Photometric Titration Method to Determine Bromination of Red and Yellow Dyes in CrackersPhotometric Titration Method to Determine Bromination of Red and Yellow Dyes in Crackers

Jutti Levita, Sandra Megantara & Mutakin
Pharmacochemistry Division, Faculty of Pharmacy, Universitas Padjadjaran
Correspondence:Jutti Levita, Jl. Raya Bandung-Sumedang Km 21, Jatinangor, West Java 45363, Indonesia.
E-mail: jutti.levita@unpad.ac.id
Received: March 21, 2012 Accepted: April 9, 2012 Online Published: May 27, 2012

Abstract
In this work, we determined red and yellow dyes in unregistered crackers sold at Jatinangor, West Java,
Indonesia, by using photometric titration method based on the bromination reaction of the dyes. The dyes were
extracted using a mixture of 2 % of ammonia in 70 % ethanol continued by preparative thin layer
chromatography on GF254 silica gel plate, then they were separated and analyzed by using FTIR-8400
Shimadzu infrared spectrophotometer. Bromination reaction was measured by using photometric titration
method. Thin layer chromatograms showed that the dyes were not either rhodamine B or tartrazine (Rf of the
red and yellow dyes were 0.714 and 0.652, respectively, while those of rhodamine B and tartrazine were 0.591
and 0.673). Infrared spectroscopy showed characteristic peaks of the red dye at 3390.6 cm-1 (O-H stretch),
2927.7 cm-1 (C-H stretch of alkyl), 1404.1 cm-1 (O-H bend), 1616.2 cm-1 (C=C stretch), and 1315 cm-1 (C-O
stretch). The peaks of yellow dye occured at 3413.8 cm-1, (O-H stretch), 3213.2 cm-1 (C-H stretch of alkene),
2927.7 cm-1 (C-H stretch of alkyl), 1400.2 cm-1 (O-H bend), 1624.0 cm-1 (C=C stretch). Visible spectroscopy
showed maximum wavelengths at 551 nm (red dye) and 432 nm (yellow dye). Photometric titration based on
bromination reaction of the dyes showed a decreasing in absorbance due to the conversion of colored analytes to
colorless products. This fact indicated that bromination reaction was occured in the red and yellow dyes
molecules via electrophilic addition reaction on its double bond, therefore this method is applicable to be used in
routine analysis to control illegal food dyes often found in Indonesian home industry crackers.

Keywords: bromination reaction, crackers, illegal food dyes, photometric titration

Available at International Journal of Chemistry: http://www.ccsenet.org/journal/index.php/ijc/article/view/15780Jutti Levita, Sandra Megantara & Mutakin
Pharmacochemistry Division, Faculty of Pharmacy, Universitas Padjadjaran
Correspondence:Jutti Levita, Jl. Raya Bandung-Sumedang Km 21, Jatinangor, West Java 45363, Indonesia.
E-mail: jutti.levita@unpad.ac.id
Received: March 21, 2012 Accepted: April 9, 2012 Online Published: May 27, 2012

Abstract
In this work, we determined red and yellow dyes in unregistered crackers sold at Jatinangor, West Java,
Indonesia, by using photometric titration method based on the bromination reaction of the dyes. The dyes were
extracted using a mixture of 2 % of ammonia in 70 % ethanol continued by preparative thin layer
chromatography on GF254 silica gel plate, then they were separated and analyzed by using FTIR-8400
Shimadzu infrared spectrophotometer. Bromination reaction was measured by using photometric titration
method. Thin layer chromatograms showed that the dyes were not either rhodamine B or tartrazine (Rf of the
red and yellow dyes were 0.714 and 0.652, respectively, while those of rhodamine B and tartrazine were 0.591
and 0.673). Infrared spectroscopy showed characteristic peaks of the red dye at 3390.6 cm-1 (O-H stretch),
2927.7 cm-1 (C-H stretch of alkyl), 1404.1 cm-1 (O-H bend), 1616.2 cm-1 (C=C stretch), and 1315 cm-1 (C-O
stretch). The peaks of yellow dye occured at 3413.8 cm-1, (O-H stretch), 3213.2 cm-1 (C-H stretch of alkene),
2927.7 cm-1 (C-H stretch of alkyl), 1400.2 cm-1 (O-H bend), 1624.0 cm-1 (C=C stretch). Visible spectroscopy
showed maximum wavelengths at 551 nm (red dye) and 432 nm (yellow dye). Photometric titration based on
bromination reaction of the dyes showed a decreasing in absorbance due to the conversion of colored analytes to
colorless products. This fact indicated that bromination reaction was occured in the red and yellow dyes
molecules via electrophilic addition reaction on its double bond, therefore this method is applicable to be used in
routine analysis to control illegal food dyes often found in Indonesian home industry crackers.

Keywords: bromination reaction, crackers, illegal food dyes, photometric titration

Available at International Journal of Chemistry: http://www.ccsenet.org/journal/index.php/ijc/article/view/15780

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