☐ An analysis where we know what analytes we are looking for is called An analysis where we do not know what analytes are in the sample is called a An example is A) untargeted, confirmation, targeted, Comprehensive drug screen - B) targeted, confirmation, untargeted, comprehensive drug screen analysis. An example is analysis. C) targeted, comprehensive drug screen, untargeted, confirmation ▪ True or false: The purpose of the internal standard is to make quantitation of the analyte insensitive to injection errors

☐ An analysis where we know what analytes we are looking for is called An analysis where we do not know what analytes are in the sample is called a An example is A) untargeted, confirmation, targeted, Comprehensive drug screen - B) targeted, confirmation, untargeted, comprehensive drug screen analysis. An example is analysis. C) targeted, comprehensive drug screen, untargeted, confirmation ▪ True or false: The purpose of the internal standard is to make quantitation of the analyte insensitive to injection errors

Chemistry

10th Edition

ISBN:9781305957404

Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste

Chapter1: Chemical Foundations

Section: Chapter Questions

Problem 1RQ: Define and explain the differences between the following terms. a. law and theory b. theory and...

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Method of Standard Addition Worksheet You are provided a stock standard solution containing : 0.0500 g/250 mL acetaminophin (APAP). You need to determine how much standard stock is required to prepare the following solutions using 100 mL flasks. Flask 12 3 4 [APAP] added ppm (mg/L) t 10 20 30 40 RI mL Stock 0.1 What method of calibration do you use if you are analyzing a product and the product contains no ingredients that interfere with the instrument response for APAP in the product? on th LI What method of analysis do you use if you are analyzing a product and the product contains ingredients that interfere with the instrument response for APAP in the product? or
Page of 5 O + 3 ZOOM Question 1: Using a well-known protein estimation technique, absorbance reading for a set of standards were obtained. You were required to plot the data. Which graph would you use? Plot the data using the graph type. Protein Absorbance concentration (mg/mL) (a.u.) 0.01 0.05 0.12 5 10 25 0.25 0.63 1.25 50 Question 2: Enzymes are biological catalysts and perform important biochemical reactions in the body. A group of scientists discovered a new enzyme – Enzyme X. To understand the working of this enzyme, they performed biochemical assays to assess the activity of the enzyme. The results for which are shown in the table below. Based on the information provided in the table, please state which graph would you use? Plot the data using the graph type. Enzyme activity (%) 35 55 pH 3 4 5 68 6 79 7 98 85 20 8 9 10
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 0.187. Assuming that the best fit linear line of the standard curve was y = 0.04144 x + 0.01521 (μ g mL), calculate the percent protein by mass in the original protein powder.
1. A wastewater sample has the following composition: NO3 = 37 mg/L as N CO3²-2.5 x 10 mol/L PO4³ = 10 meq/L Ca²+ = 75 mg/L as CaCO3(s) Express each of the above concentrations in mg/L, mol/L, meq (of charge)/L, and ppm. Make and list any necessary assumptions. Show your work and summarize the results in a table.
You are provided with a stock standard with a concentration of 100 mg/L, and a solution of unknown concentration. Prepare calibration standards using a 10 mL volumetric flask and a 1 mL piston pipette, and measure on the UV/Vis spectrophotometer (400 nm). Determine the concentration of the unknown after a 1:40 dilution, and provide the concentration of the initial solution. i need to learn how to do the calculations and draw a calibration curve to find concentration of unknown sample after i find the absorbances.
4- A sample containing H2C204 had a purity equal to 90.50% (w/w). An unknown mass of this sample was dissolved in water and transferred to a 50.00 mL flask. An aliquot of 25.00 mL was transferred to an erlenmeyer flask and 50.00 mL of a 0.2000 mol L^-1 NaOH solution were added. %3 Excess NaOH was titrated with 0.09000 mol L^-1 HCI solution using 2.000 mL. Calculate the mass (g) of the sample used. Data: H = 1.008 C= 12.01 O = 16.00
After determining the absorbance of several standards of known concentration, the trendline for a calibration curve (AKA a standard curve) plotting absorbance (y-axis) against concentration (M, x-axis) is determined to be y = 4.586x + -0.0010 %3D The absorbance of a solution of unknown concentration is determined to be 0.68. Calculate the concentration of the unknown solution in M. Give your answer to thrėe decimal places.
If the standard addition intercept is the major source of uncertainty, find the uncertainty in the concentration of Sr in tooth enamel in parts per million. Find the 95% confidence interval for Sr in tooth enamel.
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 0.11. Assuming that the best fit linear line of the standard curve was y = 0.04144 x + 0.01521 (μ g mL), calculate the percent protein by mass in the original protein powder.
Often the analyst will compare known quantities of analyte to unknown quantities of the material to be analyzed. This may be done in one of three ways: -use calibration curves; use standard additions; or use internal standards. The method of standard additions would be used when A) the quantity of sample analyzed or the instrument response varies from run to run. B) the standard solutions and the unknown solution all have similar characteristics are unaffected by the other material in the sample. C) the sample composition is unknown or complex and affects the analytical signal.
Plot a professional quality standard curve (absorbance vs. protein amount in µg) with an appropriate title and caption underneath the plot from the data give above. The caption should include the best-fit data.
As part of an analytical chemistry laboratory course, a student measured the Ca2+ content in two water samples, city-supplied drinking water and well-supplied drinking water, using two different analytical methods, flame atomic absorption spectrometry (FAAS) and EDTA complexometric titration. The results of this experiment are given in the table as the mean Ca2+concentration (?¯) and standard deviation (?) in parts per million (ppm). Each sample was measured five times (n=5) by each method. Method City-Supplied Drinking Water (?¯±?x¯±s) Well-Supplied Drinking Water (?¯±?x¯±s) FAAS 57.57±0.68 ppm 64.77±0.70 ppm EDTA titration 58.32±0.96 ppm 65.62±0.97 ppm Method Comparison: For each drinking water sample (city and well), compare the Ca2+ content measured by FAAS and EDTA titration. Calculate the ? value for each sample. Do the methods produce statistically different results at the 95% confidence level when measuring the Ca2+content of the city-supplied drinking water? Do the…