Specific Analytes

Colorimetric Analysis with the Duboscq

A system of blood analysis.

Blood Gases by Manometer

The determination of gases in blood and other solutions by vacuum extraction and manometric measurement. I.

Bilirubin With the Filter Photometer

The determination of bilirubin with the photoelectric colorimeter.

Proteins by the Biuret Reaction

17. Gornall, A. G., Bardawill, C. J. and David, M. M. (1949)

Determination of serum proteins by means of the biuret reaction.

Methods for Pediatric and Neonatal Samples

Routine use of ultramicro methods in the clinical laboratory.

Enzymatic Glucose

Use of glucose oxidase, peroxidase, and o-dianisidine in determination of blood and urinary glucose.

HCG (Human Chorionic Gonadotropin) by Immunoassay

An immunological pregnancy test.

Hemoglobin A1c

An abnormal hemoglobin in red cells of diabetics.

LDL (Low Density Lipoprotein) Cholesterol by Calculation.

22. Friedewald, W. T., Levy, R. I. and Fredrickson, D. S. (1972)

Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge.

This page is intentionally left blank page 167 14. Folin, O. and Wu, H. (1919)

COMMENTARY TO A System of Blood Analysis. Journal of Biological Chemistry 38(1):

The Medical School at Harvard University planned to hold a dinner on November 16th, 1934 to celebrate Otto Folin's retirement after 25 years of service. A commissioned portrait would be presented to the University in his honor. Three weeks before the dinner, one of the invited speakers, Philip Shaffer, asked Folin how he would sum up his contributions to biochemistry. Folin replied in a letter to Shaffer dated October 21,

My portrait includes a colorimeter and a couple of volumetric flasks, and it might therefore fit in pretty well to say something about the introduction of colorimetry into biochemistry. This is about all that I can think of at the moment (1).

Folin died on October 25, 1934. The speeches and portrait were presented at a memorial service 1 month later (2).

The colorimeter in the painting that Folin considered so important in summing up his major contribution to biochemistry was a Duboscq balancing method colorimeter (3). Folin's introduction of this instrument into biochemistry in 1904 created a technological advance in clinical chemistry that would not be surpassed until the development of the photoelectric colorimeter 35 years latter.

The Duboscq instrument was a color matching colorimeter first commercialized by Jules Duboscq in France in 1870 (4). It resembled from the outside a simple monocular microscope. Through the eyepiece the observer saw a split screen image. The left and right sides of the split image came from light that traveled up through two separate solid glass rods mounted below the eyepiece. Below each rod were glass bottom cups that sat on independently adjustable ring stands. In a typical colorimetric assay a standard was placed into the left hand cup and the unknown into the right hand cup. Each adjustable ring stand was linked to a mm scale that measured the depth of immersion of each glass rod. Reflected light passed up from a mirror below the ring stands through the solutions in the cups then up through the glass rods into the eyepiece. The color intensities of the two solutions seen through the eyepiece were made to match by varying the depth of the rods in their respective solutions. Color intensity was inversely proportional to the depth of the rods. The mm scale provided a quantitative measure of the depths of the rods. The concentration of the unknown could then be calculated from the simple formula, mm depth of the standard (concentration of the standard) mm depth of the unknown

Folin was the first to use the Duboscq colorimeter in a clinical chemistry procedure. He published methods for urine creatinine and creatine in 1904 based on the colorimetric alkaline picric acid reaction (5,6). Prior to the Duboscq, colorimetric clinical chemistry assays were read by holding the test tubes with the unknowns up against a white background and color matching them against tubes containing standards or up against colored glass filters previously matched against liquid standards for that assay. The Duboscq colorimeter replaced this with a quantitative measure of the difference in color intensity between samples. In addition, because of its optical design, it improved the ability to distinguish between weak differences in intensity.

Folin adopted his creatinine method for use with serum in 1914 (7). Colorimetric assays for glucose, urea, nonprotein nitrogen, creatinine and uric acid read with the Duboscq colorimeter were integrated into a system of analytical assays by Folin and Hsien Wu in 1919. This paper is presented here. In 2002 the editors of the Journal of Biological Chemistry selected this paper as a "Classic Article" in biochemistry (8). Folin's Duboscq procedures were the methods routinely presented in clinical chemistry manuals and textbooks for the next 40 years (9-12). Folin's own textbook of methods, Laboratory Manual of Biological Chemistry, first published in 1916, went through five editions before his death (13).

Folin's reply to Shaffer in 1934 that he could think of only colorimetry as his major contribution to biochemistry was not the simple modest reply that it seemed.


(1) Meites, S. (1989) Otto Folin America's First Clinical Chemist. American Association for Clinical Chemistry, Inc., Washington, DC, The letter from O. Folin to P.A. Shaffer dated October 21, 1934 is reproduced on pgs 355-356.

(2) Shaffer, P.A. (1935) Obituary Otto Folin. Science. 81(2089):35-37.

(3) Rosenfeld, L. (2002) Clinical chemistry since 1800: growth and development. Clinical Chemistry. 48(1):186-197, The Folin portrait is reproduced on pg 193.

(4) Stock, J.T. (1994) The Duboscq colorimeter and its inventor. Journal of Chemical Education. 71(11):967-970.

(5) Folin, O. (1904) Beitrag zur Chemie des Kreatinins und Kreatins im Harne. Hoppe-Seyler's Zeitschrift für Physiologische Chemie. 41:223-242.

(6) Folin, O. (1904) Some metabolism studies. With special reference to mental disorders. American Journal of Insanity. 60(4):699-732.

(7) Folin, O. (1914) On the determination of creatinine and creatine in blood, milk and tissues. Journal of Biological Chemistry. 17(4):475-481.

(8) Simoni, R.D., Hill, R.L., and Vaughan, M. (2002) JBC centennial 1905-2005 100 years of biochemistry and molecular biology. Journal of Biological Chemistry. 277(20):e9.

(9) Myers, V.C. (1924) Practical Chemical Analysis. A Book Designed as a Brief Survey of This Subject for Physicians and Laboratory Workers. 2nd Edition. C.V. Mosby Co., St Louis.

(10) Todd, J.C. and Sanford, A.H. (1931) Clinical Diagnosis by Laboratory Methods. A Working Manual of Clinical Pathology. 7th Edition. W.B. Saunders Company, Phildelphia.

(11) Peters, J.P. and Van Slyke, D.D. (1932) Quantitative Clinical Chemistry Vol IIMethods. The Williams & Wilkins Company, Baltimore.

(12) Gradwohl, R.B.H. (1938) Clinical Laboratory Methods and Diagnosis. A Textbook on Laboratory Procedures With Their Interpretation, 2nd Edition. The C.V. Mosby Company, St Louis.

(13) Folin, O. (1923) Laboratory Manual of Biological Chemistry With Supplement D, 3rd Edition. Appleton and Company, New York.

© 1919 The American Society for Biochemistry and Molecular Biology. Reproduced with permission.

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