ASTM D5392-2014 Standard Test Method for Isolation and Enumeration of Escherichia Coli in Water by the Two-Step Membrane Filter Procedure《使用两步膜滤法对水中大肠杆菌进行分离和计数的标准试验方法》.pdf
《ASTM D5392-2014 Standard Test Method for Isolation and Enumeration of Escherichia Coli in Water by the Two-Step Membrane Filter Procedure《使用两步膜滤法对水中大肠杆菌进行分离和计数的标准试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM D5392-2014 Standard Test Method for Isolation and Enumeration of Escherichia Coli in Water by the Two-Step Membrane Filter Procedure《使用两步膜滤法对水中大肠杆菌进行分离和计数的标准试验方法》.pdf(8页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D5392 93 (Reapproved 2006)D5392 14Standard Test Method forIsolation and Enumeration of Escherichia Coli in Water bythe Two-Step Membrane Filter Procedure1This standard is issued under the fixed designation D5392; the number immediately following the designation indicates the year oforig
2、inal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a membrane filter (MF) procedure for
3、 the detection and enumeration of Escherichia coli, abacterium found exclusively in the feces of humans and other warm-blooded animals. The presence of these microorganisms inwater is an indication of fecal pollution and the possible presence of enteric pathogens. These bacteria are found in water a
4、ndwastewater in a wide range of densities.The detection limit of this procedure is one colony forming unit (CFU) per volume filtered.1.2 This test method has been used successfully with temperate fresh and marine ambient waters, and wastewaters. It is theusers responsibility to ensure the validity o
5、f this test method for waters of other types.1.3 The values stated in SI units are to be regarded as standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safet
6、y and health practices and determine the applicability of regulatorylimitations prior to use. For specific hazard statements, see Section 9.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD3370 Practices for Sampling Water from Close
7、d ConduitsD3870 Practice for Establishing Performance Characteristics for Colony Counting Methods in Microbiology (Withdrawn 2000)3D5465 Practice for Determining Microbial Colony Counts from Waters Analyzed by Plating Methods3. Terminology3.1 DefinitionsFor definitions of terms used in this test met
8、hod, refer to Terminology D1129.3.1 Definitions:3.1.1 For definitions of terms used in this test method, refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 Escherichia coli (E. coli)coli), na species of bacteria that is a member of the total coliform group and known
9、tooriginate in the feces of warm-blooded animals.3.3 Performance Characteristics (Practice D3870):3.3.1 accuracy, nthe proportion of the observed count to the true density of a sample.3.3.2 bias, nthe persistent positive or negative deviation of the average value of the test method from the assumed
10、or acceptedtrue value.3.3.3 precisionprecision, nthe degree of agreement of repeated measurements of the same parameter expressedquantitatively as the standard deviation or as the 95 % confidence limits of the mean computed from the results of a series ofcontrolled determinations.1 This test method
11、is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.24 on Water Microbiology.Current edition approved July 1, 2006Aug. 15, 2014. Published July 2006August 2014. Originally approved in 1993. Last previous edition approved in 20002006 asD5392 9
12、3 (2000).(2006). DOI: 10.1520/D5392-93R06. 10.1520/D5392-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3
13、 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to a
14、dequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho
15、hocken, PA 19428-2959. United States13.3.2 biasthe persistent positive or negative deviation of the average value of the test method from the assumed or acceptedtrue value.3.3.4 specificityspecificity, n the ability of a test method to select or distinguish, or both, the target bacteria in the same
16、watersample; the specificity characteristic of the method is usually reported as the percent of false positive and false negative results.3.3.5 upper counting limit (UCL)(UCL), nthat colony count above which there is an unacceptable counting error; the errormay be due to overcrowding or antibiosis.3
17、.3.5 accuracythe proportion of the observed count to the true density of a sample.4. Summary of Test Method4.1 This two-step test method4 provides a direct count of bacterial colonies developing on the surface of the filter when placedon a selective nutrient medium. The water sample is passed throug
18、h a membrane filter that retains the bacteria.After filtration, themembrane filter containing the bacterial cells is placed on a selective, differential medium, mTEC. The membrane on the mediumis first incubated at 35C for 2 h so that injured or stressed bacteria can be resuscitated and then the med
19、ium is incubated at 44.5Cfor 22 h. Following incubation the filter is transferred to a filter pad saturated with urea substrate. After 15 min all yellow oryellow-brown colonies are counted with the aid of 10 to 15 magnifier and a fluorescent lamp.5. Significance and Use5.1 This test method is useful
20、 for measuring recreational water quality and chlorinated wastewaters, although it can be used forany water suspected of contamination by fecal wastes of warm-blooded animals. The significance of finding E. coli in recreationalwater samples, especially samples obtained from fresh recreational waters
21、, is that there is a risk of gastrointestinal illness, directlyrelated to the E. coli density, associated with swimming.55.2 Since small or large volumes of water or dilutions thereof can be analyzed by the MF technique, a wider range of levelsof E. coli in water can be detected and enumerated than
22、with other methods.6. Interferences6.1 Water with high levels of colloidal or suspended materials can clog the membrane filter pores and prevent filtration. Also,suspended materials cause spreading colonies that could interfere with target colonies and thereby prevent accurate counting.6.2 Smaller s
23、ample size or sample dilution can be used to minimize the interference of turbidity or high background (nontarget)bacterial densities. Replicates of sample volumes or dilutions of sample may be filtered and the results combined. However, themembrane filter techniques may not be applicable to high tu
24、rbid waters with low bacterial densities.6.3 In some samples, chemicals may have toxic effects on the target organism.7. Apparatus7.1 Stereoscopic Microscope, wide-field type with magnification of 10 to 15.7.2 Microscope Lamp, producing diffuse light from a cool, white fluorescent lamp adjusted to g
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