Significance and Use 5.1 Sulfate reducing archaea and bacteria are known to contribute to microbiologically influenced corrosion. 5.2 Sulfate-reducing bacteria are widely distributed in marine and fresh water muds which, in consequence, frequently are laden with the hydrogen sulfide produced by these organisms during dissimilatory sulfate reduction. 5.3 Traditional, culture-dependent methods such as those described in Test Methods D4412, prescribe incubation periods of as long as 21 days before assigning a below detection limit (BDL) score to a specimen. Moreover, it is well known that not all SRP will proliferate in the nutrient media specified in Test Methods D4412. 5.4 This test method uses ELISA technology to provide semi-quantitative, culture-independent, SRP bioburden test results in less than 30 min. 5.4.1 Because all the reagents and supplies used are non-hazardous and prepackaged for single test use, this test method does not require any apparatus other than a laboratory timer. Consequently, it can be performed at or near the point of sample collection. 5.4.2 The opportunity to minimize the delay between sample collection, testing, and results availability translates into timely use of the data to drive preventive and corrective SRB control measures.Scope 1.1 This test method provides a protocol for using enzyme-linked immunosorbent assay (ELISA) technology to test water samples for the enzyme adenosine 5’-phosphosulfate reductase (APSr) concentration. 1.1.1 APSr is present in all known sulfate reducing protists (SRP – sulfate reducing bacteria – SRB – and sulfate reducing archaea – SRA). 1.1.2 As reported in U.S. Patent 4,999,286, APS reductase concentration can be used as a surrogate parameter for estimating SRA bioburdens (Appendix X1 compares results from Test Methods D8243, D4412, and quantitative polymerase chain reaction – qPCR – testing). 1.2 This test method has been validated in tap water, oilfield produced water (salinities ranging from 100 g L-1 to 600 g L-1), and fuel-associated water (commonly referred to as bottoms-water). 1.3 This test method detects APS reductase semi-quantitatively in the range of 0.001M to 0.1M – correlating to 102 SRP/mL to 106 SRP/mL. 1.3.1 As described in Appendix X2 test method sensitivity can be increased 10-fold to 100-fold. However, the precision statistics provided in X apply only to 10-mL specimens. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 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 appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Some specific hazards statements are given in Section 9 on Hazards. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
