Recommended Specifications for Microchemical Apparatus. Micro

Al. Steyermark , H. K. Alber , V. A. Aluise , E. W. D. Huffman , E. L. Jolley , J. A. Kuck , J. J. Moran , and C. L. ... Journal of Insect Physiology ...
0 downloads 0 Views 5MB Size
Recommended Specifications for Microchemical Apparatus Micro-Kjelda hl Nitrogen Committee for the Standardization of Microchemical Apparatus, Division of Analytical SOCIETY Chemistry, AMERICANCHEMICAL AL STEYERMARK, Chairman, Hoffmann-LaRoche, Znc., .Vutley, IV. J . H. K. ALBER, Arthur H. Thomas Go., Philadelphia, P a . V. -4, ALUISE, Experiment Station, Hercules Powder Go., Wilmington, Del. E. W. D. HUFFAIAN, Huffman Microanalytical Laboratories, Denver, Colo. ,J. A. ICUCIC, College of the City of New York, N . Y., and American Cyanamid Co., Stamford, Conn. J. J. MORAR', Kimble Glass, Division of Owens-Illinois Glass Go., Vineland, IV.J . C . 0. WILLITS, Eastern Regional Research Laboratory, Philadelphia, Pa.

-

k 1 8 t . i M ~ AX.

t

E

T APPROX. 90 MM

APPROX.

IMM

APPROX SANDBiAST?D I S CM AREA (FOR LABELLING)

180'

MM

I5f0.5MM 0.0. WALL 1.0-1.3MM

L

11

5 0 t MM 40fZMM

The heaters must maintain a mixture of 2 ml. of sulfuric acid plus 1.30 grams of potassium sulfate at its boiling point (350" C.) The heaters must be sufficiently adjustable to provide for a mild digestion (low temperature) as well as distillation rates that will maintain refluxing of the acid into the neck of the flask. To avoid excessive heating of the flask necks, a shield is provided above the heaters. The shield should have circular openings not to exceed 26 nim in diameter, directly above each heating element. The openings must be spaced 67 * 7 mm. on centers. The rack must be provided with deflectors mounted under the burners to prevent overheating of the bench top. Gas Heaters. The burners should be individually adjustable, with handles conveniently located at the front of the rack, and so constructed that they will be cool enough to manipulate even after long periods of operation. The burner must produce a nonluminous flame. Electric Heaters. Electric heaters must perform satisfactorily at 100 volts. The controls must be convenientlv located and should not become too hot to handle on continued op-

-1 Figure 1. 10-M1. Kjeldahl Flasli

R

b 2 1 . 5 M M MAX.

Figure 2. 30-MI. ICjeldahl Flasli

ECOMMENDED specifications for microchemical appara-

tus used in the carbon-hydrogen, Dumas nitrogen, halogen, and sulfur determinations ( 8 ) and the proposed program for the future ( 1 ) have been published. The present paper includes recommendations for the apparatus used in the Kjeldahl nitrogen determination and includes the following: Kjeldahl digestion flasks, 10, 30, 30 (Soltys), and 100 ml hlicro digestion rack Manifold for micro digestion rack Micro-Kjeldahl distillation apparatus, Pregl Type (ParnasWagner); electric steam generator Micro-Kjeldahl distillation apparatus (one-piece model)

All recommendations have been made only after considerable experimental work by members of the committee. Kjeldahl Digestion Flasks. Specifications for four types of flasks are recommended-10, 30, 30 (Soltys), and 100 ml. These are shown in Figures 1, 2, 3, and 4. Micro Digestion Rack. The following specifications are recommc.nded. The micro-Kjeldahl digestion rack should be portable and consist of two parts, the flask heaters and the manifold support. The rark should provide for six Kjeldahl flasks, capacities 10 to 100 ml. HEATERS.The source of heat may be either electricity or gas.

Figure 3. 30-M1. (Soltys) Kjeldahl Flask

523

ANALYTICAL CHEMISTRY

524

Distillation flask, G Filling funnel, H Condenser tube (glass or silver), J Condenser jacket (West type), K Drain, L

eration. Not more than two heaters should he ODerated from one set of controls. MANIFOLD SUPPORT.This must hold the manifold securely, and also he adjustable, so that the manifold will support all the recommended sizes of flasks at the proper angle during digestion. Manifold for Micro Digestion Rack. Figure 5 shows the recommended manifold. Any of the four types of Kjeldshl digestion flasks may he used with it.

LL;.5

A new type of generator is recommended that provides closcr control of steam generation than tho usual gat-heated distillation flask. This all-glass steam generator, Figum 7 A , is a widemouthed commercially availahle resin reaction kettle (Corning Glass Works, Corning, N. Y.). The intorchsngmh1.blo cover, with flat-ground rim and four ground-glass ;F stopper tuhulnbions,

MM MAX.

20?0.5MM 0.D WALL 1.0-1 5 MM

7

7 0 f 2 MM

-1 Figure 4.

100-MI. Kjjeldahl Flask

Micro-Kjeldahl Distillation Apparatus, Pregl Type (ParnasWagner). This apparatus, shown in Figures 6 and 7, is composed of the following parts: Steam generator (2000-ml. capacity), A Steam Cuhe, B Wiring assembly, C Steam tram .,D Tube, E Connecting tube, F

-

Figure 6 . Micro-Kjeldahl Distillation Apparatus, Pregl Type (Parnas-Wagner)

520flOMM

,

3 7 2 1 MM

73f2MM I SLOPE 6-B'MM FOR DRAINAGE

73fZMM

260f5MM

\ ,

A-

- _. -. --

73*2MM

,

I

22-23 MM OIA. HOLES

73t2MM

..

52fP.M

SH IN SLIGHTLY

FORM REINFORCING BEAD

O.D.

WALL APPROX. 2 M M

W A L L I QMM

SECTION A-A

Figure 5.

Manifold for Miwd-Kjeldahl Digestion Rack

V O L U M E 23, N O . 3, M A R C H 1 9 5 1

525

I

CCKTER OPENING T O ACCOMMODATE

lOOf5MM

JOINT

1 W T f 3 OPENINGS

PROVIDE

b O f 5 MM

,

\

WALL I MM

78 ATTACHED HERE

140r 3 MM

195hMM

I 5422 MM

Figure 7A. Steam Generator, Micro-Kjeldahl Distillation Apparatus, Pregl Type (Parnas-Wagner)

L$\'i

40:3

1

1 1 ,d

MM

f,

is held in place with suitable clamps. To the center tubulation is attached the steam tube, Figure 7 B . Two of the outer three tubulations are used for the leads of the electric heater assembly, Figure 7 C . The remaining tubulation is used for a water inlet,

.WALL 5 MM I MM 0.D

-(,I&IoMMo.D

APPRoX.

GLAZED

7 E ATTACHED HERE

Figure 7D. Steam Trap

~ O C ~ M M

B t 0 . 5 MM O.D. WALL I M M

GLAZED

resistance of the heating spiral is about 16 ohms. The rate of steam generation is readily controlled by means of a 7.5-ampere variable autotransformer.

I O MM O.D. APPROX.

I

8f-0.5M M O.D. WALL I M M

Figure 7E. Tube

ANALYTICAL CHEMISTRY

526

I-

155f3MM

NO 18 CONDUCTOR W I R E

7G CONNECTS HERE

& D. -

6.5-7 MM(MAX

SPLICE

WALL I

RUBBER SLEEVE

410

+-SUM

NO. B W I R E (INSULATED) N0.5 ONE HOLE RUBBER STOPPERS

I N S U L A T I O N CARRIED ROUGH RUBBER S T O P P E R S

FITS INSlDE 7 K

Figure 7L.

Drain Figure 1J. Condenser Tube 73 FITS INSIDE

BRAZE OR SOLDER

l 4 t 2 MM 0.D. WALL IqLMM

40f.2 MM

GLAZEDL I I

. T 4 8 ? 0 . WALL 5 M MI MM .O:

APPROX 2 M M DIA OPENING AT' POlNfS

Figure 7H. Filling Funnel

10 MM APPROX.

-GLAZED - - _____ -1ltOSMM

O.D.

35t2UM

WALL l$MM WALL I

MM

Figure 7K. Condenser Jacket (West Type)

527

V O L U M E 23, NO. 3, M A R C H 1 9 5 1

CONNECTS TO 7F

obtained with a one-piece model by many, inoluding members of the committee, the design was studied. The specifications recommended here are the result of this work. This revised model is used with the electric steam generator, Figure 7 A , forming a sturdy, compact unit. The complete apparatus is shown in Figu r e ~8 and 9.

7

the temperature by a vacuum jacket as in Figure 7G. The Stertm enters

~rouer'(inner jacket). and

D ~ S B ~into S

portion of the tube a t the Gwer end of

Figure 7 6 .

Distillation Has

This &e&m generator is also used with the Kjeldahl di sppmatus, one-piece model (Figures 8 and 91, described Changea have been made in the conventional desigr distillation flask, Figure 7G, and the condenser tube 7 J . They include a ball and socket joint connectio should be lubricabd with stopcock grease and held togel a suitable clamp, and a We?Test-typecondenser. Kjeldahl Distillation Apparatus. ONE-PIECE MODEL(Figures 8 and 9). An apparatus of this type, but having slightly different dimensions, has been commeroidly available for 8ome time (Scientific Glass Apparatus Co., Inc., Bloomfield, N. J.). The origin of this apparatus is unknown, although attempts have been made to establish it. Because excellent results have been

the inner Irtcket. ana UD Into the center Portion or tne u1Stlll&tiOn .~ ~

~~~~

~

~~

~~

~

~

~~

chamber or d i s t k i o n flask. The alkali is added in like manner, displacing the acid portion upward. Steam is generated with the stopoocks on both the sample inlet funnel and the drainage tube closed, and the distillation is allowed to proceed.

ANALYTICAL CHEMISTRY

528

Several methods of cleaning can be used. The following one has been found satisfactory, particularly when boiling chips are em loyed in the digestion: W h i i steam is being generated and with both stopcocks closed, the sample inlet funnel is filled with water and the tip of the condenser immersed in about 100 ml. of water contained in a beaker. Steam generation is stopped, and stopcock of the funnel is opened slowly, being closed before all the water has drained into the apparatus. Reduced pressure causes water to be sucked from the beaker into the apparatus, washing it. The stopcock in the drainage tube is opened to empty t,he liquid which has

collected in the outer jacket, the steam generation is started again, and the procedure is repeated. LITERATURE CITED (1) ANAL.CHEM.,21, 651 (1949).

(2) Steyermark, Al, Alber, H. K., N u k e , V. A , , Huffman, E. W. D., Kuck, J. A., Moran, J. J., and Willits, C. O., Ibid., 21, 1555 (1949).

RECEIVED November 10, 1950

140f5 MM

B E N T BACK

1- 1 I

(CONDENSER OMITTED) IN T H I S VIEW

ir'-

MM O.D.

*WX.

ICLAZED

'A

PPROX 2 M M SPACE

260 MM RADIUS -l8+2MM

-1lfl

6OfJMM O.D.

O.D.

MM O.D. WALL I MM

\

DRAIN 7 L F I T T E D ON HERE

E A L A S POSSIBLE

l i

UOf5 MM

I-

c l l r l MM O.D. WALL I MM

.AZED

OMITTED I N THIS VIEW

Figure 9.

Kjeldahl Distillation Apparatus One-piece model