CLIAMS:1. A portable optical analysis device comprising
a thermoplastic base (1) having an aperture (2) in the middle extending away from the base to form a cuboid-shaped cavity (3) adapted to hold a sample container, the cavity having on a pair of opposite faces at its periphery, a pair of radial apertures, extending outward from the periphery and adapted to hold an Light Emitting Diode (LED) source at one end (4) and an optical detector at an opposite end (5)
2. The device as claimed in claim 1 wherein the optical detector is a non-dispersive detector

3. The device as claimed in claim 1, wherein the device has a sensitivity of 0.02 %w/w
4. The device as claimed in claim 1 or 2 wherein the sample container holds a sample in contact with cupric ion and pyridine at a pH of around 6.1.

5. The device as claimed in any one of the claims 1 to 4 wherein the device is free from an optical lens

6. The device as claimed in claim 4 or 5 wherein the sample is free from particulate matter

7. A method for determination of free fatty acid in an oil , the method comprising contacting the oil with a copper salt solution in the presence of pyridine to form a complex of free fatty acid and copper ion and irradiating the complex in a sample container of a portable optical analysis device.

8. The method as claimed in claim 7 wherein the oil is contacted with a copper salt at a pH of around 6.1

9. The method as claimed in claim 7 or 8 wherein the copper salt forms a complex with the free fatty acid

10. The method as claimed in any one of the claims 7 to 9 wherein the complex is irradiated with visible light having wavelength in the range of 430 to 450 nm
,TagSPECI:FIELD OF INVENTION
The present invention relates to a portable optical analysis device. The invention also relates to a method for determination of free fatty acid in oil.

BACKGROUND
Oils are glyceryl esters of fatty acids. Often, they undergo hydrolysis when in contact with atmospheric moisture for a prolonged period of time. The hydrolysis of oils leads to release of free fatty acids, the amount of which is indirectly a measure of the extent of oil degradation. Therefore, measurement of free fatty acids in oil sample is significant in determining the quality and stability of an oil. Conventional methods of determination of free fatty acid content in oil include chemical or thermometric titration, enzymatic methods, determination using fatty acid binding protein and measurement of metal-fatty acid complexes using spectrophotometry. Spectrometric determination of fatty acids using metal-fatty acid complexes is one of the most convenient methods of analyses. However, most spectrophotometers are voluminous and difficult to transport to the sites where analysis need to be carried out. Further, metal salts used to prepare complexes with fatty acids tend to settle down from the solution state, in the sample container. There is, therefore, a need in the art for a device and a method for determination of free fatty acids in oil that overcomes the disadvantages of conventional devices and methods.
OBJECTS OF INVENTION

An object of the invention is to provide a portable optical analysis device
An object of the invention is to provide non-dispersive analysis of free fatty acid in an oil sample
An object of the invention is to provide a reliable method for analysis of free fatty acid content in an oil sample

SUMMARY OF INVENTION

The invention provides a portable optical analysis device comprising
a thermoplastic base having an aperture in the middle extending away from the base to form a cuboid-shaped cavity adapted to hold a sample container, the cavity having on a pair of opposite faces at its periphery, a pair of radial apertures, extending outward from the periphery and adapted to hold a Light Emitting Diode (LED) source at one end and an optical detector at an opposite end.

The invention also provides a method for determination of free fatty acid in an oil, the method comprising contacting the oil with a cupric salt solution in the presence of pyridine to form a complex of free fatty acid and copper ion and irradiating the complex in a sample container of a portable optical analysis device.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 displays an embodiment of the optical device of the present invention.
Referring now to figure 1, the portable optical analysis device of the present invention comprise an thermoplastic base 1. The thermoplastic base is usually prepared from any thermoplastic polymer. Typically, the thermoplastic polymer is acrylonitrile butadiene styrene (ABS) polymer. The thermoplastic base 1 has an aperture 2 in the middle extending away from the base to form a cuboid shaped cavity 3 adapted to hold a sample container. The cavity has, on a pair of opposite faces at its periphery, a pair of radial apertures, extending outward from the periphery and adapted to hold an LED source at one end 4 and an optical detector at an opposite end 5.

The portable optical analysis device of the present invention enables non-dispersive analysis of liquid samples using an LED source and a photodiode detector. The peripheral apertures in the device allow transmission of LED light from the source to the optical detector through a liquid sample contained in an optically transparent container placed in its path. Advantageously, the device of the present invention allows determination of free fatty acid in an oil sample with a sensitivity of 0.02 %w/w.
While in operation, the optical analysis device of the present invention holds an oil sample in the sample container. The oil sample is usually in contact with cupric ions and pyridine. Typically, the sample in the container has a pH of around 6.1. Further, the sample is free from any particulate matter. In the method of the present invention, the oil sample is contacted with an aqueous solution of copper ion resulting in the formation of a complex. The complex is then irradiated in a sample container of the portable optical analysis device. The device of the present invention is, typically, free from an optical lens. This eliminates interference in analysis by dust particles usually accumulated at the surface of optical lens upon prolonged use.
The invention provides a portable and a very efficient device for determination of free fatty acid in oil. In view of its portability, the compact nature and light weight of the device, the device is capable of being transported to various sites where fatty acid analysis need to be carried out. Further, the device of the present invention is non-dispersive and does not use a monochromator. Furthermore, the device has an LED light source and an optical diode detector making the measurement less cumbersome. The method of the present invention comprises contacting the oil with a cupric salt solution in the presence of pyridine to form a complex of free fatty acid and copper ion. The method of the present invention allows accurate determination of free fatty acid content in an oil sample.
Overall, the device of the present invention and the method of analysis of the free fatty acid using the device make the determination of free fatty acid in an oil sample very convenient, simple and economical. Further, by enabling stability of the complex formed between the copper ion and the free fatty acid, the analysis is made more reliable and reproducible.

EXAMPLE
Free fatty acid analysis of oil using portable optical analysis device:
Around 5 g of Cupric Acetate was placed in a beaker, 50 ml distilled water was added to the beaker to dissolve the cupric salt completely. The solution was transferred into a 100 ml volumetric flask carefully. The volumetric flask was made up to the mark by adding distilled water. pH of the cupric acetate solution was adjusted to 6.1 by adding pure pyridine, drop by drop. 1 ml of the solution was contacted with oil sample and benzene and mixed thoroughly by shaking. The aqueous layer was allowed to settle for a few minutes. The upper layer was decanted and transferred to a sample container used for analysis in the portable optical device.

The above description is illustrative only and is not limiting. The present invention is defined by the claims that follow and their full range of equivalents