Test strips are a very effective and easy to use option, to detect trace amounts of formaldehyde in dialysis equipment. As a formaldehyde solution is used to rinse out dialysate lines and dialyzers between patient use, it is critical to ensure that there is below the recommended concentration before using the equipment on patients.
The Association for Advancement of Medical Instrumentation limits the maximum acceptable concentration of formaldehyde in dialysis equipment to 3 ppm. Ideally, concentrations should be at no higher than 2.5 ppm on semi-quantitative test strips.
There are some important steps in formaldehyde testing that need to be followed carefully. Incorrect storage of the strips or inaccurate testing protocols can result in inaccurate readings, potentially placing patients at risk for higher than safe level of formaldehyde in the equipment.
Enzyme Reactions
With formaldehyde testing, the test strip indicator pad has two different types of enzymes. When formaldehyde is present, the first enzyme reacts with the formaldehyde to create a compound (NADH or nicotinamide adenine dinucleotide). This NADH is then sensed by the second enzyme. When both enzymes react, they will result in a color change with the more intense colors indicating specific levels of formaldehyde in the sample.
Important Considerations for Test Strips
The two enzymes needed for formaldehyde testing are very sensitive. The test strips have to be correctly stored and the correct process completed with each test.
It is essential to:
* Store the test strips in the manufacturer’s bottle in a refrigerator until the bottle is opened
* Make sure the test strips are allowed to come to room temperature (59-86 degrees Fahrenheit) before using
* Store at room temperature in the original bottle after first use
* Keep the lid tightly closed on the bottle at all times
* Never use the test strip after the expiration date
* Do not remove the desiccant pack as this will allow the indicators to become moist, causing testing failures
Take the time to read and understand the test procedure before starting. If there are any questions, call the manufacturer before using the strips.
