ISO 20579-3-2021 pdf free download – Surface chemical analysis — Sample handling, preparation and mounting — Part 3: Biomaterials.
6 General requirements and classes of specimens6.1General information
General information on specimen handling of solid biomaterials is available in References [4] to [14J.Biomaterials analysis requires special methods to control many of the biological reactions occurringin response to a biomaterial.Functionality, biocompatibility and durability are of concern.Someinformation for solid surfaces is found in Reference [5].Contamination is a key concern. The degree ofcleanliness in particular for biomaterials required by surface-sensitive analytical techniques is muchhigher than for many other forms of analysisl4l. Specimens and mounts must never be in contact withthe bare hand.Handling of the surface to be analysed should be eliminated or minimized wheneverpossible. Fingerprints contain mobile species that may contaminate the surface of interest.Handcreams, skin oils and other skin materials are not suitable for high vacuum.
6.2 Handling
Care should be taken in the handling of biomaterials to ensure that nothing, apart from air or clean inertgases, comes in contact with the surface to be investigated.In particular, avoid contacting the specimensurface with solvents or cleaning solutions, gases such as compressed air or solvent vapours,metals,tissue or other wrapping materials, tape, cloth, tools, packing materials, or the walls of containers.ln response to hydrophobic environment compatible components may migrate to the surface of thespecimen, thus reducing interfacial energy.Responding to an aqueous environment, the surface mayreverse its structure and point polar (hydrophilic) groups outward to interact with the polar watermolecules.Many materials can undergo a reversal of surface structure when transferred from airinto a water environment. A hydroxylated polymer, such as a pHEMA contact lens, exhibits a surfacerich in methyl groups in air, and a surface rich in hydroxyl groups under water.Energy minimizationdrives this process.For metal alloys, one component tends to dominate the surface, as chromium instainless steel’. ln particular, the use of low-density poly(ethylene)(LDPE) bags, which are known tobe contaminated with slip agents, should be avoided.in cases where these precautions are not feasibledue to the size of the specimen, some alternative specimen storage and transporting methods arepresented in Clause 15. Some approaches to sample handling will apply to all biomaterials and someonly to subsets,i.e.liquid specimen.
6.3 Packaging If a sample is placed in a package for shipping or storage prior to surface analysis it is critical to know whether the packaging material can induce surface contamination. Plain paper in contact with most biomaterials will transfer atoms or molecules to the surface. Many plastics are processed with silicone oils or other additives that can be transferred to the specimen surface [4] . Ideally, specimens should be transported to the analyst in a container that does not come into direct contact with the surface of interest. A small vacuum desiccator is preferred. When this is not possible, clean packaging materials should be used. Examples of clean containers include Piranha-cleaned glass vials, UHV foil or tissue and specific polystyrene Petri dishes. The surface cleanliness of the container should be verified prior to use. Compare Clause 8. In some cases, it may be necessary to take a representative sample from the specimen. Selection of a smaller sample from a larger specimen should be done after considering the information being sought because in homogeneities are often present. It is recommended that this choice be made in consultation with an experienced analyst. Specific care should be taken to avoid contaminating the surface of interest during the cutting procedure (for more details see ASTM E1829 – 14 and ASTM E1078 – 14). These general principles are applicable to all materials. There are properties that are specific to specific classes of materials. Compared with metals, ceramics, glasses and carbons, organic and polymeric materials are more easily damaged by surface analysis methods. Polymeric systems also exhibit greater surface molecular mobility than inorganic systems. Surfaces of inorganic materials are contaminated more rapidly than polymeric materials because of their higher surface energy. Electrically conductive metals and carbons are often easier to characterise than insulators using electron, X-ray or ion interactive methods [1] .ISO 20579-3 pdf download.