❞ كتاب Extraction Methods for Environmental Analysis ❝ ⏤ JOHN R. DEAN

Biologically

Biology is a natural science that is concerned with the study of life, its various forms and its function, how these organisms interact with each other and with the surrounding environment. The word biology in Greek is made up of two words: bio (βίος) meaning life. And loggia (-λογία) means science or study. Biology: the similarity of vegetation and animal cover on the edges of the African and American states, and the existence of the same fossil.

Branches of biology
Biology is an ancient science thousands of years old and modern biology began in the nineteenth century. This science has multiple branches. Among them are:

Anatomy
Botany
Biochemia
Biogeography
Biofisia
Cytology or cell science
Ecology or environmental science
 

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Two common approaches are possible. In the first approach the extraction is carried out discontinuously
where equilibrium is established between two immiscible phases, or the second approach, continuous
extraction. In the case of the latter, equilibrium may not be reached. The selectivity and efficiency of
the extraction process is critically governed by the choice of the two immiscible solvents. Using
aqueous and organic (e.g. dichloromethane, chloroform, ethylene acetate, toluene, etc.) solvent pairs of
solvents, the more hydrophobic analytes prefer the organic solvent while the more hydrophilic
compounds prefer the aqueous phase. The more desirable approach is quite often reflected in the nature
of the target analyte. For example if the method of separation to be used is reversed-phase high
performance liquid chromatography (HPLC), then the target analyte is best isolated in the aqueous
phase. In this situation the target analyte can then be injected directly into the HPLC system. (Note: The
target analyte may well require preconcentration, e.g. solid phase extraction (see Chapter 4), to achieve
the appropriate level of sensitivity.) In contrast, if the target analyte is to be analysed by gas
chromatography it is best isolated in the organic solvent. In addition, isolation of the target analyte in
the organic phase allows solvent evaporation to be employed (see Section 3.1.3) thus allowing
concentration of the target analyte.
The equilibrium process can be influenced by several factors that include adjustment of pH to prevent
ionisation of acids or bases, by formation of ion-pairs with ionisable analytes, by formation of
hydrophobic complexes with metal ions, or by adding neutral salts to the aqueous phase to reduce the
solubility of the analyte (salting out).

Biology
Human biology
Who is the founder of biology?
The importance of biology
Areas of work in the field of biology
Theories of biology
Research on biology for the first grade of secondary school
Human biology