Turner Designs AquaFluor, Manual

Page: 15 / 23

Aqua Fluor
®
U
ser’s Manual
15
5.2 Extracted Chlorophyll
In extractive analysis, fluorometric measurements are made on solvent extracts from algal
cells to determine quantitative concentrations of chlorophyll and pheophytin. A Primary
Chlorophyll standard P/N 10-850 is used for calibration and the measurements are made
using the 12 x 75 mm
glass test tubes .
EPA Method 445.0 is a popular Chlorophyll extractive method that was developed using a
Turner Designs Model 10 fluorometer and is published by the United States Environmental
Protection Agency.
The extracted Chlorophyll channel on the
Aqua Fluor
®
requires performing the acidification
step to correct for the pheophytin.
This is referred to as the “corrected chlor a” method in
section 12.2 of Method 445.0.
EPA Method 445.0 is available on Turner Designs
’ website under Applications.
5.3 Ammonium Detection
Note: Readings on the ammonium channel using plastic cuvettes have a maximum
range of approximately 10 µM. Minicells are required to achieve readings of 10 µM -
100 µM.
Accurate determination of ammonium in aquatic environments is a critical measurement
when investigating Nitrogen cycling and nutrient dynamics. Historically, methods for
ammonium determination have been a source of frustration within the scientific community
due to the lack of a simple, accurate and affordable method, particularly for measurements
in the submicromolar range.
The ammonium technique offers researchers and technicians an excellent alternative to the
existing colormetric ideophenol blue method. Benefits of the fluorometric method include:

Sensitivity: Detection in the submicromolar range.

Accuracy: More accurate than previous methods for low ammonium concentration
samples.

Simple: Requires only one mixed, non-toxic reagent and no special equipment other
than a fluorometer.

Non-toxic Reagents: OPA, sodium sulfite, and sodium borate.
The colorimetric ideophenol blue method is susceptible to inconsistent results, particularly
with submicromolar ammonium concentrations, whereas, the new fluorometric technique
has been proven to provide accurate and precise data over a wide range of water quality,
ammonium concentrations and salinities. This method is particularly useful for work in
oligotrophic systems, where natural ammonium concentrations are commonly in the
submicromolar range.
For more information on ammonium visit Turner Designs
’ website under Applications.