Trace level determination of bisphenol-A in wastewater and sewage sludge by high-performance liquid chromatography and UV detection
Bibliographic record
Abstract
The purpose of this study was to develop and optimize a simple and economical method for the extraction and determination of bisphenol-A (BPA), using high-performance liquid chromatography (HPLC) coupled with ultraviolet (UV) detection at environmentally relevant concentrations in both dissolved and particulate phases. To clean-up and pre-concentrate liquid samples, solid-phase extraction (SPE) method was optimized with regard to pH, volume, washing and elution solvents for high recovery of BPA and good clean-up. For sludge samples, four extraction methods, microwave-assisted extraction (MAE), ultrasonication extraction (USE), accelerated solvent extraction (ASE) and high-pressure homogenizer (HPH), were compared for isolation of BPA from activated sludge samples. Analysis was performed by optimized procedures using HPLC–UV. Recoveries of BPA from liquid and solid phases were determined to be 90–105 and 60–90%, respectively. MAE had the highest recovery among examined extraction methods. The method detection limits were 100 ng/L and 100 ng/g dry weight. To validate the method, a mass balance study was conducted with 100 mL spiked mixed liquor volatile suspended solids (VSS) samples from three laboratory-scale porous pot reactors and concentrations of BPA in liquid and solid phases were determined using the optimized conditions. The results had an average 86% overall recovery for all samples.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".