Applied science

collecting samples

Representative sample

Analyst work with samples. the size of the smaple needed depends on what test will be carried out. sample ofany items must be representative.(should be a enough of a sample to give a picture of a whole items)

preservation of samples

It is important to prevent any changesor deterioration of asample.Some sample have to be analysed immediately.Other can be stored under suitable conditions.

Avoiding contamination

Accurate analytical results depend on the protecting samples from contamination. Crime scene investigators wear protective clothing and put all samples into sealed bags or bottle to avoid contaminating samples.They mayhave to appear in court to give evidence.

Avoiding tampering

It has been known for urine smaple taken for drugs testing to be swapped. For some sample it is important to have a chain of custody so it can show who has had access to the sample.

Planning

Taking samples needs careful planning. There are many factor to be considered such as

• where, when and how to collect sample
• how many samples, and how much of each to take
• how to store and transportthe samples to the laboratory
• how to avoid contamination
• how to safeguard the samples from tampering