FAQ - Test Kit Use & Results

Following the stated times is very important. Be especially sure to give the enzyme reaction enough time to fully complete — not allowing the reaction time to finish is the most common user mistake.

For Simple NTKs: wait at least 10 minutes after adding samples to the reaction or standard cuvettes before adding the Color Reagent. Adding extra time during the reaction step, before the color reagent is added, will not negatively affect results.

If you expected nitrate in this sample, the most likely cause is a missing reagent. Each tube must receive buffer, NADH, and NaR (enzyme), followed by both color reagents.

Exclusion of buffer or color reagents will result in a noticeably smaller volume in that tube. If NADH or NaR are left out, the volume will appear the same as other tubes.

Solution: Repeat the analysis of that sample or standard, making sure every component goes into the tube.

Light or absent color across all tubes usually means the Color Reagent was added too soon, stopping the reaction before it had time to complete.

Solution: Allow enough time for reactions to occur and follow the timeframes in the instructions carefully. For Simple NTKs, wait at least 10 minutes after adding samples before adding Color Reagent. Adding more time during the reaction step will not negatively affect results.

First, confirm whether nitrate is actually present in your samples. If you have verified nitrate is present using another method, there may be an interfering factor in the sample.

Solution: Prepare a standard by diluting it with the sample, then test it alongside a standard prepared with nitrate-free deionized water. If the sample-prepared standard shows no color but the normal standard does, your sample contains something that is interfering with the enzymatic reaction catalyzed by NaR. Contact NECi tech support for guidance on next steps.

The sample contains too much nitrate and must be diluted before reanalysis.

Solution: Dilute the sample with nitrate-free deionized water at 1:4 (five-fold dilution) and 1:9 (ten-fold dilution) and reanalyze. If the sample is still above the standard curve, dilute further — up to 50- or 100-fold if necessary.

This most likely indicates nitrate or nitrite contamination in your deionized water.

Solution: Obtain fresh deionized water and repeat the analysis.

A non-linear standard curve is most commonly caused by pipetting errors, either when preparing the standard or depositing it into tubes. Accurate, careful pipetting is essential for good results with all NECi products.

Solution: Repeat the standard curve using the same diluted standards. If it is still non-linear, prepare new diluted standards and repeat the analysis.

Leave the NADH and NaR out when preparing the sample and replace them with deionized water, then proceed with color development. Any pink color that develops indicates the presence of nitrite in your sample.

No — this is expected. The phosphate test kit reaction remains clear with no visible color change. To analyze samples, you must use NECi's handheld photometer or any spectrophotometer that accepts standard square cuvettes and can read at 360 nm.

At this time, the only sample type that has demonstrated notable interference is samples containing high levels of arsenic. If you are testing samples that may contain elevated arsenic, contact NECi tech support before proceeding.

Contact NECi tech support and we will do our best to resolve your issue as quickly as possible. We are generally available Monday through Friday, 10am–5pm EST.

Email: tech@nitrate.com