MAKING IT HAPPEN: NIR CALIBRATION TRANSFER

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1 MAKING IT HAPPEN: NIR CALIBRATION TRANSFER Peter Flinn Kelspec Services Pty Ltd, Dunkeld, Victoria

2 TRADITIONAL vs NIR ANALYSIS Traditional analysis isolates the analyte from the matrix before measurement NIR lets the sample matrix participate in measurement

3 NIR analysis relies on chemometrics to relate the spectra to chemical/physical components or functional properties

4 NIR SPECTRUM OF OAT GRAIN Combination bands Water first overtone Water OH CH NH NH CH second overtone OH first overtone CH first overtone

5 NIR CALIBRATION: BASIC STEPS Scan samples - record spectra Select representative calibration set Do reference analyses on calibration set Enter reference values - pre-treat spectra Modelling-cross validation PCA, PLS, NN Predict remaining / future samples (closed set) (open sets)

6 AN NIR CALIBRATION WILL ONLY WORK IF. it is based on accurate reference data it is derived from a large sample set it contains all sources of variation encountered in routine samples to be tested it is validated on an independent sample set before being implemented it is regularly monitored over time

7 ADVANTAGES OF NIR Rapid and cost-effective Clean and green Multiple tests from one sample scan Precision often better than reference method Often the ONLY alternative available

8 CHALLENGES WITH NIR Perception of black box : what you measure is not what you analyse for! Reference methods are the judge and jury in the trial of NIR Correct sample presentation critical Spectral interpretation difficult due to relatively broad, weak, overlapping absorptions Dealing with outliers

9 Courtesy CBH, WA

10 THE PGLP chemical components (76) physical properties (27) GRAINS (n~190): selected/grown out or acquired from 3,300 samples functional characteristics sheep poultry cattle pigs

11 NIR CALIBRATIONS 70 constituents or properties Whole and milled grain 3 separate populations: all grains; all less pulses; all less pulses, oats, maize, rice SNV/Detrend for scatter correction MPLS, cross-validation, 1 st or 2 nd derivative 3 different wavelength ranges 2 outlier options...over 5,000 CALIBRATION EQUATIONS!

12 The calibration equations to be transferred..

13 AusScan CALIBRATION STATISTICS (WHOLE GRAIN) (Foss XDS format) Animal Type Measurement N Mean SD SECV 1-VR RPD Beef Cattle Est. ME MJ/kg DM* Acidosis Index Sheep/ Cattle Oat in sacco DMD% Oat Hull ADL% Oat Hull (%grain) * Calculated from in vivo DMD%, ad libitum; excluding sorghum

14 In vivo DMD% - sheep (whole grains)

15 RELATIONSHIP BETWEEN in vivo DMD FOR CATTLE (ad lib) AND SHEEP (maintenance) (n=24) Cattle in vivo DMD Barley Wheat Triticale Oats Sorghum Sheep in vivo DMD

16 DMD CATTLE (ad lib) vs SHEEP (maintenance) All 24 grains: DMD cattle = DMD sheep R 2 = 0.54, RSD = sorghums omitted: DMD cattle = DMD sheep R 2 = 0.91, RSD = 2.04

17 In sacco Digestibility % (whole oats)

18 AusScan CALIBRATION STATISTICS (WHOLE GRAIN) (Foss XDS format) Animal Type Pigs Measurement N Mean SD SECV 1-VR RPD Faecal DE MJ/kg Ileal DE MJ/kg Ileal:Faecal DE Ratio Faecal DE Intake Index Broilers Grain AME MJ/kg Grain AME Intake Index

19 AusScan CALIBRATION STATISTICS CHEMICAL & PHYSICAL PROPERTIES (WHOLE GRAIN) (Foss XDS format) Measurement N Mean SD SECV 1-VR RPD Crude Fibre %DM ADF %DM Englyst NDF %DM Total Starch %DM Total Insoluble NSP %DM Total Soluble NSP %DM Insoluble Arabinoxylans %DM β-glucans %DM Hydration Capacity %

20 Starch in cattle faeces (%DM) (ground samples)

21 But first INSTRUMENT STANDARDISATIO N (where possible)

22 INSTRUMENT EXAMPLES Name Mode Type Spectral range (nm) No of data points Foss 6500,XDS R Scan mono Foss 5000 R Scan mono Foss IX R Scan mono Foss Infratec T Scan mono CropScan 2000 T Diode array Bruker MPA R FT-NIR

23 FOSS XDS, 6500, 5000 (with WINISI software) Straightforward: tried & tested process Whole grain standards: sealed 1/4 cups (n=23) OR Ground standards: sealed ring cups (n=30) Standards scanned on master and host instruments STD file prepared and sent to licensee Equations can be used immediately

24 FOSS InfraXact (with WINISI software) Sealed whole grain standards cannot be used A set of loose grains must be scanned on master and host instruments SIDE BY SIDE STD file prepared and sent to licensee Equations must be re-derived on spectra trimmed to IX range

25 Bruker MPA (with OPUS software) Sealed standards cannot be used A set of loose grains must be scanned on Foss and Bruker instruments SIDE BY SIDE Transfer algorithm prepared from the two spectra sets Algorithm used to convert Foss CAL files to OPUS format via JCAMP-DX All calibrations re-derived in OPUS, with transfer spectra included New equations provided to licensee

26 FOSS Infratec Standardisation is not possible (transmission instrument, nm) All calibration samples must be rescanned on the Infratec(s) The spectra are converted to WINISI format and all calibrations re-derived using Infratec range Equations provided to licensee for conversion into ODIN format

27 Other instruments assessed on a case-bycase basis eg. investigation currently in progress with CropScan

28 A WORD OF WARNING... We are dealing with... Relatively small data sets Complex in vivo measurements Relatively high errors in some cases EXPECTATIONS OF CALIBRATION TRANSFER SUCCESS SHOULD BE REALISTIC! NIR IS NOT BLACK MAGIC, BUT NEITHER IS IT MAGIC!