Method for analyzing acidic substances by high speed liquid chromatography
Abstract
Abstract Provided is a process for analyzing acidic substances by high speed liquid chromatography. An aqueous pH indicator solution is incorporated in an effluent from a column packed with a packing material, and the pH indicator-incorporated effluent is monitored by means of spectrophotometry. As the pH indicator, a sulphon phthalein indicator is used, which is at least slightly soluble in water and has a pH transformation range falling within the pH range of from about 3.0 to about 10.0 and which exhibits, when maintained at a pH lower than the pH transformation range, the minimum transmittance at a wave length of about 420-440 nm and, when maintained at a pH higher than the pH transformation range, the minimum transmittance at a wave length of at least about 558 nm. The packing material is preferably a sulfonated styrene/divinylbenzene copolymer having a total exchange capacity of about 4 to 5 milli-equivalent/gram.
Inventors
- 👤 Tsuyoshi Yamada
Bibliographic Details
Claims Analysis
Total Claims: 5References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-09-21 | 1985-03-23 | 1985-09-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-21 | 1989-03-23 | 1989-09-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-21 | 1993-03-23 | 1993-09-22 | $7700.00 | Window Closed / Lapsed |