Sampling plans and techniques are used to select representative samples from pharmaceutical populations for testing purposes. There are three main WHO sampling formulae: n Plan uses the square root of the population plus one, p Plan uses 0.4 times the square root of the population, and r Plan uses 1.5 times the square root of the population. These formulae are used depending on factors like uniformity and source. Finished products and packaging materials should follow standards like ISO 2859 level II. The AQL provides guidelines on acceptable defect levels based on sample size and inspection level.

1. Pharmaceuticals Sampling plans and
techniques

2.  Sampling is the act, process, or technique of selecting a
suitable sample, or a representative part of a population
for the purpose of determining parameters or
characteristics of the whole populations.
 All operations related to sampling should be performed
with care, using proper equipment and tools.

3. Purpose of sampling:
Sampling may be required for different purposes, such as:
 prequalification;
 acceptance of consignments;
 batch release testing etc.

4. Classes and types of pharmaceutical products and
related materials:
The materials to be sampled may belong to the following
classes:
— starting materials for use in the manufacture of
finished pharmaceutical products;
— Finished pharmaceutical products.
— Packaging materials.

5. Types of sampling tools:
1.Scoops
Small containers of solid materials may be adequately
sampled using a spatula or scoop.
2.Dip tubes
 Dip tubes should be used for sampling liquid and topical
products and should be made of an inert material, such as
polypropylene or stainless steel.
3.Weighted containers
 For taking samples from large tanks and storage vessels, a
container in a weighted carrier can be used.
4.Thieves
 Sample thieves should be used when taking samples from
deep containers of solids.

6. Figure
Sampling scoops for solids

7.  If the scoop used is too small for the sizes of
particle being sampled, large particles will roll off
and testing bias may be introduced.
 On the other hand, if the scoop is too big, an
unnecessarily large sample will be obtained for a
given number of increments.
 A scoopful of sample should be taken in a single
movement and transferred to the sample
container.

8. Avoid tapping the scoop to remove
pharmaceutical product as this is likely to cause
segregation of the sample.

9. Figure
Typical dip tube

10. Figure
Typical weighted container

11. Figure
Typical sample thieves

12. Sampling plans and techniques
 Sampling plans and techniques means how a sample
is selected from given population.
 WHO suggests 3 formulae of sampling for starting
materials.

14. n Plan:
 Only used when material is assuming a uniform material
from a recognized source and where there is a high
degree of confidence in the source.
 The n plan is based on the formula
n = √N +1
where N is the number of sampling units in the
consignment. The value of n is obtained by simple
rounding.

16. Examples of use of sampling plan n: (7)
 Consider a consignment of 40 containers of a
starting material.
 Using the n plan, samples would be taken from
seven containers selected at random.
 The appearance and identity of each of these seven
samples is checked.
 If the results are concordant, the seven samples are
combined to produce a single, composite sample from
which an analytical sample is prepared for full testing.

17. The p plan:
 The “p plan” may be used when the material is uniform,
is received from a recognized source and the main
purpose is to test for identity.
 The p plan is based on the formula:
p = 0.4 √N

18. Examples of use of p sampling plans: (3)
Consider a consignment of 40 containers of a starting
material.
 Assuming a uniform material from a recognized source
with the main purpose of checking the identity.
 Using the p plan, samples would be taken from each
container. The appearance and identity of each of
these samples is checked.
 If the results are concordant, the samples are combined
to produce a single, composite sample from which an
analytical sample is prepared for full testing.

20. The r plan:
 The “r plan” may be used when the material is suspected
to be non- uniform and/or is received from a source that
is not well known.
 The r plan may also be used for herbal medicinal
products used as starting materials.
 This plan is based on the formula:
r = 1.5√N

21. Examples of use of r sampling plans : (10)
Consider a consignment of 40 containers of a starting material.
 Assuming the material is non-uniform and/or from a source
that is not well-known.
 Using the r plan, samples would be taken from each
container.
 The appearance and identity of each of these samples is
checked. If the results are concordant, 10 samples are
selected at random and individually subjected to full testing.

23. Sampling plans and techniques for finished products:
 As for packaging materials, sampling plans for finished
products should be based on defined sampling standards
such as ISO 2859 ,level II.
What is AQL?
 AQL stands for “Acceptable Quality Limit,” and it’s an
important standard that’s used in the quality control industry.
It’s defined in ISO 2859 as:
 “The quality level that is the worst tolerable,” over the course
of many inspections.

24. The AQL Chart: How it Works:
 The AQL chart is used to determine how many units
should be inspected and how many defects are
acceptable during your inspection.
 The chart is broken down into two tables.
“Sample Size Code Letters.”
“Acceptable Quantity Level”
“General Inspection Level” is level II (also underlined).
As a rule of thumb, this is the inspection level that
you should use most of the time.

25. Example:
 your order quantity is 1,500. So, it falls between 1,201
and 3,200 (underlined in the “Lot or Batch Size”
column).
 With most consumer products, the standard AQL levels are 2.5%
for major defects, 4.0% for minor defects.
 Going by this standard, we can see that your inspector will accept
a maximum of:
7 major defects, and
10 minor defects.
 A shipment with 8 major defects, 11 minor defects, or 1 critical
defect will fail. Your inspector now has the guidelines they need to
make a pass or fail decision.

26. Table 1 – Sample Size Code Letters

28. Packaging materials
Sampling plans for packaging materials should be
based on defined sampling standards, for
example, ISO 2859.

29. Sampling of the Packaging Material:
Carry out the sampling of all P.M. as per following sampling plan
for VISUAL EXAMINATION from each selected boxes of all
packaging material.
NUMBER OF BOX RECEIVED SAMPLE SIZE
Up to 150 20
151 to 280 32
281 to 500 50
501 to 1200 80
1201 to 3200 125
3201 to 10000 200
10001 to 35000 315
35001 to 150000 500
150001 to 500000 800
500001 to above 1250