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Standard specification semi-micro determination of oxygen in organic substances
VOL.
4 (1950)
DETERMINA'I-XON
STANDARD SEMI-MICRO
OF
OXYGEN
195
SPECIFICATION
DETERMINATION ORGANIC
2.
OF OXYGEN
IN
SUBSTANCES
Princij5le
The organic substance is cracked at 1o5o~-1xoo~ C in a stream of oxygen-free nitrogen. The pyrolysis products are reduced by means of carbon which has been heated up to x050-IIOO” C, in which reduction the oxygen compounds are converted into carbon monoxide. . The CO-containing gas is oxidized to carbon dioxide by mercuric oxide and passed through baryta after which the carbon dioxide is determined titrimetrically. 2. Reagents
a. b. C.
d. ::
::
. 1. is
k. 1. m. n. 0.
Hydrochloric acid, standardized about 0.05 N Baryta, standardized about 0.05 N Sulphuric acid (3 + 4). Mix 3 parts by volume of sulphuric acid (x.84) with 4 parts by volume of water. Potassium hydroxide, pellets Ammonia (0.91) Ammoniacal ammonium chloride solution. Mix equal volumes of saturated ammonium chloride and ammonia (0.91) Calcium chloride Copper chips (thickness 0.5-1mm) Mercury Ascarite Anhydrone Phosphorus pentoxide Soda lime Nitrogen Activated carbon (2-5 mm). Condition Farnell activated carbon (PHL grade) by heating it for 5 x 24 hours at 115o-12oo~ C in a stream of oxygen-free nitrogen and cool in a nitrogen atmosphere. Red mercuric oxide. Condition the mercuric oxide in a stream of carbon dioxide-free dry air for IO hrs at 250~ C. Alcoholic solution of cresolphthalein; IO g per litre alcohol (96%).
References
p.
299.
II. W.
296
DEINUM,
A.
SCHOUTEN
VOL.
4
(1950)
3. A$~$watus
Vide figure.
coawrr,ono/
oxyo,”
do
carbonmonoxtdr
I
\Vash-bottle with ammonia (0.01) Mercury seal & D Washers filled with copper chips and ammoniacal ammonium chloride solution Wash-bottle (75 ml sulphuric acicl (1.84) + IOO ml water). To prevent obstructions by ammonium sulphatc the inlet tube must have a diameter of f 5-2 cm. Drying tower with calcium chloride Drvingi tower with ascarite Dr$inE tower with anh drone Drying tower with phosp Korus pcnt. oxide __. I< kilnngecl pusher. quartz L Gas burner hl Platinum boat N C)uartz reaction tube, length 7 5 cm, I. z cm. The carbon i;lternal diam. lrrycr (Pnrncll carbon or equivalent carbon) is kept bctwccn platinum discs. 0 T;lowmctcr U-tu bcwith solid potassium hydroxide Drying tower wath anhydrone Drying tower with soda time Wash-bottle with sulphuric acid (I 34) Tube with red mercuric oxide Mercury trap Absorption vessel with baryta Burette with hydrochloric acid
4. sanrpzc The amount of the increment shall be such that not more than 12 mg carbon ciioxide will be formed, since a larger amount of carbon dioxide will render the titration incorrect. Preliminary mani@dations (de also remark I to 3 inclusive). Arrange the apparatus in the manner shown in the figure. Put cock x in position J_ and close .the cocks 2 and 3. Sweep the air from the apparatus by means of nitrogen (rate 1.5 l/h). Then heat furnace I up to xo5o-11oo~ C and furnace II up to 250~. *Connect the watcrjet air-pump with the apparatus at V, open cock 3 and draw air through furnace II via S-R-P-Q at a rate of about 8 I/h, Reduce the temperature of furnace II to x30’ C. Referewes
p.
299.
VOL. 4 (1950)
DETERMINATION
OF
OXYGEN
297
Procedure. Weigh an appropriate amount (p mg) of the sample into a flamed platinum boat. Put cock I in position I-, remove the ground stopper and pusher K and insert boat M in the reaction tube N, just behind the nitrogen feed. Sweep any air from the apparatus by putting cock I in position J_ and by passing nitrogen for 20 min. In the meanwhile fill burette W with 50 ml hydrochloric acid and transfer 50 ml baryta, 0.03 N (titre t,), into absorption vessel V by means of a pipette; re-connect the burette with V. Close cock 3 and stop the waterjet air-pump. Put cock I in position -I, open cock 2 and adjust the rate of the nitrogen stream to 1.5 l/h. Place the platinum boat at a distance of 3 cm from the furnace by means of the pusher (if the sample should consist of a more volatile compound, at a distance of about 5 cm). Heat the reaction tube with the gas flame, gradually shifting the flame in the direction of the boat. The temperature of the tube should not rise above 6oo-7oo” c. Insert the sample in the furnace as soon as the flame has been shifted up to the boat and crack at IO~O~-IIOO~ C. If necessary, adjust the rate of the nitrogen stream by means of cock 2. After cock I has been in position -i for 50 minutes, raise the temperature of furnace II up to 250~ C. Close cock 2 after another IO minutes and put cock I in position _L . Open cock 3 and aspirate air via S-R-P-Q at a rate of 8 l/h. Titrate the excess of baryta with 0.05 N hydrochloric acid (titre t, ) using cresolphthalein as an indicator (consumption Vz ml). Perform a blank in the above manner (remark I) in which the sample is replaced by an organic oxygenfree substance.
5. Calcululion Calculate the oxygen content in y0 by weight with the formula:
(50 ’ t1 ---z-b where tl = v, = tz = P
=
C
=
)-8--cx
Ioo
P
titre of the baryta ml hydrochloric acid, consumed for titrating the excess of baryta titre of the hydrochloric acid weight of the sample in mg correction for the blank value. 6. Remarks
I.
The apparatus is calibrated for the blank value. To this end a test is performed with a pure organic oxygen-free substance. One may also use substances with a known oxygen content, taking the difference between the determined and the calculated value, as the blank value.
References
p. 299.
H. W. DBINUM,
298
A. SCIIOUTEN
VOL. 4
(1950)
The blank value only holds if furnace I is continually kept at the working tcmperaturc. 3r If, furnace I has cooled off, the apparatus should be made ready for use in the following manner. Heat furnace I, crack about 300 mg carbazole and allow the gases to escape immediately via cock I. 4. If Farnell carbon is not available benzene soot may be used, which is prepared as follows : bum an amount of thiophene-free benzene under a glass tube. Collect the soot, pellet it and crush the pellets to a grain size of 2-5 mm. Further proceed as described under Aeugenfs. 5. Substances rapidly decomposing during combustion and having an oxygen content of more than 25 o/o (for example succinic acid) are mixed with carbazole . 6. The relative accuracy of the oxygen determination is 2%. After the apparatus has been made ready for use the analysis takes x.5 hrs.
2.
SUMMARY The authors describe a m&hod, based upon the proccdurc which in 1940 already WZLYoutlined by UNTDRZAUCHDR~ and which afterwards was adapted by SPOONEIC~ to the determination of oxygen in coal. This procedure involves yrolysis of i_hc sample at high tempcraturcs and conversion of all the oxygen in tX e pyrolysis products into CO. The CO formed is dctcrmincd. In our test particular attention was paid to the elimination of the oxygen from the nitrogen, the clcgrce in which the reaction tube was attaclccd by carbon and to a simple method for dctcrmining the carbon monoxide formed. By means of the method described abt. 4 mg of oxygen can be detcrminecl with a max. error of 0.1 mg and with a mean error of 0.05 mg. The method has been applied to a wide variety of substances. A standard methocl is given.
Rl2sunu2 autcurs d&.zrivent une methodc basdc sur le pro&d& d&j& publie cn rg4o par UNTXRZAUCHER~ ct ap liqu6 plus taxd par SPOON~R au dosage de l’oxygene dans Its charbons. Cette m %thode consiste Q effectuer une pyrolyse de 1’6chantrllon h haute temperature et B transformer tout l’oxyg&ne en CO. Le CO obtenu est dose. On a 6tudiB en particulier 1’6limination de l’oxyg8ne dans l’azote, l’atta ue des tubes par le carbone et la methodc la plus simple pour determiner l’oxyde % e carbonc form& A l’aide de la m&hode propos&, on peut doser environ 4 mg d’oxygdne avcc une erreur maximum de 0.x mg et une erreur moyennc de 0.05 mg. Cette methode peut etre appliquee B un grand nombrc de substances. Une m&hode standard est donn6c.
Les
ZUSAMMENFASSUNG Die Verfasscr bcschreiben eine Methodc, welche sich auf das von UNTERZAUCHER~ im Jahre xg4o bescbriebene und spater von SPOONER~ auf die Bestimmung von Sauerstoff in Kohle angewendete Verfahrcn grtindct. In diesem Verfahren wird das zu analysierende Muster der Pyrolysc bei hohcr Temperatur unterworfen und dann der gcsamtc Sauerstoff der Pyrolyseprodukte in CO tibergeftihrt.
Refermaces fi. egg.
VOL.
4 (x950)
DETERMINATION
OF
OXYGEN
299
de8 Das gebildetc CO wird bestimmt. Wir haben insbesondere die Entfernun Sauerstoffes aus dem Stickstoff, die Korrosion des Rohres durch Kohlenstof f und die einfacbste Metbode zur Bestimmung von CO untersucht. Mit Hilfe der beschriebcncn Methode kdnnen 4 mg Saucrstoff mit einem maximalen Fehler von 0.x und einem durchscbnittlichen Fehler van 0.05 bestimmt werden. Das Verfabren wurde auf zahlreiche Substanzen aagewendet und tine Standardmcthode angegcben. REFERENCES i UNTERZAUCHER,
Der., 73 (x940) 391.
SPOONEH, FHeC in Science and Praclicc, Vol. XXVI No. x-15 (1947) A. DINERSTEIN AND R. W. KLIPP, Anal. Chem., 21 (1949) 545. W. I. CHAMBERS, Conference on Rubber Technology, London, (x948). H. W. DEINUM AND J. W. DAM, Anal. Chim. Acta, 3 (1949 353. I J. D. MCCULLOUGH, R. CRANE AND A. 0. BECKMAN, Ancrl.Crem.x9(1947)999. 1). LUNDQVIST, Ada Chem. &and., 2 (1948) 177. W. KXIXSTEN, Mihrochemie, 34 (x949) 15x. H. A. J. PIETERS, Anat. Chanr. Acta, 2 (1948) 263.
z R. b
n 7 0 0
Received
December
and,
1949
4 (1950)
DETERMINA'I-XON
STANDARD SEMI-MICRO
OF
OXYGEN
195
SPECIFICATION
DETERMINATION ORGANIC
2.
OF OXYGEN
IN
SUBSTANCES
Princij5le
The organic substance is cracked at 1o5o~-1xoo~ C in a stream of oxygen-free nitrogen. The pyrolysis products are reduced by means of carbon which has been heated up to x050-IIOO” C, in which reduction the oxygen compounds are converted into carbon monoxide. . The CO-containing gas is oxidized to carbon dioxide by mercuric oxide and passed through baryta after which the carbon dioxide is determined titrimetrically. 2. Reagents
a. b. C.
d. ::
::
. 1. is
k. 1. m. n. 0.
Hydrochloric acid, standardized about 0.05 N Baryta, standardized about 0.05 N Sulphuric acid (3 + 4). Mix 3 parts by volume of sulphuric acid (x.84) with 4 parts by volume of water. Potassium hydroxide, pellets Ammonia (0.91) Ammoniacal ammonium chloride solution. Mix equal volumes of saturated ammonium chloride and ammonia (0.91) Calcium chloride Copper chips (thickness 0.5-1mm) Mercury Ascarite Anhydrone Phosphorus pentoxide Soda lime Nitrogen Activated carbon (2-5 mm). Condition Farnell activated carbon (PHL grade) by heating it for 5 x 24 hours at 115o-12oo~ C in a stream of oxygen-free nitrogen and cool in a nitrogen atmosphere. Red mercuric oxide. Condition the mercuric oxide in a stream of carbon dioxide-free dry air for IO hrs at 250~ C. Alcoholic solution of cresolphthalein; IO g per litre alcohol (96%).
References
p.
299.
II. W.
296
DEINUM,
A.
SCHOUTEN
VOL.
4
(1950)
3. A$~$watus
Vide figure.
coawrr,ono/
oxyo,”
do
carbonmonoxtdr
I
\Vash-bottle with ammonia (0.01) Mercury seal & D Washers filled with copper chips and ammoniacal ammonium chloride solution Wash-bottle (75 ml sulphuric acicl (1.84) + IOO ml water). To prevent obstructions by ammonium sulphatc the inlet tube must have a diameter of f 5-2 cm. Drying tower with calcium chloride Drvingi tower with ascarite Dr$inE tower with anh drone Drying tower with phosp Korus pcnt. oxide __. I< kilnngecl pusher. quartz L Gas burner hl Platinum boat N C)uartz reaction tube, length 7 5 cm, I. z cm. The carbon i;lternal diam. lrrycr (Pnrncll carbon or equivalent carbon) is kept bctwccn platinum discs. 0 T;lowmctcr U-tu bcwith solid potassium hydroxide Drying tower wath anhydrone Drying tower with soda time Wash-bottle with sulphuric acid (I 34) Tube with red mercuric oxide Mercury trap Absorption vessel with baryta Burette with hydrochloric acid
4. sanrpzc The amount of the increment shall be such that not more than 12 mg carbon ciioxide will be formed, since a larger amount of carbon dioxide will render the titration incorrect. Preliminary mani@dations (de also remark I to 3 inclusive). Arrange the apparatus in the manner shown in the figure. Put cock x in position J_ and close .the cocks 2 and 3. Sweep the air from the apparatus by means of nitrogen (rate 1.5 l/h). Then heat furnace I up to xo5o-11oo~ C and furnace II up to 250~. *Connect the watcrjet air-pump with the apparatus at V, open cock 3 and draw air through furnace II via S-R-P-Q at a rate of about 8 I/h, Reduce the temperature of furnace II to x30’ C. Referewes
p.
299.
VOL. 4 (1950)
DETERMINATION
OF
OXYGEN
297
Procedure. Weigh an appropriate amount (p mg) of the sample into a flamed platinum boat. Put cock I in position I-, remove the ground stopper and pusher K and insert boat M in the reaction tube N, just behind the nitrogen feed. Sweep any air from the apparatus by putting cock I in position J_ and by passing nitrogen for 20 min. In the meanwhile fill burette W with 50 ml hydrochloric acid and transfer 50 ml baryta, 0.03 N (titre t,), into absorption vessel V by means of a pipette; re-connect the burette with V. Close cock 3 and stop the waterjet air-pump. Put cock I in position -I, open cock 2 and adjust the rate of the nitrogen stream to 1.5 l/h. Place the platinum boat at a distance of 3 cm from the furnace by means of the pusher (if the sample should consist of a more volatile compound, at a distance of about 5 cm). Heat the reaction tube with the gas flame, gradually shifting the flame in the direction of the boat. The temperature of the tube should not rise above 6oo-7oo” c. Insert the sample in the furnace as soon as the flame has been shifted up to the boat and crack at IO~O~-IIOO~ C. If necessary, adjust the rate of the nitrogen stream by means of cock 2. After cock I has been in position -i for 50 minutes, raise the temperature of furnace II up to 250~ C. Close cock 2 after another IO minutes and put cock I in position _L . Open cock 3 and aspirate air via S-R-P-Q at a rate of 8 l/h. Titrate the excess of baryta with 0.05 N hydrochloric acid (titre t, ) using cresolphthalein as an indicator (consumption Vz ml). Perform a blank in the above manner (remark I) in which the sample is replaced by an organic oxygenfree substance.
5. Calcululion Calculate the oxygen content in y0 by weight with the formula:
(50 ’ t1 ---z-b where tl = v, = tz = P
=
C
=
)-8--cx
Ioo
P
titre of the baryta ml hydrochloric acid, consumed for titrating the excess of baryta titre of the hydrochloric acid weight of the sample in mg correction for the blank value. 6. Remarks
I.
The apparatus is calibrated for the blank value. To this end a test is performed with a pure organic oxygen-free substance. One may also use substances with a known oxygen content, taking the difference between the determined and the calculated value, as the blank value.
References
p. 299.
H. W. DBINUM,
298
A. SCIIOUTEN
VOL. 4
(1950)
The blank value only holds if furnace I is continually kept at the working tcmperaturc. 3r If, furnace I has cooled off, the apparatus should be made ready for use in the following manner. Heat furnace I, crack about 300 mg carbazole and allow the gases to escape immediately via cock I. 4. If Farnell carbon is not available benzene soot may be used, which is prepared as follows : bum an amount of thiophene-free benzene under a glass tube. Collect the soot, pellet it and crush the pellets to a grain size of 2-5 mm. Further proceed as described under Aeugenfs. 5. Substances rapidly decomposing during combustion and having an oxygen content of more than 25 o/o (for example succinic acid) are mixed with carbazole . 6. The relative accuracy of the oxygen determination is 2%. After the apparatus has been made ready for use the analysis takes x.5 hrs.
2.
SUMMARY The authors describe a m&hod, based upon the proccdurc which in 1940 already WZLYoutlined by UNTDRZAUCHDR~ and which afterwards was adapted by SPOONEIC~ to the determination of oxygen in coal. This procedure involves yrolysis of i_hc sample at high tempcraturcs and conversion of all the oxygen in tX e pyrolysis products into CO. The CO formed is dctcrmincd. In our test particular attention was paid to the elimination of the oxygen from the nitrogen, the clcgrce in which the reaction tube was attaclccd by carbon and to a simple method for dctcrmining the carbon monoxide formed. By means of the method described abt. 4 mg of oxygen can be detcrminecl with a max. error of 0.1 mg and with a mean error of 0.05 mg. The method has been applied to a wide variety of substances. A standard methocl is given.
Rl2sunu2 autcurs d&.zrivent une methodc basdc sur le pro&d& d&j& publie cn rg4o par UNTXRZAUCHER~ ct ap liqu6 plus taxd par SPOON~R au dosage de l’oxygene dans Its charbons. Cette m %thode consiste Q effectuer une pyrolyse de 1’6chantrllon h haute temperature et B transformer tout l’oxyg&ne en CO. Le CO obtenu est dose. On a 6tudiB en particulier 1’6limination de l’oxyg8ne dans l’azote, l’atta ue des tubes par le carbone et la methodc la plus simple pour determiner l’oxyde % e carbonc form& A l’aide de la m&hode propos&, on peut doser environ 4 mg d’oxygdne avcc une erreur maximum de 0.x mg et une erreur moyennc de 0.05 mg. Cette methode peut etre appliquee B un grand nombrc de substances. Une m&hode standard est donn6c.
Les
ZUSAMMENFASSUNG Die Verfasscr bcschreiben eine Methodc, welche sich auf das von UNTERZAUCHER~ im Jahre xg4o bescbriebene und spater von SPOONER~ auf die Bestimmung von Sauerstoff in Kohle angewendete Verfahrcn grtindct. In diesem Verfahren wird das zu analysierende Muster der Pyrolysc bei hohcr Temperatur unterworfen und dann der gcsamtc Sauerstoff der Pyrolyseprodukte in CO tibergeftihrt.
Refermaces fi. egg.
VOL.
4 (x950)
DETERMINATION
OF
OXYGEN
299
de8 Das gebildetc CO wird bestimmt. Wir haben insbesondere die Entfernun Sauerstoffes aus dem Stickstoff, die Korrosion des Rohres durch Kohlenstof f und die einfacbste Metbode zur Bestimmung von CO untersucht. Mit Hilfe der beschriebcncn Methode kdnnen 4 mg Saucrstoff mit einem maximalen Fehler von 0.x und einem durchscbnittlichen Fehler van 0.05 bestimmt werden. Das Verfabren wurde auf zahlreiche Substanzen aagewendet und tine Standardmcthode angegcben. REFERENCES i UNTERZAUCHER,
Der., 73 (x940) 391.
SPOONEH, FHeC in Science and Praclicc, Vol. XXVI No. x-15 (1947) A. DINERSTEIN AND R. W. KLIPP, Anal. Chem., 21 (1949) 545. W. I. CHAMBERS, Conference on Rubber Technology, London, (x948). H. W. DEINUM AND J. W. DAM, Anal. Chim. Acta, 3 (1949 353. I J. D. MCCULLOUGH, R. CRANE AND A. 0. BECKMAN, Ancrl.Crem.x9(1947)999. 1). LUNDQVIST, Ada Chem. &and., 2 (1948) 177. W. KXIXSTEN, Mihrochemie, 34 (x949) 15x. H. A. J. PIETERS, Anat. Chanr. Acta, 2 (1948) 263.
z R. b
n 7 0 0
Received
December
and,
1949