NAT'L INST OF STAND & TECH R.I.C Plllf ! REFERENCE PmZms

AlllOS 03L137

NIST SPECIAL PUBLICATION 260"1 1 3

U.S. DEPARTMENT OF COMMERCE/National Institute of Standards and Technology

Standard Reference Materials:

Description and Use

of a Precision Thermometer

for the Clinical Laboratory,

SRM 934

100

j .157

; NO.260-113

1990 B. W. Mangum and J. A. Wise

Standard Reference Materials:

Description and Use

of a Precision Thermometer

for the Clinical Laboratory,

SRM 934

B. W. Mangum and J. A. Wise

Chemical Process Metrology Division National Measurement Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899

Supersedes SP 260-48

U.S. DEPARTMENT OF COMMERCE, Robert A. Mosbacher, Secretary NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY, John W. Lyons, Director

Issued June 1990
National Institute of Standards and Technology Special Publication 260-113

Natl. Inst. Stand. Technol. Spec. Publ. 260-113, 21 pages (June 1990)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1990

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402-9325
Preface Standard Reference Materials (SRM's) as defined by the National Institute

of Standards and Technology (NIST) are well-characterized materials,

produced in quantity and certified for one or more physical or chemical

properties. They are used to assure the accuracy and compatibility of measurements throughout the Nation. SRM's are widely used as primary

standards in many diverse fields in science, industry, and technology, both within the United States and throughout the world. They are also used extensively in the fields of environmental and clinical analysis.

In many applications, traceability of quality control and measurement

processes to the national measurement system is carried out through the mechanism and use of SRM's. For many of the Nation's scientists and technologists it is therefore of more than passing interest to know the details of the measurements made at NIST in arriving at the certified

values of the SRM's produced. The NIST Special Publication - 260 Series , is reserved for this purpose.

The 260 Series is dedicated to the dissemination of information on different phases of the preparation, measurement, certification and use of NIST SRM's. In general, much more detail will be found in these papers than is generally allowed, or desirable, in scientific journal

articles. This enables the user to assess the validity and accuracy of

the measurement processes employed, to judge the statistical analysis, and to learn details of techniques and methods utilized for work

entailing the greatest care and accuracy. These papers also should

provide sufficient additional information not found on the certificate so that new applications in diverse fields not foreseen at the time the SRM was originally issued will be sought and found. Inquiries concerning the technical content of this paper should be directed to the author(s) . Other questions concerned with the availability, delivery, price, and so forth, will receive prompt

attention from: Standard Reference Materials Program

National Institute of Standards and Technology

Gaithersburg, MD 20899

William P. Reed, Acting Chief Standard Reference Materials Program

iii
CONTENTS

PAGE

I. INTRODUCTION 1 II. DESCRIPTION OF THE SRM 934 THERMOMETER 2 III. CALIBRATION OF THE THERMOMETER 3 IV. PROCEDURES FOR PROPER USAGE OF LIQUID- IN-GLASS THERMOMETERS 3 A. Check for Separated Mercury Columns and for Gas Bubbles 3 B. Ice Point Determination 4

C. Emergent -Stem Correction 5 V. SUMMARY AND CONCLUSIONS 7 VI. REFERENCES 8

LIST OF FIGURES

Figure PAGE

1. The thermometer of SRM 934. The divisions are 0.05 °C and the graduations have longer lines at intervals of 0.10 °C and 0.50 °C 9

2. A drawing showing the principal features of a solid-stem

liquid-in-glass thermometer 10

iv
OTHER NIST PUBLICATIONS IN THIS SERIES

McKenzie, R. L., ed., NIST Standard Reference Materials Catalog 1990-91, NIST Spec. Publ. 260 (January 1990)

Michaelis, R. E., and Wyman, L. L., Standard Reference Materials: Preparation of White Cast Iron

Spectrochemical Standards, NBS Misc. Publ. 260-1

(June 1964). COM74-11061**

Michaelis, R. E., Wyman, L. L., and Flitsch, R., Standard Reference Materials: Preparation of NBS Copper- Base Spectrochemical Standards, NBS Misc. Publ. 260-2 (October 1964). COM74- 11063**

Michaelis, R. E., Yakowitz, H., and Moore, G. A., Stan- dard Reference Materials: Metallographic Characterization of an NBS Spectrometric Low-Alloy Steel Standard, NBS Misc. Publ. 260-3 (October 1964). COM74-11060**

Alvarez, R., and Flitsch, R., Standard Reference Materials: Accuracy of Solution X-Ray Spectrometric Analysis of Copper-Base Alloys, NBS Misc. Publ. 260-5 (March 1965). PB168068**

Shultz, J. I., Standard Reference Materials: Methods for the Chemical Analysis of White Cast Iron Standards, NBS Misc. Publ. 260-6 (July 1965). COM74-

11068**

Bell, R. K., Standard Reference Materials: Methods for the Chemical Analysis of NBS Copper-Base

Spectrochemical Standards, NBS Misc. Publ. 260-7

(October 1965). COM74-11067**

Richmond, M. S., Standard Reference Materials: Analysis of Uranium Concentrates at the National Bureau

of Standards, NBS Misc. Publ. 260-8 (December

1965). COM74- 11066**

Anspach, S. C, Cavallo, L. M., Garfinkel, S. B., Hutchinson, J. M. R., and Smith, C. N., Standard Reference

Materials: Half Lives of Materials Used in the Preparation of Standard Reference Materials of Nineteen

Radioactive Nuclides Issued by the National Bureau

of Standards, NBS Misc. Publ. 260-9 (November

1965). COM74-1 1065**

Yakowitz, H., Vieth, D. L., Heinrich, K. F. J., and Michaelis, R. E., Standard Reference Materials: Homogeneity Characterization of NBS Spectrometric

Standards II: Cartridge Brass and Low-Alloy Steel, NBS Misc. Publ. 260-10 (December 1965). COM74-

11064**

Napolitano, A., and Hawkins, E. G., Standard Reference

Materials: Viscosity of Standard Lead-Silica Glass, NBS Misc. Publ. 260-11 (November 1966). Yakowitz, H., Vieth, D. L., and Michaelis, R. E., Stan- dard Reference Materials: Homogeneity Characterization of NBS Spectrometric Standards III: White

Cast Iron and Stainless Steel Powder Compact, NBS

Misc. Publ. 260-12 (September 1966). Menis, O., and Sterling, J. T., Standard Reference Materials: Determination of Oxygen in Ferrous Materi- als—SRM 1090, 1091, and 1092, NBS Misc. Publ. 260-14 (September 1966). Yakowitz, H, Michaelis, R. E., and Vieth, D. L., Stan- dard Reference Materials: Homogeneity Character- ization of NBS Spectrometric Standards IV:

Preparation and Microprobe Characterization of W20% Mo Alloy Fabricated by Powder Metallurgical Methods, NBS Spec. Publ. 260-16 (January 1969). COM74-11062**

Paule, R. C, and Mandel, J., Standard Reference Materials: Analysis of Interlaboratory Measurements on

the Vapor Pressure of Gold (Certification of Standard Reference Material 745). NBS Spec. Publ. 260-19

(January 1970). PB190071**

Paule, R. C, and Mandel, J., Standard Reference Materials: Analysis of Interlaboratory Measurements on

the Vapor Pressures of Cadmium and Silver, NBS

Spec. Publ. 260-21 (January 1971). COM74-1 1359**

Yakowitz, H, Fiori, C. E., and Michaelis, R. E., Standard Reference Materials: Homogeneity Characterization of Fe-3 Si Alloy, NBS Spec. Publ. 260-22 (February

1971). COM74-1 1357**

Napolitano, A., and Hawkins, E. G., Standard Reference

Materials: Viscosity of a Standard Borosilicate Glass, NBS Spec. Publ. 260-23 (December 1970). COM71-

00157**

Sappenfield, K. M., Marinenko, G., and Hague, J. L., Standard Reference Materials: Comparison of Redox

Standards, NBS Spec. Publ. 260-24 (January 1972). COM72-50058**

Hicho, G. E., Yakowitz, H., Rasberry, S. D., and Michaelis, R. E., Standard Reference Materials: A Standard Reference Material Containing Nominally Four Per- cent Austenite, NBS Spec. Publ. 260-25 (February

1971). COM74-1 1356**

v
Martin, J. R, Standard Reference Materials: National Bureau of Standards-US Steel Corporation Joint Pro- gram for Determining Oxygen and Nitrogen in Steel, NBS Spec. Publ. 260-26 (February 1971). PB

81176620** Gamer, E. L., Machlan, L. A., and Shields, W. R., Standard Reference Materials: Uranium Isotopic Standard Reference Materials, NBS Spec. Publ. 260- 27 (April 1971). COM74-1 1358**

Heinrich, K. F. J., Myklebust, R. L., Rasberry, S. D., and

Michaelis, R. E., Standard Reference Materials: Preparation and Evaluation of SRM's 481 and 482 GoldSilver and Gold-Copper Alloys for Microanalysis, NBS Spec. Publ. 260-28 (August 1971). COM71-

50365**

Geller, S. B., Standard Reference Materials: Calibration of NBS Secondary Standard Magnetic Tape (Computer Amplitude Reference) Using the Reference Tape Amplitude Measurement "Process A-Model

2," NBS Spec. Publ. 260-29 (June 1971). COM71-

50282**

Gorozhanina, R. S., Freedman, A. Y., and Shaievitch, A.

B. (translated by M. C. Selby), Standard Reference

Materials: Standard Samples Issued in the USSR (A

Translation from the Russian), NBS Spec. Publ. 260- 30 (June 1971). COM71-50283**

Hust, J. G., and Sparks, L. L., Standard Reference Materials: Thermal Conductivity of Electrolytic Iron SRM

734 from 4 to 300 K, NBS Spec. Publ. 260-31 (No- vember 1971). COM71-50563**

Mavrodineanu, R., and Lazar, J. W., Standard Reference

Materials: Standard Quartz Cuvettes for High Accuracy Spectrophotometry, NBS Spec. Publ. 260-32 (December 1973). COM74-50018**

Wagner, H. L., Standard Reference Materials: Comparison of Original and Supplemental SRM 705, Narrow

Molecular Weight Distribution Polystyrene, NBS

Spec. Publ. 260-33 (May 1972). COM72-50526**

Sparks, L. L., and Hust, J. G., Standard Reference Materials: Thermal Conductivity of Austenitic Stainless

Steel, SRM 735 from 5 to 280 K, NBS Spec. Publ. 260-35 (April 1972.) COM72-50368**

Cali, J. P., Mandel, J., Moore, L. J., and Young, D. S., Standard Reference Materials: A Referee Method for the Determination of Calcium in Serum NBS SRM

915, NBS Spec. Publ. 260-36 (May 1972). COM72-

50527**

Shultz, J. I., Bell, R. K., Rains, T. C, and Menis, O., Standard Reference Materials: Methods of Analysis of NBS Clay Standards, NBS Spec. Publ. 260-37

(June 1972). COM72-50692**

Clark, A. F., Denson, V. A., Hust, J. G., and Powell, R.

L., Standard Reference Materials: The Eddy Current Decay Method for Resistivity Characterization of

High-Purity Metals, NBS Spec. Publ. 260-39 (May

1972). COM72-50529**

McAdie, H. G., Gam, P. D., and Menis, O., Standard Reference Materials: Selection of Thermal Analysis Temperature Standards Through a Cooperative Study (SRM 758, 759, 760), NBS Spec. Publ. 260-40 (August 1972) COM72-50776**

Wagner, H. L., and Verdier, P. H., eds., Standard Refer- ence Materials: The Characterization of Linear Poly- ethylene, SRM 1475, NBS Spec. Publ. 260-42

(September 1972). COM72-50944**

Yakowitz, H., Ruff, A. W., and Michaelis, R. E., Stan- dard Reference Materials: Preparation and Homogeneity Characterization of an Austenitic

Iron-Chromium-Nickel Alloy, NBS Spec. Publ. 260- 43 (November 1972). COM73-50760**

Schooley, J. F., Soulen, R. J., Jr., and Evans, G. A., Jr., Standard Reference Materials: Preparation and Use of Superconductive Fixed Point Devices, SRM 767, NBS Spec. Publ. 260^4 (December 1972). COM73-

50037**

Greifer, B., Maienthal, E. J., Rains, T. C, and Rasberry,

S. D., Standard Reference Materials: Powdered Lead- Based Paint, SRM 1579, NBS Spec. Publ. 260-45 (March 1973). COM73-50226**

Hust, J. G., and Giarratano, P. J., Standard Reference

Materials: Thermal Conductivity and Electrical Resistivity Standard Reference Materials: Austenitic

Stainless Steel, SRM's 735 and 798, from 4 to 1200 K, NBS Spec. Publ. 260-46 (March 1975). COM75-

10339**

Hust, J. G., Standard Reference Materials: Electrical Resistivity of Electrolytic Iron, SRM 797, and Austeniuc Stainless Steel, SRM 798, from 5 to 280 K, NBS Spec. Publ. 260-47 (February 1974). COM74-

50176** Mangum, B. W., and Wise, J. A., Standard Reference

Materials: Description and Use of Precision Ther- mometers for the Clinical Laboratory, SRM 933 and SRM 934, NBS Spec. Publ. 260-48 (May 1974). Superseded by NIST Spec. Publ. 260-1 13. Carpenter, B. S., and Reimer, G. M., Standard Reference

Materials: Calibrated Glass Standards for Fission Track Use, NBS Spec. Publ. 260-49 (November

1974). COM74-5 1185**

vi
Hust, J. G., and Giarratano, P. J., Standard Reference

Materials: Thermal Conductivity and Electrical Resistivity Standard Reference Materials: Electro- lytic Iron, SRM's 734 and 797 from 4 to 1000 K, NBS

Spec. Publ. 260-50 (June 1975). COM75-10698**

Mavrodineanu, R., and Baldwin, J. R., Standard Refer- ence Materials: Glass Filters As a Standard Reference

Material for Spectrophotometry-Selection, Preparation, Certification, Use-SRM 930 NBS Spec. Publ. 260-51 (April 1990, Revision of November 1975

version). COM75-10339**

Hust, J. G., and Giarratano, P. J., Standard Reference

Materials: Thermal Conductivity and Electrical Resistivity Standard Reference Materials 730 and 799, from 4 to 3000 K, NBS Spec. Publ. 260-52 (September 1975). COM75-11193**

Durst, R. A., Standard Reference Materials: Standardization of pH Measurements, NBS Spec. Publ. 260-53

(February 1988, Revision of December 1975 version). Burke, R. W., and Mavrodineanu, R., Standard Refer- ence Materials: Certification and Use of Acidic Potassium Dichromate Solutions as an Ultraviolet Absorbance Standard, NBS Spec. Publ. 260-54 (August 1977). PB272168**

Ditmars, D. A., Cezairliyan, A., Ishihara, S., and Douglas, T. B., Standard Reference Materials: Enthalpy and Heat Capacity; Molybdenum SRM 781, from 273

to 2800 K, NBS Spec. Publ. 260-55 (September 1977).PB272127**

Powell, R. L., Sparks, L. L., and Hust, J. G., Standard Reference Materials: Standard Thermocouple Material, Pt-67: SRM 1967, NBS Spec. Publ. 260-56 (Feb- ruary 1978). PB277172**

Barnes, J. D., and Martin, G. M., Standard Reference

Materials: Polyester Film for Oxygen Gas Transmission Measurements SRM 1470, NBS Spec. Publ. 260- 58 (June 1979). PB297098**

Velapoldi, R. A., Paule, R. C, Schaffer, R., Mandel, J., and Moody, J. R., Standard Reference Materials: A

Reference Method for the Determination of Sodium

in Serum, NBS Spec. Publ. 260-60 (August 1978). PB286944**

Verdier, P H., and Wagner, H. L., Standard Reference

Materials: The Characterization of Linear Polyethyl- ene (SRM 1482, 1483, 1484), NBS Spec. Publ. 260- 61 (December 1978). PB289899**

Soulen, R. J., and Dove, R. B., Standard Reference

Materials: Temperature Reference Standard for Use Below 0.5 K (SRM 768), NBS Spec. Publ. 260-62

(April 1979). PB294245**

Velapoldi, R. A., Paule, R. C, Schaffer, R., Mandel, J., Machlan, L. A., and Gramlich, J. W., Standard Refer- ence Materials: A Reference Method for the Determination of Potassium in Serum, NBS Spec. Publ. 260-63 (May 1979). PB297207**

Velapoldi, R. A., and Mielenz, K. D., Standard Refer- ence Materials: A Fluorescence Standard Reference

Material Quinine Sulfate Dihydrate (SRM 936), NBS

Spec. Publ. 260-64 (January 1980). PB80-132O46**

Marinenko, R. B., Heinrich, K. F. J., and Ruegg, F. C,

Standard Reference Materials: Micro-Homogeneity

Studies of NBS Standard Reference Materials, NBS

Research Materials, and Other Related Samples, NBS

Spec. Publ. 260-65 (September 1979). PB300461**

Venable, W. H, Jr., and Eckerle, K. L., Standard Refer- ence Materials: Didymium Glass Filters for Calibrat- ing the Wavelength Scale of Spectrophotometers-SRM 2009, 2010, 2013, and

2014, NBS Spec. Publ. 260-66 (October 1979). PB80-

104961**

Velapoldi, R. A., Paule, R. C, Schaffer, R., Mandel, J., Murphy, T. J., and Gramlich, J. W., Standard Refer- ence Materials: A Reference Method for the Determination of Chloride in Serum, NBS Spec. Publ. 260-67 (November 1979). PB80-1 101 17** Mavrodineanu, R., and Baldwin, J. R., Standard Refer- ence Materials: Metal-On-Quartz Filters as a Stan- dard Reference Material for Spectrophotometry SRM

2031, NBS Spec. Publ. 260-68 (April 1980). PB80-

197486**

Velapoldi, R. A., Paule, R. C, Schaffer, R., Mandel, J., Machlan, L. A., Garner, E. L., and Rains, T. C,

Standard Reference Materials: A Reference Method

for the Determination of Lithium in Serum, NBS

Spec. Publ. 260-69 (July 1980). PB80-2091 17** Marinenko, R. B., Biancaniello, F., Boyer, P. A., Ruff, A. W., and DeRobertis, L., Standard Reference Materials: Preparation and Characterization of an Iron- Chromium-Nickel Alloy for Microanalysis, NBS

Spec. Publ. 260-70 (May 1981). PB84-165349**

Seward, R. W., and Mavrodineanu, R., Standard Refer- ence Materials: Summary of the Clinical Laboratory

Standards Issued by the National Bureau of Standards, NBS Spec. Publ. 260-71 (November 1981). PB82-135161**

Reeder, D. J., Coxon, B., Enagonio, D., Christensen, R.

G., Schaffer, R., Howell, B. F., Paule, R. C, and

Mandel, J., Standard Reference Materials: SRM 900,

Antiepilepsy Drug Level Assay Standard, NBS Spec.

Publ. 260-72 (June 1981). PB81-220758

vii
Interrante, C. G., and Hicho, G. E., Standard Reference

Materials: A Standard Reference Material Containing Nominally Fifteen Percent Austenite (SRM 486), NBS Spec. Publ. 260-73 (January 1982). PB82-

215559**

Marinenko, R. B., Standard Reference Materials: Preparation and Characterization of K-41 1 and K-414 Mineral Glasses for Microanalysis: SRM 470, NBS Spec.

Publ. 260-74 (April 1982). PB82-221300**

Weidner, V. R., and Hsia, J. J., Standard Reference

Materials: Preparation and Calibration of First Surface Aluminum Mirror Specular Reflectance Stan- dards (SRM 2003a), NBS Spec. Publ. 260-75 (May

1982).PB82-221367**

Hicho, G. E., and Eaton, E. E., Standard Reference

Materials: A Standard Reference Material Containing Nominally Five Percent Austenite (SRM 485a), NBS

Spec. Publ. 260-76 (August 1982). PB83-1 15568** Furukawa, G. T., Riddle, J. L., Bigge, W. G., and Pfieffer, E. R., Standard Reference Materials: Application of Some Metal SRM's as Thermometric Fixed Points, NBS Spec. Publ. 260-77 (August 1982). PB83-

117325**

Hicho, G. E., and Eaton, E. E., Standard Reference

Materials: Standard Reference Material Containing Nominally Thirty Percent Austenite (SRM 487), NBS

Spec. Publ. 260-78 (September 1982). PB83-

115576** Richmond, J. C, Hsia, J. J., Weidner, V. R., and Wilmering, D. B., Standard Reference Materials: Second

Surface Mirror Standards of Specular Spectral Reflectance (SRM's 2023 , 2024, 2025), NBS Spec.

Publ. 260-79 (October 1982). PB84-203447**

Schaffer, R., Mandel, J., Sun, T., Cohen, A., and Hertz, H. S., Standard Reference Materials: Evaluation by

an ID/MS Method of the AACC Reference Method

for Serum Glucose, NBS Spec. Publ. 260-80 (October 1982).PB84-216894**

Burke, R. W., and Mavrodineanu, R., Standard Refer- ence Materials: Accuracy in Analytical Spectrophotometry, NBS Spec. Publ. 260-81 (April 1983). PB83-214536**

Weidner, V. R., Standard Reference Materials: White

Opal Glass Diffuse Spectral Reflectance Standards

for the Visible Spectrum (SRM's 2015 and 2016), NBS Spec. Publ. 260-82 (April 1983). PB83-

220723**

Bowers, G. N., Jr., Alvarez, R., Cali, J. P., Eberhardt, K.

R., Reeder, D. J., Schaffer, R., and Uriano, G. A., Standard Reference Materials: The Measurement of

the Catalytic (Activity) Concentration of Seven En- zymes in NBS Human Serum SRM 909, NBS Spec.

Publ. 260-83 (June 1983). PB83-239509**

Gills, T. E., Seward, R. W., Collins, R. J., and Webster, W. C, Standard Reference Materials: Sampling, Materials Handling, Processing, and Packaging of NBS

Sulfur in Coal Standard Reference Materials 2682,

2683, 2684, and 2685, NBS Spec. Publ. 260-84 (August 1983). PB84-109552**

Swyt, D. A., Standard Reference Materials: A Look at Techniques for the Dimensional Calibration of Stan- dard Microscopic Particles, NBS Spec. Publ. 260-85 (September 1983). PB84-1 12648**

Hicho, G. E., and Eaton, E. E., Standard Reference

Materials: A Standard Reference Material Containing Two and One-HalfPercent Austenite, SRM488, NBS

Spec. Publ. 260-86 (December 1983). PB84-

143296** Mangum, B. W., Standard Reference Materials: SRM

1969: Rubidium Triple-Point - A Temperature Refer- ence Standard Near 39.30 *C, NBS Spec. Publ. 260- 87 (December 1983). PB84-149996**

Gladney, E. S., Burns, C. E., Perrin, D. R., Roelandts, L, and Gills, T. E., Standard Reference Materials: 1982

Compilation of Elemental Concentration Data for NBS Biological, Geological, and Environmental

Standard Reference Materials, NBS Spec. Publ. 260- 88 (March 1984). PB84-218338**

Hust, J. G., Standard Reference Materials: A Fine- Grained, Isotropic Graphite for Use as NBS Thermophysical Property RM's from 5 to 2500 K, NBS Spec.

Publ. 260-89 (September 1984). PB85-1 12886**

Hust, J. G., and Lankford, A. B., Standard Reference

Materials: Update ofThermal Conductivity and Electrical Resistivity of Electrolytic Iron, Tungsten, and

Stainless Steel, NBS Spec. Publ. 260-90 (September

1984). PB85-1 15814**

Goodrich, L. F., Vecchia, D. F., Pittman, E. S., Ekin, J. W., and Clark, A. F., Standard Reference Materials:

Critical Current Measurements on an NbTi Superconducting Wire Standard Reference Material, NBS

Spec. Publ. 260-91 (September 1984). PB85-

118594**

Carpenter, B. S., Standard Reference Materials: Cali- brated Glass Standards for Fission Track Use (Sup- plement to NBS Spec. Publ. 260-49), NBS Spec. Publ. 260-92 (September 1984). PB85-1 13025**

viii
Ehrstein, J.R., Standard Reference Materials: Preparation and Certification of Standard Reference Materials for Calibration of Spreading Resistance Probes, NBS Spec. Publ. 260-93 (January 1985). PB85-

177921**

Gills, T. E., Koch, W. F., Stolz, J. W., Kelly, W. R., Paulsen.P. J., Colbert, J. C, Kirklin, D. R.,Pei, P.T.S., Weeks, S., Lindstrom, R. M., Fleming, R. F., Greenberg, R. R., and Paule, R. C, Standard Refer- ence Materials: Methods and Procedures Used at the National Bureau of Standards to Certify Sulfur in Coal SRM's for Sulfur Content, Calorific Value, Ash

Content, NBS Spec. Publ. 260-94 (December 1984). PB85-165900**

Mulholland, G. W., Hartman, A. W., Hembree, G. G., Marx, E., and Lettieri, T. R., Standard Reference

Materials: Development of a 1 Jim Diameter Particle Size Standard, SRM 1690, NBS Spec. Publ. 260-95 (May 1985). SN003-003-02665-4*

Carpenter, B. S., Gramlich, J. W., Greenberg, R. R., Machlan, L. A., DeBievre, P., Eschbach, H. L., Meyer, H., Van Audenhove, J., Connolly, V. E., Trahey, N. M., and Zook, A. C, Standard Reference

Materials: Uranium-235 Isotopic Abundance Stan- dard Reference Materials for Gamma Spectrometry Measurements, NBS Spec. Publ. 260-96 (September

1986). PB87- 108544**

Mavrodineanu, R., and Gills, T. E., Standard Reference

Materials: Summary of the Coal, Ore, Mineral, Rock, and Refractory Standards Issued by the National Bureau of Standards, NBS Spec. Publ. 260-97 (September 1985). SN003-003-02688-3*

Hust, J. G., Standard Reference Materials: Glass Fiber- board SRM for Thermal Resistance, NBS Spec. Publ. 260-98 (August 1985). SN003-003-02674-3*

Callanan, J. E., Sullivan, S. A., and Vecchia, D. F., Standard Reference Materials: Feasibility Study for the Development of Standards Using Differential Scanning Calorimetry, NBS Spec. Publ. 260-99 (August 1985). SN003-003-02675-1*

Taylor, J. K., Standard Reference Materials: Handbook

for SRMUsers, NBS Spec. Publ. 260-100 (September

1985). PB86-1 10897** Mangum, B. W., Standard Reference Materials: SRM

1970, Succinonitrile Triple-Point Standard: A Temperature Reference Standard Near 58.08 *C, NBS

Spec. Publ. 260-101 (March 1986). SN003-003-

02722-7*

Weidner, V. R., Mavrodineanu, R., Mielenz, K. D., Velapoldi, R. A., Eckerle, K. L., and Adams, B., Standard Reference Materials: Holmium Oxide Solution Wavelength Standard from 240 to 640 nm - SRM

2034, NBS Spec. Publ. 260-102 (July 1986). PB86-

245727**

Hust, J. G., Standard Reference Materials: Glass

Fiberblanket SRM for Thermal Resistance, NBS

Spec. Publ. 260-103 (September 1985). SNOO3-0O3-

02687-5*

Mavrodineanu, R., and Alvarez, R., Standard Reference

Materials: Summary of the Biological and Botanical Standards Issued by the National Bureau of Standards, NBS Spec. Publ. 260-104 (November 1985). SN003-003-02704-9*

Mavrodineanu, R., and Rasberry, S. D., Standard Refer- ence Materials: Summary of the Environmental Research, Analysis, and Control Standards Issued by the National Bureau of Standards, NBS Spec. Publ. 260- 105 (March 1986). SNO03-003-02725-1*

Koch, W. F., ed., Standard Reference Materials: Methods and Procedures Used at the National Bureau of Standards to Prepare, Analyze, and Certify SRM

2694, Simulated Rainwater, and Recommendations

for Use, NBS Spec. Publ. 260-106 (July 1986). PB86-

247483**

Hartman, A. W., and McKenzie, R. L., Standard Refer- ence Materials: SRM 1965, Microsphere Slide (10 ^m Polystyrene Spheres), NIST Spec. Publ. 260-107 (November 1988). Mavrodineanu, R., and Gills, T. E., Standard Reference

Materials: Summary of Gas Cylinder and Permeation Tube Standard Reference Materials Issued by the National Bureau of Standards, NBS Spec. Publ. 260- 108 (May 1987). Candela, G. A., Chandler-Horowitz, D., Novotny, D. B., Marchiando, J. F., and Belzer, B. J., Standard Refer- ence Materials: Preparation and Certification of an

Ellipsometrically Derived Thickness and Refractive Index Standard of a Silicon Dioxide Film (SRM

2530), NIST Spec. Publ. 260-109 (October 1988). Kirby, R. K., and Kanare, H. M., Standard Reference

Materials: Portland Cement Chemical Composition

Standards (Blending, Packaging, and Testing), NBS

Spec. Publ. 260-110 (February 1988). Gladney, E. S., O'Malley, B. T., Roelandts, I., and Gills, T. E., Standard Reference Materials: Compilation of Elemental Concentration Data for NBS Clinical, Biological, Geological, and Environmental Standard Reference Materials, NBS Spec. Publ. 260-1 1 1 (No- vember 1987).

ix
Marinenko, R B., Blackburn, D. H., and Bodkin, J. B., Standard Reference Materials: Glasses for Microanalysis: SRM's 1871-1875, NIST Spec. Publ. 260-112

(February 1990). Mangum, B. W., and Wise, J. A., Standard Reference

Materials: Description and Use of a Precision Ther- mometer for the Clinical Laboratory, SRM 934, NIST

Spec. Publ. 260-113 (June 1990).

*Send order with remittance to Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20102. Remittance from foreign countries should include an additional one fourth of the pur- chase price for postage. **May be ordered from: National Technical Information Service (NTIS), Springfield, VA 22161

x
DESCRIPTION AND USE

OF A PRECISION THERMOMETER FOR THE CLINICAL LABORATORY,

SRM 934

by

B. W. Mangum and J. A. Wise

Chemical Process Technology Division

National Measurement Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899

Because of the high sensitivity to temperature

of many facets of the clinical laboratory, e.g., in enzyme reactions and in pH and blood gas analysis, there is a need for accurate temperature measurement and its control. In order to help satisfy these needs and to aid in getting

a usable and accurate temperature scale into the clinical laboratory, the National Institute of Standards and Technology developed SRM 934. This

is a precision thermometer that is calibrated

at 0 °C, 25 °C, 30 °C, and 37 °C. The description, calibration, and the procedures for proper

usage of this thermometer are discussed. This SP 260 supersedes SP 260-48 describing both

SRMs 933 and 934. SRM 933 will no longer be issued

by the SRM Program. This publication is the same

as SP 260-48 with the exception that all references

to SRM 933 have been removed. Key words: Clinical laboratory; enzymology; health care; liquid-in-glass thermometers; standard reference material; SRM 934; thermometers

.

I . INTRODUCTION

The accurate measurement and control of temperature is of critical

importance in many aspects of the clinical laboratory and in the hospital

in general. The temperatures at which enzyme rate analyses are

1
conducted, for example, are very important because of their high

sensitivity to this parameter [1-4]. Furthermore, in order to obtain

reproducible results within a given clinical laboratory and in order to make a meaningful intercomparison among laboratories, the temperature not only must be carefully controlled but must be known absolutely. In recognition of this situation, the Expert Panel on Enzymes, which was created by the International Federation of Clinical Chemistry Committee

on Standards, has recommended [5], among other suggestions in their

proposal for I.F.C.C. Reference Methods for Enzymes, that the set point

in degrees Celsius of the reaction temperature is to be assigned as a part of the method, that the temperature accuracy must be assured to ±0.05 °C by calibration against the International Practical Temperature

Scale of 1968 (IPTS-68) [6], that the temperature variation of the reaction mixture should be held within the open interval -0.05 °C and ±0.05 °C of the set point, and that the choice of reaction temperature

for an I.F.C.C. reference method should be 25.00, 30.00 or 37.00 °C. Of

course, enzyme reactions are not unique in being sensitive to the temperature; pH and blood gas analyses are two others in a long list that could be mentioned [1]. Although the temperature scale referred to in reference 6 is the IPTS-68, the temperature requirements of that reference will be the same except that the IPTS-68 is superseded by the ITS-90 [7]. Because of these needs and in order to assist in getting a usable

temperature scale into the clinical laboratories (and hospitals

generally), NIST is providing a precision laboratory thermometer,

SRM 934, designed specifically for use in the clinical laboratory. This

SRM was produced in cooperation with the Medical Thermometry Program of

the Temperature Section in the Heat Division in 1974. Many

specifications requested by clinical laboratory personnel concerned with

accurate temperature measurements have been incorporated in the design.

II. DESCRIPTION OF THE SRM 934 THERMOMETER

The thermometer comprising SRM 934 is shown in figure 1 and its linear

dimensions are as indicated. This is a solid-stem mercury- in- glass type

instrument. In order to clarify potential problems in terminology, the principal features of a solid-stem, liquid- in- glass thermometer are shown

in figure 2. The stem has a plain front, enameled back, and is of lead glass thermometer tubing 7 mm in diameter. The bulb is also 7 mm in diameter. Nitrogen gas fills the space above the mercury. Special

markings consist of a serial number, the manufacturer's name or trade

mark, and a 95 mm immersion line. The thermometer has an auxiliary scale from -0.20 °C to +0.20 °C with 0.05 °C subdivisions. The main scale of

the thermometer is 24 °C to 38 °C with 0.05 °C subdivisions. The graduations have longer lines at intervals of 0.10 °C and 0.50 °C. In addition, there are numbers every 1 °C.

2
III. CALIBRATION OF THE THERMOMETER

Each thermometer was tested at the ice point (0 °C) by placing it in an

ice bath and at the temperatures above 0 °C by placing it in a stirred- liquid comparison bath [8]. Calibrations were performed at 0 °C, 25 °C, 30 °C, and 37 °C and the temperatures above 0 °C were determined with a standard precision platinum resistance thermometer [9] which was also in the comparison bath. The temperature of the calibration laboratory was

23 °C. The thermometer was read with the aid of a 10 power telescope,

which was placed perpendicularly to the thermometer in order to reduce parallax errors. Before each reading, the mercury thermometer was gently

tapped to eliminate any error due to a sticking mercury column. The maximum uncertainty associated with any calibration point is no greater

than 0.03 °C. IV. PROCEDURES FOR PROPER USAGE OF LIQUID-IN-GLASS THERMOMETERS

The items discussed in this section are included to focus attention on some of the more common problems encountered in the use of liquid- in- glass thermometers and thus to help assure that the thermometer will be used properly and, thereby, will yield the desired performance. All examples in this paper are given as an aid in the understanding of the subject being discussed, and have not been specifically adapted to SRM 934.

A. CHECK FOR SEPARATED MERCURY COLUMNS AND FOR GAS BUBBLES Many times, because of rough handling during shipment, separation will occur in the mercury column or gas bubbles will appear in the bulb. When

the thermometer is received it should be thoroughly examined for such occurrences

.

The process of joining separated mercury columns consists of one or a series of manipulations:

a) The bulb of the thermometer may be cooled in a solution of common

salt, ice, and water (or other cooling agent) to bring the mercury slowly down into the bulb. Only the bulb should be cooled and never the stem or mercury column. Moderate tapping of the bulb on a rubber stopper or similar soft spongy object, or the application of centrifugal force by

swinging the thermometer in a short arc, usually serves to unite the mercury in the bulb. If the salt solution does not provide sufficient

cooling, carbon dioxide snow (dry ice) may be used. Since the temperature of dry ice is about -78 °C and mercury freezes at about

-39 °C, the mercury will solidify. On warming, care must by taken to warm the top of the bulb first so that pressures in the bulb due to the expanding mercury may be relieved.

3
b) The mercury can sometimes be reunited by warming the bulb until the column reaches the separated portion in either the contraction chamber or

the expansion chamber. If this procedure is used, the bulb should never

be heated in an open flame. Great care is necessary to avoid filling the expansion chamber completely with mercury which might produce pressures

great enough to burst the bulb. The expansion chamber should never be more than two- thirds full. Joining the mercury is more readily

accomplished if the quantity in either cavity has first been shattered

into droplets by tapping the thermometer laterally against the hand. Gas bubbles, which are sometimes found along the surface of the mercury

in the thermometer bulb, may be collected by "washing" the bulb with a large gas bubble. As outlined in section (a) above, bring all of the mercury into the bulb. Hold the thermometer in a horizontal position and gently tap it against the hand to form a large gas bubble. Force the bubble to travel around the wall of the bulb by rotating the thermometer

and tapping it against the palm of the hand. When the entire surface has been "washed," rotate the bubble to the top of the bulb and reunite the mercury as described above. All of these manipulations require patience (and experience is helpful) but they will yield the desired results if care is used. A convenient

method of ascertaining that all the mercury has been joined is a check of

the ice point. It should agree with the ice-point reading on the Report

of Calibration by within approximately one scale division or better.

The ice point, known as a reference point, is found on the auxiliary

scale. It is a temperature that can be easily duplicated in any laboratory and is used to check the thermometer periodically for changes

in bulb volume

To make an ice bath, a Dewar flask may be used as a container, since the insulating properties of the vessel retard the melting of ice. Ice shaved from clear cakes or from that made with distilled water is mixed

with distilled water to form a tightly packed slush. Enough water is used to afford good contact with the thermometers but not so much as to float the ice. At periodic intervals excess water is siphoned from the bath. Care should be taken to prevent contamination of the ice and

water. Any change in the ice point will be reflected in the other calibration points by the same amount and in the same direction. An

example is given below:

B. ICE POINT DETERMINATION

Original Corrections From NIST Report

Thermometer Reading Correction

-0.013 °C 25.000 °C 30.000 °C 37.000 °C

+0.013 °C +0.010 °C +0.008 °C +0.015 °C

4
A later ice -point reading, taken after the thermometer has been at a temperature of about 23 °C for not less than 3 days, may be -0.020 °C. This means that the ice-point correction will be +0.020 °C and a new set of corrections should be made by adding +0.007 to all of

the original corrections. The new table would look as follows:

Thermometer Reading

-0.020 °C 25.000 °C 30.000 °C 37.000 °C

Correction

+0.020 °C +0.017 °C +0.015 °C +0.022 °C Because of bulb expansion, a temporary ice point depression will be introduced when the thermometer is heated above room temperature (23 °C)

Because of this depression, the thermometer should never be used at a given temperature shortly after it has been heated beyond that temperature. An error of 0.01 °C or less for each 10 °C difference between the two temperatures may be introduced. If the thermometer has been heated beyond the temperature at which it is to be used and if the corrections are to be used as given on the Report of Calibration, it must

be kept at room temperature (approximately 23 °C) for not less than 3 days to assure recovery of the bulb. A small reading telescope with a magnification of 10 diameters aids in reading the thermometer indication and reduces parallax errors. Gently

tapping the thermometer just before reading may prevent the sticking of a falling meniscus. On the other hand, too vigorous a tap will

occasionally cause the mercury to rebound to an erroneously high reading.

C. EMERGENT-STEM CORRECTION

The scale corrections for SRM 934 are reported for the condition of immersion to the depth of the immersion mark (95 mm) , and for the temperature of the emergent stem as reported on the Report of Calibration. The emergent stem is defined as the length of mercury column and stem exposed to the ambient temperature. The temperature of the laboratory was 23 °C when the measurements were made. If the thermometer is used under stem- temperature conditions other than that specified, the formula given below will provide the appropriate

correction, which should be added to the thermometer reading along with

the correction from the Report of Calibration to produce the true temperature

stem correction = 0.00016 n (tsp

- tobs ), where

0.00016 = differential expansion coefficient of mercury in glass

for Celsius thermometers,

5
t sp = specified mean temperature of the emergent stem (for which

reported scale corrections apply)

tobs = observed mean temperature of the emergent stem, and

n = number of scale degrees equivalent to the length of emergent

stem

.

In using the formula it should be noted that n applies to the whole

length of emergent stem, i.e., from the immersion mark to the top of the mercury column. The ungraduated length between the immersion mark and

the first graduation on the scale must, therefore, be evaluated in terms

of scale degrees and included in the value of n. To measure the emergent-stem temperature, a small auxiliary thermometer,

generally 15-cm long with a range from 0 °C to 100 °C and graduated in

1 °C intervals, is suspended above the bath adjacent to the main

thermometer, with the bulb approximately at the center of the liquid

column

.

For SRM 934, a 2 °C temperature difference in the stem temperature would

produce the following results, assuming n approximately equals 4.4, 9.4 and 16.4 for 25 °C, 30 °C, and 37 °C,

Temperature Correction

25 °C 0.00016 x 4.4 x ± 2 = ±0.0014 °C 30 °C 0.00016 x 9.4 x ± 2 = ±0.0030 °C 37 °C 0.00016 x 16.4 x ± 2 = ±0.0052 °C To help clarify any difficulty that may remain, an example of how to apply the corrections is given below: Thermometer = SRM 934 The reading of the thermometer (immersed 95 mm in the bath)

= 30.013 °C, Measured emergent-stem temperature =29 °C, Number of degrees from immersion mark to point of reading

(30 °C) = 9.4,

Correction on the Report of Calibration at 30 °C = -0.019

(stem temp. = 26 °C)

.

An ice point check produced the same result as shown on the Report of Calibration.

6
First, find the stem- temperature correction: stem correction = 0.00016 x n x (t sp

- tobs ) = 0.00016 x 9.4 x (26 - 29)°C

= - 0.005 °C True temperature = thermometer reading + stem correction + reported

correction

= 30.013 + (-0.005) + (-0.019)°C

= 29.989 °C

V. SUMMARY AND CONCLUSIONS

In order to obtain the accuracy of temperature measurements of which

SRM 934 is capable, the following items should be closely observed:

1) check for a separated mercury column and for gas bubbles in the bulb,

2) check the ice point periodically for changes in the bulb volume,

3) always use the thermometer at the proper immersion (95 mm)

,

4) correct for emergent-stem temperatures different from those listed in the Report of Calibration,

5) gently tap the thermometer before reading, and

6) read with a telescope, if possible, to avoid parallax errors. With the introduction and use of SRM 934 in the typical clinical

laboratory, there will be a marked improvement in the laboratory's measurement capability. The thermometer will provide a means by which

the laboratory personnel can make a start toward eliminating any uncertainty in their testing which is due to inaccurate temperature measurement and, in many cases, its control. This will assist efforts at improving measurement reproducibility within a given laboratory and intercomparisons among laboratories.

7
VI . REFERENCES

Bowers, G.N., Jr. and McComb, R.B., A Continuous Spectrophotometric

Method for Measuring the Activity of Serum Alkaline Phosphatase,

Clin. Chem. 12, 70 (1966). Bowers, G.N., Jr., Measurement of Isocitric Dehydrogenase Activity

in Body Fluids, Clin. Chem. 5, 509 (1959).

Amador, E., Dorfman, L.E., and Wacker, W.E.C., Serum Lactic

Dehydrogenase Activity: An Analytical Assessment of Current Assays,

Clin. Chem. 9, 931 (1963).

Worthington Enzyme Manual, Section III, Clinical Reagents,

Worthington Biochemical Corporation, Freehold, New Jersey, 1972,

pp. 179-216. Bowers, G.N., Jr., Bergmeyer, H.U., Moss, D.W., Draft Proposal (No.

8) for I.F.C.C. Reference Methods for Enzymes, Clin. Chem. 19, 268 (1973)

.

The International Practical Temperature Scale of 1968, Metrologia

5, 35 (1969).

Preston-Thomas, H., The International Temperature Scale of 1990

(ITS-90), Metrologia 27, 3-10 (1990).

Wise, J. A., Liquid- in-Glass Thermometer Calibration Service,

Natl. Inst. Stand. Technol., SP 250-23 (1988).

Mangum, B.W., Platinum Resistance Thermometer Calibrations,

Natl. Bur. Stand. (U.S.), SP 250-22 (1987).

8
0

+ 1 CD

COCO

+ 1 LTD CO 2

CO

LO

CD

ft

10mm MINIMUM

25 mm MINIMUM

15± 10 mm L

18t 5 mm

30 ± 5 mm

Figure 1. The thermometer of SRM 934. The divisions are 0.05 °C and

the graduations have longer lines at intervals of 0.10 °C and 0.50 °C.

9
10
IIST-114A

flEV. 3-89) U.S. DEPARTMENT OF COMMERCE

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

BIBLIOGRAPHIC DATA SHEET

1. PUBLICATION OR REPORT NUMBER NIST/SP-260/113

2. PERFORMING ORGANIZATION REPORT NUMBER

3. PUBLICATION DATE June 1990

TITLE AND SUBTITLE STANDARD REFERENCE MATERIALS: Description And Use Of A Precision Thermometer For The Clinical Laboratory SRM 934

AUTHOR(S) B. W. Mangum and J. A. Wise

PERFORMING ORGANIZATION (IF JOINT OR OTHER THAN NIST. SEE INSTRUCTIONS)

U.S. DEPARTMENT OF COMMERCE

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

QATTHERSBURG, MD 20899

7. CONTRACT/GRANT NUMBER

8. TYPE OF REPORT AND PERIOD COVERED Final

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (STREET, CITY, STATE, ZIP) Same as item 6.

SUPPLEMENTARY NOTES

| DOCUMENT DESCRIBES A COMPUTER PROGRAM; SF-18S, FIPS SOFTWARE SUMMARY, IS ATTACHED. ABSTRACT (A 200-WORD OR LESS FACTUAL SUMMARY OF MOST SIGNIFICANT INFORMATION. IF DOCUMENT INCLUDES A SIGNIFICANT BIBUOGRAPHY OR

LITERATURE SURVEY, MENTION IT HERE.) Because of the high sensitivity to temperature of many facets of the clinical laboratory, e.g., in enzyme reactions and in pH and blood gas analysis, there is a need for accurate temperature measurement and its control. In order to help satisfy these needs and to aid in getting a usable and accurate temperature scale into the clinical laboratory, the National Institute of Standards and Technology developed SRM 934. This is a precision thermometer

that is calibrated at 0 °C, 25 °C, 30 °C, and 37 °C. The description, calibration, and the procedures for proper usage of this thermometer are discussed. This SP 260 supersedes SP 260-48 describing both SRMs 933 and 934. SRM 933 will no longer

be issued by the SRM Program. This publication is the same as SP 260-48 with the exception

that all references to SRM 933 have been removed.

KEY WORDS (6 TO 12 ENTRIES; ALPHABETICAL ORDER; CAPITALIZE ONLY PROPER NAMES; AND SEPARATE KEY WORDS BY SEMICOLONS) Clinical laboratory; enzymology; health care; liquid- in-glass thermometers; standard reference material; SRM 934; thermometers

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