The retardation factor is a relationship that is often used in chemistry, more specifically in chromatography applications.
The lag factor is a relationship that is often used in chemistry. Typically used in chromatography applications, it is usually expressed as a ratio of the distance traveled by a compound to that of a liquid solvent. The measured substances can be identified by using light, which exposes the substances in a solution mixed with a dye. The composite distance is usually divided by the solvent distance when calculating the lag factor. The derived values often depend on the nature of the solvent; moisture content, grain size and substrate thickness; how much material is analyzed, as well as the temperature.
Thin layer chromatography (TLC) is one application where retardation factor is used. The value can then be included in the calculation of a sample’s retention factor (Rf), which typically ranges from 0.0 to 1.0. Proteins are often classified this way, but a specific compound may have a different Rf depending on the level of moisture or solvents in the mixture. With TLC, samples are often placed on the bottom of a glass, plastic, or aluminum plate during the stationary phase. The plate is then added to a solvent in a stage called the mobile phase, and the rate at which the sample is moving can then be calculated.
Groundwater chemicals are also often monitored using the lag factor. The rate of groundwater movement is compared to the movement of pollutants as a proportion. The chemistry, the nature of the soil and the chemical reactions that take place in the process affect the delay factor. Processes such as sorption, where substances come out of solution and become concentrated in a material like soil, can also affect this movement. In water monitoring, this can cause contaminant levels to increase in the soil, while decreasing in a given water sample.
Water volumes are often sampled in laboratories using estimates of the retention factor as well as other variables. They can be calculated mathematically and then plotted on a graph to compare the behavior of one concentration with another aspect to identify trends. Depending on the method used, specific sample sizes may be required. Soil is often tested in this way and costs can vary depending on the sample and contaminants that may be present.
The lag factor is used in many applications, such as column chromatography and other sample analysis techniques. It can be used to track the movement of substances, pollutants, and individual molecules. Solvents moving through the cellulose fibers in paper can also be measured.