(a) Identity. The color additive logwood extract is a reddish brown-to-black solid material extracted from the heartwood of the leguminous tree Haematoxylon campechianum. The active colorant substance is principally hematein. The latent coloring material is the unoxidized or leuco form of hematein called hematoxylin. The leuco form is oxidized by air.
(b) Specifications. Logwood extract shall conform to the following specifications and shall be free from impurities other than those named to the extent that such imnurities may be avoided by good manufacturing practice:
Volatile matter (at 110 °C), not more than 15 percent.
Sulfated ash, not more than 20 percent.
Hematein, not less than 5 percent and not more than 20 percent.
Lead (as Pb), not more than 70 parts per million.
Arsenic (as As), not more than 4 parts per million.
Mercury (as Hg), not more than 3 parts per million.
(c) Use and restrictions. Logwood extract may be safely used to color nylon 66 (the copolymer of hexamethylenediamine and adipic acid), nylon 6 (the polymer of e -caprolactam), or silk non-absorable sutures for use in general and ophthalmic surgery subject to the following restrictions:
(1) The quantity of color additive does not exceed 1.0 percent by weight of the suture.
(2) When the sutures are used for the purposes specified in their labeling, there is no migration of the color additive to the surrounding tissue.
(3) If the suture is a new drug, an approved new drug application, pursuant to section 505 of the act, is in effect for it.
(d) Labeling. The label of the color additive shall conform to the requirements of § 70.25 of this chapter.
(e) Exemption from certification. Certification of this color additive is not necessary for the protection of the public health, and therefore batches thereof are exempt from the certification requirements of section 721(c) of the act.