As per Pharmacy council of India syllabus of B.Pharmacy, First year, semester first this PPT covers point from unit I

1. Errors
Mrs. shinde Pooja Nilkanth

2. Unit I
Error
Definition of error
Error is the difference between true value or standard value and observed
value.
Types of error
Error
Determinate error Indeterminate error
Personal error Instrumental error reagent error Error in method

3. Determinate error
These errors are known to analyst. By preplanning and careful
working it can be avoided or kept at minimum
1. Personal error – Caused due to personal mistakes or by
carelessness of analyst. Careful working of analyst can
eliminate these type of error.
Example – If analyst wrongly calculating the weight of
NaOH required to produce 0.1N NaOH.
2 Instrumental error - Caused due to defect in instrument, may
cause due to faulty and uncalibrated glass wares, apparatus.
These error can be removed by causing good quality
apparatus and calibrated glasswares, apparatus and
instruments.

4. Example – 5ml pipette is used to take sample solution for
analysis bur pipette take out only 4.8ml due to construction
defect thus error of 0.2 ml will introduced.
3. Reagent error - Many reagents and compounds are not in
pure form they contain impurities.
4. Error in method - Selection of wrong method or responsible
for this type of error
Indeterminate or random error
These errors are called as accidental error, cause of this type of
error may or may not be known and due to unknown cause
they cannot be removed.

5. Methods of minimising error
Errors can be minimised by using following methods
1) By calibration of apparatus
Error can be minimised by calibrating all the instruments
and appropriate correction are applied to original
measurement.
2) Control determination
Standard substance is used in experiment in identical
experimental condition to minimise error.
3) Blank determination
By omitting sample determination is carried out in
identical condition.

6. 4) Parallel determination
Instead of single determination duplicate or triplicate
determination is carried out to minimise error.
Accuracy and precision
Accuracy
Accuracy is the degree of agreement between measured value and
true value. The term accuracy refers to how near the observed
value is to standard value.
Precision
Precision is defind as the degree of agreement between replicate
measurement of the same quantity.
It is the repeatability of the result. Precision may be expressed as
standard value so the precision refers to nearness between several
measurements
of the same quantity.

7. Significant figure
Significant figure of a number are those digits that carry
meaning contributing to its measurement.
The rules for identifying significant figures when writing or
interpreting numbers are as follows.
1) All non zero digits are considered significant.
For example – 27 has two signiicant figures 2 and 7.
2) Zero appearing anywhere between two non zero digits are
significant
For example – 308.896 have six significant figures 3, 0, 8,
8,9,6

8. 3) Leading zeros are not significant 0.00056 has two
significant figures 5 and 6.
4) Trailing zero in number containing decimal point are
significant.
For example – 33.55276 has seven significant figures
3,3,5,5,2,,7,6