CALDUR® Phosphate LR - Photometric

CALDUR® Phosphate LR – Photometric

Phosphate determination in the water using a photometer (0.4-5 mg/l PO₄³-)
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CALDUR® Phosphate LR Test Set – Photometric

What is phosphate measured for?

Phosphate (PO₄³-) is a key nutrient in water bodies and an important control parameter in water treatment. Elevated phosphate concentrations promote algae growth and can lead to eutrophication of surface waters.

In drinking water treatment, phosphates are specifically dosed as corrosion inhibitors to protect pipelines from corrosion. The correct dosage must be monitored to ensure the desired protective effect.

Phosphate is used in cooling water systems and boiler water for hardness stabilization and as corrosion protection. Regular monitoring is essential for economical operation.

How does the test set work?

The CALDUR® Phosphate LR Test Set – Photometric is based on the molybdate method. After adding two reagents to the water sample, a blue color complex (molybdenum blue) is formed within 5 minutes, the concentration of which is precisely determined using the WINLAB Data Line photometer.

Advantages of the CALDUR® test set

  • Sensitive measuring range 0.4 – 5 mg/l PO₄³-

    Ideal for drinking water and low-dose applications

  • 200 provisions per set

    Cost-efficient for continuous use

  • High precision due to photometric evaluation

    Objective, reproducible measurement results with the WINLAB Data Line

  • Proven molybdate method

    Reliable and specific for orthophosphate

Areas of application

Pond / lake
Groundwater / well water
Drinking / tap water
Aquaristics
Pool / Swimming pool
Industrial processing
Boiler water
Food preparation
Waste water treatment

Carrying out the measurement:

  1. Fill the round cuvette with sample up to the 10 ml mark
  2. Add 5 drops of reagent A and mix
  3. Add 5 drops of reagent B and mix
  4. Wait for 5 minutes reaction time
  5. Insert the cuvette into the WINLAB Data Line photometer
  6. Start measurement – result is displayed directly in mg/l PO₄³-

Tip for best results

The sample should be clear and free of suspended solids. Only dissolved orthophosphate is detected. A prior digestion is required for the determination of total phosphate.

Important notes

  • Adhere exactly to the response time of 5 minutes
  • Avoid direct sunlight during the measurement
  • Wipe the cuvette with a lint-free cloth before measuring
  • Thoroughly rinse the test tube with the sample before each measurement
  • Use the HR test kit for concentrations above 5 mg/l
  • Requires WINLAB Data Line photometer (Art. 37-000100)

Measuring range

Property Value
Measuring range 0.4 to 5 mg/l PO₄³-
Resolution 0.1 mg/l
Method Molybdate method, photometric evaluation
Advantage of photometric measurement:
In contrast to the colorimetric method (color chart), the photometer provides exact numerical values with a higher resolution. Intermediate values are calculated automatically – ideal for documentation and quality assurance.

Number of possible destinations

You can carry out 200 measurements with one CALDUR® Phosphate LR Photometric test kit.
This refers to the quantity of reagents contained.

Measuring accuracy and reproducibility

Resolution: 0.1 mg/l
Reproducibility: Very good if the application instructions are followed
Interference: Silicate in high concentrations (> 10 mg/l SiO₂) can influence the result. Heavily colored samples can interfere with the measurement. Only orthophosphate is recorded.

What to do if measured values are out of range?

Measured value > 5 mg/l

Use the CALDUR® Phosphate HR test set (31-073417) for higher concentrations up to 100 mg/l.

Measured value < 0.4 mg/l

Measured value is below the detection limit. For more sensitive measurements, please contact our technical support.

Specifications at a glance

Property Value
Parameters Phosphate (PO₄³-)
Item number 31-073412
Method Photometric (molybdate)
Measuring principle Photometric evaluation with WINLAB Data Line
Measuring range 0.4 to 5 mg/l PO₄³-
Resolution 0.1 mg/l
Duration of analysis 5 minutes
Number of provisions 200
Number of reagents 2
Packaging Plastic bag
Scope of delivery
2 reagent bottles (reagent A, reagent B) with detailed labeling
1 round cuvette (10 ml)
Detailed operating instructions (DE/EN)
Safety data sheets for all reagents
Resealable plastic bag

Reagent details

Reagent Volume Shelf life Notes
Reagent A (molybdate) 30 ml 24 months (24M) Molybdate reagent, shake before use
Reagent B (reducing agent) 30 ml 24 months (24M) Shake before use

Shelf life: The shelf life starts from the date of manufacture (printed on the bottle).
After opening, the reagents should be used within 12 months.
Store the test kit in a dry, cool place (10-25°C) and protected from direct sunlight.

Required accessories

For the photometric measurement you need a WINLAB Data Line photometer with the corresponding method for phosphate.
The photometer is not included in the test set and is available separately.

Additional information

Packaging

Plastic bag, Refill pack
Product category

Testset
Flyer
Operating instructions

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