Development of isotope dilution-liquid chromatography tandem mass spectrometry for the accurate determination of vitamin K1 in spinach and kimchi cabbage

Journal of Analytical Science and Technology

Table 1 Measurement results of gravimetrically fortified (A) spinach and (B) kimchi cabbage samples by the ID-LC/MS/MS method

Analytes	Gravimetric value (mg/kg)^a	Measured value (mg/kg)^a,b	Difference (%)
(A)
trans-vitamin K₁	12.764 ± 0.049	13.02 ± 0.69 (5.2%)^c	2.0
	26.86 ± 0.10	27.0 ± 1.1 (4.2%)	0.7
	73.01 ± 0.27	71.2 ± 3.6 (5.1%)	− 2.5
cis-vitamin K₁	1.955 ± 0.004	1.96 ± 0.18 (9.3%)	0.1
	4.114 ± 0.008	4.14 ± 0.37 (8.8%)	0.7
	11.184 ± 0.020	11.1 ± 1.1 (10.2%)	− 1.0
(B)
trans-vitamin K₁	7.191 ± 0.030	7.34 ± 0.38 (5.1%)	2.0
	15.298 ± 0.058	15.68 ± 0.57 (3.6%)	2.5
	45.64 ± 0.17	46.0 ± 2.7 (4.9%)	0.7
cis-vitamin K₁	1.102 ± 0.003	1.13 ± 0.18 (15.8%)	2.7
	2.343 ± 0.005	2.34 ± 0.38 (16.1%)	− 0.2
	6.990 ± 0.013	7.1 ± 1.1 (15.7%)	1.6

^aThe number after “ ± ” is the expanded uncertainty of the proceeding value with the 95% confidence level
^bMeasured values were calculated by subtracting the levels of the blank spinach or kimchi cabbage samples from the measurement results of spiked samples
^cThe percentage value provided in parentheses indicates the relative extended uncertainty compared to the corresponding mean value