The Quality and Quantity Measurements of the Different Molecules - Lab Report Example

Qualitative and quantitative analysis Introduction Quality measures refer to the degree of distinction and satisfaction as the obtained results always prove more accurate than precise. On the other hand, quantity measurement deals with the magnitude compared either as equal, more or less. In terms of biological aspect, as illustrated by Lundblad (72), specific variables like reagents and phenotypic facets like color and height are used to measure quality whereas variables like temperature, volume, concentration among others measures quantity. This biology report explains both the quality and quantity measurements of the different molecules in response to the reaction with specific reagents. In terms of quality standards, specific reagents were reacted with different solutions so as to obtain color change to determine variables like proteins. Starch that can either act as a filler depending on the concentration level from the spectrophotometer was also determined so as to get the absorbance of unknown solutions. When the absorbance is more than 50%, then absorbance is high and implies starch as a filler in a solution and when less than 50%, it explains starch as a flavor in a solution. The predicted results were then compared to actual results to determine the level of accuracy. In the quality measurements, the central hypothesis which was to be identified was the exact molecules the samples used contained; whether starch, protein, sugar or both in response to color change. This is because a solution containing protein produces purple color when reacted with Biuret reagent. In quantity measurements, the aim was to determine the role of starch whether as an acting filler or as a flavor in the above samples with reference to absorbance level. Methodology Seven different types of solution in quality measurement which were starch, protein, sugar, water, and three unknowns labelled 2, 6 and 8 were used alongside three testing reagents; Biuret reagent, Benedict reagent and Lugol’s reagent. The reagents thus showed the independent variables because their manipulation in the solutions lead to the reactions. Each solution in the volume of 2ml was tested with each reagent in the volume of 400microlitre using micropipette and the color change observed. This color change was the measured dependent variable. Constant variables were the amount of reactants in every reaction. In quantity aspect, the starch solutions were tested to measure their absorbance values using spectrophotometer. Different starch concentration and water volume were the independent variables since they were the reactants whereas absorbance of starch was the measured aspect thus showed the dependent variable. Lugol’s reagent volume was the control variable. A table was then filled using the formula of C1V1 = C2V2 to determine whether the solutions were fillers or flavors. Results For quality measurement, the color changes were observed and noted. The solutions were reacted with all the three reagents one at a time and the end result which was color change noted. Sample of water solution under the three reagents did not show any color change. A sample of protein solution in both Lugol’s and Benedict reagent did not show any color change but turned purple when reacted with Biuret reagent. Starch did not show any color change both in Biuret and Benedict reagents but turned brown in Lugol’s reagent. Sugar solution did not show any color change in both Biuret and Lugol’s reagents but turned orange in Benedict reagent. Unknown solutions of 2 and 6 did not show any color change in both Benedict and Lugol’s reagents but turned purple in Biuret reagent. Lastly, solution of unknown sample 8 turned orange in presence of benedict reagent but no color change in Biuret reagent. The color change was summarized in the table below. Sample of Solution Biuret reagent Lugol’s reagent Benedict’s reagent Water No color Change No color Change No color Change Protein Purple No color Change No color Change Starch No color Change Brown No color Change Sugar No color Change No color Change Orange Unknown 2 Purple No color Change No color Change Unknown 6 Purple No color Change No color Change Unknown 8 No color Change No color Change Orange The results obtained from quantity measurement were tabled below after which a graph was obtained from the values and showed absorbance values from the spectrophotometer in intervals of 0.2nm were found to be directly proportional to the concentration of starch in solution. However, from the concentration of 80ml of starch, the absorbance value was not correctly obtained thus the error in manipulation. Concentration Of starch in solution (standard solutions) Volume of stock Starch solution(ml) Volume of water (ml) Total volume of stock starch solution%+ volume of water (ml) Volume of Lugol’s reagent (ml) Absorbance @580 nm 100ml 2ml 0ml 2 0.4ml 1.0376 80ml 1.6ml 0.4ml 2 0.4ml 0.869 60ml 1.2ml 0.8ml 2 0.4ml 0.614 40ml 0.8ml 1.2ml 2 0.4ml 0.400 20ml 0.4ml 1.4ml 2 0.4ml 0.201 Omg/ml 0 2ml 2 0.4ml 0 (Unknown solutions) 57.524 2ml 0.4ml 0.604 39.905 2ml 0.4ml 0.419 4.381 2ml 0.4ml 0.046 From the graph, y = 0.0105x, therefore, the unknown solutions had volumes of: Unknown6= 0.0604/ 0.0105= 57.524 Unknown7= 0.419/0.0105=39.905 Unknown8= 0.046/ 0.0105= 4.381 Discussion and conclusion Various reagents show different color changes in the reactions above. Solutions of protein, unknown solution 2 and 6 showed the color change of purple with the reaction with Biuret reagent whereas sugar and unknown solution 8 showed the color change of orange. However, no color change was observed across many reactions. According to Lundblad (72), the Biuret reagent which is an aqueous solution of allophanamide treated with sodium hydroxide and cupric sulphate, which is blue color changes to purple in the presence of protein. The result, therefore, showed that the protein solution and unknown solution 6 turned purple with Biuret reagent thus unknown solution 6 contained protein. However, errors like inaccuracy and no clear color change was observed and this could be improved through making correct measurements. What will be the end results of the solutions which did not show color change? Therefore in future measurements, specific reagents which have effect on other variables apart from molecules should be used so as to identify other variables like chemical composition in samples. The spectrophotometer, at 580nm at constant room temperature and constant volume of Lugol’s reagent, measured different absorbance values both for the standard and unknown solutions. Errors were obtained from the difference values from the spectrophotometer since it was more of precision. Therefore in future measurements, accuracy should be maintained so as to meet all the hypothesis pertaining the measurements. Unknown solution 6 had a higher value more than 50% of the total value compared to solution 7 and 8 and therefore, it suggested that starch in unknown solution 6 was a filler while solutions 7and 8 were flavors due to lesser values of their absorbance. The predicted results were found to be comparing with actual results in especially in the quality measurements and therefore it can be concluded that quality approach yields more accurate values as compared to quantity approach. Work cited Lundblad, Roger L. Chemical reagents for protein modification. 3rd ed. Boca Raton, Fla.: CRC Press, 2005. Print. Read More