Download Chromatography: Gas and Paper

Chem 100 Section _______
Experiment 3
Name ____________________________
Partner’s Name ___________________________
Chromatography: Gas and Paper
INTRODUCTION
This experiment is being constructed to acquaint you, the student, with two powerful techniques used
in science to identify substances; viz., gas chromatography and paper chromatography. The reason for
introducing these concepts and procedures is to answer the basic questions posed in the very realistic
story given below.
The Case of the Corroding Cans
Adapted from a laboratory experiment developed by J. Steehler et al at Roanoke College and
Steven M. Wright at the University of Wisconsin – Stevens Point
“A law-suit is brewing, and we’ve been asked to help. An unsuspecting buyer has purchased some
land on the Chain of Lakes near Eagle River, Wisconsin for a family cottage. While walking the
property, the buyer discovered several large, partially full, corroding cans. Not knowing the contents
of the cans and fearing environmental contamination, the buyer did what any red-blooded American
would do – go straight to an attorney! The buyer is suing the seller for the cost of removing all the
barrels and testing the soil for contamination; … a total of $75,000. You have been hired by the
County Court as a legal consultant to determine the contents of the barrels and to give your opinion
concerning their hazard. Your results will determine the seller’s liability.”
“Several of the cans contain a deeply colored liquid. With some investigation of land-transaction
records at the Court House, you’ve learned that the seller (who was the previous owner of the
property) manufactured and sold inks many years ago to three different pen-manufacturing companies
– Papermate®, Pinpoint®, and Vis-à-Vis®. Ink is a reasonable first guess for these cans’ contents. The
previous owner denies any knowledge of the cans, so you will need to find some way to compare the
inks found in Papermate®, Pinpoint®, and Vis-à-Vis® pens to the colored liquids found in the
corroding cans. This will help determine whether the cans’ contents were inks possibly used by these
companies.”
“Several other cans contain clear, colorless liquids. Although the cans are corroded, you can make out
the letters “HOL” on one can. Perhaps this is the end of the word “alcohol.” Unfortunately, there are
many types of alcohol, some considered toxic, some not as toxic. Methanol, ethanol, and 2-propanol
(also known as methyl alcohol, ethyl alcohol, and isopropyl alcohol) are the most commonly used
alcohols. These alcohols may have been used in the preparation of inks. You will compare the
colorless liquids in the cans to liquid samples of common alcohols in order to identify the cans’
contents.”
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EXPERIMENTAL PROCEDURE
To identify both these liquids, you will use chromatography, a technique that is often used to perform
both qualitative and quantitative analysis on unknown samples.
Qualitative Analysis is any method used to determine the identity and/or presence of a
particular substance in a mixture.
Quantitative Analysis is a method which gives information on how much of the substance
is present in a sample.
Two forms of chromatography will be used in this experiment … gas and paper. The World Wide
Web is full of sites explaining the details and intricacies of both methods. Please familiarize yourself
with these methods by visiting the following sites (last accessed 02/01/05) prior to your laboratory
session. Your laboratory instructor will discuss these methods with you.
Gas chromatography:
http://www.shu.ac.uk/schools/sci/chem/tutorials/chrom/gaschrm.htm
http://orgchem.colorado.edu/hndbksupport/GC/GC.html
Paper Chromatography
http://www.yesmag.bc.ca/projects/paper_chroma.html
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Chromatography_paper.html
http://chemlearn.chem.indiana.edu/demos/PaperChr.htm
After collecting your chromatographic data, you are to write a report for the County Court. Your
report must be in the following format: Purpose, brief Procedure, Data and Observations, and
Conclusion. Look in the previous paragraphs for hints on the purpose of the lab exercise. Briefly
outline the procedures you used - first paper chromatography, then gas chromatography. Carefully
organize and present your data so that the County Court will be convinced of your first conclusion;
viz., the identity of the two liquids. Be sure to attach your chromatograms to your report.
Your conclusion must also include your recommendation concerning the property and how you came
to that recommendation; i.e., Is the seller liable for the clean-up? Consider some of the following
questions when making your recommendation1. Are the colored liquids found on the property the inks
sold to the pen-manufacturers? Are the colored liquids hazardous, making the property unsafe? Does
the buyer assume all responsibility, once the property is sold? To help you with these questions, find a
list of LD50’s and PEL’s for the inks and some other common substances on page 3-3. Use the
“common” substances as reference points to determine the relative hazard of the inks. Further you
will find definitions for some terms at the bottom of the page. Please note: The values for the inks
have simply been “made up.”. You will also be provided with Material Safety Data Sheets for these
alcohols. Use the MSDS’s to determine the potential hazards of the alcohols – and make your
recommendation based on that information. You may see abbreviations like UEL, LEL, flash point,
and/or autoignition temperature on the MSDS’s. These terms are also defined page 3 - 3. Be sure to
consider the hazards associated with the alcohols. Does the presence of the alcohols make the
property unacceptably risky? Who should be responsible for the clean up? Lastly, remember that you
are the court’s expert witness. Speculation and innuendo should not be a part of your report. Base
your recommendations only on data and observations.
1
These questions are meant to help you discuss your recommendation. While some may be appropriate to
include in your conclusion, you do not have to address each question individually.
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REFERENCES
Table of Toxicity Data
Substance
Sodium chloride (table salt)
Sucrose (table sugar)
Caffeine (in coffee)
Sodium cyanide (nasty poison)
Strychnine (nastier poison)
Papermate® Ink4
Pinpoint® Ink4
Vis-à-Vis® Ink4
LD502
3.75 g/kg (rats)
29.7 g/kg (rats)
0.13 g/kg (mice)
6 mg/kg (rats)
0.5 mg/kg
4.75 g/kg (mice)
80 mg/kg (rats)
2 mg/kg (rats)
PEL3
15 mg/m3 (nuisance particulate)
15 mg/m3 (nuisance particulate)
N/A
5 mg/m3
0.15 mg/m3
12 mg/m3
9 mg/m3
0.10 mg/m3
2
LD50 is the lethal dose for half (50%) of a large population of animals. These values
were taken from several sources and MSDS’s.
3
PEL is the Permissible Exposure Level for a substance. These are often given as 8hour, time weighted averages (TWA). These values have been taken from MSDS’s.
4
Remember, these are just made up the numbers for these “inks”.
Some Useful Definitions for Reading MSDS’s
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Flash Point – Lowest temperature at which a flammable liquid gives off sufficient vapor to
form an ignitable mixture with air near its surface.
Autoignition Temperature – Minimum temperature at which a substance ignites without
application of a flame or spark.
LEL – Lower Explosive Limit – The lowest concentration of a material in air (% by volume
in air) that produces an explosion when it contacts an ignition source.
UEL – Upper Explosive Limit – The highest concentration of a material in air (% by volume
in air) that produces an explosion when it contacts an ignition source.
ATTACHMENTS
Please find MSDS for methyl alcohol, ethyl alcohol and isopropyl alcohol attached. These
sheets are from Flinn Scientific Inc., of Batavia, Illinois.
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