Nitrate Source Tracking – Water Sample Types and Selection

For Nitrate Source Tracking, Isobar Science accepts these water types: creek/river, lake, pond/pool, marsh, groundwater, saltwater, rain/snow/ice, vadose-zone/soil water and stormwater.

The following characteristics are required:

  • Stabilization with a preserved vial or hydrochloric acid
  • Salinity of <40 PSU
  • Volume: 40 mL in small vials or Nalgene bottles

Ideally, the samples would also be filtered (≤ 0.2 μm if possible), however, filtration can be undertaken by Isobar Science for an additional fee.

Enhanced Nitrate Source Tracking (with Boron isotopes) – Please collect an individual non-acidified sample in a separate 100 mL plastic container for boron isotope measurements. Note: Batches of 10 samples for nitrate source tracking can be submitted in conjunction with boron isotopes.

We cannot accept the following samples:  

  • Water samples collected from an area near a nuclear power plant, commercial/medical reactors, industrial/medical waste sites or from drainage areas that would be contaminated with artificial 14C or other manipulated (enriched, depleted) isotope
  • Samples stored or handled by a laboratory that has ever used radioactive or artificially manipulated isotopes
    Water samples treated with mercuric chloride (HgCl2), sodium azide (NaN3), sodium hydroxide (NaOH) or other alkali chemicals
  • We cannot accept unstabilized samples or samples with a Salinity >40 for analysis at this time.


We can only accept samples submitted in batches of 20 (minimum).

Isobar does not report nitrate concentration.

Sample Volume & Recommended Containers

The following recommendations are general guidelines. Contact us for advice if you are concerned that your water samples are not enough for testing.

Sample volume: 40 mL

Recommended containers:

  1. Small vial – Use a small plastic vial with no prior use and fill to the top with no headspace. Isobar does not accept water samples for stable isotope analysis that still need to be pretreated (send filtered samples with no chemicals added).
  2. Nalgene bottles – Please DO NOT use glass bottles, recycled drinking water bottles, or other lightweight / low-density plastic bottles as they may allow isotopic effects to take place and bias the measurements, causing inaccuracies in the reported results. We accept no responsibility for the accuracy of testing results for samples submitted in collection bottles other than those specified.

Shipping to Isobar

Please use a box with sufficient packing to prevent breakage while in transit. Before placing the water bottles in a sturdy cardboard box, please put them inside a plastic bag and seal the bag with a zip-tie or duct tape. If any of the bottles leak during shipment, the water will not weaken the box.

We recommend commercial courier or ​registered ​first-class mail when sending the samples to the lab. Please email the courier and tracking number so we can monitor your package.

Download NST Sampling Guide

Please fill out the form to download our Nitrate Source Tracking sampling guide (500 KB PDF).