Dickey-John Instalab 700 NIR, Operator'S Manual

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OPERATOR’S MANUAL
Instalab 700 NIR Product Analyzer
11001-1574-201107
SAMPLE PREPARATION 21
SAMPLE PREPARATION
DRY POWDER
GRINDING SAMPLES
After being collected, whole grain samples or poorly ground samples must
be ground to a uniform particle size. Since the reflectance from a sample is
inversely related to particle size, it is common that particle size variations
can contribute to testing or calibration errors.
Sources of error caused by particle size variations can be minimized with
care in grinding. Obviously, the calibration sample set and the prediction set
must be treated in the same manner and should be as nearly identical in
particle size and the particle size distribution as possible.
Products such as flour, vital gluten, and dry yeast typically do not require
grinding to reduce the sample to a uniform particle size. Whole grain and
other meal products (gluten feed, corn grits, forage, silage, and oil seeds)
do require suitable grinding prior to analysis.
Low oil and low moisture products can be ground by using a Udy Cyclone
Mill (the belt driven model is preferred over the direct drive version). High oil
products can require the use of a knife mill of the type used for home
preparation of freshly ground coffee. The Krups Mill or the Mitey Mill are
examples.
Once a grinding method has been chosen, the grinding technique should be
documented and care taken to ensure the technique is repeated exactly on
all samples.
Do not grind samples near the air intake of the IL700 as dust can
be drawn into the unit.
MIXING SAMPLES
Since the Instalab determines the total sample composition by irradiating
less than one-half a cubic centimeter, that portion must be representative of
the whole. All constituents present must be distributed equally throughout
the sample. Typically, 15 to 20 complete turns of the ground sample with a
steel spatula are adequate for sample uniformity.
LOADING A STANDARD SAMPLE CUP
1. Begin by cleaning the window of the sample cup. Use a Scott lint free
microwipe or equivalent. If necessary, dampen the wiper with isopropyl
alcohol to remove oil residue. Brushing with a soft camel’s hair brush
can be sufficient for non-oily products such as wheat or oats.
2. Place sample cup cover (part with window) on loading tray (refer to
Figure 11 ). Place the cup with the glass window down and twist the
cup clockwise until it locks into place.