EXPERIMENT 2ANALYSIS OF FOOD COLOUR

1.0 Objective The objective of this experiments was to determine max of Carmoisine ( wavelength scan ) To prepare a serial dilution and generate a standard calibration graph for sample quantitation ( photometric scan )2.0 Summary

3.0 IntroductionThe purpose of this experiment was to analyze the food colouring by using an ultraviolet/visible spectrometer. UV spectrometer is a device used to study the interaction between radiation and matter in regards to the wavelength of photons. Specifically, it measure visible light and the close-to-visible range of ultraviolet and infrared spectrum ranges. The UV spectrometer allows a user to identify electronic transitions within the various regions of the electromagnetic spectrum. Food colouring are mainly used in the food processing industry today as colour gives the food product certain flavours as people associate colours with certain flavours.A spectrophotometer can be either single beam or double beam. In this experiment a double beam spectrometer was used .In a double-beam instrument, the light is split into two beams before it reaches the sample.

The Beer-Lambert law states that the absorbance of a solution is directly proportional to the concentration of the absorbing species in the solution and the path length. Thus, for a fixed path length, UV/Vis spectroscopy can be used to determine the concentration of the absorber in a solution. Absorption spectroscopy in the UVVIS region is based on the Lambert-Beers law, expressed by the following equations :A=bcWhere;A = absorbance (no unit) = molar absorptivity coefficient (M-1 cm-1)b = pathlength (cm)c = concentration (M or mol/L)

4.0 Materials and Methodology4.1 Materials:Chemicalsa) 100 ppm colorant stock (100ml)b) Unknown ( two )c) Distilled waterApparatusa) Perkin Elmer UV/Vis Spectrometer Lambda EZ210b) Sample Cuvettesc) Path length 1 cmd) Volumetric flask 50 ml (five)e) Pipette 5 m, 10 ml, 25 ml f) Rubber bulb (three)g) Beaker 100 ml h) Graduated cylinder 50 mli) Dropper j) Labelling stickerk) Tissue paper

5.2 Discussion:

The objective of the experiment was to determine max of Carmoisine ( wavelength scan ) and to prepare a serial dilution and generate a standard calibration gaph for sample quantitation (photometric scan ). In this experiment, the stock solution of 100ppm Colourant is diluted into 5 serial dilutions of 5ppm, 15ppm, 25ppm, 35 ppm, 45ppm. For sample solutions, we randomly mixed 2 serial dilutions into one and did the same way for the second sample solution. When analyzing by using UV-VIS Spectrophotometer, the blank solution used was distilled water. The cuvettes used in the instrument are the most important part to be taken care of. The cuvette has 2 different surfaces, where the rough ones can be touched by bare fingers and the other ones, which are the smooth ones shouldnt be touched by fingers. This is because the smooth sides of the cuvette are where the light will go through the sample from the source. If the smooth sides of cuvette were stick with fingerprints, the light might be diffused to another way. That was why wiping the smooth surfaces of the cuvette is very important. The instrument was run by the technician. There were two types of scanning done wavelength scanning and photometric scanning. To obtain the max for Carmoisine sample, the 45ppm dilution which is the highest concentration solution was scanned and the wavelength scan was done. For photometric scan, each dilution were scanned to produce the standard calibration graph. The data of results consist of the concentration values of the five standards with their respective absorbance with a standard calibration graph and the standard deviation. The concentration of the unknown samples also were automatically computed and printed on the data of results. Although the concentration of unknown solutions has been obtained by the instrument, manual calculations still been done for comparisons. After obtaining the data of results, the linear calibration graph were re-plotted manually to obtain the equation of linear regression using Microsoft Office Excel software. The equation obtained with standard deviation of ???? is :y =??x ??Since the value of absorbance, [A] of each of the unknown solutions are represented as y in the equation, the concentration of the unknown solutions can be calculated where:Unknown 1 : 10.778 ppmUnknown 2 : 19.740 ppmThe manually calculated values of results are slightly different than the results obtained automatically by the instrument due to the calibration that may have been done on the instrument. The maximum wavelength in the experiment was obtained ?????nm. There were no problems occurred while running the experiment.

9.0 AppendicesSample Calculations Preparation of Serial Dilutions 5 ppmM1 V1= M2 V2(100ppm) (V1) = (5ppm) (50mL)V1= 2.5 mL 15 ppmM1 V1= M2 V2(100ppm) (V1) = (15ppm) (50mL)V1= 7.5 m 25 ppmM1 V1= M2 V2(100ppm) (V1) = (25ppm) (50mL)V1= 12.5 m 35 ppmM1 V1= M2 V2(100ppm) (V1) = (35ppm) (50mL)V1= 17.5 m 45 ppmM1 V1= M2 V2(100ppm) (V1) = (45ppm) (50mL)V1= 22.5 m

8.0 References Food Analysis, Third Edition, Kluwer Acedemic/Plenum Publishers, , S.Suzanne Nielsen, 2003, New York, 2003 Lecture Notes Ultraviolet-Visible Spectroscopy . Available from https://en.wikipedia.org/wiki/Ultraviolet%E2%80%93visible_spectroscopy

6.0 Conclusion:Based on the experiment done, the experiment was successfully done and the objectives of the experiment are achieved to determine max of Carmoisine ( wavelength scan ) and to prepare a serial dilution and generate a standard calibration graph for sample quantitation (photometric scan ). The concentrations of two unknown solutions had been calculated to be ???ppm and ????ppm respectively. The maximum wavelength, max for Carmoisine sample is ???nm.

4.2 Methodology 1. Serial dilutions (5ppm, 15ppm, 25ppm, 35 ppm, 45ppm) from the 100ppm carmoisine stock were prepared.2. The volume needed, V1 from the 100ppm carmoisine stock was calculated for all dilutions3. In order to prepare a dilution, an exact volume of V1 was drew from the carmoisine stock and was poured into a 50ml volumetric flask. Distilled water then was added up to the mark level of the volumetric flask. The volumetric flask then was shook properly.4. The procedure previous was repeated for all dilutions. The formula used is:M1 V1 = M2 V2 to find the V1Where M1 = concentration of carmoisine stockV1 = volume of carmoisine stock to be drawnM2 = concentration of carmoisine (diluted)V2 = volume of carmoisine (diluted)5. After preparing the serial dilutions, the technician briefed on the standard operating procedure of Perkin Elmer UV-VIS Spectrophotometer Lambda EZ210.6. A cuvette was filled with 45pm dilution and another cuvette was filled with blank solution, then the cuvettes were inserted in the sample compartment. The clean sides of the cuvettes were wiped clean and not touched. The wavelength scan was done and the max was obtained. The data was recorded.7. For the photometric scan, the cuvette was filled as step 6 but the serial dilution prepared was used and scanned one by one. The absorbance readings were recorded ant the standard calibration graph produced was analyzed.8. The concentrations of two unknown solutions were determined.

5.0 Result and discussion 5.1 Results

7.0 Tutuorial7.1 Pre Laboratory Questions