Validation of a ¹H-NMR Spectroscopy Quantitative Method to Quantify Trimethylamine Content and K-Index Value in Different Species of Fish

Table 4

K-Index value for red mullet and bogue fish.

Red mullet (Mullus barbatus)
^# Fish sample	K-index (%)		RSD (%)^a		RSDH (%)^b		Horrat^c
	HPLC	NMR	HPLC	NMR	HPLC	NMR	HPLC	NMR
1 (T1)	32.9 (2.9)	31.2 (1.0)	1.1	1.5	1.6	1.6	0.68	0.95
2 (T3)	53.1 (1.1)	50.0 (2.3)	0.05	0.5	1.5	1.5	0.34	0.034
3 (T4)	69.3 (1.2)	69.3 (1.5)	0.7	1.0	1.4	1.4	0.48	0.74
4 (T7)	83.5 (1.2)	83.2 (0.7)	0.4	0.4	1.4	1.4	0.32	0.30
5 (T10)	88.6 (1.1)	92.7 (2.0)	0.35	1.0	1.4	1.4	0.26	0.75
Bogue fish (Boops boops)
^# Fish sample	K-index (%)		RSD (%)^a		RSDH (%)^b		Horrat^c
	HPLC	NMR	HPLC	NMR	HPLC	NMR	HPLC	NMR
1 (T1)	23.3 (1.9)	21.4 (1.2)	2.34	0.43	1.7	1.7	1.4	0.25
2 (T5)	36.7 (1.4)	35.5 (1.3)	0.90	0.77	1.5	1.5	0.60	0.51
3 (T6)	43.4 (2.99)	42.1 (2.8)	1.9	1.3	1.5	1.5	1.3	0.87
4 (T9)	66.1 (2.5)	65.7 (3.4)	1.5	1.6	1.4	1.4	1.07	1.14
5 (T10)	68.8 (1.69)	74.4 (1.9)	1.1	0.4	1.4	1.4	0.75	0.29

^aRelative standard deviation. ^bAcceptable relative standard deviation according to Horwitz’s formula for intralaboratory studies. ^cHorrat = RSD measured/RSD Horwitz predicted.