Methods

TCA metabolites and intermediates. Short-chain fatty acids.
Volume: 50-200 µL

All concentrations are reported as µmol/L; CVs (%) shown as within-day (Wtn-day) and between-day (Btw-day) variations; sample matrices: serum (s), plasma (p), cerebrospinal fluid (csf).

Amino- and carboxylic acids.
Volume: 50-200 µL

All concentrations are reported as µmol/L; CVs (%) shown as within-day (Wtn-day) and between-day (Btw-day) variations; sample matrices: serum (s), plasma (p), urine (u).

Metabolites	Abbr	Category	PubChem	Reported	LOD	CV Wtn	CV Btw	ICC	Matrix	Method
Methylmalonic acid	MMA	Carboxylic acid	487	<0.26	0.03	2.4	3	0.81	s, p, u
Total homocysteine	tHcy	Sulfur amino acid	91552	5-15	0.1	1.4	2.7	0.72	s, p, u
Total cysteine	tCys	Sulfur amino acid	5862	150-350	50	1	2	0.62	s, p, u
Methionine	Met	Essential amino acid	6137	18-50	1	2.2	4.1	0.33	s, p, u
Serine	Ser	Polar amino acid	5951	95-125	5	1.3	1.7	0.71	s, p, u
Glycine	Gly	Hydrophobic amino acid	750	200-300	3	1.3	1.7	0.81	s, p, u
Cystathionine	Cysta	Thioether	439258	<0.4	0.02	2.3	2.9	0.63	s, p, u
Sarcosine*	Sarc	Methylated amino acid	1088	0.7-2.3	0.035	1.3	1.6	0.68	s, p, u
Histidine	His	Essential amino acid	6274	50-100	1	2	3	0.44a	s, p, u
Tryptophan	Trp	Essential aromatic amino acid	6305	40-90	0.1	1.6	2.6	0.51	s, p, u
Kynurenine	Kyn	Trp metabolite	161166	1.0-3.0	0.12	1.9	2.3	0.68	s, p, u
Ornithine	Orn	Charged amino acid	6262	30-90	1	2.2	2.7	0.55a	s, p, u
Aspartic acid	Asp	Charged amino acid	5960	0-26	0.5	1.8	4		s, p, u
Glutamic acid	Glu	Charged amino acid	33032	20-140	0.5	1.7	2.7		s, p, u
Lysine	Lys	Essential amino acid	5962	120-290	1.2	1.4	1.9	0.54a	s, p, u
Alanine	Ala	Hydrophobic amino acid	5950	230-510	1	1.2	1.4	0.43a	s, p, u
Phenylalanine	Phe	Essential aromatic amino acid	6140	26-85	0.5	1.5	3	0.44a	s, p, u
Isoleucine	Ile	Essential BCAA**	6306	40-140	0.5	1.5	1.8	0.53a	s, p, u
Leucine	Leu	Essential BCAA**	6106	70-170	0.5	3.4	4	0.52a	s, p, u
Proline	Pro	Hydrophobic amino acid	145742	110-360	0.5	2.8	3.7	0.71a	s, p, u
Valine	Val	Essential BCAA**	6287	150-350	0.5	2.2	2.7	0.38a	s, p, u
Asparagine	Asn	Polar amino acid	6267	20-130	0.6	3	3	0.40a	s, p, u
Glutamine	Gln	Polar amino acid	5961	390-700	10	2.1	2.7	0.42a	s, p, u
Threonine	Thr	Essential amino acid	6288	70-240	1.2	2.4	3.3	0.44a	s, p, u
Tyrosine	Tyr	Aromatic amino acid	6057	40-110	0.5	2.1	2.8	0.55a	s, p, u
α-Hydroxyglutaric acid	aHG	α-Hydroxy acid	43	0.15-2					s, p, u
3-Hydroxyisobutyrate	3HIB	Val metabolite	440873	15-25	3	2.4	2.9		s, p, u
2-Hydroxybutyrate	aHB	α-Hydroxy acid	11266	10-60	3	1.7	2.3		s, p
3-Hydroxybutyrate	bHB	Keton body	441	20-700	3	1.9	3.4		s, p
Acetoacetate	AcAc	Keton body	96	10-200	5				s, p
Carboxymethyllysine	CML	an AGE***	123800	0.05-0.3	0.03				s, p
Carboxyethyllysine	CEL	an AGE***	23400779	0.05-0.4	0.03				s, p
2-Aminoadipic acid	2AAA	Lys metabolite	469	0.3-1.8					s, p
β-Aminoisobutyrate	BAIBA	Val metabolite	64956	0.3-2.0					s, p
β-Alanine	bAla	β-Amino acid	239	0.5-10					s, p
3-Hydroxykynurenine	HK	Trp metabolite	11811						u
Kynurenic acid	KA	Trp metabolite	3845						u
Anthranilic acid	AA	Trp metabolite	227						u
Xanthurenic acid	XA	Trp metabolite	5699						u
3-Hydroxyanthranilic acid	HAA	Trp metabolite	86						u

*Sarcosine cannot be measured in EDTA-tubes from some suppliers because of the presence of sarcosine in these tubes; **BCAA, Branched chain amino acid; ***AGE, Advanced glycation end product. 
^aXiaofei Yin, Orla Prendiville, Aoife E. McNamara, and Lorraine Brennan. Targeted Metabolomic Approach to Assess the Reproducibility of
Plasma Metabolites over a Four Month Period in a Free-Living Population. J. Proteome Res. 2022, 21, 683−690.

Choline derivatives. Charged, methylated or sulfur amino acids. Short- and medium-chain acylcarnitines.
Volume: 50-200 µL

All concentrations are reported as µmol/L; CVs (%) shown as within-day (Wtn-day) and between-day (Btw-day) variations; sample matrices: serum (s), plasma (p), urine (u).

Metabolites	Abbr	Category	PubChem	Reported	LOD	CV Wtn	CV Btw	ICC	Matrix	Method
Choline	Chol	Quarternary ammonium	305	5-15	0.5	2.8	3.2	0.36	s, p, u
Choline, total*	tChol	Choline esters		2000-3000	500				s, p
Trimethylamine N-oxide	TMAO	Amine oxide	1145	0.5-60	0.1	4	4.1	<0.38	s, p, u
Betaine	Bet	Methylated amino acid	247	20-60	0.5	3.8	4.5	0.65	s, p, u
Dimethylglycine	DMG	Methylated amino acid	673	1.5–5	0.25	5.5	5.9	0.64	s, p, u
Total homocysteine	tHcy	Amino acid	91552	6-20	0.1	1	2	0.72	s, p, u
Creatine	Crn	α-Amino acid	586	10-100	1	3.9	4	na	s, p, u
Creatinine	Creat	α-Amino acid	588	50-100	0.25	2.6	3.1	0.79	s, p, u
Methionine	Met	Essential amino acid	6137	18-50	1	4.1	4.5	0.33	s, p
Methionine sulfoxide	MetSo	Polar amino acid	158980	0.5-5	0.06	7.1	7.9	0.36	s, p
Total cysteine	tCys	Sulfur amino acid	5862	150-400	0.1	2	6	0.56	s, p
Histidine	His	Essential amino acid	6274	50-100	0.25	3.5	3.8	na	s, p
3-Methylhistidine	3-MH	Amino acid	92105	2.7-10	0.6	4.4	4.9	na	s, p, u
1-Methylhistidine	1-MH	Amino acid	64969	0.5-15	0.25	3.7	3.9	na	s, p, u
Citrulline	Ctn	Amino acid	9750	10-60	4	7-8	6-9	na	s, p
Arginine	Arg	Charged amino acid	6322	40-100	0.25	2.6	3	0.53	s, p
Asymmetric dimethylarginine	ADMA	Guanidinated amino acid	123831	0.4-0.8	0.08	5.2	5.5	0.53	s, p
Symmetric dimethylarginine	SDMA	Guanidinated amino acid	169148	0.4-0.9	0.08	4.8	5.2	0.62	s, p
Homoarginine	hArg	Guanidinated amino acid	9085	1-6	0.1	5.8	6	0.65	s, p
Trimethyllysine	TML	Methylated amino acid	440121	0.3-2	0.2	4	4.4	0.15	s, p
Butyrobetaine	BB	Quarternary ammonium	725	0.4-2	0.2				s, p
Carnitine	C0	Carnitine	288	20-80	0.5			0.69a	s, p
Carnitine, total**	tC0	Carnitines		30-90	0.5				s, p
Acetylcarnitine	C2	Acylcarnitine	7045767	3-15	0.1			0.63	s, p
Propionylcarnitine	C3	Acylcarnitine	107738	0.2-1.5	0.05			0.62	s, p
Butyrylcarnitine	C4	Acylcarnitine	213144	0.1-0.5	0.012				s, p
Isovalerylcarnitine	iC5	Acylcarnitine	6426851	0.06-0.2	0.05			0.68	s, p
Glutarylcarnitine	C5DC	Acylcarnitine	71464488	< 0.05	0.01				s, p
Hexanoylcarnitine	C6	Acylcarnitine	6426853	0.01-1.2	0.01				s, p
Octanoylcarnitine	C8	Acylcarnitine	123701	0.06-0.3	0.05			0.41	s, p
Decanoylcarnitine	C10	Acylcarnitine	10245190	0.2-1	0.02				s, p
Dodecanoylcarnitine	C12	Acylcarnitine	168381	< 0.4	0.02				s, p

*Measured in a separate assay after sample treatment with phospholipase D that does not affect the other metabolites of platform C, which are obtainable; **Measured in a separate assay involving alkaline hydrolysis of acylcarnitines.

Kynurenine pathway and B vitamins (B1, B2, B3, B6).
Volume: 60-200 µL

CVs (%) shown as within-day (Wtn-day) and between-day (Btw-day) variations; sample matrices: serum (s), plasma (p), urine (u), cerebrospinal fluid (csf).

Metabolites	Abbr	Category	PubChem	Reported	LOD	CV Wtn	CV Btw	ICC	Matrix	Method
Pyridoxal 5′-phosphate	PLP	B6 vitamer	1051	15–150 nmol//L	0.2	3.5	5.7	0.7	s, p
				7-70 nmol					csf
Pyridoxal	PL	B6 vitamer	1050	5–150 nmol/L	0.2	3.5	5.1	0.62	s, p
				10-50 nmol/L					csf
4-Pyridoxic acid	PA	B6 vitamer	6723	10–200 nmol/L	0.5	3.6	5.8	0.58	s, p
				0-15 nmol/L					csf
Pyridoxine	PN	B6 vitamer	1054	na nmol/L	1	4.5	5.2	na	s, p
Thiamine	Thi	B1 vitamer	1130	2–50 nmol/L	0.5	3.5	4.9		s, p
				5-40 nmol/L					csf
Thiamine monophosphate	TMP	B1 vitamer	1131	2–15 nmol/L	0.5	7.1	11.6		s, p
				25-75 µmol/L					csf
Riboflavin	Ribo	B2 vitamer	493570	5–100 nmol/L	0.2	6	7.1	0.79	s, p
				5-25 nmol/L					csf
Flavin mononucleotide	FMN	B2 vitamer	643976	3–30 nmol/L	0.4	5.7	8.1	0.69	s, p
				1-2 nmol/L					csf
Cystathionine	Cysta	Thioether	439258	<0.4 µmol/L	0.02	3.4	4.5	0.63	s, p
Neopterin	Neopt	Pteridine	4455	5-50 nmol/L	0.7	5.3	6.6	0.6	s, p
				5-50 nmol/L					csf
Tryptophan	Trp	Essential aromatic amino acid	6305	40-90 µmol/L	4	3.1	3.9	0.51	s, p
				2-7 µmol/L					csf
Kynurenine	Kyn	Trp metabolite	161166	1.0-3.0 µmol/L	0.007	3.6	5.1	0.68	s, p
				0.02-0.12 µmol/L					csf
Kynurenic acid	KA	Trp metabolite	3845	20-100 nmol/L	0.4	4.4	5.4	0.68	s, p
				0.5-15 nmol/L					csf
Quinaldic acid	Qld	Trp (KA) metabolite	7124	0.2-100 nmol/L	0.5	6-7	6-8	na	s, p
				0.1-10 nmol/L					csf
Anthranilic acid	AA	Trp metabolite	227	7-30 nmol/L	2	7.4	9.5	0.64	s, p
				3-14 nmol/L					csf
3-Hydroxykynurenine	HK	Trp metabolite	11811	25-80 nmol/L	2	3.2	4.5	0.62	s, p
				0.1-25 nmol/L					csf
Xanthurenic acid	XA	Trp metabolite	5699	2-35 nmol/L	0.5	4.8	5.7	0.58	s, p
				<0.5 nmol/L					csf
3-Hydroxyanthranilic acid	HAA	Trp metabolite	86	10-80 nmol/L	2	4.6	6	0.54	s, p
				0-7 nmol/L					csf
Picolinic acid	Pic	Trp metabolite	1018	20-100 nmol/L	8	6-7	5-8	na	s, p
				5-100 nmol/L					csf
Quinolinic acid	QA	Trp metabolite	1066	150-700 nmol/L	1.6	7-8	7-10	na	s, p
				10-150 nmol/L					csf
Nicotinic acid	NA	B3 vitamer	938	<20 nmol/L	10	4	5.4	na	s, p
Nicotinamide	NAM	B3 vitamer	936	100-600 nmol/L	20	4.2	6.1	na	s, p
				5-200 nmol/L					csf
N1-methylnicotinamide	mNAM	B3 vitamer	457	20-250 nmol/L	5	4	5.5	na	s, p
				5-100 nmol/L					csf
Cotinine	Cot	Nicotine metabolite	854019	<3000 nmol/L	1	3	4.2	0.92	s, p, u
Trans-3′-hydroxycotinine	OHCot	Nicotine metabolite	107963	<1500 nmol/L	2	3.6	4.5	0.85	s, p, u
Trigonelline	Trig	Alkaloid	5570	<25 µmol/L	0.01	2.9	3.8	0.66	s, p
Trimethylamine N-oxide	TMAO	Amine oxide	1145	0.5-60 µmol/L	0.1	4.2	6.9	<0.38	s, p, u
				0.2-12 µmol/L					csf
Imidazole propionate	ImP	Histidine metabolite	70630	3-500 nmol/L	2				s, p
3-Indoxyl sulfate	3IS	Indole, Trp metabolite	10258	0.9-30 µmol/L	0.2				s, p
Indole-3-acetamide	IAM	Indole, Trp metabolite	397	0-10 nmol/L	1				s, p
Indole-3-acetate	IAA	Indole, Trp metabolite	802	0.3-23 µmol/L	0.05				s, p
Indole-3-aldehyde	IAld	Indole, Trp metabolite	10256	0.01-0.20 µmol/L	4				s, p
Indole-3-lactate	ILA	Indole, Trp metabolite	92904	0.08-5 µmol/L	0.025				s, p
Indole-3-propionate	IPA	Indole, Trp metabolite	3744	0.5-12 µmol/L	0.04				s, p

Folate species and catabolites.
LC-MS/MS: 60-200 µL vol.

All concentrations are reported as nmol/L; move cursor over header for details.

Metabolites	Abbr	Category	PubChem	Reported	LOD	CV Wtn	CV Btw	ICC	Matrix	Method
5-Methyl-tetrahydrofolate	mTHF	Folate	439234	>7.5	0.07	5-9	4-5	na	s, p
5-Formyl-tetrahydrofolate	fTHF	Folate	6006	0-2	0.52	8-9	6-11	na	s, p
Folic acid	FA	Folate	6037	0-2	0.27	7-8	6-12	na	s, p
4-α-hydroxy-5-methyl-THF	hmTHF	Oxidized folate			0.2	6-10	6-7	na	s, p
Para-aminobenzoylglutamate	pABG	Folate catabolite	196473	0-0.5	0.08	6-9	3-10	na	s, p
Acetamidobenzoylglutamate	apABG	Folate catabolite	3080868	0.1-1	0.13	5-6	5-9	na	s, p
Serum folate as pABG equivalents	S pABG	Folate		>7.5					s, p
RBC folate as pABG equivalents	E pABG	Folate		>340					e

Folate (B9) and cobalamin (B12).
Microbiological assay: 20-100 µL vol.

Move cursor over header for details.

Metabolites	Abbr	Category	Reported	LOD	CV Wtn	CV Btw	ICC	Matrix	Method
Serum folate	s-Folate	B vitamin	>7.5 nmol/L	2	4	5	0.56	s, p
Erythrocyte folate	e-Folate	B vitamin	>340 nmol/L					e
Serum cobalamin	s-B12	B vitamin	>150 pmol/L	30	4	5	0.82	s, p

Protein biomarkers and variants.
MALDI-TOF MS: 30-60 µL vol.

Move cursor over header for details.

Proteins	Abbr	Category	UniProt	Proteoforms	Reported	LOD	CV Wtn	CV Btw	ICC**	Matrix	Method
C-reactive protein	CRP	Protein	P02741	1	0-10 µg/mL	0.1	4-5	7-9	0.5-0.7	s, p
Serum amyloid A and proteoforms	SAA	Protein	P0DJI8, P0DJI9	18	0-20 µg/mL	0.05	4-5	8-10	0.4-0.7	s, p
Calprotectin and proteoforms	S100A	Protein	P05109, P06702	6*	0-30 µg/mL	0.02	4-7	7-8	0.3-0.5	s, p
Cystatin C and proteoforms	CnC	Protein	P01034	5*	0-8 µg/mL	0.01	4-5	4-5	0.7	s, p
Glycated hemoglobin	HbA1c	Protein	P69905, F8W6P5	na	4-14 %	na	2-6	na	na	w

*Mass interference of S100A and CnC proteoforms; **ICCs of proteoforms can be found here.

Lipid-soluble vitamins and long-chain acylcarnitines.
LC-MS/MS: 50-200 µL vol.

All concentrations are reported as µmol/L or nmol/L; move cursor over header for details.

Metabolites	Abbr	Category	PubChem	Reported	LOD	CV Wtn	CV Btw	ICC	Matrix	Method
All-trans retinol	Vit. A	A vitamer	445354	1.46-2.84 µmol/L	0.1	2.9	3.6	0.87	s, p
25-hydroxy vitamin D2	25OH-D2	D vitamer	5710148	0-30 nmol/L	5	6.6	8.1	na	s, p
25-hydroxy vitamin D3	25OH-D3	D vitamer	5283731	32.4-98.5 nmol/L	3.3	5.1	6.1	0.71	s, p
α-tocopherol	aToc	E vitamer	14985	18.9-38.8.0 µmol/L	2	4.3	5.8	0.86	s, p
γ-tocopherol	gToc	E vitamer	92729	2-11 µmol/L	0.1	3.7	5	na	s, p
Phylloquinone	Vit. K1	K vitamer	5284607	0.1-8.7 nmol/L	0.5	4.8	7.4	0.49	s, p
Myristoylcarnitine	C14	Acylcarnitine	6426854	0.01-0.1 µmol/L	na	na	na	0.38a	s, p
Palmitoylcarnitine	C16	Acylcarnitine	461	0.05-0.25 µmol/L	na	na	na	0.49a	s, p
Stearoylcarnitine	C18	Acylcarnitine	52922056	0.03-0.1 µmol/L	na	na	na	0.40a	s, p
Oleoylcarnitine	C18:1	Acylcarnitine	46907933	0.04-0.2 µmol/L	na	na	na	0.66b	s, p
Linoleylcarnitine	C18:2	Acylcarnitine	6450015	0.01-0.1 µmol/L	na	na	na		s, p

^aFloegel A, Drogan D, Wang-Sattler R, Prehn C, Illig T, et al. (2011) Reliability of Serum Metabolite Concentrations over a 4-Month Period Using a
Targeted Metabolomic Approach. PLoS ONE 6(6): e21103. doi:10.1371/journal.pone.0021103
^bXiaofei Yin, Orla Prendiville, Aoife E. McNamara, and Lorraine Brennan. Targeted Metabolomic Approach to Assess the Reproducibility of
Plasma Metabolites over a Four Month Period in a Free-Living Population. J. Proteome Res. 2022, 21, 683−690.

This platform is under development.
Short-, medium- and long-chain acylcarnitines.
LC (HILIC)-MS/MS: 50-200 µL vol.

All concentrations are reported as µmol/L; move cursor over header for details.

^aFloegel A, Drogan D, Wang-Sattler R, Prehn C, Illig T, et al. (2011) Reliability of Serum Metabolite Concentrations over a 4-Month Period Using a
Targeted Metabolomic Approach. PLoS ONE 6(6): e21103. doi:10.1371/journal.pone.0021103
^bXiaofei Yin, Orla Prendiville, Aoife E. McNamara, and Lorraine Brennan. Targeted Metabolomic Approach to Assess the Reproducibility of
Plasma Metabolites over a Four Month Period in a Free-Living Population. J. Proteome Res. 2022, 21, 683−690.