Small particle liquid chromatography applications

Guillarme, D. et al., Method transfer for fast liquid chromatography in pharmaceutical analysis Application to short columns packed with small particle. Part II Gradient experiments, Eur. J. Pharm. Biopharm., 68(2), 430, 2008. 

Furthermore, nanodiamond is suitable to applications in liquid chromatography. A directed modification of surface polarity and adsorptive properties is feasible here by functionalization of the particles. Apart from this versatility, the nanodiamond material also stands out for another advantage the large mechanical resistance and the small particle size allow a use in high-pressure applications, which is where the best separating power is achieved. 

In the first approximation, the column packed with small particles can be considered an array of capillaries. Hydrodynamic processes augment the exclusion based separation (see section 11.7.2, Retention Mechanisms and Accompanying Processes in SEC) and form the ground of a liquid chromatography-like method called hydrodynamic chromatography, HDC. HDC found application in separation of veiy large macromolecules, particles and dispersions. Its separation selectivity is rather low and it was partially substituted by the group of methods termed fieldflow fractionation (see seetion 11.3.3, Molar Mass Dispersity). 

In MSPD, sample is completely disrupted and dispersed into particles of very small size, which enhances a surface area required for subsequent extraction of the compounds, whereas in solid-liquid (SL)-SPE, sample disruption must be carried out separately and several compounds must be discarded before an extractive solution is found suitable for application on SPE column. While in SPE the extracted compounds are usually absorbed onto the top of the column packing material, in MSPD they are absorbed throughout the column. Physical and chemical interactions among the components of the system are greater in MSPD than those occurring in classical SPE or other forms of liquid chromatography (LC). 

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