Calculate the iodine value from the expression iodine value 1. It is important to have a sample amount that corresponds to the volume of the wijs solution. 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. Petroleum iodine value of oil and fat kyoto electronics. 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. 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. Iodine value, in analytical chemistry, measure of the degree of unsaturation of an oil, fat, or wax. 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.
In linoleic acid and cod liver oil the hanus method gives 2 to 4 per cent higher values than the other. Nutrition laboratory report nt20903 food chemistry and biochemistry determination of free fatty acidffa and iodine value ivin oil lecturer name. The consensus values and their uncertainties were based on the acceptability of statistical agreement of results obtained from collaborating laboratories. Determination of free fatty acid ffa in oil and determination of iodine value iv in oil. An annex describes a method for the calculation of the iv from fatty acid compositional data. The consensus values and uncertainties for iodine values were 52. 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. 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. Find the birth control method that works for you on. A higher iodine value indicates a higher degree of unsaturation. If the iodine number is to be characteristic of the oil, the sample should be substantially free of moisture and foreign materials. The vegetable oil sample is reacted with an excess of iodine monochloride solution wijs reagent under controlled conditions. The iodine is derived from a solution of iodine monochloride in glacial acetic acid.
Depending on the expected iodine value, look at the following table to determine the correct sample amount. Alternative solvent system for iodine value determination. Iodine value quality control 1 linkedin slideshare. Sep 22, 2008 the consensus values and their uncertainties were based on the acceptability of statistical agreement of results obtained from collaborating laboratories. Iodine number wijs method free download as pdf file. Pipette out 10ml of fat sample dissolved in chloroform to an iodination flask labeled as test. Fats with high iodine value are normally soft or liquid and are less stable to oxidation. The total iodine value also includes the iodide ions which are necessary for formation of the complex. Iodine value or number is the number of grams of iodine consumed by 100g of fat. Cdr palmoiltester iodine value test shows a good correlation with aocs official method cd 1d92. Pdf a simple, fast, and green titrimetric method for the. The higher the iodine value, the more unsaturated fatty acid bonds are present in a fat.
Sources of errors in the determination of iodine value of palm oil by wijs method. It can also be used to make pure iodates, by reacting with a chlorate and releasing chlorine gas as byproduct. For example the theoretical iodine value of 100 g of linoliec acid would be 181 based on calculation as follows 100280. Several variations of iodine value have been developed, although hanus method, wijs method and hubl method are still widely used. To calculate the iodine number using the method described, below, all one need do is obtain the volume of na 2. Two collaborative studies were conducted using the wijs method for determining the iodine value in a wide range of vegetable and. It must be noted that a high iv value in oil consists of a greater number of double bonds than a low iv oil. The wijs method as the standard for iodine absorption. A simple titrimetric method for the determination of the iodine value of vegetable oils is proposed. Ive been asked this question but there are no examples of calculating iodine value in my textbook. The wijs method, the wijs potentiometric method this paper, the visual method and the potentiometric method proposed in this paper were all applied.
Presently, norm en14111 determines the use of the american oil chemists society cd125 method for the determination of the iodine number of biodiesel. The higher the iodine number is, the more unsaturated the fat. It is based on the reagent icl, iodine monochloride, dissolved in glacial acetic acid 0. Determination of free fatty acid ffa in oil and determination of iodine value iv in oil introduction acid value or free. To obtain the total iodine number of biodiesel samples astm d1541 27 is used. Halogens add quantitatively to the double bonds in the unsaturated fatty acids, principally oleic and linoleic acids in the case of corn oil. The i value iv of palm oil and fractions olein, stearin were determined by wijs method. Standard test method for determination of iodine value of.
A green potentiometric method for the determination of the iodine. The aocs recommended method d195997 wijs procedure is broadly used for determination of iv. Iodine value definition of iodine value by medical. Wijs method definition of wijs method by merriamwebster. Triglycerides are made up of three fatty acids linked to glycerol by fatty acyl esters. This method provides an assay value for a sample of povidoneiodine. Sources of errors in the determination of iodine value of. Determination of iodine value iv in fats and oils with. 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. A simple, fast, and green titrimetric method for the. It was dissolved in a 250 ml erlenmeyer using 15 ml of chloroform and 25.
The method proposed in the present communication and also the wijs. 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. The intent is not to provide an exhaustive list of analytical methods. The oil obtained was further used to determine iodine value and acid value by titration method according to aocs and ftir spectroscopy method. It is expressed as the number of grams of iodine that will react with the double bonds in 100 grams of fats or oils. Iodine value test with cdr palmoiltester palm oil analysis. This procedure, originally used for the analysis of oils and fats, is currently known as wijs method. The quantity of wijs solution consumed by the sample should be close to 50% of the total amount of wijs solution added. Iodine monochloride is an interhalogen compound with the formula icl. A new rapid titration method for determining the halogen ratio of wijs.
A simple, fast, and green titrimetric method for the determination of the iodine value of vegetable oils without wijs solution icl. Palmbased standard reference materials for iodine value. Measure another portion of 200ml of glacial acetic acid and add 3ml of. A green potentiometric method for the determination of the. This procedure, originally used for the analysis of oils and fats, is currently known as wijs. The determinations made by the proposed method were compared with the procedure described in the american oil chemists society cd125 method, which is.
Add 20ml of iodine monochloride reagent in to the flask. Used to indicate in a definite manner the class to which an unknownfatoroilbelongs. 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. Estimation of iodine value of fats and oils procedure. Simple methods via midir or 1h nmr spectroscopy for the. Determination of iodine value of palm based on triglyceride composition article pdf available in journal of the american oil chemists society 757.
Pdf a new and fast method was developed to determine the iodine number. Various factors affecting results, and possible sources of error, were investigated. One of the most used procedures to determine the iodine value is known as wijs method. The wijs method as the standard for iodine absorption j. Fatty acids are long chain hydrocarbons with carboxyl groups cooh groups. Iodine value iv is a measure of the total number of double bonds present in fats and oils. Fatty acids react with a halogen iodine resulting in the addition of the halogen at the cc double bond site.
This unsaturation is in the form of double bonds, which react with iodine compounds. This unsaturation is in the form of double bonds which react with iodine compounds. Determination of iodine value and acid value of red fruit. 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.
Determination of iodine value of oil lipids laboratory. The wijs solution, iodine monochloride dissolved in acetic acid, is used to determine the iodine value of a substance. The recovery of iodine of this sample, analyzed statistically, was 100 f 4 per cent. Firstly, sample fat is dissolved in carbon tetrachloride, and hanus reagent is added and left in a dark room for. General physical and chemical properties were evaluated that included density by pycnometer using the standard iupac method 2. Iodine value test with cdr palmoiltester palm oil analysis system. Analytical method for determining the degree of unsaturation of a material, which involves the addition of iodine to the existing double bonds. To determine the iodine value of fats and oils and thus estimate the unsaturation of the fats and oils.
By this method, the iodine content of thyroid glands of various control animals was determined. Water is used as the principal solvent, and ethanol is employed to dissolve the oil samples and to prepare a standard iodine solution. The various factors affecting the results and possible. Then to this mixture potassium iodide is added which reacts with remaining free. The vegetable oil sample is reacted with an excess of iodine monochloride solution wijs reagent under. Iso 3961 or astm d 1959 is the wijs method starting from an iodine containing wijs solution and a sodium thiosulfate and indicator solution. Pdf determination of iodine value of palm based on. About 5 g of accurately weighed povidoneiodine is placed in a 400ml beaker, and 200 ml of distilled water is added.
The approximate weight, in g, of the substance to be taken may be calculated by dividing 20 by the highest expected iodine value. Analysis for determination of iodine value of fish oils wijs method. An aliquot of the sample was weighed according to the expected iodine number. Addition of iodine chloride and backtitration with sodium thiosulphate by din 532411. Serves to characterize them and to indicate whether they are pure or admixtures. Treatment of rfo samples on accelerated temperature approximately 50 gram of each sample is introduced into 100 ml beaker glass. How do i calculate theoretical iodine value of an unsaturated. Determination of the iodine value of oils and fats. To access content within the members area, you need to login by entering your username. Iodine valuenumber is defined as the g of iodine absorbed by 100g of the oil.
Palmbased standard reference materials for iodine value and. Pdf fast determination of iodine number of biodiesel using. Find the birth control method that works for you on iodine. 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. Apr, 2014 a higher iodine value indicates a higher degree of unsaturation. It is a redbrown chemical compound that melts near room temperature. The samples are divided into 6 groups, each was labeled according. The determination is conducted by dissolving a weighed sample in a nonpolar solvent such as cyclohexane, then adding glacial acetic. Estimation of iodine value of fats and oils theory.1520 417 704 1264 1044 472 518 135 1287 560 495 821 371 458 1037 962 1152 1522 267 791 871 1090 625 651 1495 550 1343 1264 1511 619 629 1215 107 1453 318 567 681 111 739 29 203