lovibond tintometer

[Prerana Marwah]

Hello everyone,

Please someone tell me the principle behind the working of lovibond tintometer.

[Sanjeev Sharma]

The Lovibond tintometer method described in AOCS O Cc 13e–92 is the accepted international standard for measuring the color of animal and vegetable fats and oils (any product through which light can pass). It is based on the British Standard/ISO method BS 684–1.14:1998 ISO 15305:1998 (BSI, 1998a).

Principle

The method is a subjective one in which the color of light from a standard source as seen through a specific depth of sample is matched with light from same source transmitted through a selected set of standard colored glass slides, the two light beams being viewed side by side in a telescopic eyepiece. The standard slides are red, yellow, blue and neutral.

The slides of any one color are additive: for example, two 5B slides will give the same blue color as one 10B slide.
A color match is obtained using red and yellow slides only if possible. Blue slides are used only if necessary. Results are expressed in Lovibond units (e.g., 5R 50Y), and the path length of light in the sample must be reported.

 

Important points:

1. The sample must be completely liquid, optically clear, dry and bright.Thus, the color of butter is actually determined on the extracted milk fat. The AOCS method 13e–92 requires that if a sample is not liquid at room temperature, it must be heated to a temperature 10 above its clear melting point.

2.  The operator must not be color-blind.

 

Automated version of Lovibond tintometer
 

Lovibond tintometer color can also be measured using objective automated instruments. In one version, the intensities of three light beams (red, yellow and white) transmitted by the oil are measured by photoelectric cells, and the results displayed as red and yellow color readings. The white light beam acts as a reference beam, and allows compensation for variation in the intensity of the light source. AOCS method Cc 13j 97 defines the used of this automated tintometer.

This tintometer is only valid for refined oil.

Source: Physical characterization of milk fat and milk fat based product I O J McCarthy

 

## Inputs from others would be appreciated

 

[Pankaj Sharma]

Thanks Sanjeev for giving the elaborate explanation. To add to this, the basic principle involved can be understood from the fact that the Lovibond tintometer is often mistakenly called a colorimeter. While these two testing instruments do have a lot in common as far as their basic functionality is concerned, they actually work on different principles. The Lovibond tintometer is used to perform a colorimetric analysis to determine the quantity of a known substance in a solution from the colour that it yields in reaction to a specific reagent.

The Lovibond tintometer, is not concerned with specific wavelengths of light, but rather on the reaction of the reagent that is added to the solution. The reagent added to the solution is determined by the solute that is being tested for. The amount of colour change that takes place and the intensity of the final colour will determine the concentration of the solute. The intensity of the final colour is often determined in the same way as the other of the two testing instruments, the colorimeter.

With Regards,

Pankaj Sharma