red22
Bluelighter
- Joined
- Nov 23, 2009
- Messages
- 2,057
Someone on reddit was nice enough to give me instructions on how to deduce the values from what appeared to be a complicated table, but after running the info by Perplexity, I've been informed that the table is complicated for a reason. I would like input and clarification from Bluelighters.
Table 3.
Determination of ergine, ergometrine in Morning Glory seeds and relative abundance of other ergot alkaloids identified in the samples
[The IP- in the first column refers to the seed batch; each type has a duplicate entry under it because of a limitation with this forum's tables. The first two ergine and ergometrine entries are the "Concentration (μg g–1)a", and the remaining entries are "Relative abundance - compound/IS area ratiob"]
aFor quantitative analysis of samples from seeds packs, mean value with standard deviation is given, while for single seeds samples, concentration range is specified
bcalculated for most abundant isomer
Source: Identification and determination of ergot alkaloids in Morning Glory cultivars. Nowak J, Woźniakiewicz M, Klepacki P, Sowa A, Kościelniak P. 2016. Anal Bioanal Chem. 408(12):3093-102. doi: 10.1007/s00216-016-9322-5
The instructions from the reddit person:
So if ergine content is given as: 300ug/g
and [if] the ratio is given as: 2.45
x = 300/2.45 = 122.45
so let's make sure this works by checking Ergometrine!
Ergometrine = 0.41*122.45 = 50.2045 ug/g!!!
Perfect, it's the same number as the one given in the paper!!!
Now armed with the powerful technique of extrapolation, let's derive the values you desire!
LSH = 1.09*122.45 = 133.47 ug/g
Lyzergol/isobars = 0.11*122.45 = 13.47 ug/g
Penniclavine = 4.21*122.45 = 515.51 ug/g
Chanoclavine = 0.43*122.45 = 52.65 ug/g
Here are your numbers! Have fun! Let me know if you find something interesting.
Perplexity's analysis:
The logic provided in the instructions is mostly accurate for checking internal consistency between concentration and area ratio values, but it is important to clarify what these ratios actually represent and whether it is scientifically valid to use them for quantitative extrapolation to all compounds.
What the Paper Describes
• Absolute concentrations (μg/g) for ergine and ergometrine were determined via validated LC-MS using calibration standards.
• Relative abundance ratios (compound/IS area ratio) for other compounds reflect their chromatographic signal intensity relative to the internal standard (IS) area, not absolute concentration. These values are provided only for the most abundant isomer of each compound.
• The ratio for ergine (2.45) and its measured concentration (300μg/g) can be used as a scaling reference—but only if ionization efficiency and detector responses are similar for all compounds, which the paper warns is not necessarily the case.
Checking the Calculation
1. You calculate the reference constant, x: x = 300 μg/g ÷ 2.45 = 122.45
2. For ergometrine, use its ratio (0.41): 0.41 × 122.45 = 50.2 μg/g
This matches the reported value for ergometrine in the pack sample.
Extrapolating to Other Compounds
The paper cautions:
"High relative abundance of penniclavine is an interesting observation; however, it cannot be directly connected with high concentration of this clavine. As there is significant difference in ionization efficiency of different compounds in ESI ion source, comparison with standard is required for assessing penniclavine concentration."
• This means the ratio-to-μg/g conversion is robust only for compounds where standards and calibration curves were created (ergine and ergometrine).
• For LSH, lysergol, penniclavine, chanoclavine—the area ratios are not reliable for absolute quantification, since these compounds may ionize very differently than ergine or the IS. Thus, multiplying the ratio by the scaling constant (122.45) may provide a rough comparative value, but is not scientifically valid for absolute concentration.
In Summary
• The formula works for ergometrine and ergine because both had real standards and calibration.
• For other alkaloids, this method does not yield accurate concentrations, but only gives rough relative abundance estimates on the same chromatographic run.
• The technique should not be used for reporting real concentrations of LSH, lysergol/isobars, penniclavine, and chanoclavine without calibration curves for those compounds.
Conclusion:
The calculation method is correct for ergine and ergometrine, but not validated (and discouraged by the authors) for the other alkaloids. Report those numbers only as relative abundance, not as absolute concentrations, unless you have proper calibration for each compound.
Table 3.
Determination of ergine, ergometrine in Morning Glory seeds and relative abundance of other ergot alkaloids identified in the samples
[The IP- in the first column refers to the seed batch; each type has a duplicate entry under it because of a limitation with this forum's tables. The first two ergine and ergometrine entries are the "Concentration (μg g–1)a", and the remaining entries are "Relative abundance - compound/IS area ratiob"]
| Ergine | Ergometrine | Ergine RT=3.37 | LSH RT=4.17 | Lysergol/isobars RT=4.77 | Ergometrine RT=4.78 | Penniclavine RT=5.00 | Chanoclavine RT=5.05 | ||
| IP-HB | Pack | 300 ± 6 | 50 ± 2 | 2.45 | 1.09 | 0.11 | 0.41 | 4.21 | 0.43 |
| IP-HB | Single seed | <LOD – 537 | <LOD – 93 | ||||||
| IT-HB1 | Pack | 261 ± 27 | 94 ± 8 | 2.13 | 0.54 | 0.14 | 0.77 | 4.75 | 0.42 |
| IT-HB1 | Single seed | 3 – 502 | <LOD – 109 | ||||||
| IT-HB2 | Pack | 297 ± 20 | 40 ± 3 | 2.43 | 1.71 | 0.16 | 0.33 | 5.08 | 0.85 |
| IT-HB2 | Single seed | 255 – 495 | 34 – 93 |
aFor quantitative analysis of samples from seeds packs, mean value with standard deviation is given, while for single seeds samples, concentration range is specified
bcalculated for most abundant isomer
Source: Identification and determination of ergot alkaloids in Morning Glory cultivars. Nowak J, Woźniakiewicz M, Klepacki P, Sowa A, Kościelniak P. 2016. Anal Bioanal Chem. 408(12):3093-102. doi: 10.1007/s00216-016-9322-5
The instructions from the reddit person:
So if ergine content is given as: 300ug/g
and [if] the ratio is given as: 2.45
x = 300/2.45 = 122.45
so let's make sure this works by checking Ergometrine!
Ergometrine = 0.41*122.45 = 50.2045 ug/g!!!
Perfect, it's the same number as the one given in the paper!!!
Now armed with the powerful technique of extrapolation, let's derive the values you desire!
LSH = 1.09*122.45 = 133.47 ug/g
Lyzergol/isobars = 0.11*122.45 = 13.47 ug/g
Penniclavine = 4.21*122.45 = 515.51 ug/g
Chanoclavine = 0.43*122.45 = 52.65 ug/g
Here are your numbers! Have fun! Let me know if you find something interesting.
Perplexity's analysis:
The logic provided in the instructions is mostly accurate for checking internal consistency between concentration and area ratio values, but it is important to clarify what these ratios actually represent and whether it is scientifically valid to use them for quantitative extrapolation to all compounds.
What the Paper Describes
• Absolute concentrations (μg/g) for ergine and ergometrine were determined via validated LC-MS using calibration standards.
• Relative abundance ratios (compound/IS area ratio) for other compounds reflect their chromatographic signal intensity relative to the internal standard (IS) area, not absolute concentration. These values are provided only for the most abundant isomer of each compound.
• The ratio for ergine (2.45) and its measured concentration (300μg/g) can be used as a scaling reference—but only if ionization efficiency and detector responses are similar for all compounds, which the paper warns is not necessarily the case.
Checking the Calculation
1. You calculate the reference constant, x: x = 300 μg/g ÷ 2.45 = 122.45
2. For ergometrine, use its ratio (0.41): 0.41 × 122.45 = 50.2 μg/g
This matches the reported value for ergometrine in the pack sample.
Extrapolating to Other Compounds
The paper cautions:
"High relative abundance of penniclavine is an interesting observation; however, it cannot be directly connected with high concentration of this clavine. As there is significant difference in ionization efficiency of different compounds in ESI ion source, comparison with standard is required for assessing penniclavine concentration."
• This means the ratio-to-μg/g conversion is robust only for compounds where standards and calibration curves were created (ergine and ergometrine).
• For LSH, lysergol, penniclavine, chanoclavine—the area ratios are not reliable for absolute quantification, since these compounds may ionize very differently than ergine or the IS. Thus, multiplying the ratio by the scaling constant (122.45) may provide a rough comparative value, but is not scientifically valid for absolute concentration.
In Summary
• The formula works for ergometrine and ergine because both had real standards and calibration.
• For other alkaloids, this method does not yield accurate concentrations, but only gives rough relative abundance estimates on the same chromatographic run.
• The technique should not be used for reporting real concentrations of LSH, lysergol/isobars, penniclavine, and chanoclavine without calibration curves for those compounds.
Conclusion:
The calculation method is correct for ergine and ergometrine, but not validated (and discouraged by the authors) for the other alkaloids. Report those numbers only as relative abundance, not as absolute concentrations, unless you have proper calibration for each compound.
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