Efforts over the last 50 years have triggered the implementation of many laws, amendments, and regulations for environmental improvements.
Recent publications show that scientists and researchers heavily influence efforts for global climate change improvement. Their discoveries guide environmental awareness initiatives and regulations, affecting mandated local, regional, and country-specific testing and environmental health. Freshwater, seawater, soil, sludge, and other samples are studied and graded to track the Earth’s condition. Levels of pollutants, toxins, nanoparticles, genetic material, and proteins are assessed. These results are important for climate control and improvement, and findings may help to avert negative environmental impact.
Ultrafiltration (UF) methods have been incorporated into environmental research and monitoring workflows, with samples prepared from our Earth’s oceans, rivers, waterways, and soils. Small volume samples (0.5 – 70 mL) typically utilize centrifugal ultrafiltration (cUF) devices such as Amicon® Ultra filter units or centrifugal microfiltration (cMF), while large volume samples (up to 400 mL) are compatible with pressurized ultrafiltration (pUF) or pressurized microporous filtration (pMF) devices, such as Amicon® Stirred Cell assemblies. Filtration techniques are widely used in assessing levels of pollutants and evaluating methods for removal, surveying biodiversity in our oceans, identifying biomolecular indicators in soil toxicity, measuring environmental antibiotic resistance, and other studies.
When using ultrafiltration for sample concentration, particular attention should be paid in choosing the correct filter membrane. Performance may vary by manufacturer, as well as membrane material.
Generally, solutes larger than the specified MWCO will remain upstream of the filter (i.e., in the retentate), while water and solutes smaller than the specified MWCO pass through the membrane into the filtrate. This can permit removal or retention of other macromolecules that may affect critical biological and chemical determinations, downstream analysis, and assay performance based on size.
When using centrifugal ultrafiltration (cUF) devices, separation, concentration, or washing functions can be performed. Centrifugal microfiltration (cMF) devices are for pre-filtering and washing only.
Pressurized filtration (pUF and pMF) methods are utilized when centrifuges are not available, for gentler or controlled processing, or to accommodate samples volumes up to 400 mL (this volume can be further expanded with the addition of an external reservoir). The larger sample volume capacity makes pressurized ultrafiltration with stirred cells ideal for larger environmental samples such as seawater, wastewater, or freshwater. Flexible, easy-to-use filter housing assemblies can accommodate a wide range of ultrafiltration and microporous filtration membranes, allowing processing of samples at varying pressures and temperatures. Stirred cell devices for pressurized and microporous filtration are reusable and autoclavable, with magnetic stirring for minimizing concentration polarization and shear stress-induced denaturation during filtration.
Factors to consider when selecting an ultrafiltration centrifugal method or membrane for pressurized filtration methods:
Publications show ultrafiltration and microporous filtration play a critical role in environmental monitoring and research workflows. Applications include eco-analysis for water, seawater, soils, tissues, and biologicals. The utility of Amicon® cUF, cMF, pUF, and pMF devices has been demonstrated for separation, cleanup, and enrichment for lab-scale preparations. Impurities separated for analysis include ionic salts, chemical pollutants, and genomic, molecular, and physical particulate. The optimal filter choice greatly impacts yields, reproducibility of results, and data quality. Both centrifugal filtration (cUF and cMF) and pressurized filtration (pUF and pMF) processes provide quick, simple, and efficient ways to separate larger materials from smaller constituents and concentrate or purify samples. Physical composition of the sample, as well as size and shape of the target retentate or filtrate, are important attributes that need to be considered in filter selection. The Amicon® portfolio, Microcon® portfolio, and Centricon® Plus 70 portfolio offer ultrafiltration devices, assemblies, and membranes for separation, purification, enrichment, desalting, and buffer exchange. Ultrafree®-MC and Ultrafree®-CL filter devices separate by pore size for pre-filtration applications. These devices provide valuable workflow solutions used in studies for the climate challenges of our Earth.