Quantitative Evaluation of the Pyruvic Acid Content in Onion Samples with a Fully Validated High-Performance Liquid Chromatography Method

Figures & data

FIGURE 1 Enzymatic generation of pyruvic acid (PA) in onion.

TABLE 1 Calibration data for pyruvic acid: regression equation, correlation coefficient (R²) value, explored linearity range, LOD, and LOQ values

Cpd	Regression equation	R^2	Eq. #	Linearity range (mg/mL)	LOD (ng/mL)	LOQ (ng/mL)
PA	y = 55069094.26 (523397.65) x + 557611.15 (30430.71)	0.9997	1	0.01–1.00	11.03	33.42

TABLE 2 Statistical analysis for pyruvic acid in the short period (intra-day precision and accuracy values)

Solution	Theoretical concentration (mg/mL)	Day	Mean observed concentration (mg/mL)	n^a	Precision (RSD%)	Accuracy (recovery %)
1	0.05	1	0.06	3	0.84	112.10
		2	0.06		0.52	111.72
		3	0.06		2.15	111.05
2	0.35	1	0.34	3	0.42	97.41
		2	0.34		1.41	96.78
		3	0.35		0.90	98.90

^aNumber of replicates.

TABLE 3 Statistical analysis for pyruvic aci in the long period (inter-day precision and accuracy values)

Solution	Theoretical concentration (mg/mL)	Mean observed concentration (mg/mL)	n^a	Precision (RSD%)	Accuracy (recovery %)
1	0.05	0.06	9	1.25	111.62
2	0.35	0.34		1.29	97.70

^aNumber of replicates.

FIGURE 2 Chromatographic trace of the A: standard PA, and of the extract from the Dorata di Parma cultivar B: before and C: after SPE.