Overview
Optical Brighteners (OBAs) or Fluorescent Whitening Agents (FWAs) are added to products such as laundry soaps, detergents, and cleaning agents. They adsorb to fabrics or materials during the washing or cleaning process and when illuminated by ultraviolet light they fluoresce and make products and fabrics appear brighter.

Laundry wastewater is the largest contributor of brighteners to wastewater systems. FWA or OBA contributions to the total volume of most laundry detergents are less than 0.5%, however a large portion (up to 80%) can remain in discharged wastewater as dissolved compounds (molecular). The presence of brighteners in water systems, to which wastewater is being discharged, could mean failing septic systems, sewage leaks, or complete lack of water treatment. Therefore, detection of Optical Brighteners in aquatic systems can help water municipalities or researchers correct system failures and avoid increased anthropogenic input that may greatly impact ecosystems.

Fluorescence Methods
There are various sample processing methodologies for Optical Brightener determination; the underlining factor among them is that fluorescence is mandatory for the determination of brightener absence or presence.

There has recently been increased interest in detection of brighteners in natural water samples. This interest might be largely due to the potential public health risks that may be avoided by evaluating brighteners in the natural environment.

Turner Designs recently developed and released a new Trilogy Optical Brightener Module (PN 7200-047) that can be used to detect the presence or absence of Optical Brighteners in water systems.

Water quality is currently being assessed by fecal coliform standards through federal, state, and municipal agencies. Studies have shown that there is a correlation between Optical Brightener concentrations and fecal coliform levels. The Optical Brightener Module, when calibrated, can be used to determine Optical Brightener concentrations which can be correlated to coliform levels. Correlating Optical Brightener concentrations to fecal coliform levels can provide valuable information to help researchers determine if contamination sources are attributed to human waste.

Trilogy Optical Brightener Test Data
The Trilogy Laboratory Fluorometer with Optical Brightener Module was tested to determine linearity, range, and detection limits. Optical Brighteners are added to detergents; however manufacturers of these detergents do not state the brightener concentration on the product label. Three different detergents were compared (Tide, Tide with Downey, and Good Day Laundry detergent with Bleach) to show how concentrations of brighteners can vary among different or similar detergents.

Table 1: Brightener limits can vary among different or similar detergents.

Figure 1: Linear range for Tide with Downey is plotted showing the linear range and dynamic range for detection of this detergent. r₂ = 0.99 for linear regression.

Oil Spill Response teams evaluate Turner Designs' C3 as an alternative method of in situ detection

Special Monitoring of Applied Response Technologies (SMART) is a cooperatively designed monitoring program. The SMART protocol uses small efficient teams of trained personnel with rugged and easy to use field instruments. Hydrocarbon concentrations are monitored for reaction to the addition of dispersants and the use of burning techniques. The crude oil concentrations are monitored using fluorescence. The fluorometer used to monitor the dispersed oil is an essential part of the SMART process. The new C3 Submersible Fluorometer is under evaluation for integration into this system. In addition to the 10-AU-005-CE Field Fluorometer, the C3 will provide a powerful, easy to use and deployable in situ system. The C3 has a robust memory of 480,000 data points, automatic gain control and proven optic configurations ported from our Cyclops-7 line of products.

Image 1: Brian Parscal, Project Specialist for the Clean Island Council, and crew conducting tests using the C3 in Alaskan waters. (Photo provided courtesy of Brian Parscal)

Initial testing was done using the Cyclops-7 (C-7) Submersible Fluorometer. The package that was put together consisted of the Cyclops-7 sensor, an analog/digital converter and a laptop computer. Testing was conducted at Ohmsett and indicated that the Cyclops-7 optics were suitable for tier II and III of the SMART Program. Data from the C-7 was compared with the data from the Strike Team's 10-AU. A very close correlation was made between the instruments' measurements. This test illustrates the potential for in situ fluorometry within the SMART protocol. Below: Figure 1 is a laboratory comparison of the C7 & 10AU's performance and Figure 2 is a comparison of their field data.

Figure 1

Figure 2

Initial field testing with the C3 was conducted as part of the Cook Inlet Area Wide Exercise in September of 2008. John Whitney (NOAA), John Engles (Alaska DEC) and Brian Parscal (Clean Island Council) conducted a SMART exercise on board a USCG Safe Boat. Although they were unable to use fluorescein dye as a secondary reference for this exercise, they were able to gain some valuable insight into the viability of the C3 as a field instrument. The C3 used in this test was configured to detect crude oil and was used with a battery pack, a data cable, and a Panasonic ToughBook computer. The participants agreed that the C3 is easy to deploy and well-suited for the SMART mission.

Information on SMART can be obtained at http://response.restoration.noaa.gov. Contributed Images and data were provided by the Clean Island Council (http://www.cleanislands.com).

Question:
How do I calibrate my AquaFluor Handheld Fluorometer using my Adjustable Solid Standard?

Answer:
Turner Designs manufactures Adjustable Solid Standards that are used for checking:
• Stability
• Drift
• Calibration

The Red Adjustable Solid Standard (P/N: 8000-952) is recommended for the following applications:
• Chlorophyll
• Rhodamine
• Phycocyanin

The Orange Adjustable Solid Standard (P/N: 8000-951) is recommended for the following applications:
• Fluorescein
• Phycoerythrin

The Adjustable Solid Standard Kit for the AquaFluor includes:
• 1 Solid Standard
• 1 Allen Wrench for locking hex screw
• 1 Allen Wrench for the adjustable hex screw

Correlating the Adjustable Solid Standard to Direct Concentrations
1. Calibrate the AquaFluor using a liquid primary standard or solution that has a known concentration. (Post-calibration Note: the AquaFluor should display values that represent concentration estimates)

2. Loosen the locking hex screw.

3. Adjust the Solid Standard to a desired concentration value using the adjustable hex screw and measure the value of the Solid Standard using the AquaFluor. (The adjustment may need to be repeated several times to achieve the desired concentration)

4. When the desired concentration is set, lock the value into place using the locking hex screw.

5. The Adjustable Solid Standard now represents a specific concentration and as long as it is not further adjusted and is properly used/stored, the value should not change.

Correlating the Adjustable Solid Standard to Relative Fluorescence
For in vivo applications, which are qualitative in nature, such as in vivo chlorophyll, calibrations are typically made by correlating the fluorescence intensity of your natural water sample to some arbitrary fluorescence value

1. Calibrate the AquaFluor using a natural water sample or solution that contains the fluorophore of interest. (Post-calibration Note: the AquaFluor should display raw fluorescence values representing relative fluorescence intensities)

2. Loosen the locking hex screw.

3. Adjust the Solid Standard to a desired fluorescence intensity using the adjustable hex screw and measure the value of the Solid Standard using the AquaFluor. (The adjustment may need to be repeated several times to achieve the desired fluorescence intensity)

4. When the desired fluorescence intensity is set, lock the value into place using the locking hex screw.

5. The Adjustable Solid Standard now represents that specific fluorescence intensity and as long as it is not further adjusted and is properly used/stored, the value should not change.

In 2007 Turner Designs introduced its Instrument Donation Program which offers one Trilogy Laboratory Fluorometer and two AquaFluor Handheld Fluorometers annually. We developed this program in an effort to assist non-profit, government, and academic institutions to obtain the instruments needed for aquatic research and/or monitoring. Over the last two years we awarded 6 donation instruments, visit our donation recipients page to learn more about the awardees.

We will be awarding a Trilogy and AquaFluor in June and another AquaFluor in December. Application deadlines are May 1st for June awards and November 1st for the December award. You can easily apply for a fluorometer donation on our website.

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