Analisis (penentuan) angka Iod ( Iodine Number ) dengan alat potensiometer (Titrino/Titroprocessor)

Alat yang digunakan :
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0431.100 Pt Titrode; input 1

Reagents
c(Na2S2O3) = 0.1 mol/L; D0

Sample
app. 0.5 g sunflower oil
15 mL CCl4
25 mL c(ICl) = 0.1 mol/L (according to Wijs in glacial acetic acid / CCl4,
e.g. Merck No. 9163)
10 mL w(Hg acetate) = 0.025 (2.5%) in glacial acetic acid
15 mL w(KI) = 0.10 (10%)
30-50 mL dist. water

Remarks
• Calculations:

Iod.No=(C01-EP1)*C02/C00;2;g/100g

Iod.No = iodine number in g iodine / 100 g sample
C01 = consumption of blank sample (0 mL)
C02 = molecular mass of I * concentration titrating agent * 100g
sample / factor mL -> L (126.9 * 0.1 *100/1000 = 1.269)

. Answer

Iod.No = (0 – 6.149) x 1.269 / 0.5204 = 104.61 g/100g

EP1 = 6.149 mL
C00 = 0.5204 g

• Sample preparation:
According to the expected iodine number, weigh out 0.10 ... 1.00 g of the sample in an Erlenmeyer flask and add 15 mL CCl4. Add 25 mLiodine monochloride solution and add 10 mL mercuric acetate solution, mix and allow to stand for 5 min. in a dark place. Then add 15 mL KI solution, rinse into a beaker with dist. water and back-titrate the excess iodine with sodium thiosulphate. A blank control sample should be prepared and treated in the same way. Enter the blank value as C01.
• You may add a solution of w(Mg-acetate) = 0.03 (3%) instead of the Hg-acetate solution.
• The sample must be stirred well during the titration, in order to obtain a good emulsion.

Literature
• Metrohm Application Bulletin No. 141: Analysis of edible oils and fats.