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TD-700 Laboratory Fluorometer FAQ

What does the letter that is etched on the silver part of the lamp stand for?

Q = Quartz
A = Blue
BL = Near UV
CW = Cool White
D = Daylight

What is the sensitivity of the TD-700?

The TD-700's sensitivity is defined in terms of the minimum detection limits of various analytes.  The TD-700 can detect:


Do I adjust the sensitivity with a gain knob or switch?

With the TD-700, there is no need to use a gain knob or switch.  Upon calibration, the TD-700 will electronically set the optimal sensitivity for your samples.

What is the linear range of the TD-700?

The linear range, as with sensitivity, depends on the analyte being measured.  The TD-700's linear range for Chlorophyll a and Rhodamine WT are as follows:
Chlorophyll a: 10 ppt (0.01 µg/L or 0.01 ppb) to 250 ppb (using a 13 x 100 mm test tube). Rhodamine WT: 10 ppt to 100 ppb (using a 25 x 150 mm test tube).

Does the instrument attach to a printer?

Yes.  The TD-700 can be used with any RS-232 serial printer.

Do I need a special printer cable?

A standard 9 to 25 pin serial cable should be used.

How do I collect data from the TD-700 and use it in my computer? Do I need the data collection software?

You can use various communications software packages to transfer data from the TD-700 to your computer.  The signal is sent from the TD-700 in ASCII format.  If you have Microsoft Windows on your computer, data can be collected and stored in a file using Hyperterminal. Simply connect the 9-pin cable included with the TD-700 to the RS-232 serial port on the back panel of the instrument.  Then connect the other end of the cable to the serial communications port on the back of your computer (you may need a 9-25 pin serial adaptor to do this).  Step by step instructions on how to collect data are on page 39 of the TD-700 Operations Manual.

What size test tubes/cuvettes can I use? How do I decide which ones to use?

The TD-700 can accommodate 25 x 150 mm test tubes, 13 x 100 mm test tubes, 10 x 10 x 45 mm cuvettes, minicells, or capillary cells.  The size and material of your test tube or cuvette will depend on your analysis.  For example, 13 x 100 mm test tube is typically used for chlorophyll analyses.  Certain materials transmit specific wavelengths of light better than others, so your analyte's excitation and emission wavelengths will determine the best material for your sample tube.  Glass tubes and cuvettes work fine for most analyses.  Quartz cuvettes are required for excitation wavelengths below 330 nm.  Methacrylate cuvettes are used for analytes fluorescing down to 330 nm.  With regard to size, the greater the diameter of the test tube, the greater the sensitivity achieved (the lower the minimum detection limit).

What size sample tube/cuvette is standard with the TD-700?

It depends on the configuration of the TD-700 you order. The TD-700 equipped with a standard PMT, (P/N 7000-009), comes with a 10 x 10 mm cuvette holder as standard.  Other tube adaptors may be purchased separately. The TD-700 equipped with a red-sensitive PMT, (P/N 7000-000), comes with the 13 x 100 mm and 25 x 150 mm adaptors as standard.  In this case, the 10 x 10 mm, minicell, or capillary cell adaptors may be purchased separately.

How easy is it to switch between different size test tubes/cuvettes?

The adaptors quickly and easily slide in and out of the TD-700 sample compartment.  Notches on the adaptors and sample compartment enable quick and easy alignment.  Sample adaptors can be switched in seconds.

Do the sample tubes/cuvettes require minimum volumes? If so, what are they?

Sample tubes do require minimum volumes so that enough sample is exposed to the incoming light. The minimum volumes are as follows:=
10 x 10 mm adaptor with short aperture 10 x 10 mm (3.5 ml) = 2.0 ml
10x10 mm adaptor with Minicell or 75 µl capillary cell = 3 µl
13 x 100 mm adaptor with 13 x 100 mm = 3.6 ml
25 x 150 mm adaptor with 25 x 150 mm = 30 ml

What sample tubes/cuvettes, if any, can I order from Turner Designs?

The following sample tubes and cuvettes are available for purchase from Turner Designs:

10 x 10 mm Square Glass Cuvette (3.5 ml) P/N 7000-955
10 x 10 mm Square Quartz Cuvette (3.5 ml) P/N 7000-956 (For transmission >200nm)
10 x 10 mm Square Polystyrene Cuvette (3.5 ml) P/N 7000-957
10 x 10 mm Square Methacrylate Cuvette (3.5 ml) P/N 7000-959 (For transmission >300nm)
13 x 100 mm Round Glass Test Tubes P/N 10-031
13 x 100 mm Round Quartz Test Tubes P/N 10-299 (For transmission >200nm)
25 x 150 mm Round Glass Test Tubes P/N 10-028A

Why are there two lamp options? When would I use a quartz halogen lamp over the mercury vapor lamps?

Turner Designs offers both a quartz halogen lamp and application specific mercury vapor lamps with the TD-700 in order to give customers ultimate flexibility in configuring the fluorometer for their specific needs.  The quartz halogen lamp irradiates the sample with a broad range of light, operating best at wavelengths above 400 nm.  This broad range of light allows the user to analyze many different analytes without a lamp change.  The less expensive mercury vapor lamps emit a narrow band of light. Turner Designs sells mercury vapor lamps for chlorophyll, rhodamine, and hydrocarbon measurement.  For multiple applications, the user could purchase several mercury vapor lamps but would need to switch lamps between analyses.

What are the lamp lifetimes? Can I order replacement lamps?

The average life of a mercury vapor lamp is 8000 hours.  The average life of the quartz halogen lamp is 2000 hours.  Yes, you can order replacement lamps from Turner Designs. They are as follows:
Quartz Halogen Replacement Bulb 7000-970
Daylight White Mercury Vapor Lamp 10-045
Clear Quartz Mercury Vapor Lamp 10-046
Near UV Mercury Vapor Lamp 10-049
Blue Mercury Vapor Lamp 10-089
Cool White Lamp 10-047

How would I know that the lamp needed to be replaced?

It is advised that you check the lamp periodically, especially toward the end of its lifetime.  For the mercury vapor lamp, check the viewport on the back of the lamp panel.  If it needs to be replaced, the lamp will flicker.  Please note that if you remove the lamp panel to check the lamp, the lamp will automatically shut off for safety reasons, so using the viewport is advised.  The quartz halogen lamp can be easily checked through the viewport.  The quartz halogen lamp does not flicker, it will be off when it needs replacement.

When would I use a TD-700 with a red-sensitive PMT?

The red-sensitive PMT has a wider range of detection than the standard PMT.  The red-sensitive tube can detect fluorescence emission from 185 nm to 870 nm, while a standard tube detects fluorescence emission from 300 nm to 650 nm.  Certain analytes, such as BTEX and Chlorophyll a, fluoresce outside the range of the standard tube and require the red sensitive PMT.  If your analyte fluoresces between 185 and 300 nm or between 650 and 870 nm, you will require a red-sensitive PMT.

If I have a TD-700 with the red-sensitive photomultiplier tube (PMT) can I use it for other applications? How does the red tube affect the other applications?

Rhodamine is the only application that is affected by the red-sensitive photomultiplier tube, please be sure to specify which PMT you have when ordering optical kit replacements.  The red-sensitive tube will not affect the other applications.  You will simply have a wider range of light detection with the red photomultiplier tube.

Tell me about the TD-700's calibration procedure.

The TD-700 calibration procedure sets the instrument's range and sensitivity based on a fluorescent sample or standard.  The instrument can be calibrated using a single or multi-point calibration.  For direct concentration readout and samples requiring highly accurate measurement, the multi-point calibration procedure is used.

How often do I need to calibrate the TD-700?

For greatest accuracy, calibrate before running a new batch of samples.
- Recalibrate if the ambient temperature changes by ± 5 degrees °C.
- Recalibrate after changing lamps, filters, cuvette sizes, or the analyte you are measuring.
- Verify the need to calibrate by reading a stable, known concentration standard immediately after calibration and again every few hours to see if the readings have changed significantly.  - Recalibrate when the accuracy becomes unacceptable for your study.

Is it possible to upgrade the PMT in our TD-700?

If your fluorometer has a standard PMT and you would like to have it upgraded to a red sensitive PMT, Turner Designs does offer this service.  For pricing and lead time information please contact Turner Designs at 1-877-316-8049.  If you are unsure if your PMT is red sensitive, you can contact Turner Designs Technical Support for assistance.  The red sensitive PMT is commonly used in Chlorophyll applications and some near UV applications as well.

What can you use to clean the fluorometer filters?

To clean the filters in the TD-700 you can use a combination of lens tissue and molecular lens cleaner.  One brand is Purosol

Is there an emission filter that I can use for filtering out DOM when checking for Optical Brighteners?

We carry a 436 nm peak ± 10nm bandwidth filter, the part number is 034-0392.  This filter can help reduce the interferences under some circumstances.  For pricing and availability contact Turner Designs at 1-877-316-8049.

How do I install the Rhodamine Optical Kit Filter in the TD-700?

If you are using a TD-700 with a red sensitive PMT, place the blue filter 10-058R in the cylinder first then the orange 10-052R on top of it, then secure it with a quad ring. If you are using a TD-700 with a standard PMT place the blue filter 10-058R in the cylinder then secure it with a quad ring.

Which way do I install a mirrored filter in the TD-700?

Turner Designs recommends installing the mirrored side facing towards the lamp to help reflect excess heat from the lamp.  If both sides of the filter have mirrored sides, use your best judgment on which side seems most reflective.  The difference in performance is extremely subtle and will not be significant to your readings.  In the case of the Excitation filter the mirrored side should be facing the lamp and with the Emission filter the Mirrored side should face the sample.  The key is to make sure you replace the filters as they were in order to ensure consistency in your readings over time.

What could cause a decreasing Acid Ratio on TD-700?

If the fluorometer lamp is failing or it is the incorrect type, it can dramatically change the acid ratio.  For example, a customer used a UV lamp in the TD-700 instead of a daylight white lamp.  The result was a 50% reduction in the acid ratio.  If a sudden change is noted in the acid ratio the first things to check are the lamp and filters.  Check to make sure that the excitation and emission filters are in the correct positions and that the lamp is on and it is the correct part number for your application.

What Individual filters are available for the TD-700


I have been requested to perform chlorophyll analysis in samples with very high algae biomass. As long as the calibration curve is set for such high values, is the equipment (and the fluorometric method) adequate for high chlorophyll reading?

Yes, the fluorometer is capable of reading up to these levels assuming the instrument has been calibrated in such a way to provide the dynamic range you need.  There will be a point when the readings become non-linear.  As long as you can calibrate the instrument with several points in this non-linear range, the instrument will provide accurate results.  You can use up to five calibration standards with the TD-700.  This allows you to calibrate the instrument beyond the linear range.  For example, if you want to calibrate to 500µg/l, you could use 20, 100, 250, 400, and 500 µg/L standards.  This would allow the instrument to create a calibration curve and automatically correct unknown samples that are beyond the linear range of the instrument.  Of course you could do this manually as well if you chose to, in which case you would only need to use one standard that is within the linear range of the instrument when calibrating.

What causes a high sensitivity reading on the TD-700?

A high sensitivity 'condition' can occur when no light reaches the detector.  Ideally, you want the % sensitivity to be in the range of 15% to 40%.  If you are using the minicell, up to 60% is acceptable.  There are a few possibilities for experiencing a high sensitivity listed below.

•    The lamp is not on or not installed.  Check the back panel of the TD-700 to see if there is any light shining through the lamp port.  If not, check the lamp.  Make sure that the lamp pins are fully seated in the upper/lower socket connections.  Also, the lamp will not turn on if the 'black' latches on the back of the TD-700 lamp door are not fully pushed in.  There is an interlock switch that prevents the lamp from energizing if the lamp door is not installed correctly.

•    The 10x10 cuvette sample adapter is in backwards.  Notice on the top of the adapter where you hold it that one side is in the shape of an arrow.  This must point to the left, toward the silver dot on the TD-700.  If it is pointing to the right you will see this error message.

•    The filters and or filter cylinder are not installed correctly.  Excitation and Emission filters are reversed or you are using the wrong lamp.  If the filters are installed correctly, make sure the filter cylinder is installed so that the letter matching the position where the filters are installed is upright and located on the left edge of the filter cylinder aligned with the silver dot on the TD-700.
r range of the instrument when calibrating. 

What can I do if the TD-700 Lamp will not illuminate?

Here are some things to check if the lamp on your TD-700 will not come on.  
•    Make sure that the lamp is properly seated.  If the lamp is not properly seated, it will not illuminate.
•    If you have a spare lamp you should try the spare.
•    The TD-700 is equipped with a kill switch safety device that is designed to eliminate accidental exposure to UV light.  If you have equipped your TD-700 with a UV lamp use extra caution to avoid eye contact with UV light.  The kill switch is deactivated by a nylon plunger assembly that secures the lamp cover and fan assembly to the back of the TD-700. The nylon plungers are designed for durability but over time, especially if the lamps are changed often, they may wear out.  The top plunger assembly is the one that actually holds the switch in the closed position.  If one or both plunger assemblies have worn out you can order these replacement parts from Turner Designs accessory department at 1-877-316-8049.  A picture below shows the location of these two components.  Observe all proper electrical safety regulations when replacing the plunger assembly. Do not work on energized equipment.



Is there any document available if I want to diagnose issues with my TD-700?

Please refer to the TD-700 Service Manual

How do I reset the memory of the TD-700?

Note – Resetting the NVRAM will refresh the memory and put all the values and calibration back to the original default settings.  This can sometimes resolve unexplained problems due to a random corruption in the memory.

1) Turn on the TD-700 and press the ESC key
2) Press the Ent key
3) Press the * key
4) Enter the ID number, 1962
5) Press the Ent key 3 times, until the display shows 1:Reset NVRAM
6) Press the 1 key
7) Press the 0 key repeated for 10 times
8) The display will change to the startup screen.
9) Press ESC key, select the Calibration Mode you had used previously and check the TD-700 for normal operation.

What concentrations of Fluorescein can be detected with the TD-700?

The Model TD-700 (PN 7000-009) equipped with the Fluorescein Optical kit (PN 10-086R) will detect Uranine and Fluorescein dyes in the linear range of concentrations of 0.1 to 300 µg/L using either 10 mm square cuvettes or 13 x 100 mm round test tubes.

The 7000-009 comes equipped with an Adaptor for 10 mm square cuvettes.
If you want to use 13 mm Round tubes, then you need to also order the PN 7000-981, 13 mm Test tube adaptor.  These adaptors are inserted into the TD-700 so that you can easily interchange between both sizes.  The minimum sample volumes for the 10 mm square cuvettes is 2 mL and for the 13 mm tubes is 3.6 mL.

One last note, the pH of the samples can impact the sample’s fluorescence signal, but the pH of the sample can be adjusted to reverse this effect, if required.
Fluorescein is more pH-sensitive than Rhodamine dyes.  Fluorescence drops very sharply at pH values below 6.5.  For optimum results, pH should be between 6.5 and 10.

Can I use the TD-700 Solid Secondary Standard for the Phycocyanin Application?

The Solid Standard Part number 7000-994 can be used for the Phycocyanin application.  To Purchase this accessory for your TD-700, contact Turner Designs at 1-877-316-8049.