Analytical sampling Flashcards
Principle processes in a sample scheme
- Design of a sampling plan
- Obtaining the sample from the bulk
- Reduction & preparation of 1 or more Lab samples
- Analysis of the sample
- Taking the Decision!
Factors to be considered in the design of a sampling plan
- Definition of objectives, what is the aim of the measurement?
- Select Analytes and decide on analytical methods
- Determine sample locations
- Select method for sample preparation (sample preservation and or pre-treatment)
- Prepare the final protocol (and/or review in light of experience)
Incremental samples
A small portion of the product taken
by a sampling device
Aggregate sample
Several incremental samples mixed
together
Reduced sample
Aggregate sample divided into one or
more portions
Laboratory samples
Prepared from the aggregate or
reduced sample by division into 1 or
more identical portions for delivery
into seller’s, buyers and reference
labs
Test sample
Prepared from the Laboratory sample by grinding, sieving , mixing, drying or other appropriate treatment
Test Portion
A part of the test sample used in a
single test or determination
Systematic sampling
Systematic sampling is a probability sampling method where researchers select members of the population at a regular interval – for example, by selecting every 15th person on a list of the population.
Random sampling
Random sampling is a method of choosing a sample of observations from a population where every member of the population has an equal probability of being selected
Stratified sampling
Stratified sampling is a method of sampling from a population that is divided into subgroups or strata that are relatively similar or homogeneous. Researchers use stratified sampling to ensure that specific subgroups are present in their sample or to sample each subgroup independently. The subgroups are based on characteristics that the population members share
