Crude Protein by NIR – we are now accredited! | Hill Laboratories - NZ

Crude Protein by NIR – we are now accredited!

Crude Protein by NIR – we are now accredited!

Date: 8 Nov 2022
Author: Hill Laboratories

We are excited to announce that we have now successfully achieved IANZ accreditation for measuring plant Nitrogen and Crude Protein in Feeds using Near Infra-Red (NIR) Spectroscopy.

Using near infra-red spectroscopy to test feedstuffs has significant advantages for our lab and our customers. In just minutes, it can analyse for a wide range of analytes (including crude protein) that would otherwise take many hours of work by conventional ‘wet chemistry’ methods.

Nitrogen in the plant leaf tissue of horticulture crops is also very well predicted by NIR, and the “local nearest neighbours” model approach together with species matrix validation adopted at Hill Laboratories (HL) means this rapid measurement can be used with confidence.  

The species matrix protocol means that any sample types that have shown to be (statistically) invalid by NIR, will be automatically “code-swapped” to the reference method until sufficient paired data exists to give an acceptable certainty of measurement.

To learn more about the NIR technique please see this Technical Note.

Fig.1 below shows the high correlation between NIR and the reference wet chemistry method for Nitrogen and Crude Protein for mixed pasture.

                                                  crude graph

Fig 1: Plot showing correlation between NIR and conventional method analysis for Crude Protein (Nitrogen) for a sub-set of pasture samples.

While we have long held IANZ accreditation for the reference wet chemistry methods for plant nitrogen and crude protein, the IANZ accreditation requirements for the NIR indirect method have some additional components. Achieving this accreditation is an endorsement that the practices and processes for use of NIR at Hill Laboratories has been evaluated by a technical expert and deemed to meet the required criteria. NIR method validation and daily routine outlier detection are key to confident use of this technique.



 Fig 2: One of Hill Laboratories Bruker MPA NIR instruments, with plant samples loaded on auto-sampler carousel for Nitrogen and Feed analysis.