USE OF A REAL LIFE PROJECT IN QUANTITATIVE ANALYSIS TO



USE OF A REAL LIFE PROJECT IN QUANTITATIVE ANALYSIS TO

EFFECTIVELY PRESENT SOME OF THE CONCEPTS OF ANALYTICAL CHEMISTRY

BY

ANNE T. SHERREN

NORTH CENTRAL COLLEGE, NAPERVILLE, ILLINOIS 60566-7063

ABSTRACT

The use of the real life project in quantitative analysis effectively presents the total analytical process. The use this project has increased student interest in analytical chemistry. Students enjoy the elements of choice and responsibility. Some of the real life samples present problems of matrix effects and method adaptation. In all cases, the student is expected to master problems which are encountered. The overall student expectations, learning goals, types of samples, and student reactions to the project are presented.

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Quantitative analysis courses are often referred to as courses in which the laboratory is the tail that wags the dog. With proper planning the laboratory can effectively teach the concepts of analytical chemistry as it should be practiced in 1991. I have successfully used a real life project in my quantitative analysis class to serve as a summative experience for the term and to present the total analytical method to the student. The student encounters the problems of sampling, and in many samples matrix effects and interfering substances. The use of the real life sample removes some of the sterile view of quantitative chemical analysis presented by total use of commercial synthetic samples. The use of a real life project permits the instructor to provide actual experience for the student in the total analytical process. The project has many benefits and some risks. The advantages of independent projects have been cited by a number of authors including Roscher, Hicks and Bramstedt.

The initial directions for the project must state the guidelines and the instructor must be prepared to supply guidance and firmness. The real life project in my quantitative analysis course is the determination of one component of a real life substance. The student must choose the analyte, supply the analytical method (including literature references) and provide the sample to be analyzed. The student is free to consult me on matters. I do have several good references that I share with the student on request. Some students have ideas and just want support. Others cannot think of any samples.

LIMITATIONS FOR THE ANALYTICAL METHOD

1) ANALYTICAL TECHNIQUES MUST BE COVERED IN THE COURSE.

2) THE CHEMICALS CALLED FOR IN THE ANALYTICAL METHOD MUST BE AVAILABLE.

3) THE METHOD MUST BE SAFE.

4) THE METHOD SHOULD BE CAPABLE OF COMPLETION IN THE TIME AVAILABLE.

5) NO OTHER STUDENT IS DOING THE SAME METHOD AND SUBSTANCE THAT TERM.

6) THE STUDENT MUST OBTAIN THE SAMPLE.

In obtaining the sample the student is expected to describe the techniques used to obtain a representative sample. The student is discouraged from procuring samples until the method is approved.

EXPECTATIONS FOR STUDENTS FOR THE REAL LIFE PROJECT

1. DEFINITION OF THE PROBLEM.

2. LOCATION OF THE ANALYTICAL METHOD.

3. SUBMISSION OF A PROPOSAL PRIOR TO OBTAINING THE SAMPLE.

PROPOSAL WILL INCLUDE: DEFINITION OF THE PROBLEM, ANALYTICAL METHOD PREFERRED, CHEMICALS (WITH AMOUNTS) REQUIRED, EQUIPMENT REQUIRED, 3 REFERENCES.

4. OBTAIN THE SAMPLE USING GOOD SAMPLING TECHNIQUES.

5. PERFORM THE ANALYSIS USING GOOD ANALYTICAL TECHNIQUES, GOOD JUDGMENT AND KEEPING GOOD LABORATORY RECORDS.

6. PREPARATION OF THE FINAL REPORT.

THE REPORT INCLUDES

THE ANALYTICAL METHOD; DATA AND CALCULATIONS; DISCUSSION OF HOW SAMPLING WAS DONE DISCUSSION OF HOW THE PROBLEMS WERE ADDRESSED; CHANGES WHICH WOULD BE MADE IF THE ANALYSIS WERE TO BE REPEATED; COMPARISON OF STUDENT RESULTS WITH THE PUBLISHED OR LABEL VALUES; REFERENCES; THE ORIGINAL PROPOSAL; USE OF GOOD VERBAL SKILLS; SUBMISSION OF THE LABORATORY RECORD BOOK.

EVALUATION OF THE PROJECT IS BASED ON

1.OBSERVATIONS OF THE STUDENT DURING THE EXECUTION OF THE PROJECT

2.THE QUALITY OF THE DAILY RECORD IN THE STUDENT'S LABORATORY RECORD BOOK

3.THE REPORT INCLUDING THE FOLLOWING ITEMS

OBJECTIVES FOR THE ANALYSIS; THE ANALYTICAL METHOD USED; DISCUSSION OF SAMPLING METHODS USED; DATA AND CALCULATIONS; ACCURACY AND PRECISION; COMPARISON OF STUDENT RESULTS WITH THE PUBLISHED OR LABEL VALUES; GOOD JUDGMENT; DISCUSSION OF PROBLEM MANAGEMENT; CHANGES WHICH WOULD BE MADE IF THE ANALYSIS WERE TO BE REPEATED; USE OF GOOD VERBAL SKILLS; REFERENCES; CONCLUSIONS; ORIGINAL PROPOSAL FOR PROJECT

STUDENT REACTIONS TO THE USE OF REAL LIFE PROJECT IN QUANTITATIVE ANALYSIS

1. THE ANALYSIS RELATES TO EVERY DAY AREAS.

2. CHEMISTRY IS NOT JUST IN THE TEXTBOOK, IT IS EVERYDAY LIFE.

3. THE REAL LIFE HELPED TO DEVELOP MY SELF-CONFIDENCE. I HAD TO FIGURE IT OUT BY MYSELF.

4. IT WAS NOT A REGULAR PROCEDURE, I WAS ABLE TO PARTICIPATE IN PLANNING THE EXPERIMENT.

5. I LEARNED THAT WHAT WAS PRINTED DOES NOT ALWAYS WORK.

6. I HAD TO TRY SEVERAL THINGS AND WHEN IT WORKED I FELT A SENSE OF ACCOMPLISHMENT.

ADVANTAGES

INCREASED LEVEL OF STUDENT INTEREST.

VARIETY IS ADDED TO THE COURSE

HELPS THE STUDENT TO RELATE CHEMISTRY TO EVERYDAY LIFE.

FACILITATES THE CONSIDERATION OF SAMPLING TECHNIQUES.

THE TOTAL ANALYTICAL PROCESS (from problem definition to communication of results) CAN BE EXPERIENCED BY THE STUDENT.

OFTEN SERVES AS AN INTRODUCTION TO THE AREA OF CHOICE OF ANALYTICAL METHOD AND ANALYTICAL METHOD DEVELOPMENT.

THE STUDENT MUST MAKE CHOICES AT MANY STAGES IN THE PROJECT. EACH OF THESE CHOICES INCREASES THE STUDENT'S LEVEL OF RESPONSIBILITY FOR THE PROJECT.

PROBLEMS

(1) Matrix effects ARE often encountered and must be solved. (2) Interferences are often present and not anticipated by the student or the instructor. (3) Dissolving the sample is often a big problem. (3) When the student chooses and develops the analytical method a variety of chemicals must be available. (4) THE INSTRUCTOR MUST SUPPLY ADEQUATE GUIDELINES AND BE A CONSULTANT TO FACILITATE LEARNING. (5) The instructor is faced with the problem of knowing the "actual content" of the analyte in the real life substance. (6) INCLUSION of the methods of standard addition and doing "check samples" to insure the analytical accuracy CAN BE PERFORMED.

LEVEL OF STUDENT CREATIVITY EXPECTED

The student is expected to do all of the following: take an idea; locate a method; adapt the method to a given situation; preform the experiment; devise creative ways to show under-standing of the meaning of a good analytical sample and sampling techniques; Show creativity in dealing with the problems encountered in the various steps of the analysis.

LEARNING GOALS FOR THE REAL LIFE PROJECT

1. EXPERIENCE AND EXECUTE THE TOTAL ANALYTICAL PROCESS FOR A GIVEN SAMPLE.

2. LOCATE, ADAPT, AND EXECUTE A SUITABLE ANALYTICAL METHOD.

3. PROCURE A REPRESENTATIVE SAMPLE FROM EVERYDAY LIFE USING GOOD SAMPLING TECHNIQUES.

4. ANALYZE A REPRESENTATIVE SAMPLE FROM CHOSEN FROM EVERYDAY LIFE USING GOOD ANALYTICAL TECHNIQUES.

5. INCREASE STUDENT SELF CONFIDENCE AND RESPONSIBILITY.

6. PRACTICE IN REPORTING LABORATORY EXPERIMENTS.

7. INCREASE STUDENT REALIZATION THAT ANALYTICAL CHEMISTRY IS BOTH PRACTICAL AND RELEVANT TO EVERYDAY LIFE.

8. INCREASE STUDENT INTEREST IN CHEMISTRY AND ANALYTICAL CHEMISTRY.

WHERE MY STUDENTS FIND METHODS FOR REAL LIFE PROJECTS:

THE JOURNAL OF CHEMICAL EDUCATION; LABORATORY TEXTS; TEXT BOOKS; ANALYTICAL BOOKS FOR SPECIAL SUBSTANCES, I.E., FOODS, WATER, OR OTHER MATERIALS.

SAMPLES WHICH MY STUDENTS HAVE DETERMINED

The types of analytes and materials analyzed by my students are shown below:

TYPES OF SAMPLES MY STUDENTS HAVE DETERMINED

WATER, FOODS, VITAMIN SUPPLEMENTS, SOAPS, BONES, TOBACCO, TYLENOL®, TEA, COFFEE, SODA, GASOLINE, COINS, AND BODY FLUIDS. THE STUDENTS HAVE FREQUENTLY DETERMINED THE AMOUNTS OF IRON, VITAMIN C. FAT CONTENT, PHOSPHATE, CALCIUM, CAFFEINE, CHLORINE, AND COPPER IN REAL LIFE SAMPLES. THE DETERMINATION OF IRON, CALCIUM AND CHLORIDE ARE ALWAYS POPULAR.

TYPICAL ANALYTES

DETERMINATION OF IRON: Beef Liver, Vitamin Tablets, Spinach, Blood (dog & human), Water, Beer, Breakfast Cereal

DETERMINATION OF VITAMIN C: Orange Juice, Tang, Vitamin C Tablets, Multiple Vitamin Tablets

DETERMINATION OF FAT: Bread and Goat's Milk

DETERMINATION OF PHOSPHATE: Soap, Detergents, Soft Drinks, Water

DETERMINATION OF CALCIUM: Water,Egg Shells, Human Blood Serum, Milk, Hot Chocolate Mix, Soil, Cement, Beef& Chicken Bones

DETERMINATION OF CHLORIDE: Cheese, Urine, Water

DETERMINATION OF CAFFEINE: Coffee, Sanka, Tea, Soft Drinks, No-Doz Tablets

OTHER DETERMINATIONS

NICOTINE in TOBACCO, CODEINE in TYLENOL, TANNIN in TEA, LEAD in GASOLINE, COPPER in COINS, ZINC in ZINC SCREWS, PROTEIN in CORN, SUGAR in CORN FLAKES, IODIDE in TABLE SALT, ALCOHOL in AFTER SHAVE LOTION THEOBROMINE in CHOCOLATE

ANALYSIS OF WATER FOR: Iron, Total Hardness, Calcium, Chloride, Chlorine, Zinc, Fluroide, Sulfate, Phosphate, Dissolved Carbon Dioxide, Dissolved Oxygen

EXAMPLES OF CREATIVE SAMPLING: Multiple Vitamin tablets, river water, tap water, razor blades, spinach.

CHALLENGES: (1) Dissolving of analyte or isolation of analyte. (2) Colored solutions: blanks, matrix effects, interferences. (3) Not a cookbook experiment.

CONCLUSION: I have found that the real life project has helped me to effectively convey to my students the total process of analytical chemistry. The topic of sampling is one which is hard for the students to appreciate unless it is actually experienced. I have found that the use of the real life project has increased student interest, student curiosity, and the meaning of analytical chemistry. You are limited in the use only by your own creativity and imagination. I feel that the advantages are far greater than the problems. The extra effort is rewarded with much satisfaction and student interest. The real life project permits me to effectively introduce the element of analytical research in my quantitative analysis course. I have found that the students do see a purpose to analytical chemistry and want to consider it as a future career.

REFERENCES

1. A. T. Sherren, et. al, Journal of Chemical Education 51, 472 (1974).

2. Nina Matheny Roscher, J. Col. Sci. Teach. II (3) 33 (1973).

3. Donald G. Hicks, J. Col. Sci. Teach. II (4) 27 (1973).

4. Berwyn E. Jones, J. Chem. Edn. 50 (12) 822 (1973).

5. Bramstedt, W. A. Korfmacher, T. Layloff, J. Chem. Educ. 1973 50, 252 (1973).

6. James F. Corwin, J. Chem. Educ. 48, 523 (1971).

DR. SHERREN'S NOTES FROM THE PRESENTATION

Today I want to share with you a project I have had my students do for a number of years -- a real life project in quantitative analysis. The students may be third term freshmen or beginning sophomores. The project is the quantitative determination of one component of a real life substance. In addition to the analysis the student must choose the analyte (define the problem and set the scope of the analysis), supply the method (limited review of the literature and method choice), provide the sample (sampling techniques), and submit a final report (communication of results).

I am happy to serve as a free consultant and this consulting varies from encouragement and approval to the guidance and sparking of the student who comes in and says, "I can't find ANYTHING to analyze!".

There are limitations on the choice. The analytical method must involve one of the following: visible spectroscopy, titration with colored indicators, gravimetry, isolation by solvent extraction or ion exchange. Overlay on typical analytes. For iron the Spectrophotometric iron is preferred. A gravimetric iron would work, but often there are interferences and very large samples would be required. Vitamin C is usually an oxidation reduction titration. Fat is usually extracted and then weighed. Phosphate is usually gravimetric. Calcium is EDTA, Cl is Silver titration, caffeine is extraction and weight of recovered product.

I have had some creative sampling: Vitamin C and the tablets, how many do you take for your sample. There have also been problems: Charring foods in the microwaves; acid digestions, filtrations and dilutions; pulp in orange juice; the inert materials; concentration ranges; meeting the conditions for the analysis--pH.

My expectations, the student quotes, the advantages, disadvantages, and challenges.

NOTE TO CHM 210 CLASS: This paper is two pieces. (1). The Formal types part which I prepared and the materials which I had on my overheads for my presentation in April 1991 at the ACS Meeting in Atlanta. (2) My notes that I prepared in Atlanta so that I could make the talk less formal. When you prepare a journal article there is a certain degree of formality. In Atlanta I was invited to participate in a symposium on the use of chemistry laboratory teaching. I have done some formatting changes so that you could get a copy. I have also had several requests for copies of my talk by persons who were unable to attend the meeting. This paper should give you some firm directions regarding what I expect and how I intend to grade your work. I want you to read it before I lecture on the Real Life Sample and Sampling.

VARIOUS STATEMENTS OF THE TOTAL ANALYTICAL PROBLEM

METHOD SELECTION

OBTAINING A REPRESENTATIVE SAMPLE

PREPARING A LABORATORY SAMPLE

DEFINING REPLICATE SAMPLES

DISSOLVING THE SAMPLES

ELIMINATING INTERFERENCES

MEASURING A PROPERTY OF THE ANALYTE

CALCULATING RESULTS

ESTIMATING THE RELIABILITY OF RESULTS

PRESENTATION OF THE RESULTS

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DEFINITION OF PROBLEM

INFORMATION GATHERING

SELECTION OF ANALYTICAL METHOD OR TECHNIQUE

IMPLEMENT ANALYSIS OF KNOWN SAMPLE AND UNKNOWNS

REDUCE DATA AND INTERPRET DATA

REPORT RESULTS

TOTAL ANALYTICAL PROCESS

DEFINITION OF PROBLEM

INFORMATION GATHERING

SELECTION OF ANALYTICAL METHOD OR TECHNIQUE

IMPLEMENTATION OF THE ANALYSIS OF KNOWN SAMPLE AND UNKNOWNS

including

OBTAINING A REPRESENTATIVE SAMPLE

PREPARING A LABORATORY SAMPLE

DEFINING REPLICATE SAMPLES

DISSOLVING THE SAMPLES

ELIMINATING INTERFERENCES

MEASURING A PROPERTY OF THE ANALYTE

DATA REDUCTION AND INTERPRETATION ESTIMATING THE RELIABILITY OF RESULTS COMMUNICATION OF THE RESULTS

ADVANTAGES

INCREASED LEVEL OF STUDENT INTEREST.

VARIETY IS ADDED TO THE COURSE

HELPS THE STUDENT TO RELATE CHEMISTRY TO EVERYDAY LIFE.

FACILITATES THE CONSIDERATION OF SAMPLING TECHNIQUES.

THE TOTAL ANALYTICAL PROCESS (from problem definition to communication of results) CAN BE EXPERIENCED BY THE STUDENT.

OFTEN SERVES AS AN INTRODUCTION TO THE AREA OF CHOICE OF ANALYTICAL METHOD AND ANALYTICAL METHOD DEVELOPMENT.

THE STUDENT MUST MAKE CHOICES AT MANY STAGES IN THE PROJECT. EACH OF THESE CHOICES INCREASES THE STUDENT'S LEVEL OF RESPONSIBILITY FOR THE PROJECT.

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