1、Designation: E 147 61 (Reapproved 2006)Standard Specification forApparatus for Microdetermination of Nitrogen by KjeldahlMethod1This standard is issued under the fixed designation E 147; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, 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.1. Scope1.1 This specification covers digestion and distillation ap-paratus used for the microdetermination of ni
3、trogen by theKjeldahl method, and modifications thereof at atmosphericpressure.NOTE 1This specification is based on those originally developed bythe Committee on Microchemical Apparatus, Division of AnalyticalChemistry, American Chemical Society.22. Referenced Documents2.1 ASTM Standards:3E 124 Spec
4、ification for Weighing and Drying Apparatus forMicrochemical Analysis3. Tolerances3.1 The following commercial length tolerance shall beadhered to, unless otherwise specified:Up to 10 mm 61mm10 to 100 mm 62mm100 to 200 mm 63mm200 mm 64mm4. Digestion Flasks4.1 Digestion flasks of three types shall co
5、nform to therequirements prescribed in Table 1 and Fig. 1, Fig. 2, and Fig.3. The flasks shall be made of shock-resistant glass with linearcoefficient of expansion not greater than 33.5 3 107cm/cmC.NOTE 2The weighing tubes described in Specification E 124 Figs.1214 are recommended for introducing so
6、lid samples into the microKjeldahl digestion flasks. Combustion boats, Fig. 1 and Fig. 2 ofSpecification E 124, are recommended for use with waxy and nonvolatileliquid samples.5. Digestion Rack5.1 The micro Kjeldahl digestion rack shall be portable andshall consist of flask heaters (either gas or el
7、ectric), a flasksupport, and a fume duct. The rack shall be supplied with a heatdeflector mounted under the burners to prevent overheating ofthe bench top.5.1.1 HeatersThe source of heat may be either electric orgas. In operation, each heater shall supply sufficient heat to a30-mL flask to cause 15
8、mL of water at 25C to come to a1This specification is under the jurisdiction of ASTM Committee E41 onLaboratory Apparatus and is the direct responsibility of Subcommittee E41.01Apparatus.Current edition approved Nov. 1, 2006. Published December 2006. Originallyapproved in 1959. Last previous edition
9、 approved in 2001 as E 147 61 (2001).2Committee on Microchemical Apparatus, “Recommended Specification forMicrochemicalApparatus, Micro Kjeldahl Nitrogen,” Analytical Chemistry, Vol 23,1951, p. 523.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service
10、at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.TABLE 1 Digestion FlasksCapacity, mL Figure Use10 1 with digests of 1 mL or less30 2 with digests of 1 to 4 mL30 (Soltys) 3 with digests of 1 to 4 mL whendanger of
11、 spattering isgreat.FIG. 1 10-mL Kjeldahl Flask1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.rolling boil in not less than 2 or more than 3 min.Adevice shallbe provided for regulating the amount of heat supplied to theflask so that
12、 these conditions can be met. The amount of heatsupplied to the flasks also shall be so adjustable that low-temperature digestions are possible. Switches and controlsshall be conveniently located and shall remain cool enough tohandle even after long periods of operation.NOTE 3Boiling chips shall be
13、added when testing the heaters tominimize superheating, and the burners and rack shall be at equilibriumtemperature.5.1.2 Flask SupportThe support on which the bulbs of theflasks rest shall shield the necks of the flasks from excessiveheating during digestion and shall be provided with circularopeni
14、ngs not exceeding 26 mm in diameter, centered over eachheater.5.1.3 Fume DuctThe fume duct shall provide means foradequately removing the fumes evolved during the digestionand shall support the necks of the flasks at an angle greater than35 to the horizontal. Fume ducts meeting these specificationsa
15、re shown in Fig. 4 and Fig. 5. The fume duct illustrated in Fig.4 is supported and held in place by suitable clamps mounted ateither end of the digestion rack. The fume duct in Fig. 5 restsupon a circular support plate and is held in place by springsfrom the plate to the four glass hooks. The concav
16、e centerpermits clearance for the nut which fastens the support plate tothe center support post.6. One-Piece Distillation Apparatus6.1 The one-piece model distillation apparatus shall con-form to the requirements of Fig. 6. The steam-generator vesselillustrated in Fig. 7 and the immersion heater in
17、Fig. 8 arerecommended for use with this apparatus, although any othersuitable combination may be substituted.6.2 The steam-generator vessel, Fig. 7, is a wide-mouthedcommercially available resin reaction kettle. The interchange-able cover, with flat-ground rim and four ground-glass tubula-tions, is
18、held in place with a suitable clamp. The distillationunit is connected to the center tubulation. Two of the outerthree tubulations are used for the leads of the immersion-heaterassembly, Fig. 8. The remaining tubulation is used for addingwater to the kettle.6.3 The rate of steam generation may be co
19、ntrolled by a7.5-A variable transformer. The immersion heater shall be ofthe type that does not burn out when not immersed.NOTE 4Several methods of cleaning can be used. The followingmethod has been found satisfactory, particularly when boiling chips areemployed in the digestion: Turn off the steam
20、generator while bothFIG. 2 30-mL Kjeldahl FlaskFIG. 3 30-mL (Soltys) Kjeldahl FlaskFIG. 4 Manifold for Micro Kjeldahl Digestion RackE 147 61 (2006)2stopcocks are closed. The reduced pressure in the generator, brought aboutby cooling, causes the alkaline mixture in the distillation flask to besucked
21、into the outer jacket. Open both stopcocks to drain off the liquid.Then, while steam is being generated and with both stopcocks closed, fillthe sample inlet funnel with water and immerse the tip of the condenserin about 100 mLof water contained in a beaker. Stop the steam generation,and open the sto
22、pcock of the funnel slowly, closing it before all the waterhas drained into the apparatus. Reduced pressure causes water to besucked from the beaker into the apparatus, thereby washing it. Open thestopcock in the drainage tube to empty the liquid that has collected in theouter jacket. If necessary,
23、start the steam generator again, and repeat therinsing procedure.7. Pregl Type (Parnas-Wagner) Distillation Apparatus7.1 The Pregl (Parnas-Wagner) type apparatus shall con-form to the requirements of Fig. 9, Fig. 10, and Fig. 11. Thesteam-generator vessel illustrated in Fig. 7 and the immersionheate
24、r in Fig. 8 are recommended for use with this apparatus,although any other suitable combination may be substituted.FIG. 5 Manifold for Micro Kjeldahl Digestion Rack (Circular Type)E 147 61 (2006)3FIG. 6 Kjeldahl Distillation Apparatus, One-Piece ModelE 147 61 (2006)4FIG. 7 Steam Generator Vessel, 20
25、00-mL CapacityFIG. 8 Immersion Heater Assembly and Mounting PlatesE 147 61 (2006)5FIG. 9 Steam Tube, Steam Trap, and Connecting TubeFIG. 10 Distillation Flask and Filling FunnelE 147 61 (2006)6ASTM International takes no position respecting the validity of any patent rights asserted in connection wi
26、th any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible tech
27、nical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful considerat
28、ion at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Ha
29、rbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 11 Condenser Tube, Condenser Jacker (West Type), and Drain.E 147 61 (2006)7
