How to test phosphate-phosphorus (PO4-P) using the Kyoritsu packtest

What is it? Phosphorus is an element and critical nutrient required by all life, the most common form being phosphates.

Why is it important? Phosphate plays a very important role as a nutrient in aquatic ecosystems. However, it is difficult to monitor due to its low concentration and the fact that it can appear in both organic and inorganic forms. Often, water quality monitoring focuses on measuring total phosphorus rather than phosphate concentrations. While phosphorus is critical to all life, too much nutrients in the water can lead to water quality issues. High levels of phosphates can contribute to the formation of harmful algal blooms (HABS) and nuisance algae, like cladophora.

What does it mean? Phosphorus makes its way into our waterways from sources such as stormwater, urban and agricultural runoff, sewage and wastewater discharges, and erosion. In freshwater:

• 1 – 3 µg/L: level in uncontaminated lakes
• 2.5 – 10 µg/L: level at which plant growth is stimulated
• 10 µg/L: maximum acceptable to avoid accelerated eutrophication
• > 10 µg/L: accelerated growth and consequent problems

About the Kyoritsu test

How to test

• Take one tube out of the bag with the blue label (Phosphates). Pull out the plastic pin. Squeeze out the air from the tube. 
• Holding the squeezed tube, put tube into your sample, releasing to suck water up (like a baster!) Your sample container should be half full.
• Invert at least 5 times, allowing the reagent to dissolve in your sample. Set your timer for 5 minutes.
• Compare your results to the comparison chart. If results are in between, record the half-way point. If your results are above 10mg/L, record 10mg/L are your results to the comparison chart. If results are in between, record the half-way point.

Comparing results

Use the comparator provided with your kit and take your time. You're looking for if values are low/medium/high, rather than precision (not possible with this type of test)! Do not compare with a screenshot or photograph as lighting will make it inaccurate.

Watch the protocol in action