CALDUR® Ascorbic acid – Photometric
Ascorbic acid determination in water using a photometer (0.1-10 mg/l)
Private customers can also find our range in our partner store Ampha-Analyse.
Reagent for CALDUR® Ascorbic acid – Photometric:
See also:
CALDUR® Ascorbic Acid Test Set – Photometric
What is ascorbic acid measured for?
Ascorbic acid (vitamin C, C₆H₈O₆) is used in water treatment as an oxygen binding and reducing agent. In the food industry, ascorbic acid is used as an antioxidant and preservative to prevent the oxidation of food and extend its shelf life.
In steam boilers and closed cooling systems, ascorbic acid is used in a similar way to Sulfite to bind dissolved oxygen in order to prevent corrosion. Ascorbic acid reacts with oxygen to form dehydroascorbic acid and thus protects pipes and system components from oxygen corrosion.
The optimum ascorbic acid concentration in technical applications is typically 10-50 mg/l C₆H₈O₆. In the food industry, the concentrations vary greatly depending on the application and must be controlled on a product-specific basis.
How does the test set work?
The CALDUR® Ascorbic Acid Test Set – Photometric is based on the ferrozine method. Ascorbic acid reduces iron(III) to iron(II), which then forms a violet color complex with ferrozine. After adding two reagents to the water sample, a characteristic violet color develops within 10 minutes (two 5-minute waiting times).
The color intensity is measured with a photometer (e.g. WINLAB Data Line or Spectro 3) at a wavelength of 560 nm and is proportional to the ascorbic acid concentration. The photometric method offers higher precision and objective measurement values compared to the visual color comparison method.
Important note: For boiler water or other alkaline samples, the pH value must first be corrected to pH 4.3 with hydrochloric acid.
Advantages of the CALDUR® test set
- Photometric evaluation for precise measurement results
Objective measurement without color comparison – ideal for laboratory use and GMP-compliant quality assurance
- Highest measuring accuracy of ± 0.02 mg/l
Significantly more precise than colorimetric methods with color chart
- Wide measuring range from 0.1 to 10 mg/l C₆H₈O₆
Can be extended by dilution up to 100 mg/l – covers all areas of practical relevance
- 100 provisions per set – economical in continuous use
Cost-efficient for daily checks in production facilities and quality assurance
- Digital documentation of all measured values
Automatic storage with date and time in the WINLAB photometer – GMP-compliant
- Long shelf life of the reagents
Reagent A: 120 months, reagent B: 96 months – economical for sporadic use
Areas of application
Carrying out the measurement:
- Switch on the photometer and select the “Ascorbic acid” method
- Fill the first cuvette with water sample (blank value) and measure in the photometer
- Fill the second cuvette with 10 ml water sample
- Add 10 drops of reagent A and mix
- Wait 5 minutes (first reaction phase)
- Add 10 drops of reagent B and mix
- Wait another 5 minutes (second reaction phase)
- Insert the cuvette into the photometer – the measured value is automatically displayed and saved
💡 Tip for best results
For best results, the water sample should be clear and free of suspended solids.
If the water is cloudy, pre-filtration with a filter paper (e.g. Whatman No. 1) is recommended.
The response times (5 minutes each) should be strictly adhered to.
For boiler water, pH correction to pH 4.3 is absolutely essential.
⚠️ Important notes
- Bring reagents to room temperature before use (20-25°C)
- Observe response times of 5 minutes each for precise measurement results
- For alkaline samples (pH > 8), it is essential to carry out a pH correction to pH 4.3
- Rinse cuvettes thoroughly with distilled water after use
- Calibrate photometer with blank value before each series of measurements
- Other reducing substances can influence the measurement result
Measuring range
| Measuring range | Application range |
|---|---|
| 0.1 – 10 mg/l C₆H₈O₆ | Standard measurement with 10 ml sample |
| 1 – 100 mg/l C₆H₈O₆ | If exceeded: Dilution 1:10 (1 ml sample + 9 ml dist. water), result × 10 |
For alkaline samples (e.g. boiler water), the pH value must be adjusted to pH 4.3 with hydrochloric acid before measurement.
Number of possible provisions
You can carry out 100 measurements with one CALDUR® Ascorbic Acid – Photometric test kit.
This refers to the quantity of reagents contained (15 ml of reagent A and 15 ml of reagent B).
Measuring accuracy and reproducibility
Measuring accuracy: ± 0.02 mg/l (photometric)
Reproducibility: Very good if application instructions are followed and temperature is kept constant
Coefficient of variation: < 3%
Interference: Strong turbidity or inherent color of the sample can influence the measurement. Other reducing substances (e.g. Sulfite, hydrazine) lead to increased measured values.
Specifications at a glance
Reagents (reagent A, B)
| Property | Value |
|---|---|
| Parameters | Ascorbic acid (C₆H₈O₆) |
| Item number plastic bag | 31-073222 |
| Item number refill pack | 31-073221 |
| Method | Photometric (ferrozine) |
| Measuring principle | Photometric measurement at 560 nm |
| Measuring range | 0.1 to 10 mg/l C₆H₈O₆ |
| Extended measuring range | Up to 100 mg/l by 1:10 dilution |
| Measuring accuracy | ± 0.02 mg/l |
| Duration of analysis | 10 minutes (5 min + 5 min waiting time) |
| Number of provisions | 100 |
| Packaging | Plastic bag |
| weight | approx. 80 g |
| Required photometer | WINLAB Data Line or Spectro 3 |
| Wavelength | 560 nm |
| Scope of delivery |
|---|
| 2 reagent bottles (reagent A, B) with detailed labeling |
| Detailed operating instructions (DE/EN) |
| Safety data sheets for all reagents |
| Space-saving packaging in a plastic bag |
Reagent details
| Reagent | Volume | Shelf life | Notes |
|---|---|---|---|
| Reagent A | 15 ml | 120 months (120M) | Shake before use |
| Reagent B | 15 ml | 96 months (96M) | 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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