3. Sample preparation
• Sample preparation is the way in which a
sample is treated to prepare for the analysis.
• Careful sample preparation is critical in order
to accurately generate unknown sample for
nutrients measurement.
4. • Generally, errors in analytical procedures are
categorized as random or systematic.
• Random errors are errors due to change and are
often due to noise in instrument.
• However, systematic errors are due to investigator
though may cause inaccuracy.
Importance of sample preparation
5. • Errors in sample preparation are systematic errors,
which will propagate through analysis,
cause uncertainty or inaccuracies in the final
results.
• By proper sample preparation these errors may be
reduced.
Importance of sample preparation
6. • It is of utmost importance that sample preparation
should be appropriate, because
If the sample taken for analysis does not represent
the original sample accurately, the results of that
analysis will be questionable.
8. • Sample as prepared (from the lot) for sending to the
laboratory and intended for inspection or testing.
• Sub-sample prepared from the laboratory sample
from which test portions will be taken for analysis.
9. • Quantity of material drawn from the test sample.
• Left-over material from the test samples where test
portions are taken away.
10. Points to be considered during sample
preparation
12. Does the
sample
require
heating ?
Options:
1. Heat to remove the moisture
2. Dry ash to destroy the organics
Is
homogeniz
ation
required?
Options:
1. Mix the sample
2. Grind the sample, etc
14. Material required for sample preparation
• Cleaning tools (for cleaning equipment like grinders, working area etc)
a) Brushes
b) Compressed air blower
c) Vacuum cleaner
d) Ultrasound bath (useful for cleaning sieves)
• Sampling tools
Spoons, spatulas and shovels
28. Mix the sample
Mixers (tumbling
mixer, rotating mixer)
Store the sample
Plastic
bags
Wide
mouth
plastic
bottles
with
screw
cap
Refrigerator, Freezer
