Introduction: Letter from the Director of Sales & Marketing
In the Spotlight: Cyclops-7 Submersible Fluorometer
Jim's Corner: SCUFA Battery Capacity
International Distributors: Our List of International Distributors
Technically Speaking: Response Curve Linearity & Quenching
Upcoming Events: Dye Tracing Seminar in the United Kingdom

Real-time monitoring is clearly the way of the future in the world of environmental monitoring. Advances in satellite imagery, remote sensing from aircraft and ships, developments in data telemetry, in-situ sensor platforms, power management, bio-fouling prevention, etc... have all lead to where we are today; an age where real-time monitoring is becoming a realistic and accessible technology. The goal now is to provide sensors that can maintain calibration over longer periods and changing environment, prevent bio-fouling and decrease power consumption, size and cost.

The power of real-time monitoring is data, data and more data. Rather than using a very small number of temporal and spatial data points to infer the state of an environment, we can now dramatically increase our confidence in our measures of the environment by filling in the data gaps through 'continuous' monitoring. This technology not only allows us to develop a clearer and more complete understanding of natural systems but can also provide early warnings of environmental problems or dangers, allow for better decisions to be made in manipulation of natural resources and better measure impacts of natural and un-natural events on the environment.

Realizing this renaissance in environmental technology, Turner Designs is proud to introduce the next generation of in-situ sensors that have been specifically designed for integration into monitoring platforms. The Cyclops-7 Submersible Fluorometer is an extremely small, energy efficient, analog sensor that has been designed to meet the new challenges of real-time monitoring. The Cyclops-7 is a very flexible platform that can be easily configured for a wide range of applications. I encourage you to contact us if you have a custom fluorescence application and would like more information or a quote on the Cyclops-7.

Yours truly,
Rob Ellison
Director of Sales and Marketing

In The Spotlight - Cyclops-7 Submersible Fluorometer

Product Description
The Cyclops-7 line of submersible fluorometers is designed for integration into multi-parameter platforms requiring a high performance, compact sensor at a significantly lower price than traditional submersible fluorometers. The Cyclops-7 combination of price, performance and size make the sensor very attractive for oceanographic and dye tracing applications.

Although small, the sensor does not compromise measurement performance including sensitivity and dynamic range. The excellent turbidity rejection ensures superior detection limits in a wide range of environmental conditions.

The sensor requires an external power source, and delivers a standard 0 - 5V output voltage to an external data logger. The Cyclops-7 Model 2100 is an analog fluorometer that has three gain settings that can be automatically set by an external controller. The Cyclops-7 fluorometers can be factory configured for a wide range of fluorophores including chlorophyll a and rhodamine WT, or custom versions.

Pigtail Accessory Provides Standalone Operation
The Cyclops-7 sensors are provided with a pigtail cable so they can be tested and operated independently. The pigtail cable enables connection of a power supply; a multi-meter to read the sensor output voltage, plus sensor gain setting connections. Contact your CTD supplier for Cyclops-7 mounting and connection kit information.

Optional Secondary Standard Provides Stability Check
Turner Designs unique Secondary Standards provide a simple and quick way to check for correct operation of the sensor. The Secondary Standard can be adjusted so that when attached to the sensor, the sensor generates a desired output voltage, normally the voltage corresponding to a known chlorophyll or dye concentration.

Cyclops-7 stability can then be quickly and easily verified at a desired later time by measuring the sensor output voltage with the same secondary standard.

Key Cyclops-7 Features:

• Extremely small size (4.25" x 0.8")
• Affordable price / excellent value
• Very low power consumption
• Dynamic Range: (0 - 1,000 ug/L chl a, 0 - 1,000 ppb RWT)
• Excellent turbidity rejection
• Continuously updated output voltage
• Chlorophyll and dye tracing options

For a detailed specification sheet, please click on the following link for the Cyclops-7 data sheet.

Question:
Does the SCUFA's Submersible battery have enough capacity to provide power for over 30 days when deployed at a remote site ?

Answer:
The SCUFA goes into a sleep mode between logging intervals to conserve power. The battery has enough capacity to power the SCUFA until the Internal Data Logger memory is filled. For example, if a sampling rate of 5 minutes is selected, the SCUFA will log data for 40 days until the memory and battery power are used up. The data stored in the SCUFA memory is retained and can be downloaded to a PC whenever the SCUFA is retrieved.

Turner Designs has selected distributors in the following countries to provide local sales support and ordering convenience for our international customers. Please contact them for further information on our range of fluorometers.

If your country is not listed, please contact Turner Designs directly.

Technically Speaking, It All Adds Up...
is a series of articles for people who want to obtain the best possible results from their fluorometer. Last month Technically Speaking described how fluorometers can be used for flow measurements using Rhodamine dye. This month's article will discuss the importance of knowing where your readings fall on the fluorophore response curve. It will summarize how to optimize the accuracy of your results by ensuring you are in the most linear part of that response curve.

Sometimes, fluorometer readings do not change in step with the known concentration change of the fluorophore. The factor that may be responsible for this is called "concentration quenching", or sometimes just "quenching".

At low sample concentrations, the fluorescence intensity is directly proportional to the sample concentration. As the concentration increases beyond the linear range for fluorescence, an effect known as "concentration quenching" occurs. At these concentration levels, the sample starts absorbing so much light that the light cannot pass through the sample for detection, "concentration quenching" is occurring, see the representative graph below.

Refer to the specifications of the sensor you use for the maximum concentration that can be measured in the linear region. For example, the new Cyclops sensor is specified for a maximum concentration in the linear region of 1,000 ppb for Rhodamine WT dye.

For best accuracy, unknown samples should be tested for being in the linear part of the response curve by noting the reading for the sample, then diluting the sample by a factor of 10, and noting the new reading which should then be a factor of 10 lower. The need to do this applies even if the initial value appears to be in the linear range, see (1) below. There are 3 possible scenarios.

1. If the fluorometer reading increases when measuring the diluted sample, then the concentration was high enough to be in the sample quenching region, and the initial concentration value was invalid. In this region, there is a reversal of fluorometer readings, that is: diluting the concentration strength increases the displayed reading. Dilute by a factor of 10:1 again, and note if this time the reading decreases by a factor of 10:1. Repeat until the sample concentration is in the linear range.

2. If the fluorometer reading decreases, but not by a factor of 10, then the concentration level is outside the linear region, but could be accurately read by generating a "calibration curve" for the sample/test configuration and applying a correction factor.

3. If the fluorometer reading decreases by a factor of 10, then the initial sample concentration was within the linear range and was accurately read.

For (1) and (2) above, the final fluorometer reading should be multiplied by the dilution factor to obtain the absolute sample concentration.