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. 2023 Feb 27;12(5):1017. doi: 10.3390/foods12051017

Table 1.

The validation parameters of the applied methods.

CUPRAC FC DPPH Nitrates and Nitrites
Standard substance Trolox (TE) gallic acid (GA) gallic acid (GA) sodium nitrite
Calibration curve equation y = 17.3x + 0.00234 y = 0.131x + 0.000874 y = −0.481x + 0.786 y = 1.0973x + 0.0037
The determination coefficient (R2) 0.9993 0.9991 0.9991 0.9998
Linearity range 0.0005–0.070 μmol/mL 0.10–10 μg/mL 0.13–1 μg/mL 0.0027–0.6 µg/mL
LOD 0.000187 μmol/mL 0.074 μg/mL 0.040 μg/mL 0.009 μg/mL
LOQ 0.000562 μmol/mL 0.22 μg/mL 0.12 μg/mL 0.0027 μg/mL
supplement lyophilizate supplement lyophilizate gallic acid supplement lyophilizate
Precision 1.7–3.1% 0.34–1.4% 1.1–3.9% 1.1–5.5% 2.0–4.6% I stage: 1.26–1.97%
II stage: 4.73–4.91%
I stage: 0.22–4.28%
II stage: 2.11–4.95%
Recovery 95–115% 99–109% 96–106% 86–105% 91–113% I stage: 86.17–93.47%II stage: 99.06–104.07% I stage: 80.77–94.08%II stage: 93.99–104.72%