Sampling materials are classified into three main types: solid, liquid, and gas.
Solid samples include a variety of substances, such as sediments from water bodies, soil, metals, and biological tissues. Two standard methods for extracting sediments from water bodies are grab sampling and piston coring. Grab sampling involves using a device to collect a discrete sediment sample from the bottom of a water body with minimal disturbance. Grab samples do not always represent the entire area due to spatial variability (variation across different locations). Piston coring is a method used to retrieve a continuous column of sediment that allows for analyzing changes over time within the sediment layers.
A sample can be collected using a clean sampling bottle for surface water bodies like lakes or rivers. The bottle should be submerged at the desired depth to minimize contamination. Blood sampling typically uses a syringe inserted into a vein to draw a specific blood volume. The sample is then transferred to the appropriate containers for further analysis. Urine sampling involves using a clean container to collect a specific urine volume. The urine sample is then transferred to suitable containers for analysis. Industrial effluents are often heterogeneous liquids containing various chemicals and pollutants. Sampling such effluents typically requires an automatic sampler, a device designed to collect samples over regular intervals. This device is programmed to collect representative samples at predetermined time intervals, comprehensively analyzing the effluent's composition.
For gas sampling, solid sorbents like activated carbon are commonly used to selectively adsorb target compounds from a gas stream. The compounds adsorbed onto activated carbon can be extracted through various desorption methods, such as heating and solvent extraction. Depending on the specific compound and the information needed, the extracted compounds can then be analyzed using characterization techniques like spectroscopy or chromatography.
There are three types of sampling materials: solid, liquid, and gas. Solid samples can include sediment accumulated in water bodies, rocks, metals, and biological tissues.
Sediment in water bodies is extracted using a grab sampler or a piston corer. For example, after lowering a grab sampler to a riverbed, the sampler closes around the sediment to extract a sample.
Some examples of liquid samples are water, blood, urine, and solvents. A precise volume of the homogeneous liquid is collected using a pipette or syringe.
Samples can be obtained from heterogeneous liquids like industrial effluents using an automated sampler, which collects them at regular intervals.
Gaseous samples can be collected from atmospheric air, exhaust vents, and industrial smokestacks for analysis.
Solid sorbents, such as activated carbon, are widely used to selectively adsorb target compounds from the gas stream. The target compound is then extracted by desorption techniques and analyzed via suitable analytical methods.
繁體中文
