ESI‐MS quantitation of iron as its 4‐(2‐pyridylazo)resorcinol (PAR) complex: application to pharmaceutical tablets containing iron oxide pigment
Bibliographic record
Abstract
Quantitation of iron oxide (Fe(2)O(3)) in pharmaceutical formulations using electrospray ionization mass spectrometry (ESI-MS) following iron complexation with 4-(2-pyridylazo)resorcinol (PAR) was evaluated. Complexation of Fe(III) with PAR was found to produce an intense mass spectral signal at low pH compared to the free ligand. Using the selected-ion-monitoring mode of a triple-quadrupole mass spectrometer, the signal at m/z 484 arising from the singly charged [Fe(III)(PAR)(2)](+) complex gave a limit of detection of ~2 µM for total iron. The linear range of the calibration curve was found to be 2-43 µM total iron. Trace iron interference was decreased to submicromolar levels by performing an optimized labware cleaning protocol and instrument replumbing using Polyetheretherketone (PEEK) tubing. The validation parameters of this ESI-MS total iron analysis (specificity, linearity, precision, accuracy, robustness and stability) are within the acceptance criteria listed in the validation guidelines developed by the Food and Drug Administration for industry. Recovery of 93% of the added iron indicated a satisfactory extraction procedure for tablets containing Fe(2)O(3) pigment. There was no statistical difference between the results obtained by ESI-MS and the common elemental method, inductively coupled plasma-optical emission spectroscopy. Since the proposed ESI-MS method can be performed on a mass spectrometer equipped with an ESI source, which is standard instrumentation in the pharmaceutical industry, the method validated here provides an alternate method for metal ion analysis by ESI-MS.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".