Table 3.
Matrix effects using stable-isotope IS of target analytes in human milk.
| Analyte | ME dF40 (%) | CV | ME dF80 (%) | CV | p-value |
|---|---|---|---|---|---|
| Choline-d9 | 88.9 | (7.3) | 96.2 | (3.3) | 0.18 |
| PCho-d9 | 103.4 | (3.5) | 114.3 | (7.6) | 0.14 |
| GPCho-d9 | 90.5 | (5.7) | 88.1 | (6.6) | 0.63 |
| Betaine-d11 | 109.3 | (1.9) | 104.2 | (5.6) | 0.24 |
| Carnitine-d9 | 30.3 | (8.1) | 54.1 | (13.6) | 0.034 |
| Creatinine-d3 | 68.6 | (2.3) | 89.8 | (4.3) | 0.014 |
| Methionine-d3 | 73.5 | (11.6) | 90.5 | (5.7) | 0.06 |
| TMAO-d9 | 97.2 | (3.6) | 107.0 | (1.6) | 0.022 |
Matrix effects were determined on three separate days for each dilution (n = 9 for each sample set and day for a total n = 27). Means are presented. Student's t-test was used to examine significant difference in matrix effects. Bold font indicates statistical significance (p < 0.05). CV, coefficient of variation; GPCho, glycerophosphocholine; IS, internal standard; ME, matrix effect; PCho, phosphocholine; TMAO, trimethylamine N-oxide. At the time of the validation, an IS was unavailable for dimethyl glycine; thus, ME was not evaluated for this analyte.