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
0.93%
n=29
Median largest single
0.39%
n=29
Worst single observed
1.11%
n=29
Named species observed
4 / 4
n=4
| Named species | ΔRT (min) | Δ mass (Da) | Seen in | Median % area | Max % area |
|---|---|---|---|---|---|
| free histidine (−71 Da) | -0.16 | -71.037 | 93% | 0.18 | 1.11 |
| anserine (methylcarnosine, +14 Da) | +0.12 | +14.016 | 90% | 0.11 | 0.50 |
| β-alanine (−137 Da) | -0.22 | -137.059 | 83% | 0.18 | 0.53 |
| D-carnosine epimer | -0.06 | mass-identical | 79% | 0.36 | 0.99 |
free histidine (−71 Da)
- Retention offset from the main peak
- -0.16 min on RG-2
- Mass difference
- -71.037 Da
- Reported in
- 27 of 29 records (93 %)
- Level when reported
- median 0.18 %, max 1.11 %
- Resolution requirement
- Close-eluting — resolution below 1.2 is common and the peaks merge on short gradients.
anserine (methylcarnosine, +14 Da)
- Retention offset from the main peak
- +0.12 min on RG-2
- Mass difference
- +14.016 Da
- Reported in
- 26 of 29 records (90 %)
- Level when reported
- median 0.11 %, max 0.50 %
- Resolution requirement
- Close-eluting — resolution below 1.2 is common and the peaks merge on short gradients.
β-alanine (−137 Da)
- Retention offset from the main peak
- -0.22 min on RG-2
- Mass difference
- -137.059 Da
- Reported in
- 24 of 29 records (83 %)
- Level when reported
- median 0.18 %, max 0.53 %
- Resolution requirement
- Close-eluting — resolution below 1.2 is common and the peaks merge on short gradients.
D-carnosine epimer
- Retention offset from the main peak
- -0.06 min on RG-2
- Mass difference
- mass-identical — chromatography only
- Reported in
- 23 of 29 records (79 %)
- Level when reported
- median 0.36 %, max 0.99 %
- Resolution requirement
- A gradient long enough to separate it. No mass spectrometer 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.
- hydrolysis by residual carnosinase activity in impure aqueous media
- racemisation under heat