000 P].NOTE 1: This test method is suitable for use at other temperatures, but the precision is based on determinations on asphalt binders at 60 °C [140 °F].NOTE 2: Modified asphalt binders or asphalt binders that have been conditioned or recovered are typically non-Newtonian under the conditions of this test. The apparent viscosity for non-Newtonian asphalt binders varies with shear rate. When the flow is non-Newtonian in a capillary tube, the shear rate determined using this test method may be invalid. The presence of non-Newtonian behavior for the test conditions of this test can be verified by measuring the viscosity with viscometers having different-sized capillary tubes or with different pressure heads. The defined precision limits in Section 11 may not be applicable to non-Newtonian asphalt binders. Test Method D4957 may be a more applicable method for testing non-Newtonian asphalts.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.1.3 Warning—Mercury has been designated by the United States Environmental Protection Agency (EPA) and many state agencies as a hazardous material that can cause central nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) or Safety Data Sheet (SDS) for details and the EPA’s website—http://www.epa.gov/mercury/faq.htm—for additional information. Users should be aware that selling mercury, mercury-containing products, or both, in your state may be prohibited by state law.1.4 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

4.1 A measurement of the residual acrylonitrile in nitrile rubbers (NBR), styrene-acrylonitrile copolymers or ABS terpolymers will determine the polymer's suitability for various applications.4.2 Under optimum conditions, the minimum level of detection of RAN in NBR, SAN, or ABS terpolymers is approximately 50 ppb.1.1 This test method covers the determination of the residual acrylonitrile (RAN) content in nitrile-butadiene rubbers (NBR), styrene-acrylonitrile (SAN) copolymers, and rubber-modified acrylonitrile-butadiene-styrene (ABS) resins.1.2 Any components that can generate acrylonitrile in the headspace procedure will constitute an interference. The presence of 3-hydroxypropionitrile in latices limits this procedure to dry rubbers and resins.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 6.3 and 6.4.NOTE 1: There is no known ISO equivalent to this standard.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

1.1 These specifications cover operating instructions for glass capillary kinematic viscometers of all the types described in detail in Annex A1, Annex A2, and Annex A3 as follows:  Modified Ostwald viscometers, Annex A1  Suspended-level viscometers, Annex A2  Reverse-flow viscometers, Annex A31.2 The calibration of the viscometers is described in Section 6.1.3 This standard covers some widely used viscometers suitable for use in accordance with Test Method D445. Other viscometers of the glass capillary type which are capable of measuring kinematic viscosity within the limits of precision given in Test Method D445 may be used.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 843元 / 折扣价： 717 元 加购物车

5.1 The determination of the boiling range distribution of gasoline by gas chromatographic simulated distillation provides an insight into the composition of the components from which the gasoline has been blended. Knowledge of the boiling range distribution of gasoline blending components is useful for the control of refinery processes and for the blending of finished gasoline.5.2 The determination of the boiling range distribution of light hydrocarbon mixtures by gas chromatographic simulated distillation has better precision than the conventional distillation by Test Method D86. Additionally, this test method provides more accurate and detailed information about the composition of the light ends. The distillation data produced by this test method are similar to that which would be obtained from a cryogenic, true boiling point (15 theoretical plates) distillation.1.1 This test method covers the determination of the boiling range distribution of gasoline and liquid gasoline blending components. It is applicable to petroleum products and fractions with a final boiling point of 280 °C (536 °F) or lower, as measured by this test method.1.2 This test method is designed to measure the entire boiling range of gasoline and gasoline components with either high or low vapor pressure and is commonly referred to as Simulated Distillation (SimDis) by gas chromatographers.1.3 This test method has been validated for gasoline containing ethanol. Gasolines containing other oxygenates are not specifically excluded, but they were not used in the development of this test method.1.4 This test method can estimate the concentration of n-pentane and lighter saturated hydrocarbons in gasoline.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5.1 Results in degrees Fahrenheit can be obtained by simply substituting Fahrenheit boiling points in the calculation of the boiling point-retention time correlation.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 / 折扣价： 550 元 加购物车

The extensive and widespread use of organochlorine pesticides and PCBs has resulted in their presence in all parts of the environment. These compounds are persistent and may have adverse effects on the environment. Thus, there is a need to identify and quantitate these compounds in water samples.1.1 This test method covers the capillary gas chromatographic determination of various organochlorine pesticides, including some of their degradation products and related compounds in finished drinking water. This test method is not limited to this particular aqueous matrix; however, its applicability to other aqueous matrices must be determined. The tested compounds include the following:Numbering system of CAS Registry Services, P.O. Box 3343, Columbus, OH 43210-0334.Pesticide Chemical Abstract Service Registry NumberAldrin 309-00-2-BHC 319-84-6-BHC 319-85-7-BHC 319-86-8-BHC 58-89-9-Chlordane 5103-71-9-Chlordane 5103-74-2Chlorobenzilate 501-15-6Chloroneb 2675-77-6Chlorothalonil 2921-88-2DCPA 1897-45-64,4`-DDD 72-54-84,4`-DDE 72-55-94,4`-DDT 50-29-3Dieldrin 60-57-1Endosulfan I 959-98-8Endosulfan II 33213-65-9Endosulfan sulfate 1031-0708Endrin 72-20-8Endrin aldehyde 7421-93-4Etridiazole 2593-15-9Heptachlor 76-44-8Heptachlor epoxide 1024-57-3Hexachlorobenzene 118-74-1Methoxychlor 72-43-5cis-Permethrin 52645-53-1trans-Permethrin 52645-53-1Propachlor 1918-16-7Trifluralin 1582-09-81.2 and list the applicable concentration ranges and precision and bias statements for this test method. The applicability of this test method to other compounds must be demonstrated.1.3 The extract derived from this procedure may be analyzed for these constituents by using the gas chromatography (GC) conditions prescribed in Test Method D 5175 (capillary column). Although the columns used in this test method may be adequate for analyzing PCBs, no data were collected for any multi-congener constituents during methods development.1.4 This test method is restricted to use by or under the supervision of analysts experienced in the use of GC and interpretation of gas chromatograms. Each analyst must demonstrate the ability to generate acceptable results using the procedures described in Section 12.1.5 Analytes that are not separated chromatographically by either the primary or secondary chromatographic columns (for example, analytes having very similar retention times) cannot be identified and measured individually in the same calibration mixture or water sample unless an alternative technique for identification and quantitation exists (see 7.9 and 13.4).1.6 When this test method is used to analyze unfamiliar samples for any or all of the analytes listed in 1.1, analyte identifications and concentrations should be confirmed by at least one additional technique.1.7 The values stated in SI units are to be regarded as the standard.1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazards statements are given in Section 9.

定价： 0元 / 折扣价： 0 元

5.1 This test method is of particular use as a quality control tool for a molding or synthesis operation. Acetaldehyde is a volatile degradation product generated during melt processing of PET. Thus, it becomes trapped in the sidewalls of a molded article and desorbs slowly into the contents packaged therein. In some foods and beverages AA can impart an off-taste that is undesirable, thus, it is important to know its concentration in PET articles that are to be used in food contact applications.5.2 The desorption conditions of 150 °C for 60 min are such that no measurable AA is generated by the sample during the desorption process.1.1 This test method covers a gas chromatographic procedure for the determination of the ppm residual acetaldehyde (AA) present in poly(ethylene terephthalate) (PET) homo-polymers and co-polymers which are used in the manufacture of beverage bottles. This includes sample types of both amorphous and solid-stated pellet and preform samples, as opposed to the bottle test, Test Method D4509, an acetaldehyde test requiring 24 h of desorption time at 23 °C into the bottle headspace and then the concentration of the headspace quantified by a similar GC method.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车

5.1 Purgeable organic compounds have been identified as contaminants in treated drinking water, wastewater, ground water, and Toxicity Characteristic Leaching Procedure (TCLP) leachate. These contaminants may be harmful to the environment and to people. Purge and trap sampling is a generally applicable procedure for concentrating these components prior to gas chromatographic analysis.1.1 This test method covers the identification and simultaneous measurement of purgeable volatile organic compounds. It has been validated for treated drinking water, wastewater, and ground water. This test method is not limited to these particular aqueous matrices; however, the applicability of this test method to other aqueous matrices must be demonstrated.1.2 This test method is applicable to a wide range of organic compounds that have sufficiently high volatility and low water solubility to be efficiently removed from water samples using purge and trap procedures. Table 1 lists the compounds that have been validated for this test method. This test method is not limited to the compounds listed in Table 1; however, the applicability of the test method to other compounds must be demonstrated.1.3 Analyte concentrations up to approximately 200 μg/L may be determined without dilution of the sample. Analytes that are inefficiently purged from water will not be detected when present at low concentrations, but they can be measured with acceptable accuracy and precision when present in sufficient amounts.1.4 Analytes that are not separated chromatographically, but that have different mass spectra and non-interfering quantitation ions, can be identified and measured in the same calibration mixture or water sample. Analytes that have very similar mass spectra cannot be individually identified and measured in the same calibration mixture or water sample unless they have different retention times. Coeluting compounds with very similar mass spectra, such as structural isomers, must be reported as an isomeric group or pair. Two of the three isomeric xylenes are examples of structural isomers that may not be resolved on the capillary column, and if not, must be reported as an isomeric pair.1.5 It is the responsibility of the user to ensure the validity of this test method for untested matrices.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 983元 / 折扣价： 836 元 加购物车

5.1 This practice is intended to be used by all analysts using fused silica capillary chromatography. It contains the recommended steps for installation, preparation, proper installation, and continued column maintenance.1.1 This practice covers the installation and maintenance of fused silica capillary columns in gas chromatographs that are already retrofitted for their use. This practice excludes information on:1.1.1 Injection techniques.1.1.2 Column selection.1.1.3 Data acquisition.1.1.4 System troubleshooting and maintenance.1.2 For additional information on gas chromatography, please refer to Practice E260. For specific precautions, see 7.2.2.2(1), 7.2.2.2(2), 7.2.7, and 7.2.7.2.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific safety information, see Section 6, 7.2.2.2(1), 7.2.2.2(2), 7.2.7, and 7.2.7.2.21.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 / 折扣价： 550 元 加购物车

5.1 Knowledge of the individual component composition (speciation) of gasoline fuels and blending stocks is useful for refinery quality control and product specification. Process control and product specification compliance for many individual hydrocarbons can be determined through the use of this test method.5.2 This test method is adopted from earlier development and enhancement.4,5,6,7 The chromatographic operating conditions and column tuning process, included in this test method, were developed to provide and enhance the separation and subsequent determination of many individual components not obtained with previous single-column analyses. The column temperature program profile is selected to afford the maximum resolution of possible co-eluting components, especially where these are of two different compound types (for example, a paraffin and a naphthene).5.3 Although a majority of the individual hydrocarbons present in petroleum distillates are determined, some co-elution of compounds is encountered. If this test method is utilized to determine bulk hydrocarbon group-type composition (PONA), the user of such data should be cautioned that some error will be encountered due to co-elution and a lack of identification of all components present. Samples containing significant amounts of olefinic or naphthenic, or both, constituents above octane may reflect significant errors in PONA-type groupings.5.4 If water is or is suspected of being present, its concentration is determined by the use of Test Method D1744. Other compounds containing oxygen, sulfur, nitrogen, and so forth may also be present, and may co-elute with the hydrocarbons. When known co-elution exists, these are noted in the test method data tables. If determination of these specific compounds is required, it is recommended that test methods for these specific materials be used, such as Test Method D4815 and D5599 for oxygenates, Test Method D5580 for aromatics, and Test Method D5623 for sulfur compounds.1.1 This test method covers the determination of individual hydrocarbon components of spark-ignition engine fuels and their mixtures containing oxygenate blends (MTBE, ETBE, ethanol, and so forth) with boiling ranges up to 225 °C. Other light liquid hydrocarbon mixtures typically encountered in petroleum refining operations, such as blending stocks (naphthas, reformates, alkylates, and so forth) may also be analyzed; however, statistical data was obtained only with blended spark-ignition engine fuels.1.2 Based on the cooperative study results, individual component concentrations and precision are determined in the range from 0.01 % to approximately 30 % by mass. The test method may be applicable to higher and lower concentrations for the individual components; however, the user must verify the accuracy if the test method is used for components with concentrations outside the specified ranges.1.3 This test method also determines methanol, ethanol, t-butanol, methyl t-butyl ether (MTBE), ethyl t-butyl ether (ETBE), and t-amyl methyl ether (TAME) in spark ignition engine fuels in the concentration range from 1 % to 30 % by mass. However, the cooperative study data provided insufficient statistical data for obtaining a precision statement for these compounds.1.4 Although a majority of the individual hydrocarbons present are determined, some co-elution of compounds is encountered. If this test method is utilized to estimate bulk hydrocarbon group-type composition (PONA), the user of such data should be cautioned that some error will be encountered due to co-elution and a lack of identification of all components present. Samples containing significant amounts of naphthenic (for example, virgin naphthas) constituents above n-octane may reflect significant errors in PONA-type groupings. Based on the gasoline samples in the interlaboratory cooperative study, this test method is applicable to samples containing less than 25 % by mass of olefins. However, some interfering co-elution with the olefins above C7 is possible, particularly if blending components or their higher boiling cuts such as those derived from fluid catalytic cracking (FCC) are analyzed, and the total olefin content may not be accurate. Annex A1 of this test method compares results of the test method with other test methods for selected components, including olefins, and several group types for several interlaboratory cooperative study samples. Although benzene, toulene, and several oxygenates are determined, when doubtful as to the analytical results of these components, confirmatory analyses can be obtained by using the specific test methods listed in the reference section.1.4.1 Total olefins in the samples may be obtained or confirmed, or both, if necessary, by Test Method D1319 (percent by volume) or other test methods, such as those based on multidimentional PONA-type of instruments.1.5 If water is or is suspected of being present, its concentration may be determined, if desired, by the use of Test Method D1744 or equivalent. Other compounds containing oxygen, sulfur, nitrogen, and so forth, may also be present, and may co-elute with the hydrocarbons. If determination of these specific compounds is required, it is recommended that test methods for these specific materials be used, such as Test Methods D4815 and D5599 for oxygenates, and Test Method D5623 for sulfur compounds, or equivalent.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 983元 / 折扣价： 836 元 加购物车

3.1 Tall oil fractionated products derived from tall oil are important commercial materials, primarily composed of fatty acids and rosin acids, but also containing some neutral material (see Terminology D804). For many applications, it is necessary to know the level of the individual fatty acids and rosin acids present in these products. Gas chromatography has proven to be a useful tool for such determinations (see Test Methods D509), and capillary chromatography, described in these test methods, is considered to be the most effective gas chromatographic technique currently available. In particular situations, other techniques may be more suitable than gas chromatography. For example, the presence of fatty acid esters in the sample would result in transesterification during the derivatization step that may affect the results.3.2 Due to hydrogen bonding, unmodified tall oil fatty acids and rosin acids cannot be volatilized at atmospheric pressure without undergoing decomposition. So, it is necessary to convert the free acids to the more volatile and more stable methyl esters, prior to chromatographic separation.3.3 These test methods describe four ways to prepare methyl esters. The classic method is through the use of diazomethane, but diazomethane is a hazardous and toxic material, and so is no longer the preferred agent. The use of diazomethane is detailed in Appendix X1.3.3.1 TMAH causes isomerization of a sample’s di- and polyunsaturated fatty acids, when it is used in even a slight excess. This leads to inaccurate results for the individual fatty acid components. TMAH should be used for materials containing only rosin acids, or when the identification or quantitation of individual fatty acid components is not important.3.3.2 TMPAH is the recommended methylating agent when the identification or quantitation of individual di- and polyunsaturated fatty acids is required. TMPAH produces results that are very similar to those of diazomethane, but without the hazards that are associated with diazomethane. A considerable excess of TMPAH may cause isomerization of conjugated compounds similar to that encountered with TMAH.3.3.3 DMF-DMA gives results comparable to TMPAH and is easy and safe to use. However, the reagent is moisture sensitive, requiring samples to be free of any significant levels of water.3.4 Two test methods for calculating the amounts of the individual fatty acid and rosin acid methyl esters are included in these test methods. When the actual weight percentage of a given compound is required, the “internal standard” method must be used. This method involves adding a known amount of an internal standard to a known amount of test material, and comparing the area of the peak associated with the internal standard with the area of the peak of the individual fatty acid or rosin acid methyl esters. The “area percent” method will give the relative amount of each component, by comparing the area of the appropriate peak to the total area of all peaks. Non-eluting compounds will lead to erroneous (absolute) results with this method.PREPARATION OF METHYL ESTERSNOTE 1: Any of these three methods can be used, with the choice being dependent on the factors mentioned in 3.3.1.1 These test methods cover the determination of the amounts of the individual fatty acids and rosin acids in fractionated tall oil products, using capillary gas chromatographic separation of the volatile methyl esters of these acids.1.2 Four methods for forming the methyl esters, and two methods for determining the amounts of the individual fatty acids and rosin acids are described.1.2.1 The classic method for the formation of methyl esters is through the use of diazomethane, but diazomethane is a hazardous and toxic material, and so is no longer the preferred reagent. The use of diazomethane is detailed in the Appendix. Methyl esters may be formed through the use of tetramethylammonium hydroxide (TMAH), trimethylphenylammonium hydroxide (TMPAH), or N,N-dimethylformamide dimethyl acetal (DMF-DMA).1.2.2 The two methods for determining the amount of the individual fatty acids and rosin acids are the “internal standard” method, which yields absolute values, and the “area percent” method, which yields relative values.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 / 折扣价： 502 元 加购物车