Carbon-Chain Length	Number of Double Bonds	Percentage (%)
14	0	<1.0
16	0	3–5
18	0	38–42
20	0	8–10
22	0	42–50
24	0	1.0–2.0
18	1	1.0
18	2	<1.0
20	1	<1.0
22*	1	1.0
*  Erucic acid.

Periodic acid solution and Chloroform— Prepare as directed in the test for Content of 1-monoglycerides.

Test solution— Use the combined aqueous extracts obtained as directed in the test for Content of 1-monoglycerides.

Procedure— Transfer 50.0 mL of Periodic acid solution to each of two flasks: a 500-mL glass-stoppered Erlenmeyer flask containing the Test solution and a 500-mL glass-stoppered Erlenmeyer blank flask containing 75 mL of water. Continue as directed for Procedure in the test for Content of 1-monoglycerides, beginning with “Swirl the flasks during the addition of Periodic acid solution, and allow to stand for at least 30 minutes, but no longer than 90 minutes”. Calculate the percentage of free glycerin in the Superglycerinated Fully Hydrogenated Rapeseed Oil taken by the formula: in which 2.3 is the molecular weight of glycerin divided by 40; VB is the volume, in mL, of sodium thiosulfate VS consumed in the blank determination; VS is the volume, in mL, of sodium thiosulfate VS required in the titration of the Superglycerinated Fully Hydrogenated Rapeseed Oil; N is the normality of the sodium thiosulfate VS; and W is the weight, in g, of the Superglycerinated Fully Hydrogenated Rapeseed Oil taken to prepare the Test solution as directed in the test for Content of 1-monoglycerides: not more than 1% is found.

Test solution— Weigh 5.0 g of Superglycerinated Fully Hydrogenated Rapeseed Oil into a previously tared platinum or silica crucible. Cautiously heat the substance, and introduce into it a wick formed from twisted ashless filter paper. Ignite the wick. When the substance ignites, stop heating. After combustion, ignite in a muffle furnace at about 600. Continue the incineration until white ash is obtained. After cooling, transfer the residue, with the aid of two 2-mL portions of diluted hydrochloric acid, to a 25-mL volumetric flask, add 0.3 mL of nitric acid, and dilute with water to volume.

Nickel standard solution— Immediately before use, dilute 10 mL of nickel standard solution TS with water to 500 mL. This solution contains the equivalent of 0.2 µg of nickel per mL.

Standard solutions— Into three identical 10-mL volumetric flasks, introduce respectively 1.0, 2.0, and 4.0 mL of Nickel standard solution. To each flask, add a 2.0-mL portion of the Test solution, and dilute with water to volume.

Procedure— Concomitantly determine the absorbances of the Standard solutions and the Test solution at least three times each, at the wavelength of maximum absorbance at 232.0 nm, with a suitable atomic absorption spectrophotometer (see Spectrophotometry and Light-Scattering 851) equipped with a graphite furnace and a nickel hollow-cathode lamp. Record the average of the steady readings for each of the Standard solutions and the Test solution. Plot the absorbances of the Test solution and the Standard solutions versus the added quantity of nickel. [note—The Test solution should be plotted as if it had a content of added nickel equivalent to 0 µg.] Extrapolate the line joining the points on the graph until it meets the concentration axis. The distance between this point and the intersection of the axes represents the concentration of nickel, C, in µg per mL, in the Test solution. Calculate the content of nickel in the portion of Superglycerinated Fully Hydrogenated Rapeseed Oil taken by the formula: in which W is the weight, in g, of Superglycerinated Fully Hydrogenated Rapeseed Oil taken to prepare the Test solution: not more than 1 µg per g is found.

Periodic acid solution— Dissolve 5.4 g of periodic acid in 100 mL of water, add 1900 mL of glacial acetic acid, and mix. Preserve in a light-resistant, glass-stoppered bottle.

Chloroform— Use chloroform that meets the following test. Add 50.0 mL of Periodic acid solution to each of three 500-mL flasks. Add 50 mL of chloroform and 10 mL of water to two of the flasks, and add 50 mL of water to the third flask. Add 20 mL of potassium iodide TS to each flask, mix gently, and continue as directed in the Procedure, beginning with “and allow to stand at least 1 minute, but no longer than 5 minutes, before titrating”. The difference between the volume of 0.1 N sodium thiosulfate VS required in the titrations with and without the chloroform is not greater than 0.5 mL.

Test solution— Melt Superglycerinated Fully Hydrogenated Rapeseed Oil at a temperature not higher than 10 above its melting point, and mix thoroughly. Transfer an accurately weighed quantity of it, equivalent to about 150 mg of 1-monoglycerides, to a 100-mL beaker, dissolve in 25 mL of Chloroform, and mix.

Procedure— Transfer the Test solution, with the aid of an additional 25 mL of Chloroform, to a separator. Wash the beaker with 25 mL of water, and add the washing to the separator. Close the separator tightly with a stopper, shake vigorously for 30 to 60 seconds, and allow the layers to separate. [note—Add 1 to 2 mL of glacial acetic acid to break emulsions due to the presence of soap.] Collect the aqueous layer in a 500-mL glass-stoppered Erlenmeyer flask, and again extract the chloroform solution in the separator with two 25-mL portions of water. Retain the combined aqueous extracts, which will be used in the test for Limit of free glycerin. Transfer the chloroform layer to a 500-mL glass-stoppered Erlenmeyer flask, and add 50.0 mL of Periodic acid solution to this flask and to each of two blank flasks containing a mixture of 50 mL of Chloroform and 10 mL of water. Swirl the flasks during the addition of Periodic acid solution, and allow to stand for at least 30 minutes, but no longer than 90 minutes. To each flask, add 20 mL of potassium iodide TS, and allow to stand at least 1 minute, but no longer than 5 minutes, before titrating. Add 100 mL of water, and titrate with 0.1 N sodium thiosulfate VS, using a magnetic stirrer to keep the solution thoroughly mixed, to the disappearance of the brown iodine color. Add 2 mL of starch TS, and continue the titration to the disappearance of the blue color. Calculate the percentage of 1-monoglycerides in the Superglycerinated Fully Hydrogenated Rapeseed Oil taken by the formula: in which 17.9 is the molecular weight of glyceryl monostearate divided by 20; VB is the volume, in mL, of sodium thiosulfate VS consumed in the blank determination; VS is the volume, in mL, of sodium thiosulfate VS required in the titration of the Superglycerinated Fully Hydrogenated Rapeseed Oil; N is the normality of the sodium thiosulfate VS; and W is the weight, in g, of the Superglycerinated Fully Hydrogenated Rapeseed Oil taken to prepare the Test solution: not less than 90.0% and not more than 110.0% of that indicated on the label is found.