Improve the accuracy and repeatability of your measurements, especially at low concentration levels in or out of the field.
Example Setup of a Little Dipper 2 or Handheld Little Dipper
Using a glass beaker or container
Note: A cost-effective method of getting a dark container is using a spare glass container and wrapping with black electrical tape.
Use a non-fluorescent container for your water samples. Note: Certain Plastics may fluoresce and interfere with the sample’s fluorescence.
If using a glass container, place the container on a non-reflective black surface.
Ensure that the probe is more than 3 inches above the bottom of the container.
Ensure that the probe is in the center of the container and has more than 2 inches clearance between the circumference of the probe and the inside surface of the beaker.
Take measurements
Example images below to help with visualization
Using a different instrument to show the impact of using a clear container versus a dark container on readings:
Notice the amount of orange light being reflected back up to the sensor and the body of the instrument.
Notice how there is less glare in the image below:
Here are some images of the Handheld Little Dipper and Little Dipper 2 in a clear container. Notice how the ambient light drowns out the UV being emitted from the sensor face.
It is recommended to use a large enough container capable of allowing at least 3 inches from the sensor face for a submersible to have enough clearance for a reading.
Example image below of a Little Dipper 2 before being inserted in a 1 liter beaker:
Before making the instrument completely vertical, it is advised to angle the Little Dipper 2 in before straightening up to allow air bubbles to escape.
Using Shade Cap Accessories
If available, a shade cap in use with the submersible instruments is a valuable asset. Be sure that there is enough water to fully submerge the shade cap as well as the optical face of the sensor for accurate readings. We recommend use of the shade cap as it provides a fixed distance for sample measurement and minimizes affects from ambient light. The Shade Cap also offers protection for the optics and prevents damage from deploying, recovering, or transporting the instrument in fast-flowing environments, and/or from bottoming out in shallow environments
Instructions for the Handheld Little Dipper Shade cap can be found on the user manual: 998-2853.pdf
Instructions for the Little Dipper 2 and the mounting Plumbing Tee can be found here: Microsoft Word - 998-2820_LIT_SPEC.doc
Best practices for Calibration Setup
Calibration setup: Calibrating to deionized or ultrapure water and calibration standard or sample of known concentration.
Calibration standards that work with our Handheld Little Dipper or Little Dipper 2 are the PTSA calibration standards on our website or specific dilutions of PTSA from powder with this name PTSA (1,3,6,8-pyrene tetrasulfonic acid tetrasodium salt) with specifications that match our Safety Data Sheets: Technical Support | Turner Designs | United States
Fluorescent additives that are included in a solution other than PTSA and deionized water does not have the same effect that which our sensors are calibrated to, and Will Underreport fluorescence.
We offer our customers the calibration solutions of 100 ppb or 400 ppb of PTSA. For pricing, please visit our product pages and select the accessory to get pricing or request a quote:
Little Dipper 2: Little Dipper 2 In-Line Fluorometer | Turner Designs | United States
Handheld Little Dipper: Handheld Little Dipper Fluorometer | Turner Designs | United States
Fill the container enough that there are more than 3 inches of water from the bottom.
This will ensure that you are able to completely submerge the optical face of the sensor and still have the recommended 3 inches of water above the bottom of the container. If you are using the shade cap you want to be sure that there is enough water to fully submerge the shade cap as well as the optical face of the sensor.
Example image of a clear beaker below for clarity and the recommended for calibration - darkened beaker fully filled to the brim:
Shade caps used on the Handheld Little Dipper can ignore the requirement needed for 3 inches away from the sensor and the ambient light problem as seen below with a 500 mL clear beaker. However, ensure there is enough water for the instrument to be submerged to the stop line.
Fill another glass container with the Calibration Standard and set aside. This container should also be filled with roughly the same volume of standard as the blank container.
Ensure inserting the sensor into the container is done at an angle and then straightened up to prevent air bubbles from being trapped.
Now your setup is ready for sample analysis or calibrating the instrument for your needs.
Note: Rinse submersible sensor down if using calibration solution of different concentrations or wipe clean between new solution readings to keep cross contamination risk low.
Little Dipper 2 and Handheld Little Dipper Maintenance
Feel free to watch our quick video on how to maintain your Little Dipper 2: https://www.youtube.com/watch?v=rgpxLgW025c
The Little Dipper 2 and Handheld Little Dipper should NOT come into contact with any organic solvents or strong acids and bases.
There are three messages that will display during use of the Handheld Little Dipper, “td” for Turner Designs, “Lb” for Low Battery, and numerical readings from 0-199.
Rinsing with fresh water and drying the instrument thoroughly with a non-abrasive cloth after use is recommended.
Visual inspection of the optical face for fouling should be done on a regular basis.
To inspect the optical face on the Handheld Little Dipper, remove the cap. To check the optical face on the Little Dipper 2, remove from the plumbing tee.
Check for sensor light by holding a white cloth or piece of white paper while instrument is plugged in for the Little Dipper 2 or press the read button on the Handheld Little Dipper. Image below for reference.
If there is any noticeable fouling, use a soft bristle brush or non-abrasive cloth and soapy water to clean the optical window. Rinse thoroughly.
Do not expose the Little Dipper 2 or Handheld Little Dipper to temperatures outside the specified range of 5 to 40 °C or damage may occur to the unit that will not be covered under warranty.
Avoid placing heat sources near the Little Dipper 2, Handheld Little Dipper, or calibration solutions. While our instruments can withstand 0–50°C, they perform best at room temperature to prevent unnecessary strain and solution evaporation.
Do not use the Handheld Little Dipper or the Little Dipper 2 instrument under water.
The Handheld Little Dipper sensor works best when partially submerged below the Stop line. Going past the stop line will flood the sensor with water.
The Handheld Little Dipper and Little Dipper 2 is intended for use with water. Use in alcohol or other corrosive solutions may ruin the integrity of the housing on the unit or affect the fluorescent response of the instrument.
What should the sensor face on the Little Dipper 2 (LD2) or Handheld Little Dipper (HHLD) look like?
Sensor face should be clear and the filter lenses inside should not be cloudy.
Here is an image of the Little Dipper 2:
Here is an image of the Handheld Little Dipper:
Here is an image of a Little Dipper 2 whose sensor face has started to have buildup behind the lens:
This would be a degraded sensor and would not read accurately due to the lifting of the edges from the buildup.
Here is an image of a Little Dipper 2 whose filter is clouded over and can no longer fluoresce properly:
Is there a difference in readings between each of the individual Little Dippers?
While all the little dippers are factory set to be similar. Users that buy our instruments are always recommended to do their own calibration to reflect measurements taken for their specific applications, at their facility with the water system that they have. From that point, it is based entirely on the liquid calibration standards used to standardize the readings of the instrument and then measured against the standard to see if it is within +/- 5 %. However, the machine can also tell you if your liquid standard is expired considering if the repeated readings result in an average and standard deviation that are consistent. In short, all of the Little Dippers will read between +/- 5%.
Is there a way to determine if my Little Dipper 2 is off without using the computer software?
Yes there is a way to verify whether the Little Dipper 2 is reading correctly without using the Little Dipper 2 computer software! Using the software allows you to recalibrate afterwards should you find the results with the multimeter to be outside of expected performance. Instructions come from Microsoft Word - 998-2820_LIT_SPEC.doc
Connect our calibration cable and power supply which is from PN 2820-505 or use the bare lead wires from PN 021-2800 and a 12 V power source.
For bare lead wires from the connection cable for the Little Dipper 2, follow our instructions to connect to a power supply and multimeter.
When the Little Dipper 2 is connected, check to see if the multimeter reads between 4.0-4.3 mA when reading air (point instrument down and away from light sources)
Verify that it reads the same in deionized water.
If the instrument reads differently in your deionized water, try getting another source to verify whether your water was contaminated.
Do the same steps with the Little Dipper 2 in 100 ppb of PTSA calibration solution. Instrument should read within the tolerance range of 9.5-9.99 (if 10.0 or higher recalibrate for solution)
After blank and solution is verified remove Little Dipper 2 from solution and wipe with a clean, non-abrasive cloth or deionized water.