VIP impurity profile
Every named species the index has reported alongside VIP, 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
2.44%
n=12
Median largest single
1.35%
n=12
Worst single observed
2.39%
n=12
Named species observed
4 / 4
n=4
| Named species | ΔRT (min) | Δ mass (Da) | Seen in | Median % area | Max % area |
|---|---|---|---|---|---|
| Met17 sulfoxide (+16 Da) | -0.66 | +15.995 | 100% | 1.35 | 2.39 |
| C-terminal free acid (+1 Da) | +0.28 | +0.984 | 100% | 0.50 | 0.67 |
| des-His1 (−137 Da) | -0.82 | -137.059 | 100% | 0.26 | 0.40 |
| deamidated (+1 Da) | -0.30 | +0.984 | 100% | 0.23 | 0.74 |
Met17 sulfoxide (+16 Da)
- Retention offset from the main peak
- -0.66 min on RG-2
- Mass difference
- +15.995 Da
- Reported in
- 12 of 12 records (100 %)
- Level when reported
- median 1.35 %, max 2.39 %
- How it separates
- Baseline-resolved on the reference method.
C-terminal free acid (+1 Da)
- Retention offset from the main peak
- +0.28 min on RG-2
- Mass difference
- +0.984 Da
- Reported in
- 12 of 12 records (100 %)
- Level when reported
- median 0.50 %, max 0.67 %
- 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.
des-His1 (−137 Da)
- Retention offset from the main peak
- -0.82 min on RG-2
- Mass difference
- -137.059 Da
- Reported in
- 12 of 12 records (100 %)
- Level when reported
- median 0.26 %, max 0.40 %
- How it separates
- Baseline-resolved on the reference method.
deamidated (+1 Da)
- Retention offset from the main peak
- -0.30 min on RG-2
- Mass difference
- +0.984 Da
- Reported in
- 12 of 12 records (100 %)
- Level when reported
- median 0.23 %, max 0.74 %
- How it separates
- Baseline-resolved on the reference method.
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.
- Met17 oxidation
- C-terminal amide hydrolysis
- rapid aqueous instability — hours, not days