Epitalon impurity profile
Every named species the index has reported alongside Epitalon, how often, at what level, and what its presence implies about the synthesis or the handling. Reporting threshold is 0.05 % area; anything below it is invisible to this page and is silently added to the main peak.
Median total impurities
0.44%
n=90
Median largest single
0.21%
n=90
Worst single observed
1.15%
n=90
Named species observed
4 / 4
n=4
| Named species | ΔRT (min) | Δ mass (Da) | Seen in | Median % area | Max % area |
|---|---|---|---|---|---|
| aspartimide (−18 Da) | +0.12 | -18.011 | 94% | 0.09 | 0.86 |
| Ala-Glu-Asp tripeptide (−57 Da) | -0.20 | -57.021 | 88% | 0.10 | 1.15 |
| diketopiperazine (−18 Da) | +0.16 | -18.011 | 82% | 0.10 | 0.83 |
| β-Asp isomer | -0.10 | mass-identical | 70% | 0.10 | 0.71 |
aspartimide (−18 Da)
- Retention offset from the main peak
- +0.12 min on RG-2
- Mass difference
- -18.011 Da
- Reported in
- 85 of 90 records (94 %)
- Level when reported
- median 0.09 %, max 0.86 %
- How it separates
- Close-eluting on the reference method, and merged with the main peak on a short gradient. The index prints the resolution figure for such a pair and applies no criterion to it — where the two are not separated, what matters is that the integration convention is stated.
Ala-Glu-Asp tripeptide (−57 Da)
- Retention offset from the main peak
- -0.20 min on RG-2
- Mass difference
- -57.021 Da
- Reported in
- 79 of 90 records (88 %)
- Level when reported
- median 0.10 %, max 1.15 %
- How it separates
- Close-eluting on the reference method, and merged with the main peak on a short gradient. The index prints the resolution figure for such a pair and applies no criterion to it — where the two are not separated, what matters is that the integration convention is stated.
diketopiperazine (−18 Da)
- Retention offset from the main peak
- +0.16 min on RG-2
- Mass difference
- -18.011 Da
- Reported in
- 74 of 90 records (82 %)
- Level when reported
- median 0.10 %, max 0.83 %
- How it separates
- Close-eluting on the reference method, and merged with the main peak on a short gradient. The index prints the resolution figure for such a pair and applies no criterion to it — where the two are not separated, what matters is that the integration convention is stated.
β-Asp isomer
- Retention offset from the main peak
- -0.10 min on RG-2
- Mass difference
- mass-identical — chromatography only
- Reported in
- 63 of 90 records (70 %)
- Level when reported
- median 0.10 %, max 0.71 %
- How it separates
- Chromatography only. A gradient long enough to separate it; no mass spectrometer of any resolution will.
Degradation pathways
Degradants are a handling finding rather than a synthesis finding. A lot that shipped clean and arrived oxidised tells you about the courier, not the chemist.
- Asp-Gly aspartimide, then hydrolysis to the β-Asp isomer — the classic tetrapeptide problem