L-Carnosine impurity profile
Every named species the index has reported alongside L-Carnosine, 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
0.42%
n=26
Median largest single
0.22%
n=26
Worst single observed
0.75%
n=26
Named species observed
4 / 4
n=4
| Named species | ΔRT (min) | Δ mass (Da) | Seen in | Median % area | Max % area |
|---|---|---|---|---|---|
| D-carnosine epimer | -0.06 | mass-identical | 96% | 0.14 | 0.75 |
| free histidine (−71 Da) | -0.16 | -71.037 | 92% | 0.07 | 0.68 |
| β-alanine (−137 Da) | -0.22 | -137.059 | 85% | 0.08 | 0.40 |
| anserine (methylcarnosine, +14 Da) | +0.12 | +14.016 | 81% | 0.10 | 0.40 |
D-carnosine epimer
- Retention offset from the main peak
- -0.06 min on RG-2
- Mass difference
- mass-identical — chromatography only
- Reported in
- 25 of 26 records (96 %)
- Level when reported
- median 0.14 %, max 0.75 %
- How it separates
- Chromatography only. A gradient long enough to separate it; no mass spectrometer of any resolution will.
free histidine (−71 Da)
- Retention offset from the main peak
- -0.16 min on RG-2
- Mass difference
- -71.037 Da
- Reported in
- 24 of 26 records (92 %)
- Level when reported
- median 0.07 %, max 0.68 %
- 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-alanine (−137 Da)
- Retention offset from the main peak
- -0.22 min on RG-2
- Mass difference
- -137.059 Da
- Reported in
- 22 of 26 records (85 %)
- Level when reported
- median 0.08 %, max 0.40 %
- 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.
anserine (methylcarnosine, +14 Da)
- Retention offset from the main peak
- +0.12 min on RG-2
- Mass difference
- +14.016 Da
- Reported in
- 21 of 26 records (81 %)
- Level when reported
- median 0.10 %, max 0.40 %
- 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.
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.
- hydrolysis by residual carnosinase activity in impure aqueous media
- racemisation under heat