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ou obtained the following raw data when setting up a Biuret standard curve: BSA (mg/ml) Absorbancy 540nm

Principles of Instrumental Analysis

7th Edition

ISBN:9781305577213

Author:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Publisher:Douglas A. Skoog, F. James Holler, Stanley R. Crouch

Chapter9: Atomic Absorption And Atomic Fluorescence Spectrometry

Section: Chapter Questions

Problem 9.22QAP: The chromium in an aqueous sample was determined by pipetting 10.0 ml. of the unknown into each of...

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The chromium in an aqueous sample was determined by pipetting 10.0 ml. of the unknown into each of five 50.0-mL volumetric flasks. Various volumes of a standard containing 12.2 ppm Cr were added to the flasks, following which the solutions were diluted to volume. Unknown,mLStandard, mLAbsorbancc 10.00.00.201 10.010.0 0.292 10.020.0 0.378 10.030.0 0.467 10.040.0 0.554 (a) Plot the data using a spreadsheet. (b) Determine an equation for the relationship between absorbance and volume of standard. (c) Calculate the statistics for the least-squares relationship in (b). (d) I)ctcrmine the conccnt ration oÍCr in ppm in the sample. (e) Find the standard deviation of the result in (d).
You obtained the following raw data when setting up a Biuret standard curve: Absorbancy 540nm BSA (mg/ml) 0.158 1 0.210 2 0.260 3 0.305 4 0.360 0.410 0.455 7 0.510 8 0.530 9 0.550 10 0.554 After blanking against a biuret-dH20 sample, the protein concentration of an unknown sample was determined using the same method and an absorbancy of 0.279 was obtained. Set up a standard curve, excluding outliers (experimental and statistical) and determine the protein concentration in the unknown sample in mg / ml (up to 3 significant figures).
You obtained the following raw data when setting up a Bradford standard curve: BSA (mg/ml) Absorbancy 595nm 0 0.225 1 0.310 2 0.420 3 0.510 4 0.610 5 0.720 6 0.810 7 0.915 8 0.950 9 0.980 10 0.990 After blanking against a bradford-dH2O sample, the protein concentration of an unknown sample was determined using the same method and an absorbancy of 0.523 was obtained. Set up a standard curve, excluding outliers (experimental and statistical) and determine the protein concentration in the unknown sample in mg / ml (up to 3 significant figures).
In a Bradford assay, 11 µl of a protein isolate sample was diluted by adding 21 µl of water prior to the addition 2.0 mL Bradford reagent. Calculate the protein concentration (in mg/mL) of the original protein isolate sample whose absorbance reading at 595 nm is 0.304 after dilution. The protein standard solutions used for the calibration curve of the Bradford assay was constructed using bovine serum albumin (BSA) stock solution whose concentration is 200 µg/mL. The concentration and the corresponding absorbance reading at 595 nm of the protein standard solutions are summarized in the table below: Standard soln # 1 2 13 4 6 conc of BSA 12.00 24.00 36.00 48.00 60.00 (pg/mL) Absorbance at 595 nm 0.000 0.156 0.249 0.328 0.411 0.528 zNote: Final answer format must be x.xxx (three decimal places). Round off only in the final answer. Do not round off in the middle of the calculation.
The absorbance of an unknown dye solution is measured to be 1.06 by a spectrometer. The calibration plot of the spectrometer is provided below. What is the molar concentration of the unknown sample (in mole L)? Absorbance vs. Molarity 18 y3 67024x-0.0343 16 14 12 1 0.8 0.6 0.4 0.2 01 0.2 0.000005 00001 0000015 Concentration of solutions, mol/L 0.00002 0.000025 000003 0 163e-5 O 2.35e-6 0 163 0 235 Absorbance
A direct ELISA experiment was done to determine the amount of protein present in a sample. A standard curve was prepared by plotting log Absorbance versus log concentration of protein in (ng/mL). The equation of the line is Y= 0.895 X -1.25. If an unknown protein shows an absorbance of 1.23. Calculate the concentration of this protein in the sample in (ng/mL).
10 Wavelength, 1. (nm) E (Red, µ.Mcm- ɛ(Yellow, µMr'cm¬1) Absorbance 500 0.0369 0.000549 0.405 430 0.00506 0.0167 0.474 An orange colored solution is prepared by mixing a red dye solution with a yellow dye solution and the absorbance was measured at the analytical wavelengths of 430 nm and 500 nm. The table provides the molar absorptivity for the red and yellow dye at each analytical wavelength. Calculate the concentration (in u.M) of the red and yellow dye in the mixture. [red] = [yellow] =
6. Blue Blue dye stock solution 0.293 M Absorbance at 630 nm 0.00265 Calibration curve y = 0.0833x A solution is prepared by diluting 2.79 mL of the blue dye stock solution to 25.00 mL. The measured absorbance for the prepared solution is listed in the data table. (a) What is the theoretical molar concentration? [Blue]theoretical x 10 |M (b) What is the experimental molar concentration? [Blue]experimental x 10 M (c) What is the percent error? Percent error (blue) = %
(Standard addition) Tooth enamel consists mainly of the mineral calcium hydroxyapatite, Ca10(PO4)6(OH)2. Trace elements in teeth of archeological specimen provide anthropologists with clues about diet and diseases of ancient people. Student at Dankook University measured the trace element strontium (Sr) in enamel from extracted wisdom teeth by atomic absorption spectroscopy. Solutions were prepared with a constant total volume of 10 mL containing 0.750 mg dissolved tooth enamel plus variable concentrations of added standard Sr. Added Standard Sr (ng/mL=ppb) 0 2.50 5.00 7.50 10.00 Emission Signal 28.0 34.3 42.8 51.5 58.6 (a) Make a graph showing the experimental data and the calculated straight line. (b) Find the concentration of Sr in the tooth ennamel in parts per million = μg/mL.
A student mixed 5.00 mL of 0.100 M Fe(NO3)3 with 50.00 mL of 2.00x10−4 M KSCN. The student measured the absorbance of one aliquot of the solution at a wavelength of 447 nm, with a pathlength of 1.00 cm. The absorbance reading was 0.615. Compute the following quantities a. [FeSCN2+]eq = b. (mols FeSCN2+)eq = c. (mols Fe3+)initial = d. (mols SCN−)initial = e. (mols Fe3+)eq = f. (mols SCN−)eq = g. [Fe3+]eq = h. [SCN−]eq = i. Keq=
A student weighed out 0.150 g of protein powder and dissolved it in 100 mL of water (Solution 1). The student then diluted this solution by transferring 1 mL into a 25 mL flask and diluting with water (Solution 2). Finally, 1 mL of that solution was transferred to a test tube and combined with 4 mL Bradford reagent. The absorbance of the solution in the test tube was 0.144. Assuming that the best fit linear line of the standard curve was y=0.04144x+0.01521 (μgmL), calculate the percent protein by mass in the original protein powder.
3. An indicator is a dye whose spectrum changes with pH. Consider the following data for the absorption spectrum of an indicator (pK = 4) in its ionized and nonionized form. InH+ → In + H* Molar absorptivity, ɛ (M1.cm1) InH+ (nm) In 400 10,000 420 15,000 2,000 440 8,000 8,000 460 12,000 480 3,000 The absorbance of the indicator solution is increased in a 1-cm cell and found to be 400 420 440 460 480 (nm) A 0.250 0.425 0.400 0.300 0.075 a. Calculate the pH of the solution. [4.0] b. Calculate the absorbance of the solution at 440 nm and pH 6.37 for the same total indicator concentration. [0.400] c. If you want to measure the quantum yield of fluorescence of In and H* independently, what wavelength would you choose for exciting In H+? For exciting In? Why?