Direct Determination of Trace Antimony in Natural Waters by Photochemical Vapor Generation ICPMS: Method Optimization and Comparison of Quantitation Strategies
Bibliographic record
Abstract
A novel and sensitive approach for the accurate determination of antimony (Sb) in natural waters is described using photochemical vapor generation (PVG) coupled with inductively coupled plasma mass spectrometry (ICPMS) for detection. Utilizing a unique flow-through photochemical reactor capable of subjecting the samples to deep-UV (185 nm) radiation, generation efficiency was found to be independent of whether Sb(III), Sb(V), or organometallic species [trimethyltantimony(V)dibromine, TMSb(V)] were present, eliminating the shortcoming of Sb species depended sensitivity encountered during direct solution nebulization by ICPMS. Furthermore, the potentially severe matrix effect from seawater was efficiently eliminated by using a mixture of 5% (v/v) formic and 15% acetic acids (v/v) as the photochemical reductant, making direct determination of Sb in seawater feasible. The proposed method provides a 15-fold improvement in sensitivity over direct solution nebulization. A method detection limit of 0.0006 ng g(-1) based on external calibration was obtained (0.0002 ng g(-1) for isotope dilution), yielding a 15-fold improvement over that for direct solution nebulization. Accuracy is demonstrated by analysis of two water certified reference materials (CRMs, e.g., SLRS-6 and NIST 1640a) with satisfying results. In addition, spike recoveries of 100.6 ± 5.5% and 100.8 ± 3.8% (standard deviation, n = 3) were obtained for NASS-6 and CASS-5 seawater CRMs, respectively, since no certified values for Sb has been established for these materials. The performance of several calibration strategies, including double isotope dilution (ID), multiple and single-point gravimetric standard additions with internal standardization, as well as multiple and single-point gravimetric standard additions alone was examined. High precision of determination of Sb in four natural water samples (0.51-1.4%) was realized based on ID calibration, whereas one-point gravimetric standard addition calibration with internal standardization provided precisions of 1.6% and 3.3% at 0.22 and 0.44 ng g(-1) levels, respectively, in seawater.
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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 | 0.000 | 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 | 0.000 |
| 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".