3. INTRODUCTION :- [1]
Sample treatment is that process of manipulative procedures used by the analytical
chemist to prepare the sample for the analytical measurement stage.
Requirement of sample pretreatment is to bring analyte in such a form so that it will
convenient to analyze.
Analysis
Primary Sampling Secondary Sampling Instrumentation Interpretation
4.
5. SAMPLE PRE-TREATMENT OPTIONS :- [1]
Following methods are used to minimize error in sample pre-treatment.
a. Sample collection
b. Sample storage and preservation
c. Sample transport
d. Preliminary sample processing
e. Weighing or volumetric dilution
f. Alternative sample processing methods
g. Removal of particulates
h. Sample extraction
i. Derivatization
6. Sample collection :-
It should have statistically valid data and it is most important and can depends
upon factors like sampling volume and number of test samples.
Sample storage and preservative :-
i. Sample storage is important as the analysis is not done immediately.
ii. Objective of storage- It is done so that there is no change of composition /
properties / any other stability parameters of analyte.
iii. So, biological samples should be stored inert, tightly sealed containers &
requires freezing
7. Sample transportation :-
i. Transportation conditions should maintain its integrity.
ii. Sample should not have rough handling or allowed to expose to other elements.
iii. Depending upon the type of sample different storage & transportation condition is
required which will not affect the composition/properties.
iv. Demonstrate that the sample is stable.
Preliminary sample processing :-
i. For solid sample grinding and for liquid sample homogenized sample solution.
ii. Objective - Error can be minimized by producing a homogenous. sample from which
representative sample can be used. Process like drying, sieving, grinding, filtration
need to validated and checked.
iii. Grinding validated by parameter RPM of grinding and drying by temp. of drying,
filters should not have higher sieve no. All the unit operation should be validated
8. Weighing or volumetric dilution :-
Errors can be minimized by the following techniques
i. Precaution should be taken
ii. Glassware must be calibrated
iii. Instrument must be validated
iv. Must to recognise the sensitivity
v. Volumetric dilution must be carried using performance qualification.
Alternative sample processing methods :-
It includes the following
i. Solvent exchange
ii. Desalting
iii. Evaporation
iv. Freeze drying
9. Sample Extraction :-
It depends upon the type of matrix for liquid sample and solid sample that must be known
Removal of particulates :-
i. Filtration - Validated by sieve no.
ii. Centrifugation - validated by G-Force
iii. Solid Phase extraction.
Derivatization :-
i. Objective – Enhance analyte detection and improve separation.
ii. E.g. = If the analyte conc / molar absorptivity is very low then add conjugating material
to it. It is done to minimize error by ensuring that the analytes are completely bind
with the conjugating material.
10. REFERENCES :-
1. Ronald E. Majors, Wilmington, DE. “Sample preparation fundamentals for
chromatography”. Agilent Technologies.2010 August;1-4
