Table II.
A comparative HPLC separationa of ureide composition (based on identical retention time to standard references) and concentration in fractions with molecular mass ≤10 kD of Ni-S and Ni-D foliage from young pecan seedling tree
| Ureide or Unknown Substance
|
Retention Time
|
Concentration X ± sdb
|
Peak Sizec
|
||
|---|---|---|---|---|---|
| Ni-D | Ni-S | Ni-D | Ni-S | ||
| min | μm/mL | ||||
| Identified ureides | |||||
| Allantoic acid | 5.44 | 26.33 ± 0.63a | 13.99 ± 0.16b | ||
| Asn | 5.81 | ≤5.00a | ≤5.00a | ||
| Citrulline | 5.89 | 17.76 ± 0.40a | 12.90 ± 0.58b | ||
| Allantoin | 5.93 | ≤5.00a | ≤5.00a | ||
| Uric acid | 6.06 | ≤5.00a | ≤5.00a | ||
| Urea | 6.14 | 13.46 ± 1.73b | 71.85 ± 17.39a | ||
| Xanthine | 6.90 | 21.13 ± 0.48a | 15.96 ± 0.93b | ||
| Ureidoglycolate | 7.24 | 56.83 ± 0.40a | 43.66 ± 0.66b | ||
| Unknown substances | |||||
| I | 7.82 | +++ | ++ | ||
| II | 9.60 | ++ | ++ | ||
| III | 12.46 | + | ++ | ||
| IV | 14.64 | + | ++ | ||
a
To further confirm the identification of ureides if their retention time was very close to each other (e.g. Asn anhydrous and l-citrulline), two different HPLC columns were run with two different mobile phases; in this table, the retention time was listed only from the platinum EPS C18 column.
b
Means (±sd) followed by the same letter are not significantly different (t test, P ≤ 0.05).
c
+++, Large; ++, medium; +, small.