Table 3.

Literary studies proposing different analytical techniques for PCa biomarker identification.

Reference	Authors	Population Controls/Sick	Sample Preparation Method	Analytical Method	Statistical Methods	Biomarkers	Results
[25]	Sreekumar et al. (2009)	51/59	Urine collection: After DRE for PCa patients; Storage and pre-treatments: Samples were stored at −80 °C until analysis; Sample preparation: Samples underwent organic and aqueous extractions. The extracted was equally divided into LC and GC fractions, which were dried on a TurboVapR. Prior to injection, all samples were resuspended in identical volume and injection standards were added.	LC-MS: The vacuum dried sample was re-solubilised in 100 µL of injection solvent. The system was operated using a gradient of acetonitrile. The columns were maintained in temperature-controlled chambers during use and were exchanged and washed after every 50 injections. GC-MS: The column used was 5% phenyl-methyl polysiloxane, the temperature from 40 °C to 300 °C in 16 min. ID GC-MS: For analysing sarcosine and alanine, residual water was removed by forming an azeotrope with 100 uL of DMF and drying the suspension under vacuum. An Agilent 6890N GC equipped with a 15 m DB-5capillary column interfaced with an Agilent 5975 MSD mass detector.	Wilcoxon rank-sum test; t-test; Kruskal–Wallis test; Pearson’s correlation; NOVA; Z-score plot; heat maps	Sarcosine; Uracil; Kynurenine; Glycerol-3-phosphate; Leucine; Proline	Sarcosine was significantly higher in urine sediments (AUC 71%) and supernatants (AUC 67%) of PCa patients; Uracil, Kynurenine, Glycerol-3-phosphate, Leucine, Proline were elevated upon disease progression.
[26]	Jentzmik et al. (2010)	45/107	Urine collection: after DRE for PCa patients; Second morning void urine for healthy participants; Storage and pre-treatments: Samples were centrifuged (1500× g, 10 min, 4 °C) and stored at −80 °C; Sample preparation: no info	Ez:fast amino acid analysis: SPME followed on a L-LE with the subsequent GC-MS on a 5973 MS and 6890 GC system. Recovery was checked with samples spiked with known amounts of sarcosine.	Mann–Whitney U test; Wilcoxon matched-pairs test; Spearman rank correlation; Fischer’s exact test; ROC analysis	Sarcosine	Median Sarcosine/creatinine was 13% lower in PCa patients than in controls
[27]	Jiang et al. (2010)	5/5	Urine collection: no info; Storage and pre-treatments: Samples were frozen at −80 °C; Sample preparation: Samples were thawed at room T and diluted 3 times using water; 10 µL of diluted urine were mixed with 10 µL of the internal standard solution and 1480 µL of 0.1% formic acid in water; those samples were diluted 450 times and injected for HPLC/MS/MS analysis	HPLC: An LC system working at 25 °C under a flow rate of 250 μL/min using a gradient system with the mobile phase consisting of (A) 0.1% formic acid in water and (B) 0.1% formic acid in acetonitrile (100%) was used for metabolite separation. The gradient program was initial 98% A and 2% B, linear gradient to 60% A and 40% B in 5 min, and return to initial conditions in 0.1 min at a flow rate of 250 μL/min, followed by equilibration for 10 min. MS/MS: An API 4000Q trap MS/MS system operated in multiple-reaction monitoring mode with ESI-positive ionisation was used. Turbo Spray was used as the ion source. The capillary voltage was set at 5.5 kV. Nitrogen gas was used as the curtain gas and cone gas. The cone gas flow was 50 L/h, and the desolvaation gas flow was 800 L/h. Optimal detection conditions were determined by direct infusion of each standard solution (20 ppb) in solvent A using a syringe pump. Parent-ion and daughter-ion scans were performed using nitrogen as the collision gas at a pressure of 3.8 × 103 millibar and a flow of 0.2 mL/min.	Multivariate statistics	Sarcosine; Proline; Kynurenine; Uracil; Glycerol-3-phosphate; Creatinine	nMmetabolites/µMcreatinine: PCa patients: Sarcosine 120; Proline 40; Kynurenine 15; Uracil 10; Glycerol-3-phosphate 85; Controls: Sarcosine 30; Proline 5; Kynurenine 8; Uracil 5; Glycerol-3-phosphate 30
[28]	Wu et al. (2010)	8 BHP; 20 healthy male/20	Urine collection: first morning urine; Storage and pre-treatments: Samples were centrifuged within 1 h at 3000 rpm for 10 min at 25 °C; aliquoted in 1 mL and stored at −80 °C; Sample preparation: Samples were thawed by incubation at 37 °C for 3 min and vortex-mixed for 15 s. 800 µL methanol, 100 µL ribitol and 100 µ were added into each sample and vortex-mixed for 5 min and ultrasonicated at room T for 5 min. pH was adjusted to 9–10 with NaOH and solution was filtered by 0.45 µm membrane. 100 µL of filtrate were transferred to a screw vial and evaporated under N2	ID GC-MS: 1 µL of derivatised sample was injected splittless into an Agilent 6980 GC equipped with a 30 m × 0.25 nm i.d. fused-silica capillary column with 0.25 µm HP-5MS stationary phase. Injector T was set at 250 °C, column T was initially kept at 80 °C for 3 min and increased to 280 °C at 10 °C/min, where it was held for 2 min. Column effluent was introduced into Agilent 5973 mass selective detector: quadrupole T 150 °C, ion source T 230 °C, solvent delay 180 s.	Two-sample t test; PCA; ROC analysis	Sarcosine; Propenoic acid; Pyrimidine; Dihyroxybutanoic acid; Creatinine; Purine; Glucopyranoside; Ribofuranoside; Xylonic acid; Xylopyranose	PCa patients average sarcosine value were 13% higher than healthy controls and 19% higher than BPH controls. Also propenoic acid, dihyroxybutanoic acid, creatinine, and xylonic acid, dihyroxybutanoic acid and xylonic acid, concentrations were higher in PCa patients.
[29]	Stabler et al. (2011)	29 recurrent free; 25 PCa recurrence	Urine collection: before prostatectomy; Storage and pre-treatments: Samples were stored at −80 °C; Sample preparation: no info	GC-MS: A Durabond DB.1 fused silica capillary column (30 m × 0.25 mm) from J&W Scientific, Inc. and a Hewlett-Packard Co. 5992B gas chromatograph-mass spectrometer equipped with a falling needle injector were used.	Wilcoxon rank sum test; Fisher exact test; Spearman’s rank correlation	Cysteine; Homocysteine; Dimethylglycine; Sarcosine	Higher serum homocysteine, cystathionine, and cysteine levels independently predicted risk of early biochemical recurrence and PCa aggressiveness. The methionine further supplemented known clinical variables to increase sensitivity and specificity.
[30]	Bianchi et al. (2011)	13 healthy; 10 BHP/33	Urine collection: after DRE; Storage and pre-treatments: no info; Sample preparation: no info	SPME: A Gerstel MultiPurpose Sampler DualRail WorkStation MPS autosampler equipped with two sample trays, two-heated incubator shakers, a 100 µL syringe and a 3-position trays MFX was used. Hexyl chloroformate (10 μL), 10 μL of pyridine and 10 μL of hexanol were added, under continuous agitation at 500 rpm, in 0.9 mL clear crimp vials with sleeve for 10 × 32 vial containing 400 μL of urine. Norvaline was used as internal standard. After 5 min, 20 μL were diluted in 0.9 mL clear crimp vials previously filled with 800 μL of water. Simultaneously, the SPME fibres were transported between the 3-position tray and the vial. Urine sediments were washed with water under sonication and filtered. The filter was then broken up adding 500 µL of HCl and 1 mL of acetone into a 10 mL vial placed in an ultrasound bath for 10 min. Extraction was performed using PDMS/DBV fibre that was immersed in vial for 15 min at 35 °C. A constant magnetic stirring was applied. The desorption was carried out at 260 °C for 1 min. GC-MS: Oven setting was as follows: 80 °C for 0.3 min, 80 °C min−1 up to 200 °C, 200 °C for 0.3 min, 50 °C min−1 up to 290 °C. Inlet pressure, column flow and average linear velocity were 623.1 kPa, 0.97 mL min−1 and 51.3 cm s−1. The QP 2010 series MS detector (Shimadzu) equipped with the acquisition system GC Solution software was operated under the selected ion monitoring mode by applying a delay time of 2.9 min	Mann–Whitney U; Kruskal–Wallis tests; ROC analysis	Sarcosine; N-ethylglycine	µgSarcosine/gCreatinine discriminates between healthy, BHP and PCa patients Cut-off 179 µg/g: sensitivity 79%; specificity 87%
[31]	Shamsipur et al. (2012)	20/12	Urine collection: no info; Storage and pre-treatments: sample were frozen at −22 °C; Sample preparation: urine was thawed at room T and shaken vigorously for 1 min	DDLLME: 4 mL of water spiked with standard solution were treated with 12 M NaOH to obtain the desired pH. Standard amino acids were spiked into the solution at a level of 200 µg/L for initial screening and 50 µg/L for final optimisation. 150 µL acetonitrile, 200 µL pyridine and 25 µL carbon tetrachloride were added and the solution was mixed vigorously for 15 s. i-BuCF (250 µL) were added and shaken for 30 s. The solution was left to stand for 1 min and then centrifuged at 2260× g for 4 min for phase separation. 10 µL of the sediment phase was injected into the GC-MS for analysis. GC-MS: Processed samples were analysed using an Agilent 6890 GC coupled to an Agilent 5973 inert EI/CI mass selective detector. He was maintained at a constant flow of 1.8 mL min−1. The injection port was set to splitless and maintained at an optimised temperature of 280 °C. The oven temperature program was as follows: 80 °C (initial temperature), ramped to 155 °C at 10 °C min−1, holding at 155 °C for 5 min, then ramped to 172 °C at 2 °C min−1 holding for 2 min, finally ramped to 280 °C at 40 °C min−1 and holding for 6 min. T settings for the transfer-line heater, ion source, and quadrupole of the MS were 280, 150, and 150 °C, respectively. The dwell time for each scan was 150 ms ion−1, and the solvent delay was 7 min. The electron impact ionisation energy was 70 eV.	Bland-Altman	Sarcosine; Alanine; Proline; Leucine	Sarcosine mean concentrations were higher in PCa patients; Leucine mean concentration was lower in PCa patients
[32]	Struck-Lewicka et al. (2014)	32/32	Urine collection: no info; Storage and pre-treatments: Samples were stored at −80 °C; Sample preparation: no info	LC-TOF/MS: Urine samples after thawing at room temperature were vortex-mixed for 1 min and centrifuged at 4000× g for 10 min. Subsequently the supernatant was diluted in deionised water and then centrifuged at 4000× g for 15 min. After centrifugation, the samples were filtered directly to HPLC vials using 0.2 μm nylon filters. GC-MS: samples were thawed at room temperature for 1 h. The first step was addition of 50 μL of urease to 200 μL of urine. Next, the sample incubation in 37 °C for 30 min was applied (to decompose and remove excess amount of urea). Next, 800 μL of cold methanol (kept for 30 min in −80 °C) and 10 μL of pentadecanoic acid were added to urine samples. Then the samples were vortex-mixed for 5 min and centrifuged at 4000 g for 15 min. 200 μL of supernatants were transferred into glass inserts in GC vials and evaporated to dryness in 30 °C for 1 h 30 min. Next, 30 μL of methoxyamine in pyridine in concentration of 15 mg/mL was added to urine samples. The next step was vortex-mixing of each sample for 10 min and then incubation of all samples for 16 h in room temperature in dark place. The silylation process was performed with addition of 30 μL of BSTFA with 1% TMCS, vortex-mixing of each sample for 5 min and incubation for 1 h in 70 °C. Before GC-MS analysis, addition of 70 μL of hexane and vortex-mixing for 10 min were performed	MFE algorithm; PCA; PLS-DA; 7-fold cross validation	35 metabolites	LC-TOF/MS: Positive ionisation mode R2 0.756, G2 0.579; Negative ionisation mode R2 0.763, G2 0.508 GC-MS: R2 0.788, G2 0.711
[33]	Heger et al. (2014)	32/32	Urine collection: no info; Storage and pre-treatments: 500 µL of urine were mixed with 500 µL of 35% HCl and mineralised using the microwave equipment MW 3000. 100 µL of mineralised sample were diluted with 900 µL of dilution buffer and centrifuged using Centrifuge 5417R. 500 µL of the sample were diluted in 500 µL of 0.6 M NaOH; Sample preparation: no info	IELC: A glass column with an inner diameter of 3.7 and length of 350 mm was filled manually with strong cation exchanger in sodium cycle with ~12 μm particles and 8% porosity. The column was thermostated at 60 °C. Double channel VIS detector with an inner cell of 5 μL was set to two wavelengths: 440 and 570 nm. Elution of amino acids was carried out by buffer containing 10.0 g of citric acid, 5.6 g of sodium citrate, and 8.36 g of natrium chloride per litre of solution (pH 3.0). The flow rate was 0.25 mL·min−1. The reactor temperature was set to 120 °C. IEMA: The immunoenzymometric assay was used for analysis of PSA and fPSA	Shapiro–Wilk test; t test; hierarchical clustering	aspartic acid, threonine, methionine, isoleucine, leucine, tyrosine, arginine; sarcosine; proline; concentrations of K+, Na+, Cl−, uric acid, urea, PSA, glucose, total proteins, fPSA, creatinine and pH	All amino acids were increased in PCa patients, except for phenylalanine amounts. In controls, higher levels of K+ and uric acid and lower levels of urea and creatine were detected. PSA and free PSA were below the detection limit in controls.
[34]	Khalid et al. (2015)	43/59	Urine collection: no info; Storage and pre-treatments: Samples were stored at −20 °C; Sample preparation: Each sample was defrosted by immersing the vial in a water bath at 60 °C for 30 s. One single aliquot of urine sample per patient was used for VOC analysis. Thereafter, each sample was treated with an equal volume (0.75 mL) of sodium hydroxide 1 M. The mixture was equilibrated at 60 °C in a water bath for 30 min prior to SPME.	SPME: The SPME fibre was 85 μm thick and consisted of carboxen/polydimethylsiloxane. It was exposed to the headspace above the urine mixture for 20 min. GC-MS: VOCs were thermally desorbed from the fibre at 220 °C in the injection port of the GC/MS for 5 min. Injection was made in splitless mode and a split of 50 mL/min was turned on two minutes into the run. It was used helium as carrier gas (99.996% purity). Capillary column consisted of 94% dimethyl polysiloxane and 6% cyanopropyl-phenyl. The GC/MS T program of the run was as follows: initial oven T was held at 40 °C for 2 min then T was ramped up at a rate of 5 °C/min to 220 °C, with a 4 min hold at this T to give a total run time of 42 min. The mass spectrometer was run in electron impact (EI) ionisation mode, scanning the mass ion range 10–300 at 0.05 scan/s. A 4 min solvent delay was used at the start of the run.	Random Forest; LDA; 10-fold cross validation; double cross validation	2,6-dimethyl-7-octen-2-ol; Pentanal; 3-octanone; 2-octanone	Except for pentanal, all of these compounds were down-regulated and/or less frequently present in the urine samples from PCa patients. Model AUC based on 4 biomarkers discovered was 63–65%, while it was 74% (RF) and 65% (LDA) if combined with PSA level.
[35]	Tsoi et al. (2016)	88 BHP; 11 healthy/66	Urine collection: after lunch prior PBs; Storage and pre-treatments: −20 °C; Sample preparation: Firstly, urine samples were thawed and centrifuged for 5 min at 13,000 rpm at room T. Urine sample supernatant (120 μL) and 60 μL of internal standard working solution were mixed with 420 μL of water. Of this well-mixed solution, 550 μL was passed through SPE, which had been conditioned and equilibrated with 1 mL of methanol and water respectively. Water (450 μL) was passed through the cartridge afterwards to elute out all polyamines. Of these SPE-treated samples, 400 μL were then mixed with 100 μL of 10% HFBA, and the final mixture was ready for instrumental analysis	UPLC-MS/MS: The column used was an Agilent EclipsePlus C18 RRHD (2.1 × 50 mm, 1.8 μm) protected with an Agilent SB-C18 guard column (2.1 × 5 mm, 1.8 μm). The LC elution profiles were optimised as follows: Eluent A was water with 0.1% HFBA while eluent B was acetonitrile with 0.1% HFBA. Eluent A was decreased from 95% to 60% in 10 min, and from 60% to 10% in 1 min. Afterwards the gradient was held constant for 5 min. The gradient was then increased from 10% to 95% in 1 min, and held constant for 8 additional minutes. The autosampler and column temperatures were set at 4 and 35 °C respectively. Injection was achieved by 5-s needle wash in Flush Port mode for 3 times with eluent B. Ten microlitres was injected each time. For the source parameter, drying gas (N2) temperature was set as 300 °C with 5 L/min flow rate. Nebuliser pressure was 45 psi. Sheath gas temperature was set as 250 °C with 11 L/min flow rate. Capillary voltage was set as 3500 V.	Student’s t-test; ROC analysis	putrescine (Put), spermidine (Spd) and spermine (Spm)	Normalised Spd was significantly lower in PCa than in BHP patients and controls The AUC for normalised Put, Spd and Spm were found to be 0.63 ± 0.05, 0.65 ± 0.05 and 0.83 ± 0.03 respectively
[36]	Sroka et al. (2016)	25 BHP/25	Urine collection: prior and after prostate massage; Storage and pre-treatments: Sodium azide solution was added. Samples were stored at −80 °C; Sample preparation: 10 µL aliquot of each urine sample or standard solution was added to 70 µL of 200 mM borate buffer containing 25 µM 2-Aminobutyric acid, 1 mM ascorbic acid and 10 mM TCEP. The solution was vortexed, centrifuged. 20 µL of 10 mM Aqc reagent dissolved in 100%ACN was added. The solution was vortexed, centrifuged, heated with shaking at 55 °C for 10 min.	LC-ESI-QqQ-MS: Mobile phase consisted of (A) 0.1% formic acid in water (v/v) and (B) 0.1% formic acid in ACN (v/v). Flow rate was set to 300 µL min−1. Separation was performed at 30 °C with monitored pressure below 400 bar. Analysis time was 19 min. The gradient was run from 0–2 min using 1% solvent B, then linearly raised over 7 min from 1% to 15% solvent B. then raised to 30% solvent B over 5 min and dropped to 1% for re-equilibration which lasted 5 min. Concentrations were quantified using Agilent 1200 LC-system coupled to an Agilent 6410 ESI-QqQ-MS. Injection volumes of 2 µL of samples or standards were used. Ions were monitored in the positive ion mode. Source conditions were set to sheath gas temperature 315 °C. Gas flow 10 L min−1. nebuliser pressure 45 psi and capillary voltage 3800 V.	t-test; U Mann-Whitney analysis; ROC curves	Arginine; Homoserine; Proline; Tyramine	In PCa samples, higher concentrations of arginine both before (p = 0.018) and after (p = 0.009) prostate massage and higher levels of proline only after prostate massage (p = 0.032) were detected. Higher levels of proline and homoserine and tyramine correlate with GS7 with respect to GS 6 and GS 5.
[37]	Fernandez-Peralbo et al. (2016)	42/62	Urine collection: prior PBs Storage and pre-treatments: Samples were stored at −80 °C Sample preparation: After thawing at room T, urine samples were vortex-mixed for 1 min and centrifuged at 21,000× g for 5 min. Then, 50 μL of the supernatant were 1:2 (v/v) diluted with 5 mM ammonium formate in water (pH 5.5–7.5)	LC-QTOF: A Mediterranea Sea C18 analytical column thermostated at 25 °C was used. The initial mobile phase was a mixture of 98% phase A (0.1% formic acid in water) and 2% phase B (0.1% formic acid in ACN). After injection, the initial mobile phase was kept under isocratic conditions for 1 min; then, a linear gradient of phase B from 2% to 100% was applied within 16 min. The flow rate was 0.6 mL/min. The total analysis time was 17 min, and 5 min were required to re-establish the initial conditions. The injected volume was 5 μL. The autosampler was kept at 4 °C to increase sample stability.	unpaired t-test (p-value < 0.05); PLS-DA	28 metabolites	Almost all metabolites were present at lower concentrations in PCa patients than in controls, Training: Specificity 92.9%; Sensibility 88.4% Validation: Specificity 78.6%; Sensibility 63.2%
[38]	Gkotsos et al. (2017)	49/52	Urine collection: second morning void midstream; Storage and pre-treatments: −80 °C after post-centrifugation (each sample centrifuged at 1500× g, for 10 min, at 4 °C); Sample preparation: 100 μL of sample was diluted with 100 μL of MeOH. The samples were vortex-mixed (1 min) and centrifuged for 10 min (7000 g) to remove particulate matter and macromolecules. 50 μL of supernatant was diluted with 100 μL of MeCN and transferred to LC/MS vial, which was maintained at 10 °C.	UPLC-MS/MS: Separation was performed on a ACQUITY UPLC™ BEH AMIDE column 1.7 μm, 2.1 mm × 150 mm suitable for polar metabolites. Sarcosine, uracil, and kynurenic acid were detected using Multiple Reaction Monitoring (MRM) mode in a single injection of 15.5 min. The MRM transitions for the three metabolites were set as follows: sarcosine m/z 90–44, CV = 20 V, CE = 8 V; uracil m/z 113–70, CV = 40 V, CE = 15 V; and kynurenic acid m/z 190–172, CV = 32 V, CE = 12 V. For chromatographic separation the mobile phase was a mixture of (A) ACN/H2O, 95:5 v/v and (B) H2O/ACN, 70:30 v/v both with final ammonium formate buffer concentration of 10 Mm and elution was performed with a gradient program started with 100% A, then rising to 15% B linearly over the next 2 min, finally reaching 40% B over 2 min and returning to initial conditions over 5 min. The column was equilibrated for 6 min in the initial conditions. Flow rate was 0.5 mL/min	Kruskal–Wallis test; ROC analysis; Pearson correlation; Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA)	Sarcosine; Uracil; Kynurenic acid	Decreased median sarcosine and kynurenic acid and increased uracil concentrations were observed for patients with prostate cancer compared to participants without malignancy.
[39]	Derezinski et al. (2017)	40/49	Urine collection: second morning void midstream; Storage and pre-treatments: −80 °C after post-centrifugation (each sample centrifuged at 1500× g, for 10 min, at 4 °C); Sample preparation: 100 μL of sample was diluted with 100 μL of MeOH. The samples were vortex-mixed (1 min) and centrifuged for 10 min (7000 g) to remove particulate matter and macromolecules. 50 μL of supernatant was diluted with 100 μL of MeCN and transferred to LC/MS vial, which was maintained at 10 °C.	LC-ESI-MS/MS combined with aTRAQ: HPLC instrument 1260 Infinity combined with a 4000 QTRAP mass spectrometer with an EI source. The column was maintained at 50 °C with a flow rate of 800 μL/min. A mobile phase gradient of eluent A (0.1% formic acid and 0.01% heptafluorobutyric acid in water) and eluent B (0.1% formic acid and 0.01% heptafluorobutyric acid in methanol) was applied. The gradient profile was the following: from 2% to 40% of B from 0 till 6 min, maintained at 40% of B for 4 min, then increased to 90% of B till 11 min and held at 90% of B for 1 min. After 12 min the gradient decreased to 2% of B. From 13 to 18 min the mobile phase composition was unaltered. The injection volume was set at 2 µL. The mass spectrometer operated in positive ionisation mode with the following parameters: entrance potential, 10 V; declustering potential, 30 V and collision cell exit potential, 5 V. Collision energy of 30 eV was applied with the exception of cystathionine, cysteine, homocysteine, argininosuccinic acid, hydroxylysine, lysine, and ornithine (50 V). Scheduled multiple reaction monitoring mode was used with nitrogen as a collision gas. Data acquisition and processing were performed using the Analyst 1.5 software.	Mann-Whitney U test, Student’s t-test, Welch’s F test, ROC curve analysis, PLS-DA, Shapiro-Wilk test	1-methylhistidine, 3-methylhistidine, Alanine, arginine, argininosuccinic acid, asparagine, aspartic acid, citrulline, carnosine, 39 metabolites	In PCa samples, taurine was present at significant higher level, while γ-amino- The PLS-DA model built on selected metabolites achieved sensitivity and specificity of 89.47% and 73.33%, respectively, whereas the total group membership classification value was 82.35%.
[40]	Aggio et al. (2015)	73 with haematuria and poor stream without cancer/58 PCa; 24 BC	Urine collection: before PBs Storage temperature: −20 °C Headspace creation: samples were defrosted in water bath at 60 °C for 30 s, mixed with 0.75 mL of 1 M sodium hydroxide, reimmersed in water bath at 60 °C for 50 min EN analysis: 2 cm3 of headspace were extracted and analysed	Hybrid GC-MOS sensor system: It is composed of a gas chromatography (GC) oven fitted with a commercially available capillary column interfaced to a heated (450 °C) metal oxide sensor (MOS chemresistor composite of tin oxide and zinc oxide 50:50 by wt). The injection port of the GC was fitted with a 1 mm quartz linear and heated to 150 °C. Cylinder air at 35 psi was used as carrier gas. The temperature program was: 30 °C held for 6 min, up to 100 °C at 5 °C/min, hold 100 °C for 22 min. Volatile organic compounds (VOCs) exiting the GC column reach the MOS sensor, which resistance was recorded.	LOOCV; DoubleCV; SVM-P; Monte Carlo permutation	none	LOOCV: sensitivity 95%, specificity 96%; DoubleCV: sensitivity 87%, specificity 99%; SVM-P: sensitivity with respect to BC 78%; Monte Carlo permutation: chance-like accuracy 50%