Nitrite Reducing Bacteria Tube Test
Accepta’s high quality NRB tube tests offer a quick and easy means of monitoring nitrite reducing bacteria present within water systems treated by Nitrite, making them ideal for engineers, water treatment professionals; and building services and facilities management specialists.
Accepta’s NRB tubes and dipslides are manufactured to the highest quality standards and are used to measure the levels of NRB found in treated water systems. If you are looking for incubators you can find them here
Incubation Chambers Accepta’s Nitrite reducing Bacteria (NRB) Tube Test is design to assess the contamination of water samples with nitrite reducing bacteria.
The test contains a pale orange medium which reacts to metabolism by NRBs to produce a semi-quantative result within 5 days.
The NRB Tube Test is used to monitor the levels of NRB in water systems, with specific relevance to systems which use nitrite as their main corrosion inhibitor. NRB’s are able to metabolise nitrite into ammonia and nitrogen gas which are aggressive corrosive agents, as well as this the corrosion inhibition of the nitrite is lost.
Pipette 2ml of the sample into the tube and immediately replace the cap placing upright in an incubator.
For testing corrosion pits swab them with a sterile swab, pierce the gel with a swab and place into the incubator. Contamination is defined by blackening around the swab.
Incubate at 35C for up to 5 days, check daily to determine the level of contamination.
Used tests should be incinerated or autoclaved. Alternatively, open and immerse in a 10% bleach solution for 24 hours.
Classification of Results
Results are to be determined by the colour change seen on day 1 through to 5. No colour change or bubble formation can be interpreted as no contamination. A partial colour change (top of the medium is red, bottom still pale orange) and moderate bubble formation suggests a moderate contamination. Where a full colour change is seen accompanied by ample bubble formation, heavy NRB formation is assured. Strong acidic or alkaline samples can cause an instant colour change, in this event contamination can be determined by bubble formation alone.
Interpretation of Results
As noted the recommended incubation time for this test is up to 5 days. Indication of the level of contamination can best be obtained by daily checking of the incubated tubes. On a daily basis assess the percent (%) Colour Change & Bubble formation in each incubated tube. Record the percent change and the associated number of days incubated. The degree of contamination is assessed by how much change has occurred and the rate at which it occurred (the number of days).
IMPORTANT – Monitoring is not a substitute for a treatment regime, you should seek the advice of a professional water treatment or environmental company that will supply a risk assessment together with the required treatment system. Speak to us for advice on chemical treatment and maintaining control in your system.
Other Incubated Media
|Application||Media Side 1||Media Side 2||Detection of|
|Cooling water & cutting fluids||Nutrient & TTC||Malt Ext.||TVC, Yeast & Moulds|
|Standard total counts in cooling water||Nutrient & TTC||Nutrient & TTC||TVC (also TTC2 trade+)|
|Food & personal hygiene||Nutrient & TTC||MacConkey No.3||TVC Coliforms|
|Food industry – high protein samples||Nutrient & TTC||Rose Bengal||TVC Yeast & Moulds|
|Multiple applications||Nutrient & TTC||Chromogenic||TVC, Coliforms & E.coli|
Note – All Accepta dipslides can be own labelled, please contact us for further details.
Note on loss by NRB vs Nitrification
The test for NRB (Nitrite Reducing Bacteria) is based upon the detection of ammonia formed by the reduction of NO2 and subsequent biochemical pathway to form ammonia (NH3). This is nitrite reduction. There are some bacteria that will convert NO2 to form N03 or nitrates. These are known as nitrifying bacteria. This pathway can be problematic but is generally limited by how much oxygen is in the system, where oxygen availability is the limiting factor.
Nitrifying bacteria do not produce ammonia and therefore are not detected by the NRB test and there are no specific and good tests for nitrifying bacteria. However, monitoring the aerobic colony count over a period of time gives a good indication of overall microbial load in the system. This can be taken to include the nitrifying bacteria.
If you require additional information or specialist technical support concerning our dipslides please contact Accepta’s technical support team.