Table 10.

Methods for quantification of organic acids in tomato by HPLC.

Reference	Sample	Column;	Eluentb	Detectionc	Repeatabilityd	Results
	preparation	column oven temperaturea			intra-day	inter-day	confirmed by another method
This study	SPE with NH2 columns	Nucleodur C18ec, 5 μm, 250× 4.6 mm; 25 °C	Gradient, 10 mM AP pH 2.6, ACN	UV, 210 nm	C: 2	C: 2	Yese
Marconi et al. [27]	Amberlite IRA-400	Alltima C18, 5 μm, 250 × 4.6 mm; 50 °C	H2O/MeOH/TFA = 97.7/2.2/0.1	UV, 210 nm	C: 2	nr	No
Gancedo and Luh [12]	Dowex 1-X8 and SEP PAC C18	Aminex HPX-87 ion exclusion; 60 °C	10 mM H2SO4	RI	nr	nr	No
Vermeir et al. [17]	–	Prevail org. acids column 250 × 4.6 mm; nr	H2O adjusted to pH 2.5 with formic acid	UV, 200 nm	C: 11	nr	Yesf
Zushi and Matsuzone [23]	–	Shim-pack SCR-102H 300 × 7.9 mm; 40 °C	5 mM p-toluene-sulfonic acid	CDg	nr	nr	No

^anr: not reported.

^bAP, ammonium phosphate buffer.

^cRI, refractive index detector; CD, conductivity detector.

^dThe repeatability is reported as relative SD in %. C, repeatability for citric acid; nr, not reported.

^eGC–MS.

^fEnzymatic assay. The reported values for citric acid are with 0.36-0.55 g/l unusually small.

^gConductivity detection after post-column mixing with 20 mM bis-TRIS and 100 μM EDTA in 5 mM p-toluenesulfonic acid.