Fluorimeters for measuring fluorescent tracers in natural environments

Fluorimeters for measuring fluorescent tracers in natural environments

During a tracing test, visual observation is not always sufficient to detect tracer recovery or monitor how a tracer signal changes in water. A fluorimeter measures the intensity of the fluorescent signal and can identify concentrations that are difficult to distinguish with the naked eye. Used in the field or as part of a monitoring protocol, it can help confirm a hydraulic connection, measure transit time, compare several observation points or analyse a tracer breakthrough curve. Fluotechnik offers fluorimeters for consulting firms, hydrogeologists, laboratories, local authorities and researchers working on aquifers, rivers, springs, karst networks and catchment areas.

Fluorescent tracer detection

Detect the presence of a tracer in water, even when its signal is difficult to observe directly.

Tracer recovery measurement

Monitor the appearance, intensity and development of the signal at one or more control points.

Suitable for hydrological studies

Carry out measurements in aquifers, rivers, springs, resurgences, karst networks and other natural systems.

Compatible with different protocols

Select the equipment according to the tracer used, expected concentrations and monitoring duration.

Expert technical support

Fluotechnik helps you choose a fluorimeter suited to your tracing substance, study area and measurement objectives.

Fluorescent tracer detection

Detect the presence of a tracer in water, even when its signal is difficult to observe directly.

Tracer recovery measurement

Monitor the appearance, intensity and development of the signal at one or more control points.

Suitable for hydrological studies

Carry out measurements in aquifers, rivers, springs, resurgences, karst networks and other natural systems.

Compatible with different protocols

Select the equipment according to the tracer used, expected concentrations and monitoring duration.

Expert technical support

Fluotechnik helps you choose a fluorimeter suited to your tracing substance, study area and measurement objectives.

What is a fluorimeter used for in hydrological tracing?

A fluorimeter measures the light emitted by a fluorescent substance when it is excited by a suitable light source. During a tracing test, it can detect the tracer signal after injection and monitor its passage through the different control points.

The measurements obtained can help to:

  • Confirm a connection between two areas
  • Detect the arrival of the tracer
  • Monitor the development of tracer recovery
  • Determine transit time
  • Compare signal intensity at several points
  • Study tracer dispersion or dilution
  • Produce a tracer breakthrough curve.

A fluorimeter therefore provides more precise information than visual observation alone. It converts the fluorescent signal into data that can be compared and interpreted as part of the study protocol. The tracer and the instrument perform two distinct functions.

Sodium fluorescein, eosin, Rhodamine WT, Sulforhodamine B, Amino G Acid and sodium naphthionate are substances introduced into the environment. The fluorimeter detects and measures the signals they produce. However, not every instrument is suitable for every tracer. The wavelengths, measurement ranges and sensitivity of the fluorimeter must be compatible with the selected substance.

Our range of fluorimeters for tracing tests

Fluotechnik offers fluorimeters designed to detect and measure fluorescent tracers in water. These instruments can be used to monitor tracer recovery, compare several measurement points and observe how the signal develops during a hydrological or hydrogeological test. The choice depends on the tracer used, the expected concentration range, the required sensitivity, environmental conditions and measurement frequency.

Depending on the model, fluorimeters can meet different requirements:

  • Spot measurements in the field
  • Inspection of several observation points
  • Monitoring tracer recovery over time
  • Detection of weak fluorescent signals
  • Measurement of different tracer families
  • Integration into a more comprehensive monitoring system.

How do you measure a fluorescent tracer with a fluorimeter?

The quality of the results depends as much on the protocol as on the instrument itself. The tracer, control points, measurement frequency and environmental conditions must be defined before injection.

Step 1 - Define the objective of the test

Begin by identifying the question that the measurements should answer:

  • Is there a hydraulic connection?
  • When does the tracer reach the control point?
  • How long does tracer recovery last?
  • Do several flow paths need to be compared?
  • Is a spot measurement or prolonged monitoring required?
  • This objective determines the type of instrument and how the measurements should be organised.

Step 2 - Select a fluorimeter compatible with the tracer

The fluorimeter must be suitable for the signal produced by the substance. In particular, consider:

  • Excitation and emission wavelengths
  • The expected concentration range
  • The required sensitivity
  • The number of tracers used
  • Field measurement conditions.

In a multi-tracer protocol, the equipment must be able to distinguish clearly between the different signals being monitored.

Step 3 - Measure the background signal before injection

Before introducing the tracer, reference measurements should be taken at the different control points. This step identifies the fluorescence naturally present in the environment and provides a baseline against which post-injection measurements can be interpreted.

Step 4 - Prepare and calibrate the measurement

Depending on the instrument and protocol, calibration may be required to relate the signal intensity to a known concentration. Instrument settings, checks and reference solutions should be prepared under conditions consistent with those of the study.

Step 5 - Organise the measurement points and frequency

Measurements may be taken at a resurgence, watercourse, borehole, piezometer, outlet or any other potential tracer recovery point. The frequency should reflect the estimated transit time. Measurements taken too far apart may miss the passage of the tracer, particularly when recovery occurs over a short period.

Step 6 - Monitor the appearance of the signal

After injection, the fluorimeter can be used to observe:

  • The beginning of tracer recovery
  • The increase in signal intensity
  • The peak of the breakthrough curve
  • The gradual decline of the signal
  • The return to background levels

These data may be recorded through spot measurements or collected as part of a more regular monitoring programme.

Step 7 - Interpret the data in context

The values obtained must be analysed while considering:

  • Flow rate
  • Dilution
  • Possible rainfall
  • Distance between the points
  • Natural background fluorescence
  • Suspended matter
  • Measurement conditions
  • The calibration protocol

The fluorimeter provides the measurements, but their interpretation remains linked to the behaviour of the hydrological system being studied.

Why choose Fluotechnik for your fluorescence measurements?

Selecting a fluorimeter is not simply a matter of choosing the most sensitive instrument. The equipment must be compatible with the tracer, concentration range, field conditions and the way in which the results will be collected and analysed. Fluotechnik supports professionals in preparing measurement systems suited to hydrological and hydrogeological tracing tests.

Instruments designed for fluorescent tracers

Fluorimeters detect and measure the signals produced by substances used during tracing tests.

More precise measurement than visual observation

They can reveal a weak signal, monitor how it changes and make comparisons between several points easier.

Applications in hydrology and hydrogeology

These instruments support studies of hydraulic connections, tracer recovery, transit time and water circulation.

Different monitoring methods available

Depending on the model and protocol, a fluorimeter can be used for spot checks, measurement campaigns or longer-term monitoring.

Complementary tracers and equipment

Fluotechnik also offers fluorescent substances, data loggers and other equipment required to prepare a complete protocol.

Expert technical support

Our team helps you compare instruments according to the tracer, required sensitivity, field conditions and planned monitoring method.

Measuring fluorescent tracers in video

Discover how a fluorimeter can be used to prepare, carry out and monitor a water tracing test.

These videos provide a clearer understanding of:

  • Choosing the tracer and instrument
  • Measuring the background signal
  • Preparing the instrument
  • Calibration
  • Positioning the control points
  • Monitoring tracer recovery
  • Reading a breakthrough curve
  • Analysing the data collected
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FAQ about fluorimeters for fluorescent tracers

A fluorimeter is an instrument that measures the intensity of fluorescence emitted by a substance. In hydrology, it is used to detect and monitor a fluorescent tracer present in water.

It can detect the arrival of a tracer, monitor its recovery, compare several points, determine transit time and analyse how the signal changes over time.

Depending on the model, a fluorimeter may measure tracers such as sodium fluorescein, Rhodamine WT, eosin, Sulforhodamine B, Amino G Acid or sodium naphthionate. Compatibility between the instrument and the tracer wavelengths must always be checked.

Some instruments have several channels or configurations for monitoring different substances. This capability depends on the model, the fluorescent signatures and the protocol used.

The fluorimeter measures the fluorescent signal. The data logger stores and organises the values collected over time. The two instruments can work together, but they do not perform the same function.

Yes. Measuring the background signal before injection is important. It identifies the signal naturally present in the water and makes it easier to distinguish tracer recovery.

It can estimate or measure a concentration when the instrument has been correctly calibrated and the protocol accounts for environmental conditions. Raw signal intensity should not be interpreted as a concentration without suitable calibration.

Yes. Some models are designed for on-site measurements. The choice depends on autonomy, durability, installation method, environmental conditions and the required type of monitoring.

Natural fluorescence, turbidity, suspended matter, ambient light, temperature, pH and the presence of other substances can all affect the signal. These factors should be considered when preparing and interpreting the test.

Yes, depending on the model and associated equipment. For measurements recorded over a prolonged period, the fluorimeter can be connected to a data acquisition system or data logger.

The choice mainly depends on:

  • The tracer or tracers to be measured
  • The expected concentrations
  • The required sensitivity
  • The number of monitoring points
  • Measurement frequency
  • Installation conditions
  • Data logging or transmission requirements.

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Choosing a fluorimeter suited to your tracing protocol

A fluorimeter plays a central role when the objective is to detect and measure the recovery of a fluorescent tracer. It can monitor the signal over time, compare several points and provide more precise data than visual observation alone.

The choice of instrument mainly depends on:

  • The tracer used: sodium fluorescein, Rhodamine WT, eosin, Sulforhodamine B, Amino G Acid, sodium naphthionate or another substance
  • The wavelengths to be measured
  • The expected concentration
  • The required sensitivity
  • The environment being studied: aquifer, river, spring, resurgence, borehole or karst network
  • The number of control points
  • The measurement method: spot, repeated or continuous
  • The duration of the test
  • The available calibration options
  • Data storage and analysis requirements

For a short measurement campaign, an instrument intended for manual readings may be sufficient. Longer-term monitoring requires greater autonomy and may justify the addition of a data logging system. The choice must also take account of potential interference within the environment.

Water with natural fluorescence, suspended matter or several fluorescent substances may require a more advanced protocol. Fluotechnik supports you in selecting the fluorimeter, tracers and complementary equipment required to build a consistent measurement system.

Complete your measurement and tracing setup

A usable tracing test combines a suitable tracer, a compatible instrument and a consistent monitoring method. Discover Fluotechnik substances and equipment for preparing measurements, detecting tracer recovery and storing the data collected in the field.

Data loggers

Store your measurements and monitor their development throughout the test.
Data loggers
Connect your fluorimeter to a data logging system when the protocol requires regular or prolonged data collection.
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Sodium fluorescein / Uranine

Discover one of the fluorescent tracers most commonly used to monitor water circulation.
Sodium fluorescein / Uranine
Sodium fluorescein produces a characteristic signal that can be detected and measured using a compatible fluorimeter.
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Rhodamine WT 20 %

Choose a fluorescent tracer used in many hydrological protocols.
Rhodamine WT 20 %
Measuring Rhodamine WT requires a fluorimeter suited to its fluorescent signature, expected concentrations and study conditions.
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Eosin

Add another fluorescent signature to your tracing protocol.
Eosin
Eosin can be used alone or as part of a multi-tracer approach with equipment compatible with its signal.
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Sulforhodamine B

Use a wider range of substances to distinguish between several flows.
Sulforhodamine B
Sulforhodamine B can complement certain multi-tracer tests. Monitoring it requires a suitable instrument and measurement method.
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Amino G Acid

Discover a complementary fluorescent tracer for studies in natural environments.
Amino G Acid
Amino G Acid can be incorporated into certain hydrological protocols when its signature and the available equipment meet the requirements of the study.
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