Precipitation works by obtaining a chemical interaction between two chemicals as selective as possible and with a solubility constant as low as possible, which will make the product of the reaction unstable in solution.
L-L extraction is a method to separate compounds based on their relative solubility in two different immiscible liquids, usually water and an organic solvent
It can be performed without chemical changing or can be assisted with different reactions to enhance selectivity, by changing pH -transformation of ionic compounds, soluble in water, into neutral species, soluble in an organic solvent; adding ligands to favor complexation reactions –i.e. extraction of metals
Distillation is a technique to separate mixtures based on differences in their volatilities in a boiling liquid mixture. It is one of the oldest separation methods.
Lixiviation is the process of separating soluble from insoluble substances by dissolving the former in water or some other solvent.
Solid-phase extraction (SPE) is a separation process that is used to remove compounds from a mixture of impurities based on their physical and chemical properties.
Forensic laboratories use solid phase extraction to concentrate and purify samples prior to analysis
Internal Standards are added in a constant amount to samples in order to guarantee that the analysis is performed without problems, they also help to minimise errors when used in the calibration curve
The Internal Standard need to have similar chemical structure and properties that the analytes I want to study, but they cannot interfere with the analysis. As they have similar properties they will behave similarly during the process.
Blanks ensure the elimation of Contamination of the system from previous analysis i.e carry over,It also gives valuable information such as Baseline signal and Limit of detection
treatment of data (cont')
Control samples are any type of well-known forensic samples used to assure analyses are properly performed so that results are reliable (Certified Reference Materials or CRM)
Control samples are an important part of quality control and assurance procedures that forensic scientists use to eliminate the inaccuracy of laboratory results
Now we have some results obtained from our instrument. We know they have No carry over, because we have performed a blank. We also know that the Instrument is behaving because we have run a control sample.