Analysis of Reaction between -Lipoic Acid and 2-Chloro-1-methylquinolinium Tetrafluoroborate Used as a Precolumn Derivatization Technique in Chromatographic Determination of -Lipoic Acid

Table 4

Comparison of the proposed method with elaborated methods of analyzing LA.

Method	Derivatisation agent	Range of determination	LOD	LOQ	Reference
HPLC-FL	N-(1-Pyrene)iodoacetamide; N-(1-Pyrenemethyl)iodoacetamide	0.75–120 μmol L^−1	<3.1 fmol	Not given	[23]
	Ammonium 4-fluoro-2,1,3-benzoxadiazole-7-sulfonate (SBD-F)	0.94–60 μmol L^−1	0.13 pmol	0.44 pmol	[24]
Capillary LC-UV	4-Bromomethyl-6,7-dimethoxycoumarin	0.1–20 μmol L^−1	0.03 μmol L^−1	Not given	[21]
	4-Bromomethyl-6,7-dimethoxycoumarin	0.1–40 μmol L^−1	5 fmol	Not given	[22]
HPLC-UV	Derivatisation with 1-benzyl-2-chloropyridinium bromide	0.2–50 μmol L^−1	0.1 μmol L^−1	0.20 μmol L^−1	[26]
	Without derivatisation	48.5–2422.7 μmol L^−1	21.32 μmol L^−1	81.40 μmol L^−1	[25]
Proposed HPLC-UV method	2-Chloro-1-methylquinolinum tetrafluoroborate	2.5–50 μmol L^−1	0.21 μmol L^−1	0.65 μmol L^−1