Vernier Gas Chromatograph
Mini GC
(Order Code: GC-MINI)
Introduction
The Vernier Mini Gas Chromatograph, or “Mini GC,” is an instrument for
separating, analyzing, and identifying substances contained in a volatile liquid or
gaseous sample. The Mini GC can detect and distinguish between families of
compounds, including alcohols, aldehydes, ketones, aromatic hydrocarbons,
carboxylic acids, esters, ethers, and nitriles (see Appendix A for more details). It has
all of the key components of a traditional gas chromatograph, including an injection
port, temperature and pressure controls, a capillary column through which different
substances pass at different rates depending on various chemical and physical
properties, and a sensor for detecting the arrival of compounds. It has a patented
MEMS chip sensor that allows for room air to be used as a carrier gas.
The Mini GC connects to the USB port on a computer, the LabQuest 2, or the
LabQuest. Both Vernier Logger Pro and LabQuest App software allow students to
easily control data-collection parameters, then collect data in real time. After the
peaks are detected, the software allows you to determine retention times and/or
integrate peaks to help quantify the relative amount of each compound present in the
sample.
What is Included with the Mini GC?
Mini GC unit (with 11 m Restek GC column installed)
AC Power Adapter
Hamilton Syringe (1.0 μL volume)
Two extra Septa (a third Septum is already installed in your Mini GC)
Two extra Mini GC intake-valve plastic caps (a third cap is already on the unit)
USB cable
Lab Manual: Gas Chromatography Investigations with the Mini GC™
Carrying case
Important: We strongly recommend that you read the entire manual thoroughly
before using the Mini GC for the first time. There are precautions and usage
suggestions throughout this manual that are important to know about, prior to doing
your first data collection. Please wear the appropriate personal safety equipment and
use the instrument in accordance with the instructions in this manual to prevent any
injury.
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Caution: The Vernier Mini GC gas chromatograph is designed to analyze
volatile compounds. These compounds may be toxic or highly flammable; therefore,
follow the manufacturer’s instructions when operating this instrument. Serious
personal injury may result from improper use of this instrument. Due to the small
amounts of analytes, there is no hazard that exhaust from the chromatograph could
cause a fire when used according to the instructions. To minimize exposure to
vapors, use this instrument in well-ventilated areas. Refer to the Material Safety Data
Sheet for each compound to be injected into the chromatograph. For personal
protection, we recommend that open reagent containers be handled in a hood or
well-ventilated area.
Logger Pro 3 or LabQuest App Software Requirements
Logger Pro 3 (version 3.8 or newer)
software is required if you are using a
computer. LabQuest App version 1.3
or newer is required if you are using
an original LabQuest. (You can check
the LabQuest version by tapping the
Home icon, tapping Control Panel,
and then tapping System Information).
If you own an earlier version of
Logger Pro 3 software or LabQuest App, you can upgrade to the current version at
no cost by visiting our web site for updates: www.vernier.com/downloads/
Note: If you use National Instruments LabVIEW software, you can obtain a
LabVIEW VI for collecting with the Mini GC. Go to: www.vernier.com/labview/
Using the Mini GC with a Computer or with LabQuest
1. If you will be collecting
data on a computer, be
sure you are using Logger
Pro software, version 3.8
or newer.
If you will be collecting
data on an original
LabQuest, make sure the
LabQuest unit has been
updated to version 1.3 or
newer.
2. For your initial trial,
obtain a glass syringe and
a set of vials of one or more of the following five ketones: acetone, 2-butanone,
2-pentanone, 2-hexanone, or 4-methyl-2-pentanone (or a mixture of any of
these 5 ketones. You will test acetone, and also use it to clean the syringe
needle.
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Note: More detail on this experiment can be found in Experiment 1, “Using a Gas
Chromatograph: Identifying Unknown Compounds,” in the accompanying lab
manual, Gas Chromatography Investigations with the Mini GC™.
Important: The glass syringe is fragile and can be easily damaged. Be careful not to
bend the needle or bend the plunger. If the plunger is accidentally pulled out of the
glass barrel, reinserting it is extremely difficult, sometimes impossible.
3. Prepare the Vernier Mini GC for data collection.
a. Turn on the Mini GC, using its on-off switch on the left side (see Figure 5).
b. Connect the USB cable of the Mini GC to the USB port on your computer
or LabQuest.
c. Start the data-collection program, and then choose New from the File menu
(to ensure software settings are set to default values).
d. Click Collect in Logger Pro or tap ► in LabQuest 2 or LabQuest, to bring
up the Temperature-Pressure profile. This screen will look something like
this:
Figure 1 Temperature-Pressure
e. Set the Temperature-Pressure values to:
Start temperature
35C
Hold time 2 min
Ramp rate
5C/min
Final temperature
55C
Hold time 9 min
Total length 15.0 min
Pressure1 5.0 kPa
f. Select Done to initiate the Mini GC warm up. Note: A new message will
appear, “Do not inject until GC is ready,” and the LED on the Mini GC will
be red. The Mini GC will take a few minutes to warm up and stabilize.
When the Mini GC is ready for injection in Step 7, the message will read,
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Pressure values entered here represent the pressure above ambient air pressure.
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“Inject and select Collect simultaneously”, and the LED will turn to green.
Continue with Step 4 during warm up.
4. Follow the steps below to clean and flush the syringe with acetone. Important:
The glass syringe is fragile. Be careful not to bend the needle or bend the
plunger. Never pull the plunger back more than 50% of its total volume. Be
careful not to bend the plunger as you press it down.
a. Depress the plunger fully.
b. Submerge the tip of the syringe needle into the vial of acetone.
c. Pull back the plunger to fill the barrel about 1/3 full of acetone.
d. Expel the liquid onto a Kimwipe
or a paper towel.
e. Repeat Steps a–d at least two times, until you are comfortable pulling up a
liquid into the syringe and measuring the volume in the syringe barrel. Use
a Kimwipe or a paper towel to carefully pat around the tip of the syringe
needle.
5. Follow the Step 4 process to clean and flush the syringe with 2-butanone (or
another available ketone), the first ketone sample to be tested.
6. Collect a volume of 2-butanone for injection.
a. Submerge the needle into the vial of
2-butanone one last time.
b. Draw up approximately 0.2 L of liquid. It is not
critical that the volume be exactly 0.2 L; a tiny bit
more or less volume is all right.
c. After collecting your sample, gently wipe
the needle from barrel to tip, with a
Kimwipe.
7. Prepare for injection and the start of data
collection. It is important for you and your lab
partner to divide the tasks in this step. One
person will operate the syringe and the other
person will operate the computer controls.
a. When the Mini GC has reached the correct
start temperature and pressure, the message
reads, “Inject and select Collect
simultaneously,” and the LED on the Mini
GC is green.
b. To insert the needle of the syringe into the
injection port of the Mini GC, hold the syringe with one hand and steady
the needle with your other hand.
Important: Supporting the needle guard and the lower part of the needle
with two fingers, as shown in Figure 3, can prevent the possible bending of
the needle! Insert the needle into the injection port until the needle stop is
fully seated. If the needle sticks, rotate it slightly while inserting. Do not
move the plunger yet.
Figure 3
Figure 2
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c. Simultaneously, depress the syringe plunger and select Collect to begin data
collection. Pull the needle out of the injection port immediately.
8. While the data collection proceeds, repeat Step 4 to thoroughly clean the
syringe and needle. It may take more than three flushes to feel the syringe
plunger move smoothly again, which is your indicator that the syringe and
needle are both suitably clean.
9. Data collection will end after 15 minutes.
10. Analyze your chromatogram.
a. Choose Peak Integration from the Analyze menu.
b. Select and integrate the left-most peak. To do this, drag from a little before
the peak to a point far enough to the right that includes all of the peak. Then
choose Add. Note: Prior to integrating, it is also possible to drag across a
peak and then use the Zoom button to zoom in on the peak.
Figure 4 Peak integration in Vernier software
c. To analyze another peak on the same graph, repeat Step b.
d. When you are finished with all peaks, select OK to return to the graph.
11. Using Logger Pro or LabQuest App, you can do any of the following.
You can choose to Store a run. (In Logger Pro, choose Store Latest Run
from the Experiment menu. In LabQuest App, tap the File Cabinet icon.)
You can choose to save this chromatogram and peak analysis for later use,
with a unique file name, by choosing Save from the File menu.
Print your chromatogram and peak analysis table.
You can rename run names, or peak names in the software.
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1.0 Product Description and Principles of Operation
Figure 5 Side view of Vernier Mini GC
Figure 5 shows a side view of the Vernier Mini GC. The power input jack, power
switch, USB connection to the computer or LabQuest, and column ventilation grill
are shown in this view.
Principles of Operation: The Vernier Mini GC is designed to separate mixtures of
gases or volatile liquids and identify components of the mixtures by their specific
retention times. The chromatograph uses ambient air supplied from a pump to carry
a small sample of vapor through a stainless steel column.
The column is a general purpose column designed to study solvent impurities,
distillation, gases, natural gas odorants, sulfur compounds, essential oils,
hydrocarbons, semivolatiles, pesticides, and oxygenates. The column is heated using
an electric current. Temperature of the column is monitored by a built-in resistance
temperature detector (RTD) for accurate temperature measurement. The column
assembly also has an independent thermistor to protect against overheating.
At the end of the column is a Seacoast Science chemicapacitor sensor. The sensor is
a micromachined sensor chip coated with a chemoselective polymer. The polymer
absorbs analytes exiting the column. Analyte absorption by the polymer coating is
measured by the detector circuitry. While the sensor is designed to detect a wide
range of analytes, it does not detect low-polarity compounds such as alkanes.
2.0 Specifications
The Vernier Mini GC is designed for use in an educational or research laboratory.
Ambient temperature range for safe operation is 5°C to 40°C, and safe range of
ambient relative humidity of 0 to 95%. The Mini GC should not be immersed or
sprayed with liquids. Power for the chromatograph is supplied by an external power
supply. The Mini GC has a back-lit liquid-crystal display that advises the user as to
its current status.
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