Interference Problems with Phosphoantimonylmolybdenum Colorimetric Measurement of Phosphorus in Soil and Plant Materials
Bibliographic record
Abstract
Abstract A critical evaluation of potential chemical interference on a molybdenum‐based phosphorus (P) colorimetric method that is used widely for soil, plant, and water research was conducted. A wide variety of elements and compounds [aluminum (Al), manganese (Mn), iron (Fe), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), nitrate (NO3), and ethylenediaminetetraacetic acid (EDTA)] commonly found in these materials or extracting solutions used on them were shown to cause interferences. The interferences were subtle but complex, with changes to the rate at which the color product was formed and its apparent final chemical composition. There were interactions between the type of element or compound involved and the concentration of P in the test solution. The effect of nitrate on the color product could not be distinguished from the effect of the cation (K versus Na) with the nature of salt used because of the complexity of interacting factors. Increasing the time and temperature allowed the final absorbance for the color product to develop and produce more stable values, but the final absorbance was changed by the interfering element. Significant errors in P by the colorimetric method were observed in soil extracts and plant digests, showing that the resulting values were not accurate. Historic data using values measured by this method need re‐evaluation. Alternative methods need examination to select for accurately measuring the P content to refine our knowledge of the role of this important element in soil, plant, and water studies. Keywords: Colorimetric analysisinductively coupled argon plasma spectroscopyphosphorusplant digestionsoil test Notes Contribution number 722 of Pacific Agri‐Food Research Centre, Agassiz.
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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 | 0.003 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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".