Postnova model PN3621 MALS high-performance MALS detector

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Postnova’s model PN3621 MALS is a high-performance MALS detector that has been specifically designed for filed flow fractionation.

The detector system employs 21 angles affording the claimed broadest angular range available. These 21 angles are crucial to fulfil the exacting accuracy required when measuring complex particulate samples, ensuring the highest precision in molecular weight and particle size determination. With 21 angles the PN3621 MALS can achieve the highest quality data fit for the most scientifically meaningful results, particularly for high molar mass polymers and large particles.

MALS is typically being used to measure larger sample species, such as protein aggregates, high molar mass macromolecules and particles. Because of their size and fragile nature, these samples have to be treated gently to avoid any alteration. Shear forces, chain degradation, conformational changes and deterioration or complete loss of bioactivity can be induced by highly turbulent light-scattering cells. In addition, aggregation, adsorption and sedimentation phenomena can cause problems in light-scattering cells, particularly when they incorporate edges, dead volumes or right-angle flow paths. The PN3621 MALS avoids these limitations via a vertical flow cell so that the sample passes though easily, without any obstacles or restrictions. The flow cell has no right-angle entry and outlets which could induce shear forces or cause particles to settle and adsorb.

The precision of molar mass and particle size determination is not only dependent on the number of angles but also on the number of low angles which are available for calculation. The most significant of these are between 0 and 35° in determining accurate and precise molar mass and size determination. Previously, static light scattering detectors were largely ineffective because low angles were either unavailable or did not deliver sufficient sensitivity or precision. A lack of low angles is satisfactory when investigating smaller species, such as proteins or macromolecules where there is no angular intensity dependence; but for larger and more complex samples, such as branched polymers, high molar mass macromolecules, large protein aggregates and nanoparticles, the existence of high-quality low angles is critical to obtain optimal precision and accuracy. The PN3621 MALS overcomes these limitations by offering a complete set of stable working low angles, starting from 7, 12, 20 and 28° onwards.

The detector employs the latest optoelectronic design, including digital signal processing for each of the 21 angles. The electronics are based on a 24-bit resolution AD system which facilitates a broad dynamic signal range. For maximum flexibility it is possible to read-in up to three external analog signals.

It is suitable for challenging applications including: biotechnology - alginates, carrageenans, hyaluronic acids, cell organells, exosomes; biopharmaceuticals - peptide, protein, antibody, virus aggregates and conjugates; food and agri science - starches, pectins, polysaccharides, proteins, casein micells; polymer science - rubbers, latex dispersions, polyolefins, polyelectrolytes; environmental research - humic-fulvic colloids, iron oxides, clays, silica particles; nanotechnology: tio2, cnt, c60, latex, zno nanoparticles and silica nanoparticles.