TABLE 3.

Identification of the most discriminant metabolomic variables between pre- and post-dialysis with both dialysates.

Accurate mass (m/z)	Retention time (min)	Adduct ion	Formula	Identification of variables		Compound class	Fold change (Post- vs pre-dialysis)
				Metabolite annotation	Confidence level		Acetate dialysate	Citrate dialysate
136.0485	0.621	M + Na	C4H7N3O	Creatinine	3	Alpha amino acids and derivatives	0.46	0.46
98.98454	0.682	M + H	H3O4P	Hydrogen phosphate	3	Non-metal phosphates	0.31	0.25
160.1335	0.715	M + H	C8H17NO2	Pregabalin	3	Gamma amino acids and derivatives	0.24	0.23
				DL-2-Aminooctanoic acid		Alpha amino acids
				Methacholine		Tetraalkylammonium salts
				Propionylcholine		Acyl cholines
229.1549	0.723	M + H	C11H20N2O3	L-isoleucyl-L-proline	1	Dipeptides	0.13	0.13
		M + Na	C14H220	2-Benzylheptanol		Benzyl alcohols
				4-(1.1,3,3-Tetramethylbutyl)-phenol		Phenylpropanes
				Etaspirene		Dihydrofurans
				Neocaspirene		Monoterpenoids
				α-Irone, (Z)-α-Irone, Methyl-δ-ionone, Methyl-ionone, δ-Methylionone, β-Methylionone, α-Isomethylionone		Sesquiterpenoids
151.0617	0.725	M + H	C6H6N4O	1-Methylhypoxanthine, 7-Methylhypoxanthine	3	Hypoxanthines	0.14	0.12
			C6H14S2	xi-1-(Propylthio)-1-propanethiol		Hemiacetals
				1,6-Hexanedithiol		Alkythiols
				Diisopropyl disulfide, Methyl pentyl disulfide, Dipropyl disulfide, Methyl isopentyl disulfide, Butyl ethyl disulfide		Dialkyldisulfides
			C8H8NO2	Aminochrome o-semiquinone		Indolines
153.0666	0.726	M + H	C7H8N2O2	2-Amino-4-nitrotoluene, 4-Amino-4-nitrotoluene	1	Nitrobenzenes	0.34	0.33
				N1-Methyl-2-pyridone-5-carboxamide, N-methyl-4-pyridone-3-carboxamide		Nicotinamides
				3-Pyrimidin-2-yl-Propionic Acid, 2-Pyrimidin-2-yl-Propionic Acid	2	Propanoic acids and derivates
			C7H5NO2	2-benzoxazolol	1	Benzoxazolones
207.1111	2.982	M + Na	C9H16N2O2	N-(3-acetamidopropyl)pyrrolidin-2-one	3	N-alkylpyrrolidines	0.19	0.19
				3-[(3-methylbutyl) (nitroso)amino]but-3-en-2-one		α-branched α,β-unsaturated ketones
				3-[(3-methylbut-3-en-1-yl) (nitroso)amino]butan-2-one		Organic N-nitroso compounds
307.0875	3.963	M + H	C20H15ClO	4-(2-chloro-1,2-diphenylethenyl)phenol	3	Stilbenes	0.06	0.06
		M + Na	C10H14N5O5	arabinofuranosylguanine		Purine nucleosides
		M + H-H2O	C12H20O8S	3,4,5-trihydroxy-6-{[(1-hydroxy-2-methylidenepentan-3-yl)sulfanyl]oxy}oxane-2-carboxylic acid, 3,4,5-trihydroxy-6-{[(5-hydroxy-4-methylpent-1-en-3-yl)sulfanyl]oxy}oxane-2-carboxylic acid
84.04482	3.963	M + H-H2O	C4H7NO2	1-Aminocyclopropanecarboxylic acid, (S)-2-Azetidinecarboxylic acid	3	Alpha amino acids	0.19	0.22
				L-3-Aminodihydro-2(3H)-furanone		Alpha amino acid esters
				2,3-Dihydroxy-2-methylpropanenitrile		Alcohols and polyols
91.05471	3.963	M + H-H2O	C7H8O	p-Cresol, m-Cresol, o-Cresol	3	Cresols	0.16	0.16
				Benzyl alcohol		Benzyl alcohols
				Anisole		Anisoles
185.0239	3.963	M + H	C4H11ClN2O2P	Ifosforamide aziridinium	3	Organic phosphoric acid diamides	0.11	0.12
		M + Na	C6H10O3S	1,2-Dihydroxy-3-keto-5-methylthiopentene		α-branched α,β-unsaturated ketones
				1-(Methylsulfanyl)-1-oxopropan-2-yl acetate		Thioesters
		M + H-H20	C11H6O4	Bergaptol		Bergaptols
				Xanthotoxol		8-hydroxypsoralens
335.0825	3.963	M + H-H20	C16H17ClN2O5	N-(Carbethoxyacetyl)-4-chloro-L-tryptophan	3	N-acyl-alpha amino acids	0.12	0.11
364.0358	3.963	M + Na	C18H12ClNO4	7-Chloro-6-demethylcepharadione B	1	Oligosaccharides	0.11	0.09
265.1192	3.963	M + H/M + Na	C13H16N2O4	Acetyl-N-formyl-5-methoxykynurenamine	1	Alkyl-phenylketones	0.09	0.09
				N(2)-phenylacetyl-L-glutaminate		Glutamine and derivatives
		M + Na	C16H18O2	4.4´-(2-methylpropylidene)bisphenol, 4.4´-(Butane-1,1-diyl)disphenol, Bisphenol B		Bisphenols Cyclohexylphenols
				4,4a,5,6,7,8-hexahydro-6-(p-hydroxyphenyl)-2(3H)-napthalenone
287.1013	3.964	M + H	C15H14N2O4	3′,4′-Dihydrodiol	1	Phenylhydantoins	0.06	0.06
			C20H14O2	S-1-1′Bi-2-naphtol	2	Naphthols and derivatives
153.0665	0.990			Unknown	4		0.34	0.33
Confidence level: 1: identified metabolites, 2: putatively annotated, 3: putatively characterized; 4: unknown