Separation of Hydroxycitric Acid Lactone from Fruit Pectins and Polyhydroxyphenols on Poly(4-Vinylpyridine) Weak-Base Resin
Bibliographic record
Abstract
Poly(4-vinylpyridine) (PVP) has been used for the separation of hydroxycitric acid lactone (HCAL) from polyhydroxyphenols and fruit pectins, as the study has relevance to the problem of extraction of the antiobesity substance hydroxycitric acid from Garcinia cambogia fruits, a rich source of the acid. PVP has been used both in free-base form and in protonated or salt form as a sorbent, while catechol and pyrogallol have been used as representative polyhydroxyphenols. Though the protonated form, used as PVP(HCl), has a low sorption capacity (96 mg/g dry resin) and low selectivity for pectin (at pH 8), its higher, but comparable, sorptions (at pH 8) of HCAL, catechol, and pyrogallol, with respective saturation values of 354, 349, and 366 mg/g dry resin, coupled with high selectivity for the hydroxyphenols, make the sorbent unsuitable for the desired separation of HCAL. On the other hand, PVP free-base resin has significantly high sorption of HCAL as compared to catechol and pyrogallol in mildly acidic media (pH 1.8–2.8), the respective saturation values being 576, 206, and 303 mg/g dry resin, but the free-base resin also shows high saturation capacity (500 mg/g dry resin) for pectin. However, at low substrate concentrations (1 g/L) or relatively low pH (2), pectin has an order of magnitude lower sorption than HCAL, making separation of the latter possible on PVP free-base resin. Column operation using PVP free-base resin with influent maintained at pH 1.8, followed by stripping with less than the theoretical amount of alkali, produces good separation and high yield of HCAL from the mixed influent. Reillex HP, a macroporous PVP resin, used in free-base form, has relatively fast kinetics for HCAL sorption, with a t 1/2 value of about 5 minutes and diffusivity of the order of 10−6 cm2/s.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".