Alat yang digunakan :
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0309.100 double Pt sheet electrode; input Pol
polarized Ipol = 1 mA
Voltametric indication
Reagents
c(DPIP) = 0.001 mol/L; D0
2,6-Dichlorophenol indophenol
Sample
5 mL sample solution
Dissolve 1 effervescent vitamin C tablet in 1 L dist. water
15 mL oxalic acid solution 1 g/L
1 mL w(sodium acetate) = 0.10 (10%)
10 mL dist. Water
Remarks
• Calculations:
Vit.C=EP1*C01*C02*C03;0;mg/pc
Vit.C=EP1*C01*C02/C00;4;g/l
Vit.C = content of Vitamin C in mg/pc (tablet)
Vit.C = content of Vitamin C in g/L
C01 = mg Vitamin C / 1 mL titrating agent (0.088)
C02 = factor of titrating agent (1.00)
C03 = dilution factor (200)
. Answer
Vit.C = 15.291 x 0.088 x 1.00 x 200 = 269 mg/pc
Vit.C = 15.291 x 0.088 x 1.00 / 5.00 = 0.2691 g/L
EP1 = 15.291 mL
C00 = 5.00 mL
• Titrating agent:
Dissolve 295 mg 2,6-Dichlorophenol indophenol with vigorous agitation in 1 L dist. water, then filter and mix with 100 mg sodium bicarbonate. This solution can be stored in the refrigerator for about 1 month, the factor should be checked daily with standard ascorbic acid. (As a titrating agent, the more readily soluble sodium salt may be used instead.)
• Standard solution:
r (Vitamin C) = 500 mg/L
Dissolve 50 mg ascorbic acid in oxalic acid solution (1 g/L) and make up to 100 mL. This solution should be freshly prepared daily.
• Sample preparation:
Place dist. water, oxalic acid solution and sodium acetate buffer in the titration vessel and deaerate by passing a stream of nitrogen for 3...5 min. Then add a quantity of sample or standard solution containing about 0.05...0.5 mg vitamin C. Now titrate under nitrogen with titrating agent.
• Store electrode in acidified Na2S2O3 solution.
• Select the appropriate formula. The other may be deleted.
• The 6.0431.100 Pt Titrode may be used together with mode MET U.
Literature
• Metrohm Application Bulletin No. 98: Determination of ascorbic acid
(Vitamin C) and its compounds.
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0309.100 double Pt sheet electrode; input Pol
polarized Ipol = 1 mA
Voltametric indication
Reagents
c(DPIP) = 0.001 mol/L; D0
2,6-Dichlorophenol indophenol
Sample
5 mL sample solution
Dissolve 1 effervescent vitamin C tablet in 1 L dist. water
15 mL oxalic acid solution 1 g/L
1 mL w(sodium acetate) = 0.10 (10%)
10 mL dist. Water
Remarks
• Calculations:
Vit.C=EP1*C01*C02*C03;0;mg/pc
Vit.C=EP1*C01*C02/C00;4;g/l
Vit.C = content of Vitamin C in mg/pc (tablet)
Vit.C = content of Vitamin C in g/L
C01 = mg Vitamin C / 1 mL titrating agent (0.088)
C02 = factor of titrating agent (1.00)
C03 = dilution factor (200)
. Answer
Vit.C = 15.291 x 0.088 x 1.00 x 200 = 269 mg/pc
Vit.C = 15.291 x 0.088 x 1.00 / 5.00 = 0.2691 g/L
EP1 = 15.291 mL
C00 = 5.00 mL
• Titrating agent:
Dissolve 295 mg 2,6-Dichlorophenol indophenol with vigorous agitation in 1 L dist. water, then filter and mix with 100 mg sodium bicarbonate. This solution can be stored in the refrigerator for about 1 month, the factor should be checked daily with standard ascorbic acid. (As a titrating agent, the more readily soluble sodium salt may be used instead.)
• Standard solution:
r (Vitamin C) = 500 mg/L
Dissolve 50 mg ascorbic acid in oxalic acid solution (1 g/L) and make up to 100 mL. This solution should be freshly prepared daily.
• Sample preparation:
Place dist. water, oxalic acid solution and sodium acetate buffer in the titration vessel and deaerate by passing a stream of nitrogen for 3...5 min. Then add a quantity of sample or standard solution containing about 0.05...0.5 mg vitamin C. Now titrate under nitrogen with titrating agent.
• Store electrode in acidified Na2S2O3 solution.
• Select the appropriate formula. The other may be deleted.
• The 6.0431.100 Pt Titrode may be used together with mode MET U.
Literature
• Metrohm Application Bulletin No. 98: Determination of ascorbic acid
(Vitamin C) and its compounds.
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