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Sub-sampling (chemistry) In analytical chemistry, sub-sampling is a procedure by which a small, representative sample is taken from a larger sample. Good sub-sampling technique becomes important when the large sample is not homogeneous .
Sample size determination or estimation is the act of choosing the number of observations or replicates to include in a statistical sample. The sample size is an important feature of any empirical study in which the goal is to make inferences about a population from a sample. In practice, the sample size used in a study is usually determined ...
In analytical chemistry, sample preparation (working-up) refers to the ways in which a sample is treated prior to its analyses. Preparation is a very important step in most analytical techniques, because the techniques are often not responsive to the analyte in its in-situ form, or the results are distorted by interfering species.
Samples of different Rosé Wines in glass tubes showing range of colours available. In general, a sample is a limited quantity of something which is intended to be similar to and represent a larger amount of that thing (s). [1] The things could be countable objects such as individual items available as units for sale, or an uncountable material.
Representative layer theory. The concept of the representative layer came about though the work of Donald Dahm, with the assistance of Kevin Dahm and Karl Norris, to describe spectroscopic properties of particulate samples, especially as applied to near-infrared spectroscopy. [1] [2] A representative layer has the same void fraction as the ...
Stoichiometry. A stoichiometric diagram of the combustion reaction of methane. Stoichiometry ( / ˌstɔɪkiˈɒmɪtri /) is the relationship between the weights of reactants and products before, during, and following chemical reactions . Stoichiometry is founded on the law of conservation of mass where the total mass of the reactants equals the ...
Particle size is a notion introduced for comparing dimensions of solid particles ( flecks ), liquid particles ( droplets ), or gaseous particles ( bubbles ). The notion of particle size applies to particles in colloids, in ecology, in granular material (whether airborne or not), and to particles that form a granular material (see also grain size ).
Crystallography. Crystallography is a technique that characterizes the chemical structure of materials at the atomic level by analyzing the diffraction patterns of electromagnetic radiation or particles that have been deflected by atoms in the material. X-rays are most commonly used. From the raw data, the relative placement of atoms in space ...