ASTM D7658-17(R2021) pdf free download

ASTM D7658-17(R2021) pdf free download.Standard Test Method for Direct Microscopy of Fungal Structures from Tape
1. Scope
1.1 This test method uses optical microscopy for the detection, semi-quantification, and identification of fungal structures in tape lift preparations. 1.2 This test method describes the preparation techniques for tape-lift matrices, the procedure for confirming the pres- ence of fungal structures, and the reporting of observed fungal structures 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Terminology
3.1 Definitions—For definitions of other terms used in this test method, refer to Terminology D1356. 3.2 Definitions ofTerms Specific to This Standard: 3.2.1 fungal structure (sing.), n—a collective term for a fragment- or groups of fragments from fungi, including but not limited to conidia, conidiophores, hyphae, and spores. 3.2.2 magnification/resolution combination 1, n— ~100–400× total magnification and a point to point resolution of 0.7 µm or better. 3.2.3 magnification/resolution combination 2, n— ~400× or greater total magnification and a point to point resolution of0.5 µm or better. 3.2.4 mounting medium, n—a liquid, for example, lactic acid or prepared stain, used to immerse the sample particulate matter and to attach a cover slip to the sample. 3.2.5 tape lift sample, n—material lifted from a surface using clear, transparent, single sided, adhesive collection medium, typically tape or commercially available prepared slides.
4. Summary of Test Method
4.1 A tape lift sample is prepared. 4.2 The prepared sample is examined on an optical micro- scope for the presence, type and semi-quantification of fungal structures and reported.
5. Significance and Use
5.1 The significance of this test method is to standardize the analysis of the detection of removable fungal structures lifted from a surface with tape to improve consistency between laboratories and analysts. 5.2 This test method is intended to ensure consistent data to the end user. 5.3 Fungal structures are identified and semi-quantified regardless ofwhether they would or would not grow in culture. 5.4 It must be emphasized that the detector in this test method is the analyst, and therefore results are subjective, depending on the experience, training, qualification, optical acuity, and mental fatigue of the analyst. 5.5 This test method can be used to assess the presence and characteristics of fungal material on a surface.
6. Interferences
6.1 Look-alike Non-fungal Particles—Certain types of par- ticles of non-fungal origin may resemble fungal structures.These particles and artifacts may include air or plant resin, bubbles, starch, talc or cosmetic particles, or combustion products. Non-fungal reference slides (mounted similarly to tape-lift samples) should be examined by laboratory analysts to know how to differentiate such particles. Examination of suspect particles using optical conditions other than bright field microscopy (for example, polarized light microscopy, phase contrast microscopy, differential interference contrast) may be helpful whenever significant concentrations of look-alike par- ticles are present. In some cases dust and debris can mimic the morphology of particles of interest. 6.2 Particle Overloading—High levels of non-fungal back- ground particulate may obscure or cover fungal structures. 6.3 Staining—Fungal structures of different fungal species absorb stains at different rates, under or over-staining makes identification difficult. The problem can be minimized with careful control of stain concentrations. N OTE 1—Staining, while optional, may help the analyst differentiate fungal structures from debris. Without staining, clear spores (especially small ones) may exhibit negative bias because the analyst has insufficient contrast to detect them while scanning.