Sample classification

There are many types of solid materials with different shapes, and the properties and uniformity of the materials vary greatly.

Since the components of solid materials are unevenly distributed, sampling at different points should be selected in a certain way and then mixed (sometimes not mixed, but processed and analyzed separately) to ensure the representativeness of the samples taken.

Number of sampling units n=(ts/E)^2

Liquid samples include water, beverages, oil and industrial solvents, etc. They are generally relatively uniform, so the number of sampling units can be relatively small.

Collection method

Sampler: Typically, either plastic or glass bottles will work

Preservation methods: control the pH of the solution, add chemical stabilizing reagents, refrigerate and freeze, protect from light and seal, etc.

Liquid samples are suitable for detection by most analytical methods. Therefore, original liquid samples generally can be used for measurement without additional processing.

Gas samples include automobile exhaust, industrial waste gas, atmosphere, compressed gas and gas soluble matter, etc.

Collection method

The chemical composition of gas samples is usually relatively stable and does not require special measures to be preserved.

Biological materials are different from general organic or inorganic materials. Their compositions vary greatly depending on the location and season. Therefore, the selection should be representative of the group, timely and typical of the location.

plant sample

Animal samples: After collection, they should be processed appropriately according to the requirements of the analysis project

(1) Crushing and screening

(2) Mixing and reduction

Acid melting method

alkali fusion method

(1) The state of the sample

(2) The existence form of the component being measured

(3) Concentration or content of the component being measured

(4) Interference from coexisting substances

(5) Selection of auxiliary reagents