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Any of various instruments used to determine or specify colors, as by comparison with spectroscopic or visual standards.

Definition :

Definition Colorimeter ( Absorptiometer ) An instrument that measures the concentration of a known constituent of a solution by comparison with colors of standard solutions of that constituent. Spec 20 and Spec 21 .

Essential parts:

Essential parts Source of light-incondesent lamps Means to select narrow wavelength Cuvetts Photosensitive elements-detector


Laws Beer-Lambert’s, which states that the absorption of light transmitted through a medium is directly proportional to the concentration of the medium. Beer's Law A = abc . A is absorbance, a is a proportionality factor called the molar absorptivity, b is the path length, and c is the molar concentration. When light passes through a homogenous medium, a part of the light is absorbed by the medium. As a result, there is a decrease in the intensity of the light emerging from the medium.

Important Factors :

Important Factors The most important factor- color intensity is proportional to the concentration . colors are -absorbance and intensely they are absorbed Instruments report both A (absorbance) and %T (transmittance). It depends on 1.The chemical being used and 2.How the electrons and energy levels within it are arranged.

General Principles :

General Principles When light of a particular color (or wavelength range) is directed through a chemical solution, some light is absorbed by the solution and some of it is transmitted. (According to Beer's Law) the concentration of the absorbing material is proportional to a quantity known as "absorbance," Thus, if you can determine the absorbance of a solution of a substance of unknown concentration and compare it with the absorbance of solutions of known concentrations, you can find the concentration of the substance in the solution being tested .

Approximate wavelength of color:

Approximate wavelength of color Violet 400-450nm Blue 450-500nm Yellow 570-590nm Orange 590-620nm Green 500-570nm Red 620-760nm

Mathematical Equations :

Mathematical Equations (1) The ratio of the intensity of transmitted light (I) to the intensity of incident light (Io) is called transmittance (T). In mathematical terms, T = I/Io. (2) The absorbance (A) of the solution (at a given wavelength) is defined as equal to the logarithm (base 10) of 1/T. That is, A = log (1/T). (3) The absorbance of the solution is directly proportional to the concentration (c) of the absorbing material in solution. That is, A = kc, where "k" is a proportionality constant.


Applications Sugar in the plasma(630nm/red filter) Liver glycogen(490nm) Total serum proteins and A:G ratio(540nm/green filter) Increases in Multipal myeloma A Increase- Nephritis . Severe burns, Chronic liver disease, TB G Increase Chronic disease

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Fibrinogen in plasma(680nm/red filter) Increase Pneumonia , Rheumatic fever, Decreases Acute hepatic necrosis Typhoid fever, Anti partum hemorrhage

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Blood urea(480nm) Higher values All forms of kidney disease, Sever vomition, Intestinal obstruction, Haematemesis,

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Serum creatinine Serum uric acid(700nm/red filter) Increase Gout Renal failure, Leukemia, Multiple myeloma, Myocardial infraction Decrease Wilson disease Fanconi syndrome

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Serum bilurubin Indirect bilurubin- hemolytic jaundice Conjugated bilurubin- obstructive jaundice

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Serum triglycerides I ncrease Diabetes mellitus, Nephrosis Myxoedema

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Serum total cholesterol(560nm/yellow filter) Increase Diabetes mellitus, Obstructive jaundice, Hypothyroidism Decrease Hyperthyroidism Anemia Hemolytic Jaundice

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Serum Mg(520nm/green filter) Serum Cu(440nm /violet filter)

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Serum inorganic phosphatase(680nm/red filter ) Increase Hypervitaminosis D Hypothyroidism Renal failure Serum tranceaminase(520nm) SGOT Increase Infectious hepatitis Hepatic damage Intestinal infraction SGPT Increase Acute hepatitis Relapsing cirrhosis

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Serum alanine and aspartate tranceaminase(520nm/green filter) Serum acid phosphatase Increase Prostate carcinoma alkaline phosphatase(670NM/RED FILTER) Increase Hepatitis Obstructive jaundice Liver cancer Bone cancer Osteocalcemie Ricketts

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Serum lactate dehydrogenase(440nm) increase Myocardial infraction Leukemia Acute pancretitis Serum lactic dehydrogenase

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Serum amylase(700nm/red filter) Increase Intestinal obstruction Acute peritonitis

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Ascorbic acids(540nm/green filter) Largest concentration- WBC and platelets


CSF Glucose in CSF Total proteins in

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