CALDUR® Chlorine LR (free + combined) – Photometric
Chlorine determination (free + bound) in water photometrically (0.05-1.0 mg/l Cl₂)
Private customers can also find our range in our partner store Ampha-Analyse.
Reagent for CALDUR® Chlorine LR (free + combined) – Photometric:
See also:
CALDUR® Chlorine LR test set (free + combined) – Photometric
What is chlorine measured for?
Chlorine is the most commonly used disinfectant in the world for treating drinking water and swimming pool water. It reliably kills bacteria, viruses and other pathogens, thus ensuring hygienically safe water. In chlorination, a distinction is made between free chlorine and combined chlorine (chloramines), the sum of which is referred to as total chlorine.
Free chlorine is the active, disinfecting form and should be between 0.1 and 0.3 mg/l in drinking water. Combined chlorine is produced by the reaction of free chlorine with nitrogen-containing compounds (e.g. urea, ammonia) and has a significantly lower disinfecting effect. In swimming pools, combined chlorine is responsible for the typical “chlorine smell” and eye irritation.
Limit values according to the Drinking Water Ordinance:
– Free chlorine: max. 0.3 mg/l Cl₂
– Combined chlorine: max. 0.1 mg/l Cl₂
Regular measurement of both forms of chlorine is essential for effective disinfection while minimizing by-products. The CALDUR® Chlorine LR Test Set – Photometric enables the precise determination of free and combined chlorine with the WINLAB Data Line photometer.
How does the test set work?
The CALDUR® Chlorine LR Test Set – Photometric is based on the proven DPD method (N,N-diethyl-p-phenylenediamine). DPD reacts with free chlorine to form a pink-violet dye, the intensity of which is proportional to the chlorine concentration and is measured photometrically.
Measurement of free chlorine: After adding reagent A, a pink coloration develops immediately corresponding to the free chlorine content. The absorbance is measured photometrically.
Measurement of combined chlorine: After adding reagent C, the combined chlorine is also measured. The difference between total chlorine and free chlorine gives the combined chlorine content.
The photometric evaluation with the WINLAB Data Line photometer provides objective, highly precise measurement results. The DPD method is internationally recognized and complies with the DIN EN ISO 7393-2 standards and WHO recommendations.
Advantages of the CALDUR® test set
- Quick analysis in just 1 minute
Immediate results for free chlorine – ideal for daily routine checks
- Separate determination of free and combined chlorine
Differentiated assessment of water quality and disinfection efficiency
- Low measuring range 0.05 – 1.0 mg/l Cl₂
Perfect for drinking water monitoring and monitoring limit values
- 150 provisions per set – economical in continuous use
Cost-efficient for daily checks in waterworks and industry
- Photometric precision measurement
Objective measurement results with high resolution – independent of subjective color assessment
- DPD method according to international standards
Standard-compliant according to DIN EN ISO 7393-2 – globally recognized reference method
Areas of application
Carrying out the measurement:
Measurement of free chlorine:
- Fill water sample into test tube up to the 10 ml mark
- Add 5 drops of reagent A and mix
- Perform photometric measurement immediately (within 1 minute)
Measurement of total chlorine (free + bound):
- After measuring the free chlorine: add 5 drops of reagent C
- Wait 2 minutes
- Perform photometric measurement again = total chlorine
- Combined chlorine = total chlorine – free chlorine
Tip for best results
The measurement should be carried out immediately after sampling, as chlorine is volatile.
Avoid exposure to sunlight and do not heat the sample.
For maximum precision, the photometer should be calibrated regularly.
At high chlorine concentrations, the color may fade again after the maximum (bleaching) – in this case, dilute the sample.
Important notes
- Measure the sample immediately after taking it – chlorine volatilizes quickly
- Do not exceed the reaction time for free chlorine (max. 1 minute)
- Avoid direct sunlight during the measurement
- If the color fades: Dilute the sample and measure again
- Rinse test tubes and photometer cuvette thoroughly before each measurement
Measuring range
| Measuring level | Description |
|---|---|
| 0.05 mg/l | Very low concentration |
| 0.1 mg/l | Low concentration |
| 0.2 mg/l | Normal drinking water concentration |
| 0.3 mg/l | Upper limit for drinking water |
| 0.5 mg/l | Elevated concentration |
| 1.0 mg/l | High concentration |
The photometric measurement enables a continuous reading between the measuring points
with high precision (resolution 0.01 mg/l possible).
Number of possible provisions
You can carry out 150 measurements with a CALDUR® Chlorine LR – Photometric test kit.
This refers to the quantity of reagents contained.
Measuring accuracy and reproducibility
Readability: ± 0.01 mg/l (photometric)
Reproducibility: Excellent if the application instructions are followed
Interference: High concentrations of manganese or chromium can influence the result. Ozone and bromine also react with DPD.
What to do if measured values are out of range?
Measured value > 1.0 mg/l
| Dilution | Procedure | Calculation of the measured value |
|---|---|---|
| 1:1 | 5 ml sample + 5 ml chlorine-free water | Measured value × 2 |
| 1:4 | 2 ml sample + 8 ml chlorine-free water | Measured value × 5 |
Measured value < 0.05 mg/l
Measured value is below the detection limit. A minimum concentration of 0.1 mg/l free chlorine should be present in drinking water to ensure disinfection.
Specifications at a glance
Reagents (3 reagents)
| Property | Value |
|---|---|
| Parameters | Chlorine – free + combined (Cl₂) |
| Item number | 31-073252 |
| Method | Photometric (DPD) |
| Measuring principle | Photometric measurement with WINLAB Data Line Photometer |
| Measuring range | 0.05 to 1.0 mg/l Cl₂ |
| Resolution | 0.01 mg/l (photometric) |
| Analysis duration | 1 minute |
| Number of provisions | 150 |
| Packaging | Plastic bag or refill pack |
| weight | approx. 120 g |
| Scope of delivery |
|---|
| 3 reagent bottles (reagent A, reagent B, reagent C) with detailed labeling |
| 1 test tube with 10 ml scale |
| Detailed operating instructions (DE/EN) |
| Safety data sheets for all reagents |
| Packaging: plastic bag or refill pack |
Reagent details
| Reagent | Volume | Shelf life | Notes |
|---|---|---|---|
| Reagent A | 30 ml | 24 months (24M) | For free chlorine, shake before use |
| Reagent B | 10 ml | 24 months (24M) | Buffer, shake before use |
| Reagent C | 10 ml | 24 months (24M) | For total chlorine, 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 away from direct sunlight.
Additional information
| Packaging | Plastic bag, Refill pack |
|---|---|
| Product category | Testset |
Flyer
Operating instructions
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