Vernier Go Direct GDX-POL User manual

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6. Select your Go Direct sensor from
the list of Discovered Wireless
Devices. Your sensor's ID is located
near the barcode on the sensor. The
LED will blink green when it is
successfully connected.
7. Click or tap Done. You are now
ready to continue your experiment
Charging the Sensor
Connect Go Direct Polarimeter to the included Micro USB Cable and any USB
device for two hours.
You can also charge up to eight Go Direct Polarimeters using our GoDirect
Charge Station, sold separately (order code: GDX-CRG). An LED on each Go
Direct Polarimeter indicates charging status.
Charging Red LED next to battery icon is solid while
sensor is charging.
Fully charged Green LED next to battery icon solid when
sensor is fully charged.
Connecting the Sensor
See the following link for up-to-date connection information:
www.vernier.com/start/gdx-pol
Connecting via Bluetooth Wireless Technology
Ready to connect Red LED flashes when sensor is powered and
ready to connect.
Connected Green LED flashes when sensor is connected via
Bluetooth wireless technology.
Connecting via USB
Connected via USB, data
collection software is not
running
Red LED flashes when sensor is powered and
ready to connect.
Connected via USB, data
collection software is run-
ning
Green LED is solid when connected to the soft-
ware via USB.
Identifying the Sensor
Use the Identify feature to flash the LED on the sensor that is connected via
Bluetooth wireless technology. In Instrumental Analysis, Identify is accessed
Go Direct®Polarimeter
(Order Code GDX-POL)
Go Direct Polarimeter provides a visual representation of chirality by
measuring the optical rotation of optical isomers, such as sugars,
amino acids, and proteins.
Note: Vernier products are designed for educational use. Our products
are not designed nor are they recommended for any industrial, medical, or
commercial process such as life support, patient diagnosis, control of a
manufacturing process, or industrial testing of any kind.
What's Included
lGo Direct Polarimeter
lSample cell
lMicro USBCable
Compatible Software
See www.vernier.com/manuals/gdx-pol for a list of software compatible with Go
Direct Polarimeter.
Getting Started
Please see the following link for platform-specific connection information:
www.vernier.com/start/gdx-pol
Bluetooth Connection USB Connection
1. Install Vernier Instrumental
Analysis™ on your computer,
Chromebook™, or mobile device. If
using LabQuest, make sure
LabQuest App is up to date. See
www.vernier.com/ia for
Instrumental Analysis availability
or www.vernier.com/downloads to
update LabQuest App.
2. Charge your sensor for at least
2hours before first use.
3. Turn on your sensor by pressing the
power button once. The LED will
blink red.
4. Launch Instrumental Analysis or
turn on LabQuest.
5. If using Instrumental Analysis,
click or tap Polarimetry. If using
LabQuest, choose Wireless Device
Setup > Go Direct from the Sensors
menu.
1. If using a computer or
Chromebook, install Vernier
Instrumental Analysis. If using
LabQuest, make sure LabQuest
App is up to date. See
www.vernier.com/ia for
Instrumental Analysis availability
or www.vernier.com/downloads to
update LabQuest App.
2. Connect the sensor to the USB
port.
3. Launch Instrumental Analysis or
turn on LabQuest. If using
Instrumental Analysis, click or tap
Polarimetry. You are now ready to
continue your experiment.
Note: This sensor does not work with
the original LabQuest. It works with
LabQuest 2 or LabQuest 3.

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method is the most time consuming; however, it will result in
reproducibility of the angle of rotation measurement of ±0.1°.
5. A compound will consistently have the same specific rotation under
identical experimental conditions. To determine the specific rotation of the
sample, use Biot’s law:
α = [α] ℓ c
where αis the observed optical rotation in units of degrees, [α] is the specific
rotation in units of degrees (the formal unit for specific rotation is degrees dm-1
mL g-1, but scientific literature uses just degrees), ℓis the length of the cell in
units of dm, and cis the sample concentration in units of grams per milliliter.
6. To calculate a percent optical purity (or enantiomeric excess):
The value for the pure enantiomer can be obtained from literature or it can be
measured using a neat sample, considering the purity of that sample as described
by the manufacturer.
Calibrating the Sensor
You should perform a new calibration each time you power on the Go Direct
Polarimeter. Refer to the Using the Sensor section of this user manual for
additional instructions.
Specifications
Accuracy (optical rotation measurements) ±1°
Light source LED
Wavelength 589 nm
Care and Maintenance
Battery Information
Go Direct Polarimeter contains a small lithium-ion battery. The system is
designed to consume very little power and not put heavy demands on the
battery. Although the battery is warranted for one year, the expected battery life
should be several years. Replacement batteries are available from Vernier
(ordercode:GDX-BAT-650).
Storage and Maintenance
To store Go Direct Polarimeter for extended periods of time, put the device in
sleep mode by holding the button down for at least three seconds. The red LED
will stop flashing to show that the unit is in sleep mode. Over several months,
the battery will discharge but will not be damaged. After such storage, charge
the device for a few hours, and the unit will be ready for use.
from Sensor Information. In LabQuest App, Identify is accessed by tapping the
sensor meter, then tapping Go Direct.
Using the Product
Follow these steps when using the Go Direct Polarimeter when performing
optical rotation experiments.
1. Connect the Go Direct Polarimeter according to the Getting Started
instructions.
2. Calibrate Go Direct Polarimeter.
a. Pour distilled water or the appropriate solvent in the Go Direct
Polarimeter cell to a height of 10 cm. It is important to read the height to
the nearest 0.1 cm. Read to the bottom of the meniscus.
b. Place the cell in Go Direct Polarimeter and select Finish Calibration.
c. When the polarimeter is ready, select Done.
3. You are now ready to add your optically active sample into the polarimeter
cell.
a. Rinse the polarimeter cell with a few milliliters of your optically active
sample. Pour your sample into the polarimeter cell to a height of 10.0 cm
(1.00 dm). It is important to read the height to the nearest 0.1 cm. Read
to the bottom of the meniscus.
b. Place the sample cell in the polarimeter.
c. Start data collection. Data collection will stop automatically. Data are
stored automatically in Instrumental Analysis. In LabQuest App, you can
store a run by tapping the file cabinet icon on the graph screen.
4. Record the first angle closest to 0° where the illumination is at a maximum.
This is the observed angle of rotation for the optically active sample (α).
There are several ways to locate this angle.
lStatistics: To simply get the angle with the highest illumination,
highlight the peak of interest in Instrumental Analysis or LabQuest App.
In Instrumental Analysis, click or tap Graph Tools and select Statistics.
In LabQuest App, choose Statistics from the Analyze menu. Record the
angle value where the illumination is at a maximum, as presented in the
box. This method is the fastest and will result in reproducibility of the
angle of rotation measurement of ±2.0°.
lCosine Squared: To incorporate all your data into the fit, you can fit the
data to their true waveform, a cosine squared, in either Instrumental
Analysis or LabQuest App. In Instrumental Analysis, click or tap Graph
Tools and select Curve Fit. Then select cosine squared from the drop-
down list. In LabQuest App, choose Curve Fit from the Analyze menu.
From the list of available General Equations, select Cosine Squared. The
fit will run automatically. In this fit, the x-value corresponding to the
maximum y-value is obtained from the negative of the phase shift
parameter, –C. This is a nonlinear fit that undergoes numerous iterations
and may not converge, which may result in an unreasonable answer.
Make sure the resulting value is reasonable based on the data. This

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Troubleshooting
lDue to the nature of light transmission, it is important that the sample be
transparent and homogeneous. The sample can have a moderate amount of
color (up to OD of 2) but make sure it is not too dark to ensure that light
will still pass through it onto the detector.
lThe illumination value should not be used as a quantitative value for this
device. If you choose to use it for this purpose, note that this value is very
sensitive to change. These slight variations can be brought on by several
different variables in the sample including inhomogeneity (such as
particulates and bubbles), height of the sample in the cell, concentration of
the sample, and aberrations in the glass cell or pathlength.
lThe standard in polarimetry is to use a 10 cm pathlength. However, since it
is not always feasible to have this large of a sample volume, you can
accurately take readings with sample heights lower than 10 cm. To remain
within the ±1° accuracy of the device, keep sample heights between 2 cm
(~5 mL) and 10 cm (~ 25 mL). Outside of this region, there can be
deviations in the light path that decrease the accuracy of the detector.
lA package of four additional sample cells is available. Order code: CELLS-
POL.
For troubleshooting and FAQs, see www.vernier.com/til/10458
Repair Information
If you have followed the troubleshooting steps and are still having trouble with
your Go Direct Polarimeter, contact Vernier Technical Support at
[e-mail] or call 888-837-6437. Support specialists will work with
you to determine if the unit needs to be sent in for repair. At that time, a Return
Merchandise Authorization (RMA) number will be issued and instructions will
be communicated on how to return the unit for repair.
Accessories/Replacements
Item Order Code
Chemical Polarimeter Accessory Cells CELLS-POL
Go Direct 650 mAh Replacement Battery GDX-BAT-650
Micro USBCable CB-USB-MICRO
Warranty
Warranty information for this product can be found on the Support tab at
www.vernier.com/gdx-pol
General warranty information can be found at www.vernier.com/warranty
Disposal
When disposing of this electronic product, do not treat it as household waste. Its
disposal is subject to regulations that vary by country and region. This item
should be given to an applicable collection point for the recycling of electrical
and electronic equipment. By ensuring that this product is disposed of correctly,
Exposing the sensor to temperatures below –15°C or over 45°C will damage the
sensor. Additionally, temperatures over 35°C (95°F) will reduce the battery's
lifespan. If possible, store the device in an area that is not exposed to
temperature extremes.
Water Resistance
Important: Go Direct Polarimeter is neither waterproof, nor is it water resistant
and should never be immersed in water.
If any liquid gets into the device, immediately power the unit down (press and
hold the power button for more than three seconds). Disconnect the sensor and
charging cable, and remove the battery. Allow the device to dry thoroughly
before attempting to use the device again. Do not attempt to dry using an
external heat source.
Note: Damage due to liquids is not covered under warranty.
How the Sensor Works
Go Direct Polarimeter is a vertical polarimeter that uses an LED source, a fixed
polarizer, and a rotating polarizer (also called an analyzer) to detect changes in
rotation of plane-polarized light in the presence of an optically active
compound. Go Direct Polarimeter uses a light sensor and a bidirectional optical
encoder to detect the quantity of light passing through the sample at each angle
as the analyzer is rotated by a motor. A graph is produced that shows a clear
change in the light’s polarization with respect to angle. This allows the user to
determine various characteristics, including the identity, of the specific chemical
compound being investigated.
Incident non-polarized light is transmitted through a fixed polarizer that only
allows a certain orientation of light into the sample. The sample then rotates the
light at a unique angle. As the analyzer is turned, the rotated light is maximally
transmitted at that unique angle, allowing the user to determine properties of the
sample. A (+) enantiomer rotates the plane of linearly polarized light clockwise,
dextro, as seen by the detector. A (–) enantiomer rotates the plane counter-
clockwise, levo.

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Avertissement d’exposition RF: L’équipement est conforme aux limites d’exposition aux RF établies pour un environnement non
supervisé. L’antenne (s) utilisée pour ce transmetteur ne doit pas être jumelés ou fonctionner en conjonction avec toute autre antenne ou
transmetteur.
Note: This product is a sensitive measurement device. For best results, use the cables that were provided. Keep the device away from
electromagnetic noise sources, such as microwaves, monitors, electric motors, and appliances.
Vernier Software & Technology
13979 SW Millikan Way • Beaverton, OR 97005-2886
Toll Free [phone] • [phone] • Fax [phone]
[e-mail] • www.vernier.com
Rev. 12/15/2020
Go Direct, Graphical Analysis, LabQuest, and other marks shown are our trademarks or registered trademarks in
the United States. All other marks not owned by us that appear herein are the property of their respective
owners, who may or may not be affiliated with, connected to, or sponsored by us.
The Bluetooth®word mark and logos are registered trademarks owned by the Bluetooth SIG, Inc. and any use of
such marks by Vernier Software & Technology is under license. Other trademarks and trade names are those of
their respective owners.
you help prevent potential negative consequences on human health or on the
environment. The recycling of materials will help to conserve natural resources.
For more detailed information about recycling this product, contact your local
city office or your disposal service.
Battery recycling information is available at www.call2recycle.org
Do not puncture or expose the battery to excessive heat or flame.
The symbol, shown here, indicates that this product must not be disposed of
in a standard waste container.
Federal Communication Commission Interference Statement
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to Part 15 of the FCC rules.
These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment
generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause
harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If
this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and
on, the user is encouraged to try to correct the interference by one or more of the following measures:
Reorient or relocate the receiving antenna.
Increase the separation between the equipment and receiver.
Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
Consult the dealer or an experienced radio/TV technician for help.
FCC Caution
This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions:
(1) this device may not cause harmful interference and
(2) this device must accept any interference received, including interference that may cause undesired operation
RF Exposure Warning
The equipment complies with RF exposure limits set forth for an uncontrolled environment. The antenna(s) used for this transmitter must
not be co-located or operating in conjunction with any other antenna or transmitter. You are cautioned that changes or modifications not
expressly approved by the party responsible for compliance could void your authority to operate the equipment.
IC Statement
This device complies with Industry Canada license-exempt RSS standard(s). Operation is subject to the following two conditions:
(1) this device may not cause interference, and
(2) this device must accept any interference, including interference that may cause undesired operation of the device.
Industry Canada - Class B This digital apparatus does not exceed the Class B limits for radio noise emissions from digital apparatus
as set out in the interference-causing equipment standard entitled “Digital Apparatus,” ICES-003 of Industry Canada. Operation is subject
to the following two conditions: (1) this device may not cause interference, and
(2) this device must accept any interference, including interference that may cause undesired operation of the device.
To reduce potential radio interference to other users, the antenna type and its gain should be so chosen that the equivalent isotropically
radiated power (e.i.r.p.) is not more than that permitted for successful communication.
RF exposure warning: The equipment complies with RF exposure limits set forth for an uncontrolled environment. The antenna(s) used
for this transmitter must not be co-located or operating in conjunction with any other antenna or transmitter.
Le présent appareil est conforme aux CNR d’Industrie Canada applicables aux appareils radio exempts de licence. L’exploitation est
autorisée aux deux conditions suivantes :
(1) l’appareil ne doit pas produire de brouillage, et
(2) l’appareil doit accepter tout interférence radioélectrique, même si cela résulte à un brouillage susceptible d’en compromettre le
fonctionnement.
Cet appareil numérique respecte les limites de bruits radioélectriques applicables aux appareils numériques de Classe B prescrites dans
la norme sur le matériel interférant-brouilleur: “Appareils Numériques,” NMB-003 édictée par industrie Canada. L’utilisation est soumise
aux deux conditions suivantes:
(1) cet appareil ne peut causer d’interférences, et
(2) cet appareil doit accepter toutes interférences, y comprises celles susceptibles de provoquer un disfonctionnement du dispositif.
Afin de réduire les interférences radio potentielles pour les autres utilisateurs, le type d’antenne et son gain doivent être choisie de telle
façon que l’équivalent de puissance isotrope émis (e.i.r.p) n’est pas plus grand que celui permis pour une communication établie.