Single-Laboratory Validation for the Determination of Flavonoids in Hawthorn Leaves and Finished Products by LC-UV
Bibliographic record
Abstract
Suitably validated analytical methods that can be used to quantify medicinally active phytochemicals in natural health products are required by regulators, manufacturers, and consumers. Hawthorn ( Crataegus ) is a botanical ingredient in natural health products used for the treatment of cardiovascular disorders. A method for the quantitation of vitexin-2″- O - rhamnoside, vitexin, isovitexin, rutin, and hyperoside in hawthorn leaf and flower raw materials and finished products was optimized and validated according to AOAC International guidelines. A two-level partial factorial study was used to guide the optimization of the sample preparation. The optimal conditions were found to be a 60-minute extraction using 50 : 48 : 2 methanol : water : acetic acid followed by a 25-minute separation using a reversed-phased liquid chromatography column with ultraviolet absorbance detection. The single-laboratory validation study evaluated method selectivity, accuracy, repeatability, linearity, limit of quantitation, and limit of detection. Individual flavonoid content ranged from 0.05 mg/g to 17.5 mg/g in solid dosage forms and raw materials. Repeatability ranged from 0.7 to 11.7 % relative standard deviation corresponding to HorRat ranges from 0.2 to 1.6. Calibration curves for each flavonoid were linear within the analytical ranges with correlation coefficients greater than 99.9 %. Herein is the first report of a validated method that is fit for the purpose of quantifying five major phytochemical marker compounds in both raw materials and finished products made from North American ( Crataegus douglasii ) and European ( Crataegus monogyna and Crataegus laevigata) hawthorn species. The method includes optimized extraction of samples without a prolonged drying process and reduced liquid chromatography separation time.
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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 | 0.009 | 0.008 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| 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".