Table 2.

Figures of merit of the proposed UHPLC-MS/MS method for quantification of TXA based on the [M + ACN + H]⁺ adduct ion and comparison with the analytical parameters obtained using the pseudo-molecular [M + H]⁺ ion.

Parameters	Precursor ion [M + ACN + H]+ (This Work)	Precursor ion [M + H]+ [30]
Linear range (ng mL−1)	30–600 (180–3600 in plasma)	30–600 (180–3600 in plasma)
Calibration curve	y = 0.00291 (±0.00003) x + 0.026 (±0.009)	y = 0.00296 (±0.00002) x + 0.035 (±0.007)
Correlation coefficient (r2)	≥0.9983	≥0.9974
LOD (ng mL−1) a	3	18
LOQ (ng mL−1) a	6	36
Precision (CV, %) b
Intra-day	0.6	1.7
Inter-day	2.4	1.7
Accuracy (%) b
Intra-day	94.7	96.3
Inter-day	92.2	94.7
Recovery (%) c
TXA	98.8 ± 0.5 I	96.3 ± 3.6 I
TXA-IS	100.6 ± 1.0 II	94.4 ± 1.0 III
Matrix factor (%) d
TXA	105.4 ± 3.5 IV	110.0 ± 7.6 IV
TXA-IS	103.6 ± 6.9 V	110.0 ± 6.3 V
IS normalized matrix factor e	102.0 ± 5.4 VI	100.0 ± 1.4 VI

LOD, limit of detection; LOQ, limit of quantification; CV, coefficient of variation; TXA, tranexamic acid; IS, internal standard, ¹³C₂,¹⁵N,trans-tranexamic acid; ^a LOD and LOQ values in plasma samples; ^b Precision and accuracy estimated in plasma extracts spiked with 300 ng mL⁻¹ TXA (corresponding to 1800 ng mL⁻¹ in plasma); ^c Recovery (mean ± CV, n = 2) assessed by spiking plasma samples with 1800 ng mL⁻¹ of TXA and IS before extraction and sample processing; ^d Matrix effect (mean ± CV, n = 6) assessed by the post-extraction addition method, at 300 ng mL⁻¹ concentration level (in plasma extract); ^e IS normalized matrix factor calculated by division of the matrix factor of the analyte by the matrix factor of the IS; ^I–VI Comparison between the experimental means obtained for the different analytical parameters. The same superscript number indicates that no statistically significant difference was found for the results obtained by the two quantification methods (p < 0.05).