SAMPLING

Question 1

A defined procedure whereby a part of a substance, material or product is taken
to provide for testing or calibration a representative sample of the whole. (ISO /IEC 17025)

Answer 1

Sampling

Question 2

The process of selecting a portion of material, in some manner, to represent or provide information about a larger body of material.

Answer 2

Sampling

Question 3

To reduce the size of the bulk material;

Answer 3

Sampling

Question 4

To preserve information contained in the bulk material

Answer 4

Sampling

Question 5

A portion of a material, selected in a specialized manner, which represents a larger body of material

Answer 5

Sample

Question 6

Representative of the bulk (system)

Answer 6

Sample

Question 7

Of reduced size that can be handled by the sampler and analyst

Answer 7

Sample

Question 8

Retains the properties of the lot, or properties change the same way as the
lot

Answer 8

Sample

Question 9

Suitable in amount and form to provide needed information

Answer 9

Sample

Question 10

Forms of the lot / bulk / system

Answer 10

o Solid / Liquid / Gas
o Homogeneous / Heterogeneous
o Static / Dynamic
o Inorganic / Organic / Biological

Question 14

Types of Sampling

Answer 14

o Random Sampling
o Judgmental / Selective Sampling
o Systematic Sampling
o Stratified Sampling

Question 15

Sample is collected a random from the target population
(Random sample).

Answer 15

Random Sampling

Question 16

Increments are taken in such a way that any portion of the bulk has the same probability of being sampled out.

Answer 16

Random Sampling

Question 17

Bias is reduced to minimum if not eliminated.

Answer 17

Random Sampling

Question 18

Used when the number of independent variables influencing the results of an
analysis are to be limited

Answer 18

Judgmental / Selective Sampling

Question 19

More biased, but fewer samples are required

Answer 19

Judgmental / Selective Sampling

Question 20

Sample are taken according to a sampling plan to screen out
materials with certain characteristics and/or select materials
with other relevant characteristics

Answer 20

Judgmental / Selective Sampling

Question 21

Available information about the target population is used to
help select samples (Selective samples)

Answer 21

Judgmental / Selective Sampling

Question 22

The target population is sampled at regular intervals in space or time
(Systematic sample).

Answer 22

Systematic Sampling

Question 23

Increments are taken at predetermined intervals as defined by the sampling
plan

Answer 23

Systematic Sampling

Question 24

Intermediate bias with respect to random and selective sampling.

Answer 24

Systematic Sampling

Question 26

Target populations are conveniently subdivided into distinct units (strata), in each of which random sampling is done.

Answer 26

Stratified Sampling

Question 27

Advantage: the composition of each stratum is often more homogeneous than that of the entire target population, leading to lower sampling variance (uncertainty).

Answer 27

Stratified Sampling

Question 28

Sampling Operations

Answer 28

1. Grab sampling 1. Composite sampling 1. In-situ sampling

Question 29

Sampling done within the population without physically removing the sample

Answer 29

In-situ sampling

Question 30

Several grab samples combined to form a single sample

Answer 30

Composite sampling

Question 31

A single sample taken from the target bulk.

Answer 31

Grab sampling

Question 32

Sampling Equipment

Question 33

For Solids

Answer 33

1. Hand scoops 1. Sampling thief 1. Sampling probe / core sampler 1. Bayonet samplers

Question 34

for sampling solids with loose particles from bags or the bulk

Answer 34

Hand scoops

Question 35

a tube with a slit running its entire length, with one end attached to a handle and the other end with a sharp cutting edge. Used for solids with loose or compacted particles.

Answer 35

Sampling thief

Question 36

a metal tube that is inserted into the bulk to retain a core of the sample

Answer 36

Sampling probe / core sampler

Question 37

a hollow tube with one end open and sharpened and the other end attached to a sample container. Useful for sampling free flowing solids from sacks

Answer 37

Bayonet samplers

Question 38

Proper Behavior

Answer 38

▪ Know beforehand the hazardous characteristics of the chemicals with which you plan to work ▪ Never wear or bring lab aprons or lab coats or jackets into areas where food is consumed. ▪ Never pipet by mouth. Always use a pipet aid or suction bulb. ▪ Do not handle contact lenses in the laboratory except to remove them when an emergency requires the use of the eyewash fountain or safety shower. ▪ Never perform unauthorized experiment. ▪ When moving about in the laboratory, anticipate sudden backing up or changes in direction of others