The determinations made by the proposed method were compared with the procedure described in the american oil chemists society cd125 method, which is. It is important to have a sample amount that corresponds to the volume of the wijs solution. Then to this mixture potassium iodide is added which reacts with remaining free. Iodine monochloride is an interhalogen compound with the formula icl. Analytical method for determining the degree of unsaturation of a material, which involves the addition of iodine to the existing double bonds. By this method, the iodine content of thyroid glands of various control animals was determined. Iodine number wijs method free download as pdf file. Pdf a new and fast method was developed to determine the iodine number. The recovery of iodine of this sample, analyzed statistically, was 100 f 4 per cent. The higher the iodine value, the more unsaturated fatty acid bonds are present in a fat. Iodine value or number is the number of grams of iodine consumed by 100g of fat. If the iodine number is to be characteristic of the oil, the sample should be substantially free of moisture and foreign materials. A higher iodine value indicates a higher degree of unsaturation.
The wijs method as the standard for iodine absorption j. The aocs recommended method d195997 wijs procedure is broadly used for determination of iv. Used to indicate in a definite manner the class to which an unknownfatoroilbelongs. Fatty acids are long chain hydrocarbons with carboxyl groups cooh groups. The vegetable oil sample is reacted with an excess of iodine monochloride solution wijs reagent under. This unsaturation is in the form of double bonds, which react with iodine compounds.
Iodine value test with cdr palmoiltester palm oil analysis. Various factors affecting results, and possible sources of error, were investigated. Test method for measurement of iodine value of fats and oils stipulated in the below quoted standards is generally practiced by wijs method using monobasic. It is expressed as the number of grams of iodine that will react with the double bonds in 100 grams of fats or oils. Pdf determination of iodine value of palm based on. Arrange all the reagent solutions prepared and the requirements on the table. An annex describes a method for the calculation of the iv from fatty acid compositional data. The method proposed in the present communication and also the wijs. Iodine value iv is a measure of the total number of double bonds present in fats and oils. To determine the iodine value of fats and oils and thus estimate the unsaturation of the fats and oils.
This method provides an assay value for a sample of povidoneiodine. Wijs method definition is a method for determining the iodine number as of an oil or fat that consists in adding a solution of iodine monochloride in glacial acetic acid and estimating the excess of unused halogen by titration with sodium thiosulfate. Palmbased standard reference materials for iodine value. This procedure, originally used for the analysis of oils and fats, is currently known as wijs. Serves to characterize them and to indicate whether they are pure or admixtures. Determination of the iodine value of oils and fats. Test method for measurement of iodine value of fats and oils stipulated in the below quoted standards is generally practiced by wijs method using monobasic iodine, however, hanus method is demonstrated here using iodine bromide. Presently, norm en14111 determines the use of the american oil chemists society cd125 method for the determination of the iodine number of biodiesel. Iodine value test with cdr palmoiltester palm oil analysis system. A simple, fast, and green titrimetric method for the. A simple titrimetric method for the determination of the iodine value of vegetable oils is proposed.
A green potentiometric method for the determination of the. As a general rule, if the iodine number is in the range of 070, then youre looking at a fat. Firstly, sample fat is dissolved in carbon tetrachloride, and hanus reagent is added and left in a dark room for. Simple methods via midir or 1h nmr spectroscopy for the. General physical and chemical properties were evaluated that included density by pycnometer using the standard iupac method 2. Determination of iodine value iv in fats and oils with. This procedure, originally used for the analysis of oils and fats, is currently known as wijs method. A green potentiometric method for the determination of the iodine. Treatment of rfo samples on accelerated temperature approximately 50 gram of each sample is introduced into 100 ml beaker glass. Standard test method for determination of iodine value of. Fatty acids react with a halogen iodine resulting in the addition of the halogen at the cc double bond site. Pdf a simple, fast, and green titrimetric method for the. One of the most used procedures to determine the iodine value is known as wijs method. Pipette out 10ml of fat sample dissolved in chloroform to an iodination flask labeled as test.
Halogens add quantitatively to the double bonds in the unsaturated fatty acids, principally oleic and linoleic acids in the case of corn oil. The determination is conducted by dissolving a weighed sample in a nonpolar solvent such as cyclohexane, then adding glacial acetic. The higher the iodine number is, the more unsaturated the fat. The wijs solution, iodine monochloride dissolved in acetic acid, is used to determine the iodine value of a substance.
Iodine valuenumber is defined as the g of iodine absorbed by 100g of the oil. The approximate weight, in g, of the substance to be taken may be calculated by dividing 20 by the highest expected iodine value. It can also be used to make pure iodates, by reacting with a chlorate and releasing chlorine gas as byproduct. Triglycerides are made up of three fatty acids linked to glycerol by fatty acyl esters. A simple, fast, and green titrimetric method for the determination of the iodine value of vegetable oils without wijs solution icl. The total iodine value also includes the iodide ions which are necessary for formation of the complex. The i value iv of palm oil and fractions olein, stearin were determined by wijs method. Sources of errors in the determination of iodine value of palm oil by wijs method. Determination of iodine value of palm based on triglyceride composition article pdf available in journal of the american oil chemists society 757.
The oil obtained was further used to determine iodine value and acid value by titration method according to aocs and ftir spectroscopy method. It was dissolved in a 250 ml erlenmeyer using 15 ml of chloroform and 25. The iodine value or iodine adsorption value or iodine number or iodine index in chemistry is the mass of iodine in grams that is consumed by 100 grams of a chemical substance. This unsaturation is in the form of double bonds which react with iodine compounds. Add 20ml of iodine monochloride reagent in to the flask. The wijs method as the standard for iodine absorption. It must be noted that a high iv value in oil consists of a greater number of double bonds than a low iv oil. Calculate the iodine value from the expression iodine value 1. Determination of iodine value and acid value of red fruit. Iso 3961 or astm d 1959 is the wijs method starting from an iodinecontaining wijs solution and a sodium thiosulfate and indicator solution. On the determination of iodine value by the wijs method. The wijs method, commonly used, requires 30 minutes absorption time.
Two collaborative studies were conducted using the wijs method for determining the iodine value in a wide range of vegetable and. Determination of iodine value of oil lipids laboratory. Alternative solvent system for iodine value determination. Water is used as the principal solvent, and ethanol is employed to dissolve the oil samples and to prepare a standard iodine solution. In linoleic acid and cod liver oil the hanus method gives 2 to 4 per cent higher values than the other. It is a redbrown chemical compound that melts near room temperature. Fats with high iodine value are normally soft or liquid and are less stable to oxidation. How do i calculate theoretical iodine value of an unsaturated. If more than half the available halogen is absorbed, the test must be repeated with a smaller.
To access content within the members area, you need to login by entering your username. About 5 g of accurately weighed povidoneiodine is placed in a 400ml beaker, and 200 ml of distilled water is added. Nutrition laboratory report nt20903 food chemistry and biochemistry determination of free fatty acidffa and iodine value ivin oil lecturer name. Petroleum iodine value of oil and fat kyoto electronics. The iodine is derived from a solution of iodine monochloride in glacial acetic acid. Measure another portion of 200ml of glacial acetic acid and add 3ml of. To calculate the iodine number using the method described, below, all one need do is obtain the volume of na 2. Apr, 2014 a higher iodine value indicates a higher degree of unsaturation. The various factors affecting the results and possible. Analytical methods the purpose of this chapter is to describe the analytical methods that are available for detecting, measuring, andor monitoring iodine and its radioisotopes, their metabolites, and other biomarkers of exposure and effect to iodine and its radioisotopes.
Determination of free fatty acid ffa in oil and determination of iodine value iv in oil introduction acid value or free. The quantity of wijs solution consumed by the sample should be close to 50% of the total amount of wijs solution added. Palmbased standard reference materials for iodine value and. Determination of free fatty acid ffa in oil and determination of iodine value iv in oil. Depending on the expected iodine value, look at the following table to determine the correct sample amount. Iodine value definition of iodine value by medical. Hoffman and green modified the wijs method by employing mercuric acetate as catalyst and made it possible to determine the iodine value of a sample in ten minutes or so. A new rapid titration method for determining the halogen ratio of wijs.
Wijs method definition of wijs method by merriamwebster. For the determination of the iodine number of oleic and ricin oleic acids both the hanus and the rosenmund methods give the same value which is very near the theoretical. Addition of iodine chloride and backtitration with sodium thiosulphate by din 532411. The vegetable oil sample is reacted with an excess of iodine monochloride solution wijs reagent under controlled conditions. The samples are divided into 6 groups, each was labeled according. For example the theoretical iodine value of 100 g of linoliec acid would be 181 based on calculation as follows 100280. Iodine numbers are often used to determine the amount of unsaturation in fatty acids. Mercuric acetate, however, cannot be empolyed now because the reaction solution is hard to meet the regulation of water pollution and its disposal has become difficult. Iso 3961 or astm d 1959 is the wijs method starting from an iodine containing wijs solution and a sodium thiosulfate and indicator solution. Iodine value quality control 1 linkedin slideshare. To obtain the total iodine number of biodiesel samples astm d1541 27 is used. The consensus values and their uncertainties were based on the acceptability of statistical agreement of results obtained from collaborating laboratories. The intent is not to provide an exhaustive list of analytical methods. The iodine number is determinated with a carrier for the iodine, in which case the solution may be iodine monochloride in glacial acetic acid wijs.
The consensus values and uncertainties for iodine values were 52. Find the birth control method that works for you on iodine. The wijs method, the wijs potentiometric method this paper, the visual method and the potentiometric method proposed in this paper were all applied. Iodine value, in analytical chemistry, measure of the degree of unsaturation of an oil, fat, or wax.
Several variations of iodine value have been developed, although hanus method, wijs method and hubl method are still widely used. It is based on the reagent icl, iodine monochloride, dissolved in glacial acetic acid 0. It is expressed as the number of grams of iodine that will react with the double bonds in 100 grams of fats or oils the determination is conducted by dissolving a weighed sample in a nonpolar solvent such as cyclohexane, then adding glacial acetic. Sources of errors in the determination of iodine value of. Ive been asked this question but there are no examples of calculating iodine value in my textbook. An aliquot of the sample was weighed according to the expected iodine number. Cdr palmoiltester iodine value test shows a good correlation with aocs official method cd 1d92. Find the birth control method that works for you on. Pdf fast determination of iodine number of biodiesel using. Estimation of iodine value of fats and oils theory. Analysis for determination of iodine value of fish oils wijs method. Estimation of iodine value of fats and oils procedure.
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