The delay factor is a ratio often used in chemistry, more specifically in chromatography applications.
The delay factor is a ratio 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. Measured substances can be identified by the use of light, which exposes the substances in a solution mixed with a dye. The compound distance is usually divided by the solvent distance in calculating the delay factor. 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 an application where the delay 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 can have a different Rf depending on the moisture level 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 at a stage called the mobile phase, and the rate at which the sample moves can then be calculated.
Groundwater chemical compounds are also often monitored using the lag factor. The rate of groundwater movement is compared to the movement of contaminants 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 separate from solution and become concentrated in a material such as soil, can also affect this movement. In water monitoring, this can cause contaminant levels to increase in the soil, while becoming lower in a given water sample.
Water volumes are often sampled in laboratories using retention factor estimates as well as other variables. They can be calculated mathematically and then plotted on a graph to compare the behavior of one concentration to another aspect to identify trends. Depending on the method used, specific sample sizes may be required. Soil is often analyzed in this way and costs can vary depending on the sample and the contaminants that may be present.
The delay 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, contaminants as well as individual molecules. Solvents moving through the cellulose fibers in the paper can also be measured.