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Monsanto Chemical Company
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DATE ISSUED
5/7/62
| 1 OF 6
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1 11,505
STANDARD ANALYTICAL METHOD
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Method 10,875, Drawing 155,154,155,157
Aroclors, Pyranols, and Electrical Orade Chlorobenzenes
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Monsanto Stability_______________________________________________
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THIS FORM
K(v||n INSTRUCTIONS
IUUCO ON 12/4/57
SCOPE
This method Is used to determine the stability of chlorinated benzenes and biphenyls used as dielectrics. Certain components In the dielectric may break down at elevated temperatures to form HC1. The volatile HC1 Is swept out of the sample with air, absorbed In water and titrated potentlometrlcally with sliver nitrate.
EQUIPMENT
a. Heating bath - Drawing No. 155, assembled In our laboratory to maintain a set temperature to within + 0.5*C. see attached drawing for particulars. Two 5 x 5" 'stainless steel plates not shown In the drawing are placed on top of the straighten ing vanes In the bottom of the bath.
1. Thermoregulator - American Instrument Co., Sliver Springs, Maryland, Cat. No. 4-255.
2. Relay - Our relay Is fabricated in our own laboratory, but any sensitive, reliable relay can be used.
5* Lo-Lag heater - 500 watt, 110 volt, American Instrument Co., Silver Springs, Maryland, Cat. No. 5-404.
4. Varlao - 115 volt Input, General Radio Corp., Cambridge 59, Mass., Type V-20M.
5. Strip heater - 500 watt, 110 volt. General Electric Co., Cat. No. 2A-404.
6. Stirring motor - l/5 H.P. Bodlne motor. General Radio
Co., Chicago, 111., Type NSE-12.
7. Powerstat - The Superior Electrical Co., Bristol, Conn.
8. Stirrer - 4 bladed metal, 10-1/2" long, American
Instrument Co., Cat. No. 4-640.
9. Bath fluid - Dow Corning 550, Dow Corning Corp, Midland, Mich.
MOHS 075938
Product; Aroolors, Pyranols, and Electrical Grade Chlorobenzenes
Test: Monsanto Stability
Method No. 11,503 Page 2 of 6 pages
The heating bath is essentially a 29" x 7" x 8" bath nade
from #16 gauge 316 S3 which has been Insulated with 1" of Magnesia. The three 500 watt strip heaters are connected to the varlac. The thermoregulator controls the relay for the Lo-Lag heater. The bath temperature is regulated with the strip heaters to 210'C. and then the thermoregulator is set to control the temperature within + 0.5'C. The powerstat controls the stirring motor speed"at a rate to maintain a uniform temperature throughout the bath.
b, Air supply - 40 psi air is reduced to 8 psi by a pressure regulator. The 8 psi air Is purified by passing through an
empty trap, a scrubber bottle containing 200 NaOH, a second empty trap, a scrubber bottle containing C.P. HaSO*, a third empty trap, and a vapor trap immersed in dry ice and aoetone. The purified air line la connected to a capillary tube, cut to regulate the pressure at 24 - 26 mm Hg. on the
manometer, and then to a glass T; one side going to a 6"
meroury manometer, the other side going to a glass manifold having one connection for each sample. Capillaries are cut to a length that permits a flow of 45 ml. per minute of air and inserted between the manifold and the inlet down tube of the absorption flask.
1. Empty traps - 1000 ml. filtering flask, Fisher Scientific Co., Cat. No. 10-180.
2. Scrubbers - Flsher-Mllllgan Gas Washer, Fisher Scientific Co., Cat. No. 7-513.
3. Flow meter - Fisher Scientific Co., Cat. No. II-163,
fitted with flowrater tube No. 08-150/13.
4. Vapor trap - fabricated by our glassblower according to speciflcatlons given on Drawing No. 153
5. Evacuated flask, 1 quart capacity - Fisher Scientific Co., Cat. No. 10-197. The flask is wrapped with plastic tape to help prevent injury by flying glass Should the flask be accidentally broken.
6. Pressure regulator - outlet pressure range, actual
0-35 psi, Fieher Oovernor Co., Marshalltown, Iowa.
7. Capillaries, 0.25 mm I.D. - Fisher Scientific Co., Cat. No. 11-367.
MENS 075939
Product: Arodors, Pyranols, and Electrical Orade Chlorobenzenes
Tests: Monsanto Stability
Method No. 11,503 Page 3 of 6 pages
8. Flask, 300 ml. Erlenmeyer with 34/45 S Joint - Ace Olass CO., Vineland, N. J.
9. Absorption flasks - Fabricated In our laboratory from 125 ml. Volhard flask, E. H. Sargent and Co., Cat. No. S"03585 See Drawing No. 154.
e. Potentiometer - our potentiometer Is fabricated In our laboratory, but any sensitive, reliable potentiometer can
be used.
d. Sliver wire electrode - B and S #12 gauge silver wire. Handy and Harman, 1800 W. Kenzle, Chicago 22, Illinois.
e. Mercurous sulfate reference electrode - modified L and N oalomel referenoe electrode, L and N #7724-6-P2 (inner element) and #7724-6-Pl (outer element). Prepared as
follows: Dismantle the internal element from the salt bridge tube of a standard L and N calomel reference electrode. Dlsoard the saturated KC1 solution from the tube and clean out the mercurous ehlorlde and meroury from the Internal element. Clean the parts thoroughly. Add sufficient new clean mercury to the Internal element to make contact with the electrode wire and repack chamber of Internal element with mercurous sulfate moistened with 0.5 M potassium sulfate. Seal the ohamber with non-absorbant cotton. Fill the salt bridge tube with 0.5 M potassium sulfate and re assemble units.
f. Magnetic stirrer - tabline Inc., Chicago, 111., Cat. No. 1250 with plastic coated stirring bar.
g. Buret, 1.0 ml. mloroburet - Koch-Flsher Scientific Co., Cat. No. 20-110.
h. Other usual laboratory glassware.
HKAOENTS
a. Acetone, Malllnckrodt Cat. No. 2440, or equivalent. A blank determination of 100 ml. acetone must not exceed 0.10 ml.
0.0025 N AgNOs.
b. Silver Nitrate, A.R., Malllnckrodt Chemical Co., St. Louis, Mo.,
Cat. No. 2169, or equivalent, 0.1 N solution, standardized.
Dissolve 17.00 grams AgNOe In distilled water and dilute to 1 liter.
. Standardize against Primary Standard NaCl using the sliver wire/
' mercurous sulfate electrode system.
HONS C75940
0. Silver Nitrate solution, 0.0025 N.
Dilute 25.0 ml. standardized 0.1N AgNOe to one liter with distilled
water. Store in a dark glass container. N-0.025 x N of AgNOe used.
Product: Aroclors, Pyranols, and Electrical Orade Chlorobensenes
Teat: Monaanto Stability
Method No. 11,505 Page 4 of 6 pages
d. Nitric acid, Vf> solution, A.R. grade - Malllnckrodt Chemical Co., Cat. No. 2704, Dilute 14 ml. cone, acid to 1 liter.
SAFETY
Trichlorobenzene, Trl-Tetrachlorobenzene blends and Aroclors are Irritating to the skin. The vapors of the hot materials are Irritating to the eyes and upper respiratory system. If accidental contaot Is made with the eyes, flush Immediately with large quantities of water. Exercise caution to avoid possible thermal burns through contact with the hot bath or equipment.
DETERMINATION
The following Items must be checked before the Determination Is started:
a. Check the vapor trap for water or Ice. If either la present, clean the trap with water, rinse with acetone, and dry In an oven. Blow trap with air before using.
b. Fill the evacuated flask with dry Ice and acetone.
c. Adjust the temperature of the bath to 210 + 0.5C.
d. Check to see that the HaS0 and NaOH scrubbers are clear of any turbidity or solid material whloh might plug up the sorubber.
a. Adjust the air pressure to 24 - 26 mm Hg on the manometer.
1. Weigh on a beam balance 290 + 1 grams sample Into a 500 ml. wide mouth Erlenmeyer flask."
NOTE: See Discussion for glassware oleaning procedure.
2. Insert the absorption flask and position the flask In the bath.
W: The level of the oil In the bath must be approximately Inch below the bottom of the ground glass joint on the flask.
5. Place 15 - 20 ml. distilled water In the absorption flask and stopper tightly with a clean rubber stopper.
4. Connect the purified air supply from the capillary to the Inlet down tube in the flask.
HONS 075941
Product: Arodors, Pyranols, and Electrical Grade Chlorobenzenes
Testi Monsanto Stability
Method No. 11,505 Page 5 of 6 pages
5. Cover the oil bath with the transits boards and the exposed part of the flasks with aluminum foil.
. 6. Bubble air through the sample for 16 hours at the rate of 45 ml. per minute.
7. Disconnect the air supply.
8. Remove the absorption flask and transfer the contents to a 100 ml. beaker, rinsing the absorption flask Into the beaker with two 5 ml. portions of acetone.
9. Add 50 ml. of acetone and 2 drops of 1% HN0 to the beaker.
10. Titrate the sample potentlometrlcally following the procedure outlined In Oeneral Method No. 55, WOK Method No. 10,875 with the following modifications:
a. Use a Ag-Hg*HgaS0, 0.5 M KsS0 electrode system.
b. Use 0.0025 N AgNO,.
c. Use a magnetic stirrer.
d. Titrate to the maximum change In potential, usually ' between 75 and 100 mv.
CALCULATION
#
Chlorides (ppm) - ml. (0.0025 N AgNOa) x N x .055457 x 100 x 10,000 Sample weight
- ml. 0.0025 N AgN0 x 0.505
Report results to the nearest 0.1 ppm.
Duplicate results should check within + 0.04 ppm.
PRECISION
Based on 20 duplicate determinations by different analysts using different apparatus. The standard deviation of this method Is + 0.04 ppm.
DISCUSSION
The precision of the method Is based on material having a chloride content of approximately 0.5 ppm. Our material Is normally In this range so no effort has been made to estimate precision at higher concentrations.
HONS 075942
Producti Aroclors, Pyranols, and Electrical Grade Chlorobenzenes
Teatt Monsanto Stability
Method No. 11,50? Page 6 of 6 pages
For directions on the setting and wiring of the thermoregulator, consult "instructions for 'Quickset' Bimetallic Thermoregulator
-Instructions No. 5*5" supplied by American Instrument Co., Silver Springs, Maryland.
The apparatus Is cleaned with acetone to remove the dielectric
and then rinsed throroughly with distilled water. After the
distilled water rinse, check the last water rinse from the
flask for chlorides by the Tyndall beam method using 10%
AgNQe solution. The water must be beam free at the end of
*5 seconds.
If S' beam appears, wash the apparatus until the
distilled water Is beam free. Dry the apparatus In an oven
before use.
In oase the electrode system shows abnormal behavior. It may be cheoked by titrating a standard chloride solution. Prepare a 1.00 ppm standard by diluting 1.64 ml. of 0.5 N HC1 to 1000 ml. In a volumetrlo flask with distilled water. Dilute a 10 ml.
aliquot with 50 - 75 ml, methanol in a 100 ml. beaker and titrate with 0.005 N AgN0. Calculate the ppm chlorides In dicated by the titration and compare with the standard value. Fresh standard should be prepared eaoh time.
REFERENCE a. Laboratory Notebook Reference: 146, 47.
b. "Instructions for 'Quickset* Bimetallic Thermoregulator" -Instructions No. 545, American Instrument Co. Inc., Silver Springs, Maryland. '
"The Information contained herein Is, to our best knowledge, accurate; but all recommendations or suggestions are made without guarantee, since the conditions of use are beyond our control. Monsanto disclaims any liability for loss or damage Incurred in connection with the use of the above."
MGNS 075943
VAPOR TRAP MONS 075944
ABSORPTION TRAP
125 Volhard flask
10/30 S Joint
34/45 S Joint .............. B m O.D. tubing
DRAWINO NO. 154 HONS 075945
HIATINO BATH
l/*" Rod
Tap Vim
Bafflea on 3" Cirole
Stirrer
Heat Braeketa
_500 Watt In-Lag Heater, Aalnoo 110 V
3-500 watt no V a. I. atrip haatara. Bolt to botton of bath and vald around head of bolt to l/t" Raoa^*l}**te8>$or Support
of Stirring Motor
1" Nagnaala Inaulatlon twMit TUlf
------- Haatara 3/A" pipa Lega
Soale: 1-1/8* 1'
GE
Oovara for bath aade froa
tranalta board. Muabor required Hated underneath
DRAWIHQ HO. 155
V HONS 075946
ASSEMBLED APPARATUS
A. Mercury Manometer B. Relay C. Varlao D. Powerstat B. Air Scrubbing System P. Thermoregulator 0. Heating Bath
"ONS 075947 DRAWINO HO. 157