Picking the Proper Tools
Click Icon to View Within The Classroom Artifact
Click Icon to View Beyond The Classroom Artifact
Artifacts: Explained
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The within the classroom artifact that I chose is an image of the notes that I took during Chem 621, Instrumental Analysis. The notes reflect my professor's teachings regarding the large number of criteria that need to be considered when one is choosing which scientific instrument to use for an experiment.
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The beyond the classroom artifact that I chose is a powerpoint with notes and images compiled from my time working in the Marquette research lab. The notes were taken by me when I was taught how to use the high performance liquid chromatography. The image on the first slide is of the actual machine that was used during my research. Finally, the image on the last slide is of the graph that was produced from the data collected using high performance liquid chromatography. All of these artifacts provide support for the decision to use HPLC in my research and exhibit some of the selection criteria that I was taught in my CHEM 621, Instrumental Analysis class.
On the first day of my CHEM 621, Instrumental Analysis class the professor said something I thought was profound: “You can’t build a house with only a hammer. You need a saw, a screwdriver, a ruler, and many other tools. Therefore, if you only know how to use a hammer, you can’t build a house.” He then went on to equate this with analytical techniques in science. If you only know one analytical technique, you will not be a successful scientist. Different techniques are more suited for different types of analysis in the same way that different tools are more suited for different aspects of building a house. He then went on to tell stories of graduate students who got really good at one type of instrumental analysis and failed to find jobs because the places they applied to did not use that specific technique. The moral: to be a successful and employable scientist, you need to learn all of the instrumental analysis techniques instead of just one.
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Once you know and understand all of the analytical techniques at your disposal, it is important to know the selection criteria for picking the proper tool for the type of analysis you are doing. In Instrumental analysis we learned the questions to ask so we select the correct analytical technique:
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How much accuracy and precision is required in your analysis?
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How much sample is available?
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What is the concentration range of the analyte?
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What are potential interferents in the sample?
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What are the volatility, solubility and optical characteristics of the sample?
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How many samples need to be analyzed?
Those criteria are designed to take into consideration the instrumental limitations, financial constraints, time availability, sample limitations, and all other possible conditions that would affect your choice for experimental instrumentation.
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After learning these criteria, I thought back to my research experience at Marquette University where I was analyzing astrocytic cell samples from mice using a high performance liquid chromatography (HPLC) machine. I had never thought to ask my research advisor why that instrumental method was selected for the experiment, but upon reflection I realized that the HPLC satisfied all of the criteria required for cell sample analysis in solution.
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Since the experimental cells were harvested from live animals, the quantity available was limited. Therefore, the required technique needed to be consistently accurate because we could not afford to re-run experiments more than a few times to build a data set. The concentration range of the analyte was high since we were analyzing microliters of samples with high cell volumes. The concentration of calcium chelator (which was used as the experimental variable) was measurable by the HPLC machine. The potential interferents in the sample did not affect the data, because the wavelength of light that was used by the HPLC machine to measure the analyte (glutamate) concenterations from the samples was not absorbed by any of the other reactants. Volatility was not a factor because the HPLC system was closed and therefore no evaporation of sample solution could occur to skew data. The solubility of the sample was also not a limiting factor in instrument selection because the samples were already suspended in a liquid solution. The optical criteria could be set on the HPLC to search for the analyte of interest. Finally, we had over 100 samples to analyze so the HPLC was a good choice for instrumentation because it contains an autosampler that can run without human supervision. This eliminated time as a limiting factor because the samples could be run at night and data analyzed in the morning.
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Overall, the HPLC was the best choice for this experiment based on the criteria I learned in CHEM 621. In reflecting on my lab experience I was able to find a real-life application of these criteria which made them much more tangible than just learning them abstractly in class. I have learned the importance of instrument selection and seen practical applications of the selection criteria. This knowledge will be useful for me in the future as I go on to graduate school and beyond where I will be designing my own experiments and choosing the proper instrumental analysis methods.
These experiences have given me an understanding of all of the tools, not just the hammer, in my toolbox so I can successfully build a sturdy home.