Click to edit Master subtitle style 4/13/10 Making the best of ASDL resources: the case of Lake...

Click to edit Master subtitle style 4/13/10

Making the best of ASDL resources:

the case of Lake Nakuru

Anna G. Cavinat

oDepartment of Chemistry and Biochemistry

Eastern Oregon Univers

ityPITTCON 2010

4/13/10

Outline

Overview of Lake Nakuru case study

Implementation of sampling module in the analytical chemistry course

Case study as a tool to learn chromatography in instrumental analysis

Assignments/assessments

Conclusions

4/13/10

http://www.asdlib.org/index.php

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Lake Nakuru Case Study

Overarching problem

Introduction to analytical problem solving

Narrowing the problem

Experimental design

Sampling

Sample preparation/analysis

Detection

Validation

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Analytical curriculum at EOU Fall – analytical chemistry

Winter – instrumental analysis

In the past…..

Traditional quantitative analysis

Developing at present….

Adoption of David Harvey’s Analytical Chemistry 2.0

Increased instrumentation coverage

AA

Introduction to chromatography



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Fall term - sampling

General Chemistry (End Creek project)

Sampling

Harvey’s textbook (chapter 7)

Lake Nakuru assignment

From where within the target population should we collect samples?

What type of samples should we collect?

What is the minimum amount of sample for each analysis?

How many samples should we analyze?

How can we minimize the overall variance for the analysis?

www.safarypatrol.com



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Sampling at Morgan Lake

Assignment

Students survey area and design individual sampling plan

Groups are formed according to similar sampling strategy

Some compromises are reached…



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Sampling at Morgan Lake

Field trip

water samples collected at 5 sites (GPS)

Hardness determined by EDTA titration

Analysis of Ca2+ and Mg2+ by AA

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Chromatography unit

Basic elements of separation science and chromatography

Lake Nakuru case study used for UWR 5000 words essay

Hypotheses of flamingo’s death are revisited

High levels of pesticides

Heavy metals (Hg, As, Pb)

In lab students are introduced to GC-MS and qualitative analysis of pesticides using standards.

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UWR essay

A report on the Lake Nakuru case study (see attached document) is due by the end of week 8 (Friday November 20th by 5:00 pm). The report should be at least 5,000 words in length and should contain detailed information on the methods of analyses discussed as well as an appropriate bibliography.A scoring rubric is attached below. Please post the rough draft of your essay in the rough draft folder in Blackboard.

After reading about the potential causes of death for flamingos, particularly as it relates to presence of potential toxins in the lake, choose to pursue one of the two hypotheses (high levels of DDT pesticide or presence of heavy metals such as lead, mercury or arsenic) and answer the following questions:

what is the solubility in water of your chosen chemical toxin?

how would you go about sampling for your chosen chemical in Lake Nakuru?

what kind of information about your chosen chemical can you find out through the Material Safety and Data Sheet (MSDS)?

does EPA regulate the use of your chosen chemical? If so, what are the limits permitted in water environments?

what is the biological fate of your chosen chemical?

what are the physiological effects of exposure?

how does the sensitivity of aquatic organisms to the chosen chemical toxin compare to terrestrial ones?

Research and describe what analytical techniques are commonly used to detect and measure your chosen chemical in water. Make sure to report what detection limits and reproducibility each technique can achieve.

An appropriate bibliography according to the scoring rubric provided needs to be included.

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Winter term - Instrumental

Intro to chromatography

Case study is reintroduced

Students research EPA method 525.2

Determination of organic compounds in drinking water by liquid-solid extraction and capillary column gas chromatography/mass spectrometry

and integrated with mass spectrometry

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Group assignments

Group 1:

overall summary of the method including information about the detection limit and reproducibility

the strategy for sample collection, preservation and storage

the steps involved in the initial calibration of the GC-MS

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Group assignments

Group 2:

- description of the liquid/solid extraction procedure.

- what stationary phase is used and why?

- what is the potential benefit of using an extraction disk over an extraction cartridge?

- what is the purpose of a surrogate analyte and how is it chosen?

- what is the difference between laboratory fortified blank (LFB) and Laboratory Fortified Sample Matrix (LFM) and what role do they have in the analysis?

- If you were limited in the number of samples you can run, which blanks would you choose to analyze and why?

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Group assignment

Group 3:

refer to table 1 in module 7 of the Lake Nakuru case study (posted in Blackboard under Course Documents). Create a graph of the boiling points of the listed linear alkanes as a function of mass. Can you separate these compounds by boiling point?

Using the information found at DelLoyds Analytical Chemistry Resources http://delloyd.50megs.com/moreinfo/gcphases.html find the columns recommended for boiling point based separation of linear alkanes. What is their chemical composition?

refer to table 2 (pesticide data) and plot the data as above to determine if we can separate the pesticides with the same column used for alkanes.

Research a DB-5 column. What is the composition of the stationary phase? Why does the EPA method 525.2 recommend a DB-5.MS column? What is the difference?

What is meant by “bleeding” of a column? How would you know that your column is bleeding?



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Pre/post test - sampling



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Pre/post test

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2

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12Pre/post test assessment

% correct answers

•Question 1-3 - narrowing the problem

•Questions 4-6 - sample prep

•Questions 7-9 - column and injection method

•Questions 10-11 - mass spectrometry

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Students’ feedback

How easy was to read/comprehend the case study?

I thought the case study was fairly easy to comprehend.

It was easy but did not provide enough details.

It was right to the point!

I liked that it was divided into sections and each section gave a brief outline. Each section pointed out important questions that helped guide us in the right direction when we were researching the topic.

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Students’ feedback

Was it useful in learning about chromatography?

This was a very interesting way to teach chromatography. I learned quite a bit about the topic.

Applying the theory of chromatography to a case study did give me a good idea of the extensive process required from collecting the sample to analyzing the data.

Yes! It was good to see that what we are learning has practical applications out in the world!

The case study has given me some insights into how chromatography is used for real world applications.

It brought up good points like the use of surrogates. It was good to learn about EPA methods, something I had never seen or thought of before.

It helped me to see the big picture and how important the different parameters are.

I think it is a decent supplement but not necessarily a good way to learn chromatography if you have no prior knowledge.

For me, this case study was helpful but no more than a laboratory experiment accompanied by a brief lecture.

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Conclusions

ASDL provides many useful resources for classroom and lab activities.

Project-oriented approach

Class and lab activities revolving around solution of real problems

Students required to invest time and efforts in research solutions

The case study provides an engaging context to teach elements of chromatography, mass spectrometry and environmental analysis.

Needs fine tuning and possibly more interactive type of built-in activities.

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Acknowledgements

Lake Nakuru case study authors:

Alanah Fitch

Cindy Larive

Heather Bullen

Rick Kelly

ASDL crew

My students!!

Click to edit Master subtitle style 4/13/10 Making the best of ASDL resources: the case of Lake...

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