Low level Phosphate analysis on the San++ Continuous Flow Analyzer

Flow cell

Increased sensitivity can be achieved for the automated  Phosphate method by implementation of a special flow cell in the San++. This long pathlength flow cell combines an increased optical pathlength of 50 or 100 cm with a small sample volume.

This makes this application particularly well suited for challenging samples with ultra low concentrations of Phosphate as for instance in seawater, but also for Phosphate analysis in other aqueous samples such as drinking & surface water.

Skalar’s automated method for Phosphate analysis is based on the following procedure. The ammonium hepta molybdate and potassium antimony (III) oxide tartrate react in an acidic medium with diluted solutions of phosphate to form an antimony-phospho-molybdate complex. This complex is reduced by L (+) ascorbic acid to an intensely blue-colored complex which is measured spectrometrically at 660 nm.

Application performance:
Typical performance data and analysis results of Skalar’s  Phosphate application on the San++ analyzer using the new type of flow cell can be found in the table  and graphs below.

San++ analysis data Phosphate


1. 50 cm

2. 100 cm


1. 0,1 - 40 µg P/L

2. 0,05 - 20 µg P/L

Minimum Detection Limit (MDL)

1. 50 cm

2. 100 cm


1. 0,07 µg P/L

2. 0,05 µg P/L

RSD (%) 0.3%
Regression (r) 0.99993


Total Phosphate calibration curve (up to 40 µg P/L)  


    Total Phosphate calibration (up to 40 µg P/L)

The high sensitivity of phosphate analysis obtained with this new flow cell makes Skalar’s San++   analyzer the perfect choice for detecting extremely low levels of phosphate and other parameters in aqueous samples.

If you require more information on this Phosphate application or other Skalar analyzers & applications, please do not hesitate to contact us.