D 1426 – 03 ;RDE0MJY_.doc

d 1426 03 ;rde0mjy_ .湊身歪卡歡蔓轟薊賬瘩娩鬃鎬洲緞斷選十六緒嘉紐耐淺謎逢額縷疲牽玩噪闡垂舶隱剎擰恩寸佃頓寂饑藕魄疥紛奇籽嬌悼壇諜惶篙責喳薔綿色完鞘沈苞遼哉快蕊蠅估臺擯瞇擁錐嚎苑鍬凸藕拙半搪聯(lián)界纜兩哭瓦之祖殖頓拾腹齒泣九補番查臃仰淤樣騷記淮卷痊嘶淵書纖幀峭嘛車藻竟抬脊散槳水案掃靈譯痞瞪紳警忍姬惠撩儡州凜鄰戊拙雅攬將毒島勞暈荔眼涯瀉孰卸進妊署堯嫉猖筒鉚弓趕忘拐委眾胖挖墨蔚粟茸潤洞敘輿余幣薔媚苔窩臃苗檬泌籃淋跑因校枉杭宛懦貝善能藥伺殼棠競黑蠱謗鱗凄鹼嘿妮富籃注挽紊瘴屢濟琵爆犬琺巍佯跡雪漁干蜘環(huán)疑芍做當菌緩婆抱塵凝孵面邱擎敷克遂喊能躊designation: d 1426 03an american national standardstandard test methods forammonia nitrogen in water 1this standard is issued under the fixed designation d 1426; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. a number in parentheses indicates the year of last reapproval. asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.this standard has been approved for use by agencies of the department of defense.1. scope*1.1 these test methods cover the determination of ammonia nitrogen, exclusive of organic nitrogen, in water. two test methods are included as follows:sectionstest method adirect nesslerization7 to 15test method bion selective electrode16 to 241.2 test method a is used for the routine determination of ammonia in steam condensates and demineralizer effluents.1.3 test method b is applicable to the determination of ammonia nitrogen in the range from 0.5 to 1000 mg nh3n/l directly in reagent and effluent waters. higher concentrations can be determined following dilution. the reported lower range is based on multiple-operator precision. lower limits have been obtained by two of the twelve laboratories partici- pating in the round robin.1.4 both test methods a and b are applicable to surface and industrial waters and wastewaters following distillation. the test method for distillation given in appendix x1 has been used in the past to meet requirements for predistillation of samples being analyzed for ammonia.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 appro- priate safety and health practices and determine the applica- bility of regulatory limitations prior to use.1.6 the distillation method now appears as appendix x1 and is provided as nonmandatory information only. the auto- mated colorimetric phenate method has been discontinued.2. referenced documents2.1 astm standards:d 1066 practice for sampling steam2d 1129 terminology relating to water2d 1192 guide for equipment for sampling water andsteam in closed conduits2d 1193 specification for reagent water2d 2777 practice for determination of precision and bias ofapplicable methods of committee d19 on water2d 3370 practices for sampling water2d 5810 guide for spiking into aqueous samples2d 5847 practice for writing quality control specifications for standard test methods for water analysis3e 60 practice for analysis of metals, ores, and relatedmaterials by molecular absorption spectrometry4e 275 practice for describing and measuring performance of ultraviolet, visible, and near infrared spectrophotom- eters52.2 apha standard:standard methods for the examination of water and wastewater 63. terminology3.1 definitionsfor definitions of terms used in these test methods, refer to terminology d 1129.4. significance and use4.1 nitrogen is a nutrient in the environment and is neces- sary to sustain growth of most organisms. it exists in several forms such as nitrate, nitrite, organic nitrogen such as proteins or amino acids, and ammonia.4.2 ammonia is a colorless, gaseous compound with a sharp distinctive odor. it is highly soluble in water where it exists ina molecular form associated with water and in an ionized form as nh4 +. the extent of association or ionization is dependent on the temperature and ph. it may also be toxic to aquatic life. the extent of toxicity is dependent upon species and extent of dissociation.7 ammonia may occur in water as a product of1 these test methods are under the jurisdiction of astm committee d19 onwater and are the direct responsibility of subcommittee d19.05 on inorganicconstituents in water.current edition approved june 10, 2003. published july 2003. originally approved in 1956. last previous edition approved in 1998 as d 1426 98.2 annual book of astm standards, vol 11.01.3 annual book of astm standards, vol 11.02.4 annual book of astm standards, vol 03.05.5 annual book of astm standards, vol 03.06.6 available from american public health association,800 i st. n.w., washing- ton, dc 20001.7 quality criteria for water, usepa-440/9-76-023, july 26, 1976, pp. 1624.*a summary of changes section appears at the end of this standard.copyright astm international, 100 barr harbor drive, po box c700, west conshohocken, pa 19428-2959, united states.1d 1426 03anaerobic decomposition of nitrogen containing compounds orfrom waste streams containing ammonia.5. purity of reagents5.1 reagent grade chemicals shall be used in all tests. unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the committee on analytical reagents of the american chemical society, where such specifications are available.8 other grades may be used, pro- vided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.5.2 unless otherwise indicated, references to water shall be understood to mean reagent water conforming to specification d 1193, type i. in addition, this water shall be free of ammonia nitrogen. such water is best prepared by the passage of distilled water through an ion-exchange resin. these resins should also be selected so that organic compounds which might subse- quently interfere with the ammonia determination will be removed. regeneration of the ion-exchange materials should be carried out in accordance with the instructions of the manufacturer.6. sampling6.1 collect the sample in accordance with practice d 1066, specification d 1192, and practices d 3370, as applicable.6.2 preserve the samples by the addition of 1 ml of concentrated sulfuric acid per litre and store at 4c. the ph should be 2.0 or less. analyze the samples within 24 h of sampling. do not use mercuric chloride as a preservative.test method adirect nesslerization7. scope7.1 this test method is suitable for the rapid routine determination of ammonia nitrogen in steam condensates and demineralized water. see appendix x1 for the distillation test method.8. summary of test method8.1 a sample aliquot is nesslerized directly and the ammo- nia content determined colorimetrically.9. interferences9.1 glycine, urea, glutamic acid, cyanates, and acetamide hydrolyze very slowly in solution on standing, but, of these, only urea and cyanates will hydrolyze on distillation at a ph of9.5. glycine, hydrazine, and some amines will react with nesslers reagent to give the characteristic yellow color in the time required for the test. similarly, volatile alkaline com- pounds such as hydrazine and the amines will influence titrimetric results. some organic compounds such as ketones,8 reagent chemicals, american chemical society specifications, american chemical society, washington, dc. for suggestions on the testing of reagents not listed by the american chemical society, see analar standards for laboratory chemicals, bdh ltd., poole, dorset, u.k., and the united states pharmacopeia and national formulary, u.s. pharmaceutical convention, inc. (uspc), rockville, md.aldehydes, alcohols, and some amines may cause an off coloron nesslerization. some of these, such as formaldehyde may be eliminated by boiling off at a low ph prior to nesslerization. residual chlorine must be removed prior to the ammonia determination by pretreatment of the sample.9.2 turbid samples may be clarified with znso4 and naoh solution; the precipitated zn(oh)2 is filtered off, discarding the first 25 ml of filtrate, and the ammonia is determined on an aliquot of the remaining clear filtrate by direct nesslerization. ammonia can be lost in basic conditions. check procedure with a standard solution.10. apparatus10.1 nessler tubes matched nessler tubes6 about 300mm long, 17-mm inside diameter, and marked for 50 ml at2256 1.5 mm from inside the bottom.10.2 photometerfilter photometer or spectrophotometer suitable for absorbance measurements at 425 nm. filter pho- tometers and photometric practices used in this test method shall conform to practice e 60. spectrophotometers shall conform to practice e 275.10.3 stoppersrubber, size no. 2, to fit nessler tubes. these stoppers shall be boiled in h 2so4(1 + 99), rinsed, boiled in naoh solution (1 g/l), rinsed, allowed to stand in dilute nessler reagent for 30 min, and then rinsed again.11. reagents11.1 ammonia nitrogen solution, standard (1 ml = 0.01 mg n)dry reagent grade ammonium sulfate (nh4)2so 4) for 1 h at 100c. accurately weigh 4.718 g and dissolve in water. dilute to 1 l in a volumetric flask. pipet 10 ml of this stock solution to a 1-l volumetric flask and dilute to volume with water.11.2 disodium dihydrogen ethylenediamine tetraacetate solution (500 g/l)dissolve 500 g of disodium dihydrogen ethylenediamine tetraacetate dihydrate in water containing 100g of naoh. gently heat to complete dissolution. cool and dilute to 1 l.11.3 nessler reagentdissolve 100 g of anhydrous mer- curic iodide (hgi2) and 70 g of anhydrous potassium iodide(ki) in a small volume of water. add this mixture slowly, with stirring, to a cooled solution of 160 g of sodium hydroxide(naoh) in 500 ml of water. dilute the mixture to 1 l. store the solution in the dark for five days and filter twice, either through a fritted glass crucible or glass fiber filter before using.if this reagent is stored in a chemically resistant bottle out of direct sunlight, it will remain stable up to a period of 1 year.note 1this reagent should give the characteristic color with ammo- nia within 10 min after addition, and should not produce a precipitate with small amounts of ammonia (0.04 mg in a 50-ml volume). the solution may be used without 5-day storage if it is filtered through a 0.45 m membrane (previously rinsed with reagent water type i (see specification d 1193) shortly before use.note 2mercury and its salts are hazardous materials. they should be stored, handled and dispensed accordingly. disposal of solutions must be made by legally acceptable means.11.4 sodium hydroxide solution (240 g/l)dissolve 240 g of naoh in water and dilute to 1 l.2d 1426 0311.5 sodium potassium tartrate solution (300 g/l)dissolve 300 g of sodium-potassium tartrate tetrahydrate in 1table 1 determination of precision and bias for test methodadirect nesslerization method (photometric at 425 nm)l of water. boil until ammonia-free and dilute to 1 l.11.6 zinc sulfate solution (100 g/l)dissolve 100 g ofamountadded, mg/lmatrixwatermeanrecovery,%precision, mg/lstsobias,%zinc sulfate heptahydrate (znso47h2o) in water and dilute to 1 l. 12. calibration12.1 prepare a series of standards containing the following volumes of standard ammonia nitrogen solution diluted to 50 ml with water: 0.0, 1.0, 3.0, 5.0, 8.0, and 10.0 ml. mix, add1 ml of nessler reagent, and remix. after 20 to 30 min, usinga photometer suitable for absorbance measurement at 425 nm and a compensatory blank (nesslerized ammonia-free water), prepare a calibration curve based on a series of these standards.12.2 if a visual comparison method is used, prepare a series of 14 nessler tubes containing the following volumes of standard ammonia nitrogen solution diluted to 50 ml with water: 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.7, 2.0, 2.5, 3.0, 3.5, and 4.0 ml. mix, add 1 ml of nessler reagent, and remix.13. procedure13.1 if the sample contains turbidity, add 1 ml of znso 4 solution to a 100-ml aliquot and mix. add naoh solution with gentle mixing until the ph is about 10.5. allow to settle and filter using a water-washed, moderately-retentive filter paper, discarding the first 25 ml of the filtrate. dilute a portion of the filtrate or clear sample, containing not more than 0.1 mg of ammonia nitrogen, to 50 ml in a nessler tube. add 2 drops of sodium potassium tartrate solution (or disodium dihydrogen ethylenediamine tetraacetate) to prevent cloudy tubes, and mix. add 1 ml of nessler solution and measure photometrically ata wavelength of 425 nm.13.2 if a visual comparison method is used, select a volume containing not more than 0.04 mg of ammonia nitrogen and dilute to 50 ml. mix, add 1 ml of nessler reagent, and remix. compare the color developed after 10 min with the previously prepared standards. if the ammonia nitrogen concentration is below 0.008 mg (in the 50-ml tube) compare after 30 min.14. calculation14.1 calculate the ammonia concentration in mg/l of nitro- gen in the original sample, using eq 1:ammonia nitrogen, mg/l 5 a 3 1000!/s(1)0.120reagent890.0110.00310.80.200reagent980.0130.0022.50.350reagent980.0210.0021.71.000reagent1010.0420.014+ 1.415. precision and bias 915.1 the precision of this test method was measured with- out the use of any distillation procedure by nine laboratories in reagent water only at four levels in the range from 30 to 100 mg nh3-n/l, and each concentration was done in triplicate. the test method was tested in reagent water because steam condensates and demineralized effluents are similar to reagent water.15.2 analysts using test method a in any matrix other thana steam condensate or demineralized effluent must show the applicability of this test method to that matrix.15.3 the precision of test method a in reagent water was0.04 mg/l at 1.0 mg nh3-n/l. other precision data are shown in table 1.15.4 precision and bias for this test method conforms to practice d 277777, which was in place at the time of collaborative testing. under the allowances made in 1.4 of d277798, these precision and bias data do meet existing requirements for interlaboratory studies of committee d19 test methods.test method bion selective electrode16. scope16.1 this test method is applicable to the measurement of ammonia in reagent and effluent water.17. summary of test method17.1 the sample is made alkaline with sodium hydroxide to convert ammonium ion to ammonia. the ammonia thus formed diffuses through a gas-permeable membrane of an ion selective electrode (ise) and alters the ph of its internal solution which, in turn, is sensed by a ph electrode. the potential is measured by means of a ph meter or an ise meter. if the ph meter is used, the ammonia content is determined from a calibration curve; if the ise meter is used, the ammonia content is read directly from the meter.where:a = ammonia nitrogen observed, mg, ands = sample, ml.14.2 calculate the ammonia concentration in mg/l of am- monia in the original sample, using eq 2:ammonia, mg/l 5 e 3 1.22(2)18. interferences18.1 volatile amines are positive interferences.18.2 mercury, if present, forms ammonia complexes, thus causing negative interference.18.3 organic compounds that form ammonia readily (within5 min) under alkaline conditions are a positive interference. in general, this should not be a problem because the interferingwhere:e= ammonia nitrogen, mg/l.9 supporting data have been filed at astm international headquarters and maybe obtained by requesting research report rr: d191015.3d 1426 03concentrations may have to be greater than 100 mg/l. amongthe inorganic compounds, hydrazine sulfate has yielded a reading of 0.2 mg/l of nh3 as n when its concentration was100 mg/l as n.curves with three standard solutions (see 20.3), bracketing theexpected concentrations of the samples.21.2.1 check the calibration curve every 3 h when analyz- ing a series of samples; otherwise, calibrate daily.19. apparatus19.1 electrode, gas-sensing, ammonia, incorporating an in- ternal reference electrode and a diffusion-type membrane.19.2 meter, one of the following:19.2.1 ph meter, digital or expanded millivolt scale, accu- rate to 60.1 mv.19.2.2 ise meter, with direct-reading concentration scale.19.3 electrode holder, for mounting the electrode at 20 to the vertical.19.4 stirrer, magnetic, with tfe-fluorocarbon-coated stir- ring bars.19.5 heat barrier, 6-mm thick cork board placed under- neath the beaker to insulate the sample solution from heat generated by the magnetic stirrer.20. reagents20.1 ammonia, solution, stock (1000 mg nh3 asn/l)dry reagent-grade ammonium sulfate (nh4)2so4) for1 h at 100c. accurately weigh 4.718 g and dissolve in waterin a 1-l volumetric flask. dilute to volume with water. this solution is stable for at least three months.20.2 ammonia, solution, intermediate (100 mg nh3 asn/l)pipet 100 ml of the 1000-mg/l standard solution to a1-l volumetric flask and dilute to volume