---
kind: "section"
citation: "40 C.F.R. § 425.03"
title: "40"
number: "425.03"
heading: "Sulfide analytical methods and applicability."
url: "https://uscodex.org/cfr/40/425.03"
---

# §425.03. Sulfide analytical methods and applicability.

- (a) The potassium ferricyanide titration method described in appendix A to [part 425](/cfr/40/part425.md) shall be used whenever practicable for the determination of sulfide in wastewaters discharged by plants operating in all subcategories except the hair save or pulp, non-chrome tan, retan-wet finish subcategory ([subpart C](/cfr/40/subpartC.md), see [§ 425.30](/cfr/40/425.30.md)). In all other cases, the modified Monier-Williams method as described in appendix B to [part 425](/cfr/40/part425.md) shall be used as an alternative to the potassium ferricyanide titration method for the determination of sulfide in wastewaters discharged by plants operating in all subcategories except subpart C.
- (b) The modified Monier-Williams method as described in appendix B to [part 425](/cfr/40/part425.md) shall be used for the determination of sulfide in wastewaters discharged by plants operating in the hair save or pulp, non-chrome tan, retan-wet finish subcategory ([subpart C](/cfr/40/subpartC.md), see [§ 425.30](/cfr/40/425.30.md)).

## Notes

### Amendments

[53 FR 9181, Mar. 21, 1988]

### Authority

Authority: 33 U.S.C. 1311, 1314 (b), (c), (e) and (g), 1316 (b) and (c), 1317 (b) and (c), 1318 and 1361.

### Source

Source: 47 FR 52870, Nov. 23, 1982, unless otherwise noted.

### Amendments

[53 FR 9181, Mar. 21, 1988]