NTA

The investigation of particle size distribution and concentration of natural or artificial nanoparticulate phases in different fluids, e.g. pore waters, ground waters or additives to cements like superplasticizers, is of high importance for the understanding and control of several processes.

With NTA the determination of number weighted sphere-equivalent hydrodynamic diameters of nanoparticulate phases with a certain dn/dc is possible in different fluids in the size range of a few tens of nanometers up to 1-2µm under controlled conditions.

In a dark field microscope, particles get visible through the scattering of light at particles. A video (approx. 25 fps) of particles, which move due to Brownian behavior, is recorded with a SCMOS camera and particles are tracked from frame to frame. Their diffusion coefficient is measured by evaluating their displacement and the resulting hydrodynamic diameter is determined by Stokes-Einstein law.

Funded by the Federal Ministry of Education and Research (Förderkennzeichen: 02NUK051CExternal link)

Ausstattung

Zur Messung von Einzelpartikelgrößenverteilungen und Konzentrationen in einem breiten Spektrum von flüssigen Probenmatrizes steht ein Malvern Nanosight NS300 Nanopartikel Tracking Analysesystem (NTA) mit 405 nm Laser und Spritzenpumpe zur Verfügung.

Nanopartikel/Kolloide können statisch oder unter Flussbedingungen gemessen werden.

Es können zudem mittels geeigneter Fluoreszenzfarbstoffe und eines Bandpass (490–550 nm) oder Longpass (> 715 nm) Fluoreszenzfilters selektiv markierte Partikel gemessen werden.

Probenvolumina von ≥ 1ml können in einer O-Ring-Top-Plate gemessen werden; für Volumina ≤ 1ml steht eine Niedrig-Volumen-Durchflusszelle zur Verfügung.

Equipment

A Malvern Nanosight NS300 Nanoparticle Tracking Analysis (NTA) equipped with a 405nm laser and a syringe pump is used for the measurement of single particle size distributions and concentrations in a wide range of fluids.

Nanoparticles/colloids can be measured under static or dynamic flow conditions.

Selectively dyed particles can be measured through the usage of suitable fluorescence dyes and a bandpass (490-550 nm) or a longpass (>715nm) filter.

Sample volumes of ≥ 1ml can be measured in an O-ring-top-plate; a low volume flow cell is available for sample volumes ≤ 1ml.

Sample preparation

Generally, for the exact determination of measuring conditions an agreement is necessary.

Liquid samples are measured with a minimum sample volume of 1-2 ml, whereas smaller sample volumes are possible with a prior arrangement.

The specific sample preparation depends on sample origin and sample matrix, due to individual necessity of e.g. filtration and/or dilution.

A constraint to ideal measurement conditions in environmental samples are motile microorganisms, which need to be killed through suitable methods.

Suitable fluorescence dyes need to be chosen for measuring in fluorescence mode.

Contact

Ruth Ewouame