FAQ - Analysis in the Lab

Laboratory test kits are supplied with an optimized amount of enzyme, co-factor, a standard, and all other necessary reagents. Some kits may include additional materials depending on the kit.

Lab kit users should have lab-quality water and 3N HCl available.

We recommend that laboratory users begin with a complete test kit for the convenience of pre-made buffers and detailed instructions. This limits error and helps with troubleshooting. Once you are familiar with the assay, economical reagent packs are available that include only the enzyme, co-factor, and enzyme reconstitution buffer.

For high-throughput automated laboratory analysis, NECi has developed reagent packs with instructions customized to your equipment — including discrete analyzers, flow-through analyzers, and more. Contact NECi to develop a custom kit for your automated instrument.

For test-tube formatted phosphate lab kits, customers can choose from a low-range option measuring 0.5 to 5 ppm phosphate, or a standard-range kit measuring 0 to 20 ppm phosphate.

If you need a different testing range, contact NECi — if possible, a kit can be formatted to meet your specific needs.

NECi's nitrate test kits use a purified form of nitrate reductase (NaR) and a natural reducing agent (NADH) for accurate, easy-to-use nitrate testing. Unlike other kits that rely on toxic metals such as cadmium or zinc, NECi's NaR is more stable and does not require expensive NADPH as its cofactor — NADH is used instead.

The NaR reaction is: NADH + NITRATE → NITRITE + NAD+ + OH-

NADH (nicotinamide adenine dinucleotide) is a derivative of a B vitamin. The resulting nitrite reacts with color reagents via the Griess Reaction to form a pink color, detectable by eye or by a photometer at 540 nm ± 10 nm. In most kits, you compare the color to that of nitrate standards supplied with the kit to determine nitrate content.

Most commercial nitrate analysis methods use a heavy metal — such as cadmium or zinc — to reduce nitrate to nitrite. These metals are toxic and present a health risk for the analyst and for the environment. Cadmium disposal is particularly difficult and regulated.

NECi's systems use natural NaR and NADH, which are both user- and environmentally safe. Because NECi NTK systems are as accurate, if not more accurate, than other commercial systems, enzyme-based analysis is simply the better choice.

You can choose to analyze nitrate in the Standard Range (0.5 to 10 ppm nitrate-N) or the Low Range (0.01 to 1.0 ppm nitrate-N). Because NECi NTK systems use a photometric method for evaluating nitrate content, results are highly accurate across both ranges.

Saltwater kits for low-range nitrate (less than 1 ppm nitrate-N, or 7 micromolar) include nitrate standards in saltwater and the AtNaR form of nitrate reductase, which is not sensitive to chloride (Cl-).

For lab and microplate kits, the standard curve used for quantifying results must be made using standards that contain saltwater. Let us know you are testing saltwater when you order and we will provide a saltwater solution for sample preparation.

If you purchased the Standard Range kit, no changes are required. Any necessary modifications for test-tube format kits are noted in the instruction sheets in blue font.

Both are recombinant forms of nitrate reductase. YNaR (Yeast Nitrate Reductase) is produced in yeast. AtNaR is derived from Arabidopsis, a small plant in the Brassica family.

YNaR is moderately inhibited by chloride (Cl-), but remains highly effective for EPA or standard-range nitrate levels as well as seawater testing.

AtNaR is not inhibited by the complex organic acids found in plants (such as humics and tannins), and functions efficiently at higher temperatures (peak activity at 35°C). It also works well for soil extracts in the presence of 2M KCl.

We recommend AtNaR for all plant extracts, high-salt samples, and very low nitrate samples (below 1 ppm nitrate-N).

NECi's phosphate test kits use an enzyme that reacts with all of the phosphate in a sample to convert it to a new molecule. Unlike the nitrate kits, no color change occurs — instead, absorbance is measured in the UV range at 340 nm.

A spectrophotometer or NECi's handheld dual-wavelength photometer is required to read phosphate results. The amount of newly formed product detected correlates directly to the amount of phosphate in the sample.