Development of in‐house materials for the verification of specific gravity measurements: Homogeneity, stability, and proficiency studies
Bibliographic record
Abstract
We developed and evaluated the properties of in-house urine reference materials for the verification of laboratory refractometers, which are frequently used in clinical chemistry and doping testing laboratories. Urine was gathered from 26 healthy volunteers (16 male 30 ± 5 years old and 10 female 29 ± 4 years old), from which two urine batches were obtained: one with a low specific gravity (1.012± 0.003) and the other with a high specific gravity (1.027 ± 0.003). Homogeneity studies were conducted over 20 consecutive days. For short-term stability studies, aliquots of both urine batches were stored at -20 ± 2°C; 3 ± 2°C; 20 ± 2°C; 45 ± 2°C for 0, 2, 7, 14 and 35 days, under both light and dark conditions. Similarly, another study was conducted to measure the long-term stability of urine at -20 ± 2°C, over a 24-month evaluation period. Our data showed that the urine was homogeneous and stable at -20 ± 2°C, 3 ± 2°C, 20 ± 2°C, and 45 ± 2°C under both light and dark conditions. In all cases, the urine was evaluated by specific gravity and no statistically significant differences (p ≤ 0.05) were recorded. Additionally, a proficiency test was conducted in collaboration with 15 ISO/IEC 17025 accredited laboratories, and z-scores and performance factors were evaluated. These data indicate that this material could be used for the verification of refractometers.
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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 | 0.015 | 0.021 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
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".