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Domoic Acid (DA) & Amino Acids in Algae Extracts
Low level analysis without analyte derivatization
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printable Application Sheet
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Note: Toxic pseudo-nitzschia australis produces the potent neurotoxin domoic acid. In 1998, a widespread bloom of these algal
species affected the central California coastline and resulted in the mass death of over 400 sea lions. The animals died by the ingestion
of shellfish (e.g. mussels) that have fed upon diatom blooms that include toxic species of pseudo-nitzschia.
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Method Conditions
| Column |
Cogent Diamond Hydride™, 4µm, 100A |
| Catalog No. |
70000-15P-2 |
| Dimensions |
2.1 x 150 mm |
| Solvents |
| A: | 50% DI H2O/ 50% MeOH/ 0.1% formic acid |
| B: | Acetonitrile/ 0.1% formic acid |
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| Gradient |
| time (min.) |
%B |
time (min.) |
%B |
| 0 |
95 |
10 |
20 |
| 7 |
20 |
11 |
95 |
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| Post Time |
5 min |
| Injection Vol. |
1 microL |
| Flow rate |
0.4 mL/min. |
| Detection |
ESI – POS - Agilent 6210 MSD TOF mass spectrometer |
| Sample |
Methanolic extracts of pseudo-nitzschia australis diatom cultures 1 and 2, isolated by filtration. |
| Peak |
1. Domoic acid 312.1442 m/z (M +H)+
2. L-Tryptophan 205.0972 m/z (M +H)+
3. L-Leucine 132.1025 m/z (M +H)+
4. L-Histidine 156.0773 m/z (M +H)+ |
| t0 |
0.9 min |
Discussion
This LC-MS method can achieve very low detection levels of DA and amino acids without the need for analyte derivatization. Figures A and B show
the chromatograms of both algae extracts. Figure C shows a zoom-in overlay of both cultures 1 and 2 for the histidine peak.
The data show how the tryptophan levels are significantly different between the two cultures whereas the other levels are comparable. The method
also produces sufficient separation of DA from tryptophan, which is often an interferent in DA quantitation.
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