Cyclic polyamide oligomers extracted from nylon 66 membrane filter disks as a source of contamination in liquid chromatography/mass spectrometry
Bibliographic record
Abstract
Background interferences are perhaps an unavoidable part of analytical detection schemes, particularly when analyzing trace level samples or when using detectors with high levels of sensitivity. In liquid chromatography, mobile phase solvents are routinely filtered using membrane filter disks to trap particulates in hopes of minimizing contamination, providing improvements in data output and instrumental operation. In this study, we report that one such filter disk leads to a significant level of contamination in LC and LC/MS experiments. Extractable compounds from nylon membrane filters generate significant background signals in UV absorption chromatograms at 214 nm, and are also detected by electrospray ionization mass spectrometry, with nominal m/z values of 453 and 679. It is shown that rinsing the nylon membranes before their use can reduce, but will not eliminate, the extractable contaminants from the mobile phase. Through MS and tandem MS analysis, we have identified these contaminants as cyclic oligomers of polyamide 66. Based on these results, it is recommended that nylon membrane filters be avoided when conducting trace level analysis, particularly when conducting LC/MS experiments.
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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 | 0.002 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".