9. EXPERIMENTAL RESULTS/CALCULATIONS/QUESTIONS 9.1 Experimental Context You are back in working in an analytical lab. Th
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9. EXPERIMENTAL RESULTS/CALCULATIONS/QUESTIONS 9.1 Experimental Context You are back in working in an analytical lab. This week, you have been given a sample of a new energy drink ACTIVATION Energy - Berry-Flavoured Energy Drink with Guarana. The drink uses colourants E124 (red) and methyl violet. Your job is to check that the E124 concentration is within safe limits. To get accurate results, you will first need to separate the E124 from the methyl violet using SPE. 9.2 Determining the Concentration of E124 TABLE 1 Conc. /mg mL-1 Absorbance at 510 nm Conc. /mg mL-1 Absorbance at 510 nm 0 0 0.006 0.213 0.002 0.074 0.008 0.290 0.004 0.143 0.238 Unknown (your sample) Plot absorbance vs concentration for the samples of known concentration on the graph paper provided, and draw the line of best fit through the four points and the origin (At 0 mg mL-1 concentration of absorbing sample the absorbance is 0.) Determine the concentration of your sample from the graph, showing workings. E124 concentration in 25 mL sample = All of the E124 in your 1 mL sample is now in the 25 mL volumetric flask. This means your sample was diluted to 25 mL before you took the absorbance measurement. Calculate the concentration of E124 in the original solution. E124 concentration in the original sample = Calculate the slope of your calibration plot – showing workings on the graph. Use this to determine e for E124 (including units), given that b= 1 cm. E =
E124 concentration in the original sample = Calculate the slope of your calibration plot – showing workings on the graph. Use this to determine ε for E124 (including units), given that b = 1 cm. E = What is the mass of E124 (in mg) in a standard 300 ml bottle of ACTIVATION Energy? Is this within safe limits for a 80 Kg adult? Show workings. 0.062 Explain why E124 comes off the column first and methyl violet second. Your explanation should consider the structures of the SPE column and the solvents used for the separation.