Sampling and preparation of samples is an important link in the analysis work, which directly affects the representativeness of samples and the reliability of analysis results. Therefore, if the analysis results can reflect the real situation of the material, we should not only choose the appropriate analysis and determination method and careful operation according to the properties and analysis requirements of the sample, but also pay attention to the sample collection and processing before the test. The specific process includes: sampling, sample preparation, sample decomposition, and pretreatment before determination.
Sampling
Sampling refers to taking a small number of samples from a large number of materials as the original sample. The original sample is then processed and used for analysis, and the analysis results are regarded as reflecting the actual situation of the original material. Therefore, the collected samples should be highly representative, that is, the composition of the collected samples can represent the average composition of all materials. Otherwise, the follow-up analysis work will be meaningless.
Sample Preparation
The amount of sample required in the analysis experiment is usually a few tenths of a gram to a few grams, while the amount of original solid sample is generally large, ranging from several kilograms to tens of kilograms. Its composition is complex, and the distribution of chemical components is often uneven. Therefore, they need to be processed so that they are substantially reduced in number but still represent the original specimen. It is usually processed into a final sample of about 100g and 300g for analysis, that is, a laboratory sample.
Sample Decomposition
In the analysis work, except for the dry analysis, the test of the sample is basically carried out in the solution. Therefore, if the sample is in a non-solution state, it needs to be converted into a solution by an appropriate method. This process is called the decomposition of the sample. The decomposition of the sample is an important part of the analysis work. It is not only related to whether the component to be tested is transformed into a suitable form, but also related to the subsequent separation and determination.
Pretreatment before Determination
After decomposition, the sample sometimes needs further treatment before it can be used for determination. The method of treatment should be determined according to the composition of the sample and the determination method adopted, and different analysis methods and items have different requirements for the sample. There are many pretreatment methods for samples, and the appropriate method should be adopted according to experiments or reference materials for specific samples.
