Comparison of Three Solid Phase Materials for the Extraction of Carboxylic Acids from River Water Followed by 2D GC × GC-TOFMS Determination

Table 2

Selected carboxylic acids extracted by silica, C-18, and Strata X.

GC × GC-TOFMS determinations
Peak #	Name	Unique mass	Weight	Retention times (1st, 2nd) (sec)	Library similarity (%)	Area
	Silica SPE
91	Benzoic acid, 3,5-bis(1,1dimethylethyl)-4-hydroxy-ethyl ester	263	278	676, 2.8	75.2	133966
92	1,2-Benzenedicarboxylic acid, bis(2-methyl) propyl ester	149	278	688, 2.81	93.1	406649
106	Cyclobutanecarboxylic acid, 2-tridecyl ester	80	226	588, 2.850	70.5	495527
152	Phthalic acid, di(2-propylpentyl) ester	146	370	884, 2.730	75.0	7249
731	7-Phenylheptanoic acid	233	436	968, 2.840	79.9	117828
	C-18
104	1,2-Benzenedicarboxylic acid, bis(2-methylpropyl) ester	149	278	688, 2.820	93.4	313930
287	Benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, methyl ester	156	254	1080, 2.660	76.1	9054.8
316	Phthalic acid, di(oct-3-yl) ester	183	282	1136, 2.570	84.6	90552
330	1,2-Benzenedicarboxylic acid, butyl 2-ethylhexyl ester	280	280	1152, 2.590	74.7	4870.7
350	Phthalic acid, butyl undecyl ester	256	256	1188, 2.520	89.9	517199
	Strata X
15	Benzoic acid, 4-ethoxy-, ethyl ester	121	194	536, 2.710	88.5	126885
117	1,2-Benzenedicarboxylic acid, bis(8-methylnonyl) ester	149	446	1092, 3.08	74.9	310
44	Benzenedicarboxylic acid, butyl 2-ethylhexyl ester	149	334	724, 3.70	86.8	1045431
77	Phthalic acid, di(oct-3-yl) ester	149	390	928, 2.76	89.3	643832
66	4-Ethylbenzoic acid, 3-fluorophenyl ester	133	244	732, 2.840	85.3	126054