Evaluation of a water-jacketed spray chamber using time-of-flight inductively coupled plasma mass spectrometry (TOF-ICP-MS)
Bibliographic record
Abstract
The application of a water-jacketed spray chamber was evaluated at several temperatures between 4 and 30 °C using a time-of-flight inductively coupled plasma mass spectrometry (TOF-ICP-MS) instrument. As expected when the spray chamber was operated at lower temperatures, less water vapour was transported to the ICP. However, sensitivity (signal per unit concentration) was unchanged when the nebuliser gas flow was optimized at each of the different temperatures, and the expected lowering of the degree of formation of oxide polyatomic ions was not achieved. The effect of lowering the temperature of the water that controlled the temperature of the spray chamber apparently did lower the rate of introduction of water vapour into the ICP. This decrease in water vapour introduced into the ICP resulted in (at the same value of nebuliser gas flow) an apparent increase in plasma temperature. This in turn resulted in a decrease in sensitivity, which was regained by increasing nebuliser gas flow (lower plasma temperature). The maximum sensitivity was comparable at all spray chamber temperatures studied, with higher nebuliser gas flows being required with lower spray chamber temperatures. Other parameters of interest, the background, oxide formation, doubly charged ion formation and detection limits, were comparable at all spray chamber temperatures. This study emphasizes the importance of making multidimensional studies of the ICP-MS. The figure of merit behaviour of the system was comparable to that obtained with first generation quadrupole ICP-MS instruments. With increasing nebuliser gas flow (0.5 to 0.9 l min−1) very striking changes were observed in several parameters. The background decreased from ca. 700 counts s−1 to less than 10 counts s−1; the sensitivity (M counts s−1 ppm−1 abundance−1) varied from very low to a high of ca. 3 and then decreased; the formation of polyatomic oxide ions (using as an example CeO+/Ce+) was approximately 30% at the maximum sensitivity; and the detection limit for Ce reached a minimum of less than 0.01 ppb at an intermediate value of the nebuliser gas flow.
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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 | 0.003 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".