New SEAL Fluorometer Simplifies Ultra-Low Ammonia Analysis

For laboratories performing ultra-low level ammonia analysis, especially in seawater and other high-salinity samples, traditional colorimetric methods can create challenges. Refractive index differences, salt matrix interference, and the need for multiple reagents can make low-level ammonia testing more difficult than it needs to be.

SEAL Analytical’s new fluorometer was designed specifically to solve these problems.

Built for use with SEAL segmented flow analyzers, the new fluorometer provides a more streamlined, compact, and cost-efficient approach to low-level ammonia analysis using the OPA method.

A Better Approach to Low-Level Ammonia Analysis

Traditional ammonia analysis in seawater is often performed using the Berthelot or phenate colorimetric reaction. While effective, these methods can be sensitive to salinity differences, refractive index effects, and optical disturbances created by seawater matrices.

The OPA ammonia method offers a different approach.

In this method, ammonia reacts with o-phthalaldehyde (OPA) in the presence of borate buffer and sodium sulfite to create a fluorescent compound that can be measured with extremely high sensitivity. Unlike colorimetric ammonia methods, the fluorometric OPA method is not affected by refractive index differences caused by salinity. This is particularly important for seawater laboratories and oceanographic research programs analyzing low-level ammonia concentrations across samples with varying salt content.

The fluorometric method also simplifies reagent preparation by using a much simpler reagent set than traditional Berthelot chemistry, which often requires three or four reagents and careful attention to sample and reaction pH.

Designed Specifically for Segmented Flow Analysis

Unlike many third-party fluorometers originally adapted for flow analysis, the new SEAL fluorometer was designed specifically for segmented flow analyzers from the beginning.

The detector integrates directly with the SEAL AA500 segmented flow analyzer as a standard detector module, while also remaining compatible  QuAAtro39 systems and legacy AA3 systems as a standalone module. This allows laboratories to upgrade existing analyzers without replacing their full system. The compact, lightweight design reduces bench space requirements and simplifies installation compared to older fluorometer options.

For laboratories already running multiple nutrient chemistries, the fluorometer fits naturally into existing automated workflows for parameters such as ammonia, nitrate + nitrite, nitrite, phosphate, silicate, total nitrogen, and total phosphorus. SEAL segmented flow analyzers can run multiple methods on the same platform while also supporting inline techniques such as gas diffusion, UV digestion, dialysis, and distillation.

Ideal for Seawater Nutrient Analysis and Oceanographic Research

For oceanographers and seawater researchers, ultra-low detection limits and stable performance in difficult environments are critical.

SEAL segmented flow analyzers are already widely used for seawater nutrient analysis at research institutes and oceanographic organizations around the world, including NOAA, Woods Hole Oceanographic Institution, Scripps Institution of Oceanography, NIOZ, IFREMER, JAMSTEC, and the University of Hawaii.

The fluorometric ammonia method offers detection limits as low as 2 nMol for ammonia in seawater, while eliminating refractive index interference entirely. By comparison, traditional colorimetric ammonia methods can show varying refractive index effects depending on salinity.

Because SEAL analyzers are designed for shipboard and laboratory use, they are well suited for research vessels, coastal monitoring programs, aquaculture facilities, estuary studies, and marine nutrient cycling research. Stable LED light sources, vibration-resistant detectors, and automated startup and shutdown features make these systems particularly useful for long unattended runs and operation in challenging field conditions.

A New Option for Ultra-Low Detection

The new SEAL fluorometer is more than just a new detector. It gives laboratories a more practical way to perform ultra-low level ammonia analysis without the complications often associated with seawater colorimetry or third-party fluorescence detectors.

Compact, lightweight, and purpose-built for segmented flow analysis, it helps laboratories improve low-level ammonia testing while reducing interference, simplifying reagent preparation, and integrating seamlessly into existing nutrient analysis workflows.

For laboratories focused on seawater nutrient analysis, environmental monitoring, or municipal ammonia testing, the new SEAL fluorometer offers a new level of performance and flexibility.

Interested in simplifying ultra-low ammonia analysis in seawater or environmental samples? Contact SEAL Analytical to learn how our new fluorometer can integrate with your existing segmented flow analyzer and support your automated nutrient analysis.

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