| Not official USP-NF text | ||||
| TRYPTOPHAN | ||||
| PF | LGS# | Brand | Type of Test | Additional Information |
| 33(4) | L1 | Delta-Pak C18 | Limit of . . . . . . . . . | Limit of tryptophan related compound A. 3.9 mm x 15 cm, 5 µm. |
| 18(3) | G43 | None Cited | Organic volat. impurities | See Method IV  467 |
| 32(5) | L1 | Ultrasphere ODS | Related compounds | 4.6 mm x 25 cm, 5 µm, manufcturer Beckman. |