SAM-TR-65-89

00

OXYGEN CONCENTRATION, TEMPERATURE, ANDq• VISCOSITY DE"TERMINATIONS

, iPolarograplhic Te'chnic

EDWARD A. RICE, Mtjor, UISAFROBERT E. VOPAT, B.S.

CLEARINGHOUSEFOR FEDERAL SCIENTIFIC AND ....

TECHNICAL INFORMATION P i9 "

K-Hiidjip TMiorof iehe

$ " •',, 1/_ .p ,,J ,, ,.ecember 1965 MAR

(C-,e• /

USAF School of Aerospace MedicineAerospace Medical Division (AFSC)

Brooks.Air Force Ba'e. Texas

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II

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OXYGEN CONCENTRATION, TEMPERATURE, AND VISCOSITY DETERMINATIONS

Polarographic Technic

EDWARD A. RICE, Major, USAF

ROBERT E. VOPAT, B.S.

4 ,

T

FOREWOIRI)

This report was prepared in the Radiobiology Branch under task No. 571003. Itwas submitted for publication on 26 October 1965. The work was accomplishedbetween June and October 1965.

This report has been reviewed and is approved.

HAROLD V. ELLINGSONColonel, MC, USAFCommander

ik

ABSTRACT

A technic was developed for determining the effects of ionizing radiation onmolecular oxygen concentration in an aqueous solution. The polarographic principlewas used for determining oxygen concentration, temperature, and viscosity of solution,and oxygen concentration in gas. The polarographic system has the followingprincipal characteristics: (1) param'..ters can be remotely measured, permitting thesystem to be used in environments hostile to observers (i.e., radiation); (2) temperaturemeasurement can be made within 1V C.; (3) changes in temperature are recordedinstantly; (4) oxygen concentration can be measured with a resolution well within1 mm. Hg; and (5) oxygen changes are recorded instantly.

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OXYGEN CONCENTRATION, TEMPERATURE, AND VISCOSITY DETERMINATIONS

Polarographic Technic

I. INTRODTY TION the system has the capability of being extendedto utilize simultaneously many gas cylinders

The polarographic A;nod of determining and many cells.oxygen concentration in gaseous and solutionenvironments has been used many times (1). A close-up of the cell, in which may be seenUse of polarography to measure oxygen con- the protrusion of platinum and silver electrodescentration has been limited in the past to into a saline solution, is shown in figure 2.oxygen measurement. The influence of tem- The cover over cell A provides . a means forperature, viscosity, and fluid movement on the controlling the gaseous environment over thediffusion coefficient of oxygen has been in- solution. The leads extending from thevestigated (2-5), and a knowledge of these electrodes are coupled to a polarograph thatvariables must be ascertained at the time the can be located far enough from the test cell tooxygen measurement is made, if the oxygen permit this system to be used in environmentsmeasurement is to be accurate. If all but one hostile to the observer (i.e., radiation).of these variables (e.g., viscosity) were main-

* tained constant, the system would then meas- Instrumentationure the coefficient of viscosity of the solution.Likewise, the principle could be applied to de- The polarographic circuit (fig. 3) used intermine quantitative values of such other the system involves the following principle:variables as temperature, dynamics of fluid oxygen is reduced at the cathode (platinummovement, and oxygen concentration. This electrode), and electron flow resulting fromcommunication describes the use of polarog- this reduction is measured as a voltage dropraphy to measure temperature, oxygen con- across resistor A, B, or C. The basic equationcentration, and viscosity, for this principle is:

0,. + 2e + 2H+ - H.,O., + 2e + 2H+ - 2H.,OII. METHODS The measurements are made in a dilute solu-

tion of an electrolyte (e.g., 0.9 N NaC1). TheApparatus external current control shown in the circuit

was not used in this study; however, it pro-The apparatus that is used to measure vides the capability of applying to the cathode

the parameters listed in the introduction is an a.c. voltage rather than a d.c. voltage. Inillustrated in figure 1. Both cell A and cell B certain experiments, it is advantageous to usecan be used interchangeably as test and con- an a.c. voltage owing to the effect of con-trol cells. C represents a solenoid valve that tamination upon the electrode by the mediumcan permit the control of the system remotely, in which the electrode is inserted (1). Theand D indicates a tank of gas that can be circuit on the positive side of the output isused to change the concentration of oxygen in used primarily to suppress the voltage dif-the fluid medium in either cell. Only two cells ferences that are created in the cell by theand one cylinder are .;hown in this figure, but combination of platinum, silver, and sodium

FIGURE 1

Cell A with cover to control atmosphere over the solution. Cell B can be used with or

without the cover. Solenoid valve (C) can be remotely operated. Tank containing nitrogen

(D); bubbling nitrogen through the glass filter in cell A removes the oxygen. Extension

cable connected to F permits remote control of solenoid valve.

chloride, thereby permitting at the output for across the resistors (indicated in fig. 3) makes

further amplification only oxygen-reduction it necessary to use d.c. amplifiers to gain an

current. This arrangement makes possible a acceptable degree of resolution. With this

resolution of oxygen concentration within system, changes of 1 mm. Hg can be detected.

1 mm. Hg. Also, the system permits easy determinationof temperature changes within 1' C.

In this system, the applied voltage on the

platinum electrode is 1 v., permitting the III. RESULTS AND DISCUSSION

system to function on the plateau of the cur-

rent-voltage curve (fig. 41). Oxygen concentration

A thermistor is used to measure the tern- It is well known that polarographic systems

perature of the saline solution in the test cell can measure the concentration of oxygen in

(see block diagram, fig. 5). A glass filter fluid and tissue mediums (6, 7, 8). The use of

permits the passage of gas into the cell and nitrogen to reduce the oxygen concentration

prohibits the leakage of saline solution from in a saline solution and the use of air to return

the cell. The reactor core is shown to indicate the solution to normal oxygen concentration

a possible use of all the remote features of the are illustrated in figure 6. The oxygen-reduc-

system. The low level of the voltage drop tion current is increased with the onset of the

produced by the oxygen-reduction current nitrogen bubbles that are forced through the

2

1. Calibrate the polarographic system bymeasuring the oxygen-reduction current flowin a saline solution in air. This current flowrepresents 150 mm. Hg (201/( oxygen in air, or20,C/ of 750 mm. Hg). Bubble nitrogenthrough the glass filter, removing all oxygenin the saline solution. If proper use is madeof the circuit on the positive-output side of theschematic shown in figure 3, no current flowwill be detected after nitrogen is bubbled

X, through the solution for several minutes. Therelationship is linear between oxyger currentflow and oxygen concentration.

2. Force the gas containing the unknownoxygen concentration through the saline solu-tion equilibrated to oxygen concentration inair, and use the calibration curve (plotted asdescribed above) to determine the current

A, flow resulting from the gas mixture in thesolution, thus ascertaining the oxygen con-centration in the gas mixture.

3. Replace the saline solution with a solu-tion containing the unknown oxygen concentra-tion and measure the oxygen-reduction currentflow. With this value and the calibration curve,determine the oxygen concentration in the solu-tion. The viscosity and temperaturc of thesaline solution used to calibrate the system and

FIGURE 2 of the solution contairing the unknown oxygenTest and control cells indicating the protrusion of concentration must be the same.

platinum-wire aad silver-wire electrodes into a normalsolution of sodium chloride. Glass filter is located atthe bottom of the cell (white ring). The cover A Temperatureover control cell C permits the environmental gas toremain constant. B is clone-up of the test cell, The polarographic system as a tempera-

glass f ilter. This increase in the o~rngen- ture-measuring device was compared with a

reduction current is typical cf all bare oxygen- thermistor (fig. 7A). The temperature change

sensitive electrodes and is dr ý to a phenomenon was produced in a medium in which these

known as "stirring potentials" (constant curves were made simultaneously in each

changing of the oxygen-diffusion gradient). system. The thermistor lagged the polro-

Also, it may be noted i.-. 'tigure 6 that when graphic system by approximately 0.5 sec.;oxygen was returned to the solution, the therefore, when one is interested in measuringoxygen concrenturain exedt hed itsorgional t instantaneous temperature changes, the polaro-oxygen concentration exceeded its original g a h c m t o o a i g t e e m a u evale. his to, ws de t th efectof graphic method for making these measure-value. This, too, was due to the effect of ments is far nuperior to a system in which astirring potentials. thermistor is used. The difference in the

To measure the unknown oxygen concentra- s' nsitivity of the two systems is apparent.tion in a solution or in gas, the following steps The actual change in temperature was ap-are required: proximately 10" C.; however, it is obvious from

3

-i

EXTERNALCUMNTCOTL

•1EXT ZERO ., 4-

0 SAVEPM (PATINUMA)

+~ +

VV

I

A - 0- 15OOHMS

8 -0- 5 MEGOhMSC - 30 MEGO*M

FIGURE 3

Polarographic circuit. The exampi,- "biologic fluid" represents any medium contai;,ingoxygen in molecular form. Zero supprcssior. positire side of output, permits greater se,'-sitility cnd provides det,,rmination ýtithin I mm. Hg or P C. change. Selection of resistorA, B, or C changes the output sensitivity.

1&0

L

ATEST

°r ?r

&0 0 CEL0 06|8 0 2rA Ii 2

0 0,2 0.4 OG 08 10 12 14 1.6 la 20 ,NLEr

APPLIED VOLTAGE(241C)

FIGURE 5

FIGURE 4 Block diagram indicating a reactor core, to demon-strate a use requiting the remote features of the:Typical current-voltage curve. s:ystem.

44

- z bw

-~ -- --PE

250250 100S (Y(

200-9

N 1 0 70

150 4I 3

-50

o --.-..- -- -- -- -- - - --0

0 I 2 3 4 5 6 7TIME (SECONDS A1 1

TIME (SE00PDSI

FIGURE 6 'UN 00

Sytmsresponse. curve to oxygen reduction.. -- EPRTN 490

200L .90)STMING, POTENTIAL 170

the magnitude of the change when the polaro- 1.'0 4

IN, CAIgraphic method is used that a resolution can TEMPERATURE - V)

0 INCREASED

be made much less than 10 C. 100 -_kI

K 1 30

An experiment was performed to indicate 7EMPERATURj ý Dj ABSJ 10

th ncesiy oro:ygen when the system is OF -

used as a temperature indicator (fig. 7B). 0B 2 4 5 6 7

Tw.%o things are apparent: (1) the oxygen must T SCIIS

be present, andl (2) the temperature-sensitivityof the system (the degree of rn-solution withrespect to temperature change) depends on FIGURIF 7

the magnitude of the oxygen concentration ; J'irgahcsjstein ust-d as a trfinperatutfll inl-

the higher the oxygen concentration, the more drl~tior. A, Note instantane-ous react jun of the- poa/a in

sensitive the system is to temperature changes, giraphic systemi to tempferature chantges. Reaction timechag betiveen the tivo systems in approximately 0.5 5E'o.

When the oxygen concentration reaches zero, Hi, Note the necessity for the presence of oxygenpthe system is no longer sensitive to tempera- to measure temnperature change. Thermistor registere-dture changes,. As shown in figure 7B, at ap- tempe-ra tutre change (dotted line), but chapige wa-is

proximately 6.5 sec. the temperature in the absent in the polarographie tentperature curve, (Morid

souinwas changed and the thermistor ln)(.shown by a dotted line) indicated a changeof approximately 10' C. During this period, Nocagintevlgefth lrgapchowever, bubbling nitrogen through the solu- Note change te in thevlae ofntherol rographention had removed the oxygen from the ?ystem sytmwsnedith corlcll heat 1.0 .sec., and no change due to temperature saline was added; however, each addition ofvariation in the solution was noted in the agar solution to the test cell decreased thepolatrographic oxygen curve, voltage output of the test cell. It is important

to realize at this point that, even though theVriscosity oxygen-diffusion current had been reduced, the

oxygen concentration was maintained at 150The polarographic system wats used to incas- mm. 11g. Each addition of agar essentially

tire the viscosity of a solution (fig. 8). Saline changed the oxygen-diffusion coefficient, pro-was added to the control cell each time a ducing a lower voltage for the same oxygenmixture of agar wits added to the test cell, concentration.

51

A Wbe*n this method is used to r.easure,--- ---- viscosity, it is imperative that the temperature

I ard the oxygen concentration be unchangedduring the measurement. Once a solution withknown viscosity has been added and the system

-. .60• has been calibrated, the test cell wi!l b. readyfor determination of the unknown viscosity.Additions of a solution in which the viscoaityis unknown into a test cell should register a

% -' 3• , s , voltage output of the system which, whenW %P matched with the calibration curve, should give

a fair approximation of the viscosity of theFIGURE 8 new solution.

Poiarogrcphir. 4stem ased, t-o wsearr iis~r~tl.

A ard B, Saline xolwtim ad4MeS to cowtrol cell reoxiut-isp salinw (dotted lie) smd arar added *o tet ovllcotoibmaiag agar golxtion (n*iMd imO.

REFERENCES

1. Brezina, M., and P. Zuman. Polarography in 5. Wanner, H. The influence of temperature on themedicine, biochemistry, and pharmacy, New oxygen diffusion- coefficient in solution. Helv.York: Interscienee Publishers, Inc., 1358. Chim. Acta 28:23 (1945).

2. Foffani, A., and E. Vecchi. Vis-osity and dif- 6. Davis, E. W., W. S. McC-lloch, and E. Roseman.fasion current of oxygen in so.tion. Ric. Sci. Rapid changes in 0. tension of cerebral cortex22:81 (1952). during induced convulsion. Amer. J. Psychiat.

100:825 (1943).

3. Foffani, A., and E. Vecchi. The effects of vis- 7. Rice, E. A. Polarographic studics of cat'scosity on diffusion coefficient of oxyge-n in auditory cortex. J. Neurophysiol. 23:350solution. Sbornik mezinarod. polarog. sjezdu (1960).praze, 1st Cong., 1951, Pt. I. Proc. 64.

8. Rice, &. A., D. C. Sawyer, E. T. Still, and S. E.4. Pircher, L. Viscosity and diffusion current in a Beard. Early physiologic changes in primates

solution containing methylmeglobin. Helv. following mixed gamma-neutron pulsed radia-Physiol. Pharmacol. Acta 10:110 (1952). tion. SAM-TR-65-31, June 1965.

6

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1 ORIGINATING ACTIVI'V (Corporate iitho,. 20 RE(PORT SCCURITY C LA~I-WrCA 'SONUISA? School of Aerospoace Medicine

* Aerospace *e6ical Division (AFsc) 26 bRUnasFie

* Brooks Air Force Base, Texas

3 nEPORT TITLE

OXYGEN CONCETRATION, TEEMPERATUR, AND VISCOSITY¶ DETERMINATIONSPolarographi c Technic

4 OESCRIJITIVE wo-as fry"e of report and inchuasve dates)

.Finvil rupnrt June-Oct. 19655 AUTHOR(S) Laoataim.. fltar naee. Initilal)

* Rice, Edward A., Major,, USAFVopat,, Robert E.

6: REPORT OATE 7a CYLNO OF PAGrS 76 140 OF nflI

Dec. 1965 6 81&a ZONTRACT Olt GRANT NO0 go ORIGINATOM-S REPORT NLi"SasERS

VPROJECT NO sAm-TR-65-89

c- Tas No. 51003 b OTH'JEm REPORT 'dOAS) (Any other ntumbes thatirmay be 06sliied

Distribution of this document is unlimited.

11 1UPPL EMENTARY NOTES (12 SPONSORING MILITARY ACT IVI'tY

USAF School of Aerospace Medicine*Aerospace Medical Division (AFSC)

___________ __________ J Brooks Air Force Base, Texas13 ABSTRACT

A technic was developed foi. da,'-ermining tne affects of' ionizing radiation onmolecular oxygen concentratioz.* in an- aqueous solu~tion. The polarographic principlewas used for determining oxygen concentration, temperature, and viscosity of solu-tion, and oxygen concentration in gas. The polarographic system has the followingprincipal characterji.3tics: (1) param~eters can be remotely measured,, permitting thesystem to be used in environments hostile to observers (i.e., radiation); (2) tem-perature measurement can be made withiin 10 C.; (3) changes in temperature are re-corded instantly; (4) oxygen concentration can be measured with a resolution wellwithin 1 mm. Hg; and (5) oxygen changes are recorded instantly.

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wcurity ClassificationLINK A LINK 9 LINK C

KEY WitO$ NOis wr oi0 a W NUOL WT

Physical chemistry (polarography)FI

Viscosity measurement

Oxygen ccncentration measurement

Temperature measurement

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