Products & Accessories
Applications & Customer Care
Search - Contactenhanced_search
Case Studies
Turner Blog
Products & Updates
General Information
Contacts
Content Categories
Content Sections

Note from the Director
Instruments In Action: Center for Applied Aquatic Ecology (CAAE) Using SCUFA and 10AU for Monitoring the Neuse River Estuary
Instruments In Action:
Nutrient Limitation Research in African Great Lakes using 10AU
Tom's Corner: Fluorometer Data Transfer to a Computer
Technically Speaking: How Time and Temperature Affects Fluorometer Repeatability and Consistency

In the Spotlight: Update on Turner Designs DataBank
Upcoming Events: View Our Upcoming Tradeshows

TD News Archives: View the Archives
 

Note From the Director

Welcome to the latest edition of TD News. In this issue you will see articles on a wide variety of laboratory fluorescence applications. These articles are intended to tell you more about the multiple uses of fluorometers so you can make the most of your instrument, and to discover unrealized possibilities of fluorescence sensors.

The most common laboratory technique we provide instruments for is extracted chlorophyll analysis. Our aim is to offer the best instruments and support available for this important application. We appreciate the contributions of our scientific partners who have helped us pioneer some of these techniques. Currently we offer two kits for extracted analysis; the acidification technique kit and the non-acidification (aka Welschmeyer) technique kit. Both techniques have been certified by the US EPA and the procedures are described in EPA Method 445.0.

The Acidification Techique is the older of the two techniques and provides data on the chlorophyll a and pheophytin a concentrations while the Non-Acidification Technique is the most accurate fluorescent technique, and supplies only chlorophyll a concentration data.

Other laboratory techniques we provide instrumentation for include;

  • A sensitive and simplified ammonium technique
  • A kit to detect histamine levels in fish most commonly used in fish packing
  • An ATP kit that measure total living biomass in environmental samples
  • A method to detect formaldehyde levels


For detailed information on any of these and other applications, please visit the Application Section of our website.

I would like to let you know that this will be my last Newsletter at Turner Designs. After eight, great years with the company, I am leaving Turner and the warm, sunny weather of California for the dark, cold winters of the Northeast! I think I may have sniffed too much acetone doing chlorophyll extractions!. Anyway, it has been a real pleasure. David Doting ( This e-mail address is being protected from spambots. You need JavaScript enabled to view it ) will be taking over as Vice President of Sales. David has been with Turner for over 11 years and has in-depth knowledge of our products.

Many of you know Jim McCormick who has provided technical support for Turner's products for the last 4 years. Jim has also decided to relocate to the East Coast - he's going to live in Florida. Our thanks to Jim for the fine support you provided over the years.

We are very pleased to tell you that we have hired Tom Brumett to take over the mantle of providing technical support from Jim. Tom brings a strong background in providing technical support to customers, he has already spoken with some of you. Tom's e-mail address is: This e-mail address is being protected from spambots. You need JavaScript enabled to view it . For Tom's first support article, click here.

I hope you enjoy this edition of the TD Newsletter. We are always interested in hearing from you; please do not hesitate to contact us with feedback on the newsletter, or our products and services


Yours truly,
Rob Ellison
Director of Sales and Marketing
 

fluorometer

Long-time Water Quaility Monitoring for the Neuse River Estuary (10AU & SCUFA)

fluorometerThe Center for Applied Aquatic Ecology (CAAE) is part of the Botany Department of North Carolina State University and is dedicated to research involving aquatic botany, ecology and water quality. One of the Center's key water quality research projects is the long-term water quality monitoring and modeling of the mesohaline Neuse River Estuary. The Neuse River is a highly eutrophied system in eastern North Carolina and was listed as one of the 20 most threatened rivers in the nation in from 1995 - 1997. Sections of the river are currently classified by the USEPA as "nutrient sensitive". The monitoring has been conducted since 1994 and includes 20 stations, seven of which are permanent solar powered platforms (see photo) that house a sonde sensor bundle from Hydrolab, a Turner Designs corporate partner. These stations provide continuous measurement and vertical profiling of temperature, dissolved oxygen, redox, salinity, and turbidity. The CAAE website displays near real-time (2 hour update interval) data upload for these parameters from the Neuse River stations.

The CAAE has utilizes a Turner Designs, Self Contained Underwater Fluorescence Apparatus (SCUFA) for in vivo chlorophyll a measurement in the field. The system allows for quick calibration with a very stable solid form standard. The Center's field crews are currently performing SCUFA casts at key stations as part of routine sampling. The data values and trends will be compared to chlorophyll data from extracted chlorophyll-a measurements of water samples collected in parallel with the SCUFA measurements. Deployment of the SCUFA on a platform is planned to enable continuous vertical profiling of chlorophyll, which will also provide an opportunity to evaluate the unit's antifouling system. The resulting data will be available in the near future via the website link referenced above.

Discrete water samples are also collected from all stations for analysis in the CAAE analytical chemistry lab. Samples are routinely collected for nutrients, solids, BOD, and extracted pigment (chlorophyll a) analysis. A Turner Designs 10-AU Fluorometer is employed for routine analysis of chlorophyll extracts and has proven to be highly stable and versatile for over seven years of use in our laboratory. US EPA method 445.0 (acidification - optical kit 10-037) has been the method historically employed within the laboratory and recent side-by-side studies have shown good agreement with the Welschmeyer method (optical kit 10-040). The Welschmeyer method produced results approximately 5% higher on average.

Algae and therefore chlorophyll will tend to demonstrate significant spatial heterogeneity in the environment, more so than the other analytical parameters/indicators we measure. This trait makes it advisable to collect and filter of a significant sample volume (200 - 500 mL). A large sample volume from a eutrophied system, such as the Neuse River produces high levels of analyte. We extract the sample into 14 mL of 90% acetone, instead of the standard 10 mL. in order to lower the extract concentration, however, the pre-acidification measurements in particular are still high enough to warrant calibration at high levels. The wide dynamic range of the instrument allows us to achieve high linearity at high levels over a large range with low residuals. Calibration in the high range with a span of approximately 20% and removal of the reference filter enables these high yet accurate measurements, which minimizes the number of samples requiring error vulnerable dilution. The table and graph below includes the data from a recent calibration. The calibration standard used was diluted from a spinach extract stock prepared in 90% acetone, which was purity adjusted via spectrophotometric measurement.

fluorometer

Contact Info

Mail:
620 Hutton Street Suite 104
Raleigh, NC 27606

Email:
This e-mail address is being protected from spambots. You need JavaScript enabled to view it

fluorometer

Nutrient Limitation Research in African Great Lakes using 10AU

Rebecca North is a doctoral student under the supervision of Dr. Stephanie Guildford and Dr. Ralph Smith at the University of Waterloo. She was awarded an International Development Research Centre (IDRC, Ottawa, Canada) doctoral research grant to continue her studies on nutrient limitation in African Great Lakes by visiting Lake Tanganyika and Lake Victoria in the fall of 2004. The goal of her thesis project is to understand the relationships between phosphorus (P), nitrogen (N), iron (Fe) and light in controlling algal biomass in temperate and tropical Great Lakes: Lake Erie, Lake Malawi, Lake Victoria and Lake Tanganyika.

fluorometer

Her research has identified which nutrients, P, N, or Fe, are limiting to the phytoplankton communities in the pelagic and littoral zones of the lakes. These issues are important as changing nutrient regimes can affect all freshwater systems and it is critical to understand which type of nutrient inputs can have the most impact. She investigated the nutrient status of the Lake Tanganyika phytoplankton and the role of iron in mediating nutrient uptake and interactions.

The Lake Tanganyika data will be incorporated into her Ph.D. thesis entitled “The influence of Fe bioavailability on the nutrient status of phytoplankton communities in temperate and tropical Great lakes” as well as in primary scientific journals. Her hypothesis is that the bioavailability of Fe affects N and P limitation of phytoplankton communities in Great Lakes. Lake Tanganyika is a N limited system where Fe appears to influence the availability and species of N and P utilized by the phytoplankton communities. Ammonium assimilation is the only means of meeting N demands of the phytoplankton communities that does not require Fe.

Using the 10-AU Field Fluorometer and employing a new sensitive fluorometric technique for the detection of low concentrations of ammonium [Holmes et al. 1999] has allowed her to measure the extremely low ammonium concentrations in Lake Tanganyika. Her research will build upon previous studies of Lake Tanganyika and its phytoplankton by Dr. Piet Verburg and Dr. Robert Hecky at the University of Waterloo [Verburg et al. 2003].

Verburg’s research published in 2003 has established that the nutrient regime of the lake may be changing due to a warming climate and this may be increasing the probability of iron limitation of algal growth. Her specific program for Lake Tanganyika was to measure a variety of nutrient status indicators for the nutrients N, P, and Fe and incorporate this data into a summary of the phytoplankton nutrient status of Lake Tanganyika. Her research will greatly expand on the understanding of phytoplankton-nutrient relationships on the lake to support ongoing efforts to manage the lake’s productivity and in particular, its valuable fishery.

fluorometer


References

Holmes, R. M., Aminot, A., Kerouel, R., Hooker, B. A., and Peterson, B. J. A simple and precise method for measuring ammonium in marine and freshwater ecosystems. Canadian Journal of Fisheries and Aquatic Sciences 56, 1801-1808. 1999.
Verburg, P., Hecky, R. E., and Kling, H. Ecological consequences of a century of warming in Lake Tanganyika. Science 301, 505-507. 2003.

Fluorometer Data Transfer to a Computer

Question:
The data from our fluorometer is not being displayed on our computer. What are the things that we can check?

Answer:
Communication problems of this nature can be caused by faulty cabling or issues related to the configuration of the computer serial port. It may also be possible that the port in question is being used by another program. Check the serial cable first. Make sure that the cable is properly seated at both ends and the captive screws are tightened. Inspect the cable for physical damage or bent pins. If you are using a gender changing connector on the cable, make sure the transmit and receive data lines are not reversed. Try a different cable if you have any doubts and have one available. The port settings in your terminal program can also be a source of communication failure. If you are using a windows based terminal program, the port settings should be at the following: 9600 bps, 8 data bits, no parity, 1 stop bit and flow control set to none. The 10-AU, Aquafluor and TD-700 can all be used with any RS-232 serial printer or Windows based terminal program. For more information refer to the instrument operational manuals. The operational manuals are available in pdf format on the web at http://www.turnerdesigns.com. Use the table below for a current software and serial cable reference.

Fluorometer Software Spreadsheet Interface Software Compatible Provided Serial Cable p/n:
10-AU Download Program Version 2.1 YES** 10-AU-115S / 10-AU-12C
TD-700 *** YES 021-0700
SCUFA Version 2.1 SCUFA* NO 2000-960
AQUAFLUOR *** YES 021-0830
CYCLOPS-7 N/A NO n/a
ALGAEWATCH Version 2.0 NO** 6000-119
* If you purchased your SCUFA unit prior to February 2001. You do not have the latest firmware and your SCUFA must be updated prior to using 2.1.

** The 10-AU and the Algaewatch have datalogger interface programs to facilitate downloading and data incorporation into Excel.

*** May be used with typical terminal type programs for interface and data capture.

Turner Designs also has Spreadsheet Interface Software available for direct data import into Excel.

The illustrations below show the Spreadsheet Interface Software with and without a com port available.

fluorometer

fluorometer

 

fluorometer

fluorometerTechnically Speaking, It All Adds Up…….

is a series of articles for people who want to obtain the best possible results from their fluorometer. This month's article explains how time and temperature affect the repeatability and consistency of fluorometer readings. It includes some ideas on minimizing the effects of these two parameters' contribution to measurement uncertainty.

Introduction:
There are many different fluorescent materials measured with a fluorometer, and they can be measured in several different ways. For example, chlorophyll a can be measured by taking discrete samples or by using a continuous flow configuration.

To get repeatable solution concentration readings, (same reading is obtained when measured with another fluorometer); and consistent readings, (readings do not change with duplicated measurements), the effects of instrument warm-up time and changes in measurement environment temperature need to be factored in to the measurement procedures.

Warm-Up Time:
The Turner Designs 10-AU and TD-700 use lamps and photomultiplier tubes, so the effects of warm-up drift will be more noticeable than their solid-state counterparts including SCUFA, CYCLOPS-7 and the Aquafluor. (These use LEDs and Photodiodes).

Graph 1 shows the warm-up drift of a 10-AU when measuring a solid secondary standard. The secondary standard is a passive device that far exceeds the stability of the 10-AU. The graph shows that readings will be more consistent after 2 minutes warm up time. This is important to take into account when using the 10-AU or TD-700 for discrete samples.

fluorometer
click for larger view

Solid state fluorometers stabilize much faster, and typically require only a few seconds to provide consistent readings.

 

Measurement Tip:
To reduce the effect of drift immediately after turning on the fluorometer, take a minimum of three readings and record the average value. If possible, leave the fluorometer on continuously to achieve instrument thermal stability.

 

Temperature Effects:
It is important to measure at the same temperature as when calibrating the fluorometer. Typically, solutions and hardware will be at a different temperature in the lab than when taking measurements in the field.

Most fluorescent materials have fairly high temperature coefficients. Usually, as temperature increases, the fluorescence signal decreases. Unless corrected for, this can produce significant errors. The 10-AU features an automatic temperature compensation option for use when making continuous flow measurements. Manual corrections need to be applied to measurements made with other Turner Designs fluorometers.

 

Measurement Tip:
Record the temperature during instrument calibration and operation, and apply a temperature correction to your data for improved repeatability and consistency.

 

Further Information:
Additional information on improving the integrity of your data can be found in the many technical articles in the application section of Turner Designs web site:



Update on the Turner Designs Databank

What?
In response for more 'real-world' data from our customers, Turner Designs has launched the TD DataBank Program where we present examples of customer research for all instruments and applications. The DataBank is organized according to instrument type and application and offers our users real-world examples of how researchers and technicians are using Turner Designs instruments in their work. In addition to providing meaningful information for our customers, by having a description of your work highlighted on our website, it will serve as a means of reaching a greater number of scientists around the globe. We see this as a highly effective means of assisting our users in making informed decisions. In order for this type of program to succeed, we need information from you on your application and how a Turner Designs fluorometer is helping you.

How?
fluorometerWe have designed the TD DataBank to make submitting an application summary as easy as possible. The entire process should not take more than 20 minutes. We ask for a brief description of your research, and how you use Turner instruments. Also, a picture or graph of data collected with Turner instruments is requested. To show our appreciation for your data bank articles, we will send you a Turner Designs sports bag. Claim your sports bag now by submitting your DataBank article!

Why?
We hope you will join us in this exciting and useful program by sharing your knowledge and experience with scientists and technicians around the globe. To take part, please visit the following link http://www.turnerdesigns.com/databank/submit_data.html or call us directly at 1(877) 316-8049 ext 163.


 

Turner Designs Inc. | 845 W. Maude Avenue, Sunnyvale, CA 94085
(877) 316-8049 | www.turnerdesigns.com
All Rights Reserved