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THE EFFECT OF 11 ME AND TEMPERA- 
 TERE UPON THE BROMINE VALUE 
 OF FISH OILS 
 
 MY 
 
 VIVIAN JONKS YAl.E 
 
 THESIS 
 
 FOK THE 
 
 DEGREE OF BACHELOR OF SCIENCE 
 
 IN 
 
 LIBERAL ARTS AND SCIENCES 
 
 COLLEGE OF LIBERAL ARTS AND SCIENCES 
 
 UNIVERSITY OF ILLINOIS 
 
 1922 
 

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 i?;i . r4:tXX». «' 
 
TABLK OF COTv^TF^TTB. 
 
 A 3 kn o wl e dgrn en t p ag e 
 
 Introduction 1 
 
 Historic 3,1 u 
 
 Theoretical 4 
 
 Experimental 9 
 
 Results — Table for Cod Oil 16 
 
 Table for Herring Oil 16 
 
 Table for Salmon Oil 17 
 
 Ta'^le for Sardine Oil 17 
 
 Table for Japanese Herring Oil 18 
 
 Table for Menhaden Oil 18 
 
 Conclusions 25 
 
 Bibliography 26 
 
Digitized by the Internet Archive 
 in 2015 
 
 https://archive.org/details/effectoftimetempOOyale 
 
ACKNOWLEDGMENT. 
 
 I wish to express my sincere appreciation of 
 the valuable assistance vihich has been received during this 
 investigation, from Dr. George D, Beal, under whose direction 
 it was carried out. 
 
INTRODUCTION. 
 
 Natural oils and fats are widely distributed throughout 
 the vegetable and animal kingdon, from the lowest organisms up td 
 the most highly organized forms of vegetable and animal life, and 
 are found in almost all tissues and organs. 
 
 In plants they are chiefly found in the seeds and are 
 associated therein with the starch to nouri^ the embryo. In the 
 animal organisms, the oils and fats are mainly enclosed in the cel 
 Lular tissues of the intestines and in the tissues nearest the 
 outer skin. 
 
 Considered chemically, fats and fatty oils consist 
 chiefly of glycerol tri-esters (glycerides) of saturated fatty 
 acids a.nd of related, unsaturated acids. 
 
 The properties of the fats run parallel with those of 
 the fatty acids and since this paper will deal with the unsat- 
 urated fatty acids a few of their properties will be considered 
 kiere. 
 
 These acids contain one or more pairs of carbon atoms 
 united by a double bond and are therefore, capable of taking up, 
 oy direct addition atoms of halogen or halogen acid to form 
 saturated compounds; the quality of the halogen absorption being 
 dependent entirely upon these double unions. 
 

 HISTORICAL. 
 
 In about the year 1857 Cailletet' communicated to the 
 Societe Industrielle de Mulhouse a titration process for the 
 determination of the bromine absorption value of an unsa tur- 
 
 ated f atty acid, to be thus performed: 
 
 "To any given oil add a five per cent aqueous 
 
 solution of caustic potash and agitate; then pour in an excess 
 of a 33 1-3 per cent alcoholic solution of bromine; lastly, 
 add a two per cent solution of turpentine until the color of the 
 free bromine is completely discharged. The turpentine solution 
 is supposed to be known in terms of the bromine solution, and 
 thus the bromine absorption of any oil can be determined. If 
 stand ard pure oils be at hand, their admixture can be 
 quantitatively ascertained by this means." 
 
 Cailletets' process had some very obvious disadvantage 
 according to E, J, Mills^, the solution of bromine can not be 
 preserved unchanged, probably even for a few hours; and the 
 presence of water and alcohol must inevitably tend to promote 
 oxidation of the oil under treatment. Again, Cailletet’ admits 
 that the absorption increases in total amount with so moderate 
 a rise of temperature as from 10° to ZOP c, and that a consid- 
 erable amount of bromination occurs. It occurred, accordingly, 
 
 to Mills^ (1379-1880), more particularly in connection with 
 Hydrocarbon oils, that weak aqueous bromine alone might give 
 
-3- 
 
 gentler and steadier results. 
 
 This plan v/as accordingly tried with various samples 
 
 of petroleum, the sample being agitated with 100 parts of water, 
 
 and a one-tenth per cent solution of bromine added, with constant 
 agitation, until potassium iodide and starch, used as an 
 external indicator, gave a "^lue color. Under these circumstances 
 
 constant bromine absorptions were obtained accompanied always 
 
 with some bromine absorption. The chief difficulty in applying 
 
 this otherwise satisfactory method consisted in the extreme 
 
 amount of technique required to obtain uniform measurements. 
 
 (1831) subsequently st^'gested agitating 
 0 s with excess of aqueous sodium hypobromite and hydrochloric 
 
 aoid, and titrating the ultimate free bromine. This amounts 
 
 to treatment with nascent as well as free bromine in the 
 
 presence of water; so that the results are of a very composite 
 character. 
 
 As it was evidently desirable to confine the absorption 
 to the formation of additive and not substitution products, it 
 was decided to employ CS3 as the common solvent of the bromine 
 and the substance to be titrated. Water was thus practically 
 
 excluded and the reaction was marked by great regularity and 
 considerable sharpness. 
 
 Mills later substituted CCI4 explaining the change 
 
 by saying that at ordinary temperature the solution of ©romine 
 is more stable in CCl^ than in CS3. Thus it is to him that we 
 owe the application of the bromine absorption value to the 
 analysis of fats. His method is as follows: 
 

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 .1 gram of oil or fat is tried tnoroughly and filtered, 
 then dissolved in 50 cc of CCla and placed in a narrow-mouthed 
 stoppered hottle of 100 cc . capacity. To this solution is 
 added a standard carbon tetrachloride solution (about .006- 
 .008 grams per c .c . ) until after a lapse of fifteen minutes, 
 a coloration persists. The excess of bromine can be measured 
 either by this color compared to that produced by a blank 
 experiment or, more accurately by titrating back with a standard 
 solution of B-napthol in carbon tetrachloride, when monobrom 
 
 naphthol is formed. The bromine is calculated to -t,bsorb 100 grams 
 of fat . The average probable error is said to be about .46 
 per cent . 
 
 Mills emphatically stressed the fact that moisture must 
 be rigidly excluded, since in its presence the bromine absorption 
 number was found to be too high. Instead of B-naphthol, potassium 
 iodide may be added, and the liberated iodine titrated with 
 standard sodium thio-sulf ate . 
 
 THEORETIC L . 
 
 The bromine (or iodine) absorption value is defined 
 as the per cent of bromine (or iodine) absorbed by the sample . 
 
 This value is a quantitative measure of the proportion of 
 unsaturated fatty acids, which, both in their free state and in 
 combination with glycerol, have the property of assimilating 
 halogens to form saturated compounds. 
 
# 5 * 
 
 Two factors influence the result; 
 
 (l)' the nature of the unsaturated acid yj hich is present, 
 
 those with two doubl e bonds absorbing more than those 
 with one even though the number of carbon atoms is the 
 same, and 
 
 (3) the chemical composition of the glycerides, those with 
 the lower molecular weights absorbing a greater 
 percentage than those with higher, where the degree of 
 saturation is the same. 
 
 It is hardly possible to allow dry bromine to act on an 
 oil since it is absorbed with a more or less violent 
 reaction and hydrobromic acid is evolved, hence the 
 reaction m.ust be moderated by previously dissolving 
 both the bromine and the oil in a suitable solvent . 
 
 Carbon tetrachloride, as was first used by Mills® is generally 
 employed as the solvent. In the course of the reaction, even 
 when carbon tetrachloride is used, a small q uantity of hydro- 
 bromic is formed, due to the substitution of hydrogen by bromine 
 in the molecule of the fatty substance. Therefore the total 
 absorption of bromine is due to both substitution and addition, 
 and since greater amounts of substitution products are formed wjJh 
 more concentrated brom.ine solutions, moderately dilute solutions 
 should be used. The amount of substitution which has taken place 
 can be determined by a measure of the hydrobromic acid formed and 
 the true bromine a bsorption value, will be the total absorption 
 
- 6 - 
 
 value minus the bfomine reacting by substitution. 
 
 Mcllhiney'^ in 1894 determined the bromine addition and 
 the substitution values as follows: 
 
 ^Dissolve from .35 to 1 gram of the oil or fat in 10 cc 
 of carbon tetrachloride in a 500cc stoppered bottle and add an 
 excess of one-third normal solution of bromine. Place in ice 
 after a few minutes in order to create a partial vacuum. Next 
 slip a piece of rubber tubing over the neck to form a well and 
 through this suck 35 cc water into the bottle. The contents are 
 well shaken and about 1 0 cc of 30 percent potassium iodide e.nd 
 about 75 cc of v/ater added. The iodine liberated is measured by 
 titrating it with a standard solution of sodium thiosulfate and 
 then calculated to bromine. The total amount of bromine added is 
 ascertained by a blank test, and the difference betw'een the two 
 equals the to tal bromine absorption. This is calculated to units 
 in per cent of the sample taken. The contents of the bottle are 
 now transferred to a sep'aratory funnel, and the aqueous solution 
 separated and filtered. If the filtrate is blue, it is decolorize! 
 by sodium thiosulphate and the free acid is determined as hydrobro- 
 mic acid by titration w ith decinormal alkali, methyl orange being 
 the indicator. The bro mine calculated from the hydrobromic acid 
 and expressed in per cent of the sample gives the bromine 
 substitution value, Tw ice this number subtracted from the total 
 
 bromine absorption value furnishes the bromine addition number. 
 
 In order to have a standard by which to measure the 
 
 experimental portion of this paper, the iodine values of the oils 
 
I 
 
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-7- 
 
 under exa mination were first determined. There are three methocb 
 at present which are most commonly used for the determination of 
 the iodine absorption value, those of H-Cibl, Wijs and Hanus. 
 
 The first (Httbl)^ consists in the main in s.dding 50 cc 
 of the iodine solution (consisting of a mixture of 26 grams of 
 pure iodine in 500 cc of 95 per cent alcohol and 30 grams of 
 mercuric chloride in 500 cc of alcohol, mixed in equal volumes 
 and let stand 12 hours) t6 the sample, which is dissolved in 
 chloroform in a special Erlenmeyer flaslfc. The flask is stoppered 
 tightly and the gutter filled with fifteen per cent potassium 
 iodide, then allowed to stand three hours — a blank being run at 
 the same time — then 20 cc more potassium iodide is added and the 
 contents titrated v/ith thiosulfate. The absorbed iodine is cal- 
 culs.ted in terms of percentage of the weight of the sample. 
 
 This method has been proven to be one of the most 
 valuable ones to be used in the technical analysis of oils and 
 fats. Long before any detailed explanation had been found for 
 the reactions involved, the numbers obtained afforded a valuable 
 guidance in the examination of oils. 
 
 Experiments by Wijg led to a satisfactory explanation 
 of the reactions occurring in the Hftbl solution. The important 
 change which takes place on mixing the solutions of mercuric 
 chloride and iodine is thus represented: 
 
 HgCl3 +■ 2 12 «= Hgip. 4 g ICl 
 

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 Thus it is to he discerned that provided no other reaction has 
 taken place, all of the iodine originally employed must he found 
 in the hi ank test as iodine. Wijs' method differs from that of 
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 13 grams of iodine in a liter of glacial acetic acid and then 
 passing in chlorine gas until all is converted into iodine chlor- 
 ide. This amounts practically to a tacit acceptance that iodo- 
 chloride is the active agent. 
 
 Hanui^ suggested that Wi^s’ method he modified hy 
 using iodine bromide instead of iodine chloride. In this method 
 the oil is dissolved in 10 cc of chloroform and 35 cc of the 
 iodine solution is added. The mixture is allowed to stand for 
 some time with occasiona,! shaking and then 1 0 cc of a 15fj 
 solution of potassium iodide and 100 cc of water are added and 
 the excess iodine titrated vfith standard thiosulphate until the 
 blue color obtained with the aid of starch paste just fails to 
 reappear . 
 
 The results of this method agree very closely with those 
 obtained hy Hiihls’ method but the results obtained by the Wijs 
 method are higher than the others. 
 
 EXPERIMENTAL . 
 
-9- 
 
 EXPERIMENTAL . 
 
 The experimental portion of this paper represents an 
 attempt to determine the conditions necessary for the accurate 
 determination of the bromine absorption values of fish oils. Tbe 
 oils used for the work of this paper were Cod Oil, Salmon Oil, 
 Herring Oil, Sardine Oil, Japanese Herring Oil and Menhaden Oil. 
 
 The solutions used in the determination of the bromine 
 absorption values were prepared as follows; 
 
 1. Standard potassium permanganate, used for the 
 standardization of the thiosulphated solution. The 
 potassium permanganate was standardized against chemically 
 pure sodium oxalate in the usual manner. 
 
 I, II. III. 
 
 Wt . of Sample .1843 .1467 .3031 
 
 CCS Mn04 3^6 23.6 33.5 
 
 NF. KMno4 .0939 .0938 .0933 
 
 Average Normality Factor .0930 
 3. Sodium P^*^^sulphate, standardized against the 
 potassium permanganate as follows: 
 
 Approximately 10 cc of 15 per cent potassium iodicfe 
 was placed in a glass-stoppered flask, then 10 cc 
 potassium permanganate solution vir ere added from 
 a burette, followed by ten cc dilute hydrochloric 
 acid; and the solution allowed to stand ten 
 minutes . 
 
- 10 - 
 
 One hundred cc E^O were then added and the solution was titrated 
 with the sodium thiosulphate-starch being used as the indicator. 
 The results were as follows for the three standard 
 
 solutions: 
 
 I . II . 
 
 (a) No. CCS KI«'Ino 4 10. 10. 
 
 " " Na2Ss03 9.92 9.9 
 
 N. F. Na^SgOs .0937 ■ .0939 
 
 Average Normality Factor .0938 
 
 I. II. 
 
 (b) No. CCS KMr .04 10.25 10. 
 
 " " NagSoOs 10.05 9.8 
 
 N. F. Na3S30;3 .0948 .0948 
 
 Average Normality Factor .0948 
 
 III, 
 
 10 . 
 
 9.92 
 
 .0937 
 
 (c) I. II. 
 
 No. CCS KMno 4 10. 10. 
 
 " " NagSgOs 9.4 9.4 
 
 N. F. NagSgOs .0989 .0989 
 
 Average Normality Factor .0989 
 3, Bromine solution — prepared by diluting 5 1-3 cc 
 
 or approximately 16 grams of bromine with enough carbon 
 tetrachloride to make 1 liter of solution. 
 
 4. Potassium Iodide — 150 gras, to the liter. 
 
 5. Starch solution prepared by boiling 0.5 grams of 
 soluble starch with 100 ccs. water. 
 
 

b -11- 
 
 The following additional solution was used for the 
 determination of the iodine values: 
 
 6. Hanus solution — 13.3 grms . iodine were dissolved 
 in 1000 cc. of glacial acetic acid and enough bromine — 
 about 3 cc — added to double the halogen content. 
 
 In order to establish a standard for the determined 
 bromine absorption values — and hence iodine values calculated 
 from them — the iodine values of the six oils were first determined, 
 according to the Hanus method. 
 
 (see following page) 
 
Menhaden .3146 25 28.1 75.4 .0938 178.95 
 
 Average 178.79 
 
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-13- 
 
 The bromine absorption va,lues of the oils were obtained 
 
 as follows: 
 
 From .3 to ,3 grams of oil were weighed into a flask 
 with a well fitting glass stopper, 10 cos carbon tetrachloride 
 were then added in order to dissolve the oil and then 35 ccs of 
 the bromine solution, and the flask packed in ice and salt for 
 varying lengths of time as shovm belov/. 
 
 A blank v/as run for every group of samples, being treated 
 exactly the same as the samples. At the end of the specified tim.e, 
 the flasks were removed from the container, 15 ccs of a fifteen 
 per cent solution of potassium iodide and 100 ccs of water were 
 added and the m.ixture titrated at once v/ith sodium thiosulphate, 
 starch being used as an indicator. 
 
 With the exception of the Menhaden oil, very little 
 trouble was encountered in securing good results. The am.ateur 
 is apt to shake the mixture too vigorously — and perhaps he may 
 wait just too long before adding the indicator — but after a certain 
 technique is secured the titration becomes quite accurate and the 
 endpoint is easily discerned. 
 
 After the liberated iodine had been titrsvted with tenth 
 normal sodium hydroxide, using phenol thalein as the indicator. 
 Practically no variation occurred in the amount of alkali used so 
 it was shown that very little substitution was taking place and 
 hence it was deemed unnecessary for the most accurate to calculate 
 this . 
 
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 - 14 - 
 
 In order to study the length of time necessary for the 
 most accurate determination of the bromine absorption value, as 
 compared with the iodine value, determinations were made in the 
 following series one hour, two hours, four hours, eight hours, 
 and sixteen hours. The temperature was that of an ice and salt 
 mixture and varied from -10^ C to -16*^ C-being kept constant in 
 each case by mieans of a heavily insulated box in which the samples 
 were surrounded by the freezing mixture. 
 
 The results obtained were calculated to the percentage 
 of bromine absorbed, or the number of grams of bromine v/hich 
 lOG grams of fat v\Tould absorb; then from this the Iodine number 
 was calculated and compared with the theoretical value for the 
 Iodine number. 
 
 The following explains the determination and calculations 
 
 involved . 
 
 Cod Oil. 
 
 First V/t . 
 
 Second Wt . 
 
 Sample Wt . 
 
 Ccs Bromine solution 
 Ccs llagSsOs 
 Ccs Na 2 Sg 02 blank 
 N. F. NagSgO^ 
 
 T ime 
 Br . No. 
 
 47.4377 
 47 .2077 
 .2300 
 25 . 
 
 35 . 
 
 61.3 
 .0948 
 8 hours 
 86.52 
 
 Calc. r. No. I Br. 
 
 137.35 
 
-15- 
 
 ' Now 61.3 - 35 = 26.3 vvhich represents the number Cos of 
 
 .0948 N. bromine absorbed by .S3 grams of cod oil. 
 
 One cc of normal bromine contains .07992 grams of Brs 
 
 therefore the following gives the bromine value 
 
 36.5 X .0948 X .07992 s 86.53 the bromine absorption 
 .23 
 
 value of cod oil standing in contact with bromine for 8 hours 
 at the tem.perature of ice and salt . 
 
 Since the previously determined iodine value is the 
 measure of the fo maximum possible absorption, the iodine value 
 is calculated in terms of the bromine value. 
 
 Results : 
 
 The following present the results by varying the time 
 and the appended curves represent the same in, graphical form. 
 

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- 35- 
 
 The preoeding ta’-les and curves for the various fish oils 
 indicate that the bromine a";' sorption values of these oils increase 
 with the length of time in which they are allowed to remain in 
 contact with the bromine. 
 
 In general the rise seems to take place rather uniforii.ly, 
 a few ■‘^rea fis being noted — but since the ’whole increase is over 
 such a small range — this might be due to slight differences in 
 temperature, or a little loss in bromine because of its volatility. 
 
 The oils with the lower iodine values seem to give the 
 most consistent results, menhaden, as has been said before, giving 
 the most trouble along this line, pro’^ably due to its greater 
 degree of unsaturation. The increase in this case is also more 
 marked with time. 
 
 CONCLUSIONS . 
 
 1 . The Bromine absorption values of fish oils as 
 determined vary with the time of contact with bromine. 
 
 2. The increase with time is related to the unsaturation 
 of the fat, the less saturated sho'ving a more marked rise than the 
 more saturated ones . 
 
 3. The conditions which come nearest the time of true 
 absorption values as calculated from the iodine numbers are as 
 represented with each oil — 16 hours at -10^ C . 
 
-r^ 
 
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