Organic matter in the form of serum, blood, pus, or fecal material can interfere with the antimicrobial activity of chlorine and iodine based disinfectants.

Interference occurs when there is a chemical reaction between the chlorine or iodine solution and organic matter which results in less to no germ killing power.

This problem is most common in hospitals and long term care facilities and may require much higher disinfectant concentrations. You can test disinfectant solutions up to 10000ppm with Indigo™ chlorine test strips.

The biochemical mechanisms behind chlorine microbiocidal effects are not clearly understood. They range from breaking disulfide bridges between cysteines in enzymes, decreased ATP production and breaks in DNA.

Most chlorine based compounds are fast acting microbicides but they work best when pH is between pH5-8 which is mildly acidic to mildly alkaline.

Effectiveness of hypochlorites (chlorine bleach) solutions are reduced in the presence of organic compounds such as blood and feces. It is also reduced when carbon dioxide in the air is absorbed to make them more acidic. At pH5 or less they are quickly deactivated.

Keep your chlorine bleach tightly sealed, stored in a cool place & shield from sunlight.

Chlorine dioxide in alkaline media is more efficient and less sensitive to pH changes.

Chlorine use in sanitation and disinfection has rare cases of serious toxicity but careful handling is nevertheless recommended. Fumes from undiluted household bleach can cause eye irritation. Ingestion can cause oropharyngeal, esophageal & gastric burns. Consult first aid instructions on bleach container & seek medical aid if necessary.

How to Use Chlorine Test Strips?

Instructions for chlorine/chlorine dioxide/iodine test strip use is the same regardless of concentration range.

1. Remove test strip from vial.
2. If paper, dip any end in bleach solution
3. If plastic, dip pad end in bleach solution
4. Remove and compare to color chart. Times vary-see individual strips for specifics.

The color charts on chlorine (hypochlorite), chlorine dioxide and iodine solutions indicate concentrations from 5ppm up to 10000ppm.

Use our hydrogen peroxide dilution calculator to take the guesswork out of making up accurate sanitizer solutions.

Simply enter:

1. Strength of your chlorine bleach (%)
2. Strength you want after dilution (ppm)
3. How much you need to prepare (litres, mL, quarts, cups)
4. Press "Calculate"

It will tell you how much undiluted peroxide to mix with water. Confirm solutions are in the correct range with the appropriate Indigo™ test strip.

You can also prepare calibration solutions for your test strips to confirm they can still be used past their expiration date. Do this only with freshly opened concentrates. You may find one of our graduated cylinders & graduated medicine droppers useful for this.