Problem solving Chemistry

Type of service: Writing from scratch
Work type: Coursework
Deadline: N/A
Academic level: College (3-4 years: Junior, Senior)
Subject or discipline: Chemistry
Title: Problem solving
Number of sources: 0
Provide digital sources used: No
Paper format: MLA
# of pages: 2
Spacing: Double spaced
# of words: 550
# of slides: ppt icon 0

4.Below there are a list of problems (i-iii) and a list of analytical techniques (A-G). For each problem (i-iii) find the best technique (A-G) to solve it. In order to find the best solution you need to take into account the required selectivity, sensitivity, accuracy, throughput, portability, and the cost of the analysis. It is possible that several techniques may be able to solve the problem. For some problems absolutely the best solution may be a technique that we have not studied in class yet. You need to select your answer only from the techniques listed below. Some techniques may be useful for several problems and other techniques for none.

 

You will get full credit if your solution can work and if your description addresses the most critical issues in the analysis. For each technique you should specify sample preparation, chemical reactions (if needed) and the method of calibration.You will get bonus points if your answer is the best solution for the particular situation.

Be brief. 3-7 sentences should be enough. (Total = 24 points; 3*8 points each)

The techniques are:

  1. A) Molecular UV-spectroscopy (specify the light source, wavelength selector and detector).
  2. B) Optical atomic absorption spectroscopy (specify the type of atomization, light source and detector).
  3. C) Optical atomic emission spectroscopy (specify the type atomization and wavelength selector).
  4. D) Fluorescence Spectroscopy (specify the light source and wavelength selector)
  5. E) Infrared spectroscopy (specify the sample preparation and spectral sampling techniques).
  6. F) Near –IR spectroscopy (specify sample preparation, solvent).
  7. G) Mass-spectrometry (specify the type of ionization and mass-analyzer, including tandems)
  1. i) As a chemist working for an oil company you need to quantify the amount of tetraethyl lead, Pb(C2H5)4, in gasoline sold to foreign markets. The expected content of the additive is 0.050% and you need to analyze 1-2 samples a day.

 

 

  1. ii) Biochemists at your University discovered a new protein, which they believe is responsible for proliferation of cancer cells. They were able to isolate only 1ng of the compound and they want to determine the molecular weight as well as the purity of the isolated protein.

 

iii) A private analytical company wants to develop a test for Δ9-tetrahydrocannabinol ( the active ingredient in marijuana, see Fig below) in urine and offer it as a pre-employment test for government agencies. The expected concentration of the analyte is 50 ppm and the expected throughput is 20 samples a day.

  1. 8. Suggest analytical procedures which can solve the problems described below. You will need to take into account the required selectivity, sensitivity, accuracy, throughput, portability, and the cost of the analysis. There are no restrictions of what type of techniques you can use (feel free to use those that you studied in Quantitative Analysis too). You will get a full credit if you propose a technique that would do the job, and if you address all the steps named below (when relevant):

 

1) sampling

2) sample preparation, preconcentration, matrix removal, etc.

3) all chemical reactions, including derivatization.

4) separation (stationary phase., mobile phase, mass-analyzer, etc.)

5) detection (type of detector, light source, monochromator, etc.)

6) calibration: calibration curve, standard addition, internal standard; matrix for standards and sample.

 

You will get bonus points if your answer is the best solution for the particular situation.

Be brief. 5-8 sentences should be enough. (Total = 36 points; 4q*9 points each)

 

The problems are:

  1. i) Resveratrol (F-la below) is believed to be responsible for positive health effect of red wine and it is currently marketed as a nutritional supplement. If you are hired as a consultant by a winery that wants to analyze the concentration of resveratrol in its wines, what method would you suggest? You need to determine the total concentration of resveratrol (both trans- and cis- isomers together). The expected concentration is in the 0.1-20 mg/L range and the customer wants to analyze 5-10 samples a day.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. ii) Floyd Landis, the winner of 2006 Tour de France bicycling competition, became the first athlete convicted of using a performance-enhancing drug testosterone with the help of a new analytical technique. The main problem in testosterone analysis is that it is naturally produced by the human body, particularly in males, and the concentration of testosterone in different people (or in the same person at different times) may vary significantly. The new technique relies on the fact that the testosterone produced by the human body from the animal-derived cholesterol has a different 13C/12C isotope ratio than that of the synthetic testosterone derived from diosgenin of plant origin. How do you think the new analytical technique works? Provide requested details.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. iv) Imagine that you’ve got a job with the Center for Disease Control and Prevention and you are assigned to a project aimed to determine the distribution of heavy metals (Pb, Cd, Hg, Cu) in salmon of different provenances (wild Pacific/Atlantic, farm-raised in Oregon/Scotland etc.). How would you do the analysis? The safe concentrations of heavy metals in seafood are in the 0.01 ppm range. You will need to analyze over 200 samples in 1 year.

 

 

 

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