WHO/Food Add./24.65
FAO Nutrition Meetings
Report Series No. 38A
SPECIFICATIONS FOR IDENTITY AND
PURITY AND TOXICOLOGICAL EVALUATION
OF SOME ANTIMICROBIALS AND
ANTIOXIDANTS
The content of this document is the result of the deliberations of the
Joint FAO/WHO Expert Committee on Food Additives which met 8-17
December 1964a
a Eighth Report of the Joint FAO/WHO Expert Committee on Food
Additives, Wld Hlth Org. techn. Rep. Ser., 1965, 309; FAO
Nutrition Meetings Report Series 1965, 38.
DILAURYL THIODIPROPIONATE
CHEMICAL NAMES Dilauryl ester of ß,ß'-thiodipropionic acid;
dilauryl ester of 3,3'-thiodipropionic acid
EMPIRICAL FORMULA C30H58O4S
STRUCTURAL FORMULA
CH2 - CH2 - COO - (CH2)11 - CH3
'
S
'
CH2 - CH2 - COO - (CH2)11 - CH3
MOLECULAR WEIGHT 514.86
DEFINITION Dilauryl thiodipropionate is an ester of
thiodipropionic acid and a food grade lauryl
alcohol. It contains not less than 99% of
C30H58O4S and conforms to the following
specifications.
DESCRIPTION White crystalline flakes having a
characteristic sweetish ester-like odour.
USE As an antioxidant for fats and other
foodstuffs.
IDENTIFICATION
A. Solubility: Water: Insoluble
Organic solvent: Soluble in most organic solvents
B. Solidification point: Not below 40°
C. Saponification number: Not less than 210
PURITY TESTS
Acidity (as thiodipropionic acid): Not more than 0.2% of C6H10O4S.
To 50 ml of a mixture of 1 part of methanol and 3 parts benzene add
phenolphthalein TS and neutralize with ethanolic potassium hydroxide.
Add 2 g, accurately weighed, of dilauryl dithiopropionate, swirl to
dissolve, add 3 drops of phenolphthalein TS and titrate with 0.1 N
ethanolic potassium hydroxide. Each ml of 0.1 N ethanolic potassium
hydroxide is equivalent to 8.91 mg of C6H10O4S.
Heavy metals: Not more than 20 mg/kg.
Place 2 g, accurately weighed, in a porcelain crucible, add sufficient
nitric acid to wet the sample and ignite carefully at a low
temperature until thoroughly charred, covering the crucible loosely
with a porcelain lid during the ignition. When carbonization is
complete, add 2 ml of nitric acid and 5 drops of sulfuric acid, heat
cautiously until white fumes are evolved, and then ignite, preferably
in a muffle furnace at 550° ± 50° until the carbon is removed. Cool,
add 1 ml of diluted hydrochloric acid (1 in 2), cover, and digest on a
steam bath for 15 minutes. Remove the cover and evaporate on a steam
bath to dryness. Moisten the residue with 0.05 ml of hydrochloric
acid, add 10 ml of hot water, and digest on a steam bath for 5
minutes. Filter if necessary and dilute to 25 ml.
Arsenic: Not more than 3 mg/kg.
Lead: Not more than 10 mg/kg.
ASSAY
Weigh 0.700 g of dilauryl thiodipropionate and add 10 ml of acetic
acid and 50 ml of ethanol, and heat the mixture gently until the
sample dissolves completely. Add 3 ml of hydrochloric acid and 4
drops of p-ethoxychrysoidin TS and immediately titrate with 0.1 N
bromide-bromate TS. As the endpoint is approached (pink colour), add
4 more drops of the indicator solution and continue the titration,
dropwise, to a colour change from red to pale yellow. Perform a blank
determination and make any necessary correction. Each ml of 0.1 N
bromide-bromate TS is equivalent to 0.02574 g of C30H58O4S.
Subtract the per cent. of thiodipropionic acid determined in the
acidity tests from the per cent. of dilauryl thiodipropionate
calculated from this titration to obtain the per cent. of C30H58O4S.
Biological Data
Biochemical aspects
No information available.
Acute Toxicity
Animal Route LD50 Reference
(mg/kg
body-weight)
Thiodipropionic Mouse oral 2000 1
acid Mouse intraperitoneal 250 1
Mouse intravenous 175 1
Rat oral 3000 1
Rat intraperitoneal 500 1
Rat intravenous >300 1
Dilauryl Mouse oral >2000 1
thiodipropionate Mouse intraparitoneal >2000 1
Rat oral >2500 1
Distearyl Mouse oral >2000 1
thiodipropionate Mouse intraperitoneal >2000 1
Rat oral >2500 1
Short-term studies
Rat. Mixtures of thiodipropionic acid and dilauryl thiodipropionate
were heated with lard in concentrations at least 10 times that
recommended for use and fed to rats. There was no detectable toxic
effect.1
Guinea-pig. Thiodipropionic acid was fed to guinea-pigs at a level
of 0.5% in the drinking-water for a period of 120 days. No
significant effect was noted on weight or mortality.1
Dog. Dogs were fed a mixture of 10 parts by weight of dilauryl
thiodipropionate and 1 part of thiodipropionic acid in the diet at
concentrations of 0.1% and 3.0% of the acid-ester mixture. No
untoward effects were noted over a period of 100 days.
Long-term studies
Rat. Thiodipropionic acid or its dilauryl or distearyl ester was
fed to groups of 20 rats each at levels of 0%, 0.5%, 1.0% and 3.0% in
the diet for a period of 2 years. No discernable adverse effects were
observed in any of the experimental animals, as determined by growth
rate, mortality, and pathological examination.1
Comment on experimental studies reported
It would be desirable to have further details on the experimental work
that has been carried out on thiodipropionic acid; the published
report gives only a summary. Biochemical studies and observations on
human subjects are not available.
Evaluation
Level causing no significant toxicological effect in the rat
3.0% (= 30 000 ppm) in the diet, equivalent to 1500 mg/kg body-weight
per day.
Estimate of acceptable daily intakes for man
mg/kg body-weight
Unconditional acceptance 0-3.0
Conditional acceptance 3.0-15.0
Further Work Considered Desirable
1. Long-term studies in a species other than the rat.
2. Biochemical studies in animals and in man.
Reference
1. Lehman, A. J., Fitzhugh, O. G., Nelson, A. A. & Woodard, G. (1951)
Advanc. Food Res., 3, 197