Supplementary Materials

Effectiveness and intermediates of microcystin-LR degradation by UV/H2O2 via 265 nm ultraviolet light-emitting diodes

Juan Liu a, Jin-shao Ye a, b, Hua-se Ou *a, Jialing Lin a

a School of Environment, Guangzhou Key Laboratory of Environmental Exposure and

Health, and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan

University, Guangzhou 510632, China b Joint Genome Institute, Lawrence Berkeley National Laboratory, Walnut Creek 94598,

CA, USA

* Corresponding author.

Tel: +86 020 37278961

E-mail: [email protected]

1 SI Content Text S1 Chemical reagents………………...……………………………………….…………………...3 Text S2 Intermediate Screening Method……………………………………………………………...3 Text S3 Computational methods of MC-LR properties……………………………………….……...... 4 Fig. S1 Molecular structure of MC-LR…………………………………………………………….…6

Fig. S2 Control and UV-LED/H2O2 experiments of MC-LR.…………………………………………6 Fig. S3 Consecutive oxidation pathway of Mdha and the possible oxidized candidates of product A…7 Fig. S4 Isotope distribution, MS2 spectrum and possible molecular structure of product B…………...8 Fig. S5 Isotope distribution, MS2 spectrum and possible molecular structure of product C………...... 8 Fig. S6 Isotope distribution, MS2 spectrum and possible molecular structure of product D series……9 Fig. S7 Isotope distribution, MS2 spectrum and possible molecular structure of product E series…10 Fig. S8 Isotope distribution, MS2 spectrum and possible molecular structure of product F……11 Fig. S9 Isotope distribution, MS2 spectrum and possible molecular structure of product G……11 Fig. S10 Isotope distribution, MS2 spectrum and possible molecular structure of product H……12 Table S1 Operational parameters of tandem mass spectrometry………………………………………13 Table S2 CID energy and pairs used for TripleQuad 5500 MS2 system………………………………13 Table S3 Apparent rate constant and half-live of MC-LR...... 13 Table S4 Selected candidates of MC-LR intermediates from published literature……………………14 Table S5 Structure elucidation of stable intermediates……………………………………...... ……16 Table S6 MS2 ions observed in the spectrum of [MC-LR+2H]2+………………………………….…17

Table S7 EE/O values for 265 nm UV-LED/H2O2 systems.………………………………………..…18

2 Text S1 Chemical reagents

Crystal MC-LR (purity ≥ 95%, HPLC grade) was purchased from Enzo Life Sciences

(Switzerland) and stored at -20°C. HPLC grade acetonitrile and formic acid were purchased from Merck (Germany). Analytical grade ascorbic acid and H2O2 were purchased from Sinopharm (China). All reagents were used with received. All of the solutions were prepared using ultrapure water (electrical resistivity: 18.2 MΩ) produced by a Milli-Q Integral system (Millipore, USA).

Text S2 Intermediate Screening Method

In the current study, the targeted and non-targeted screening functions in PeakView and

MasterView were used for the identification intermediates. For the published intermediates, thirty-one possible candidates were selected based on the literature of photocatalysis/photolysis for MC-LR degradation (Table S4). The molecular formulas of these candidates were input into MasterView, and the software then automatically acquired the matching extracted ion chromatograms (EIC, presented as peak) from the sample data. For the unknown intermediates, a non-targeted peak finding function was applied to automatically acquire the possible EICs. Subsequently, a three-step screening of these two part EICs was conducted to distinguish between the impurities and true reaction intermediates of MC-LR.

In the first step, two “peak criteria” were used following ref. (Antoniou et al., 2008a).

The peaks of EICs which fulfilled the following two criteria, including (1) signal-to-noise ratio > 3 and (2) if the peaks appeared in the control samples, the difference between the peak areas (intensity) of the control and analyzed samples had to be at least two times, were selected to perform the second step. In the second step, comparisons of the mass

3 and isotope distribution between the candidates and EICs were conducted. The EICs that were highly consistent with the candidates (absolute mass error < 0.01 Da and difference ratio of isotope distribution < 10%) were selected for the third step.

The third step was the “structure elucidation” of the MS2 fragments. The possible molecular structure of an intermediate candidate was drawn using ChemBioDraw

(CambridgeSoft, UK) and was then transformed into a .mol file. This .mol file was imported into PeakView and linked with the relevant MS2 chromatography of EIC. The identification of the MS2 fragments was automatically conducted by PeakView, and a

Matching Score (MaS) was calculated (Table S5). MaS reflected the percentage of the intensity regarding the MS2 fragments, which can be directly matched with a given .mol file. Ultimately, eight candidates (the ones had MaS > 75%) were chosen, including five published intermediates and three novel ones (Table S5). Detailed information about the screening functions of PeakView and MasterView can be found at http://www.absciex.com/products/software/peakview-software and http://www.absciex.com/products/software/masterview-software.

Text S3 Computational methods of MC-LR properties

Briefly, the structures of MC-LR and OH• were drawn using ChemBioDraw and their three-dimensional models were created by ChemBio3D. Subsequently, their interaction was subjected to energy minimization by molecular mechanics until the root-mean-square gradient became smaller than 0.01 kcal mol–1 Å. To reveal MC-LR degradation by OH• at studied concentration, the molecular dynamics between 1 molecular MC-LR and 100 molecular OH• was calculated. The step interval, frame interval, terminate time,

4 heating/cooling rate and target temperature were 2.0 fs, 10 fs, 10000 steps, 1.0 Kcal atom–1 ps–1 and 300 Kelvin, respectively.

5 Fig. S1 Molecular structure of MC-LR

Fig. S2 Control and UV-LED/H2O2 experiments of MC-LR. Experimental conditions:

UV irradiating intensity 180 µW cm-2, solution volume 20 mL, solution temperature 25 ±

2°C, pH 6.8-7.2, [MC-LR]0 = 0.1 μM, [H2O2]0 = 100 μM. All the experiments were carried out in triplicate with error bars representing the standard error of the mean.

O OH O OH O OH O O O N N N HN NH HN NH HN NH OH O O O O O O O O O O O

R4 Mass: 994.5 Mass: 1010.5 R Mass: 1014.5 NH R4 4 R NH NH MC-LR 4 C49H74N10O13 R4 C48H74N10O14 R4 C49H74N10O12 m/ z = 1011.5 m/ z = 1015.5 O R m/ z = 995.5 O O 2 R2 R2

O OH O OH O OH O O O N N N HN HN NH NH HN NH OH OH OH OH O O O O O OH O O OH O O O O O O O O HN HN HN NH NH NH H H H H N N H H N N N N NH O NH O NH O O O O O O O H2N N HO O H2N N HO O H H2N N HO O H H Candidate 1030-1 Candidate 1030-2 Candidate 1030-3

6 Fig. S3 Consecutive oxidation pathway of Mdha and the possible oxidized candidates of product A. The intermediate with a m/z 1011.5 was identified as product

E2, and the intermediate with a m/z 1015.5 was not observed in the current study.

7 Spectrum from 20141218-7.wiff (sample 1) - 40min+AA, Experiment 3, +TOF MS^2 (100 - 1200) from 4.648 min Precursor: 428.2 Da, CE: 35.0 CE=35 100% 90% 599.3156 80%

) 470.2763 0

. 70% 2 8

f 60% o (

50% y t i

s 40% 112.0857 n

e 453.2351 542.2649 t 30% 470.2933

n 185.1234 300.1589 356.7113 I

20% % 10% 0% 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 Mass/Charge, Da

O OH O N HN NH OH O O O O O HN NH H H N N NH O O O H2N N HO O H Mass: 854.4 C36H 58N10O14 m/ z = 428.2 m/ z = 855.4 Fig. S4 Isotope distribution, MS2 spectrum and possible molecular structure of product B (MW = 854.4134 Da, RT = 4.648 min).

Spectrum from 20141218-4.wiff (sample 1) - 10min+AA, Experiment 1, +TOF MS (100 - 1200) from 4.250 to 4.289 min C33H54N10O14 +2H

408.1986 400

300 408.7014 y t i s n e

t 200 n I

100 409.1935

0 408.0 408.2 408.4 408.6 408.8 409.0 409.2 409.4 Mass/Charge, Da Spectrum from 20141218-4.wiff (sample 1) - 10min+AA, Experiment 7, +TOF MS^2 (100 - 1200) from 4.280 min Precursor: 408.2 Da, CE: 35.0 CE=35 100% 90% 301.1034 515.2962 80%

) 130.0508 0

. 70% 2 138.0555 8

o 302.1058 (

50% 127.0845 y t

i 184.1151 331.1692 470.2716 598.3285

s 40% n

e 286.1570 444.2503 t 30% 331.1886 516.3004 n I

20% % 598.3023 372.1329 571.3102 10% 0% 150 200 250 300 350 400 450 500 550 600 650 700 750 800 Mass/Charge, Da

8 O OH O N HN NH OH O O O O O HN NH H H N N NH O O O H2N N HO O H Mass: 814.4 C33H54N10O14 m/z = 408.2 m/z = 815.4 Fig. S5 Isotope distribution, MS2 spectrum and possible molecular structure of product C (MW = 814.3821 Da, RT = 4.280 min).

Spectrum from 20141218-4.wiff (sample 1) - 10min+AA, Experiment 1, +TOF MS (100 - 1200) from 5.945 to 5.984 min C49H76N10O14 +2H 3500 515.2839 3000

2500 y

t 2000 i 515.7850 s n e

t 1500 n I 1000 516.2853 500

0 515.1 515.2 515.3 515.4 515.5 515.6 515.7 515.8 515.9 516.0 516.1 516.2 516.3 516.4 Mass/Charge, Da

SP pectrumrecursor: from 515.3 20141218-4.wiffDa, CE: 35.0 (sampleCE=35 1) - 10min+AA, Experiment 4, +TOF MS^2 (100 -1200) from 5.970 min 100%1 35.0806 90% 895.4864

9 . 0 ) 70%80% 5 73.2973

f 4 9 60%

y ( o 50%

n s i t 40% 2 43.1339 496.3215 556.2676

I n t e 30% 1 61.0943 286.1512 5 93.3762 727.4128 877.4776 896.4839

% 10%20% 213.1346 3 03.1773339.2080416.2574499.2675 692.41067 59.4239 877.5042 878.4873 0 % 2 00 300 4 00 500 6 00 7 00 800 9 00 1000 M ass/Charge, Da O OH O OH O OH O O O N N N HN HN HN NH NH NH O O O OH O O O OH O O OH O O O OH O Type 1028-2 Type 1028-3 Type 1028-1 HN HN HN NH NH NH H OH H H OH H H H N N N N N N NH O NH O NH O O O O O O O HO O H2N N HO O H2N N H H2N N HO O H H Mass: 1028.5 Mass: 1028.5 Mass: 1028.5 C49H76N10O14 C49H76N10O14 C49H76N10O14 m/z = 515.3 m/z = 515.3 m/z = 515.3 m/ z = 1029.6 m/z = 1029.6 m/z = 1029.6 Fig. S6 Isotope distribution, MS2 spectrum and possible molecular structure of product D series (MW = 1028.5542 Da, RT = 5.970 min).

9 O OH O OH O O N N HN NH HN NH O O O O OH O O O O O Type 1010-2 Type 1010-1 HN HN NH H H NH N H H N N NH O N NH O O O O H2N N HO O O H H2N N HO O Mass: 1010.5 H Mass: 1010.5 C49H74N10O13 C49H74N10O13 m/ z = 506.3 m/z = 506.3 m/ z = 1011.6 m/ z = 1011.6 Fig. S7 Isotope distribution, MS2 spectrum and possible molecular structure of product E series (MW = 1010.5437 Da, RT = 5.813 min).

Spectrum from 20141218-4.wiff (sample 1) - 10min+AA, Experiment 1, +TOF MS (100 - 1200) from 4.386 to 4.424 min C37H58N10O12 +2H

418.2198 700

500 y t i

s 400 418.7218 n e t

n 300 I

0 418.1 418.2 418.3 418.4 418.5 418.6 418.7 418.8 418.9 419.0 419.1 419.2 419.3 419.4 Mass/Charge, Da Spectrum from 20141218-4.wiff (sample 1) - 10min+AA, Experiment 3, +TOF MS^2 (100 - 1200) from 4.447 min Precursor: 418.2 Da, CE: 35.0 CE=35 100% 90% 127.0866 522.2712 722.3509 80% 681.3565 ) 0

. 70% 157.1368 439.2319 568.2730 651.3066 1 6

f 60% 418.2212 540.2705 o 155.0791 213.0885

( 312.1607 623.3506 50% y

t 206.0917 456.2597 i 318.1825

n 276.1344 e

t 30% n

I 210.1306 723.3535 20% % 10% 764.4016 0% 150 200 250 300 350 400 450 500 550 600 650 700 750 800 Mass/Charge, Da O OH O N HN NH

O O O O HN NH H H N N NH O O O H2N N HO O H Mass: 834.4 C37H58N 10O12 m/ z = 418.2 m/ z = 835.4 Fig. S8 Isotope distribution, MS2 spectrum and possible molecular structure of product F (MW = 834.4235 Da, RT = 4.447 min).

10 Spectrum from 20141218-4.wiff (sample 1) - 10min+AA, Experiment 1, +TOF MS (100 - 1200) from 4.173 to 4.211 min C34H54N10O12 +2H 800 398.2046 700

500 y t i s

n 400 e t

n 398.7063

200 399.2027 100

0 398.1 398.2 398.3 398.4 398.5 398.6 398.7 398.8 398.9 399.0 399.1 399.2 399.3 399.4 Mass/Charge, Da Spectrum from 20141218-4.wiff (sample 1) - 10min+AA, Experiment 4, +TOF MS^2 (100 - 1200) from 4.178 min Precursor: 398.2 Da, CE: 35.0 CE=35 100% 127.0867 90% 80% ) 0

. 70% 2

8 157.1349 389.1967 682.3099

f 60% o

( 213.0861 528.2460 583.2882 641.3290 50% y 398.2095 t 583.3195 641.3064 i 353.1960 s 40% 151.0866 n

e 332.6521 464.2234 694.3548 t 30% 240.1471 399.1971 565.2712

n 209.0955

I 683.3331 20% % 10% 0% 150 200 250 300 350 400 450 500 550 600 650 700 750 Mass/Charge, Da O OH O N HN NH

O O O O HN NH H H N N NH O O O H2N N HO O H Mass: 794.4 C34H54N10O12 m/ z = 398.2 m/ z = 795.4 Fig. S9 Isotope distribution, MS2 spectrum and possible molecular structure of product G (MW = 794.3922 Da, RT = 4.178 min).

Spectrum from 20141218-4.wiff (sample 1) - 10min+AA, Experiment 4, +TOF MS^2 (100 - 1200) from 4.545 min Precursor: 392.2 Da, CE: 35.0 CE=35 100% 378.2053 ) 642.3235 0

. 80% 670.3221 2 0 112.0866 392.2042 626.3501 1

513.2786 f 60% o 161.0914

( 144.0639

510.2292 558.3027

y 303.1795 t 40% 157.1062 i

s 269.1302 378.7049 482.2384 595.3368 n 670.2881 e

t 213.1395 429.2160

n 20% 673.3765 I

% 0% 150 200 250 300 350 400 450 500 550 600 650 700 750 Mass/Charge, Da Spectrum from 20141218-4.wiff (sample 1) - 10min+AA, Experiment 1, +TOF MS (100 - 1200) from 4.559 to 4.598 min C33H54N10O12 +2H

800 392.2042 700

y 500 t i s

n 400 e t n

I 300 392.7053

100 393.2035 0 392.0 392.2 392.4 392.6 392.8 393.0 393.2 393.4 Mass/Charge, Da

11 O OH O N HN NH

O O O HO HN NH H H N N NH O O O H2N N HO O H Mass: 782.4 C33H 54N10O12 m/ z = 392.2 m/ z = 783.4 Fig. S10 Isotope distribution, MS2 spectrum and possible molecular structure of product H (MW = 782.3923 Da, RT = 4.545 min).

12 Table S1 Operational parameters of tandem mass spectrometry. Parameter (unit) TripleTOF 5600+ TripleQuad 5500 Ion source mode Positive Positive Scan mode Full scan MRM* ESI needle voltage (V) 3500 3500 Turbo-gas temperature (°C) 350 350 Curtain gas pressure (psi) 40 40 Nebulizer gas pressure (psi) 35 35 Auxiliary gas pressure (psi) 40 40 Declustering potential (V) 80 80 CID energy (eV) 40 ± 15 See in Table S2 *MRM: multi-reaction monitoring.

Table S2 CID energy and pairs used for TripleQuad 5500 MS2 system. Intermediates or MC-LR CID Energy (eV) Ion Pairs MC-LR 85 498.3/135.1 A 85 516.3/135.1 B 75 428.2/185.1 C 70 408.2/301.1 D 80 515.3/135.1 E 80 506.3/119.1 F 80 418.2/127.1 G 75 398.2/127.1 H 70 392.2/112.1

Table S3 Apparent rate constant and half-live of MC-LR. MC-LR initial concentration Confidence Observed rate constant Half-life (μg L-1) coefficient (min-1) (min) 100 0.9722 0.2077 3.3 500 0.9756 0.1567 4.4 1000 0.9965 0.0811 8.5 5000 0.9926 0.0663 10.5

13 Table S4 Selected candidates of MC-LR intermediates from published literature. No Formula m/z ([M+2H]2+/2) Reported literature .

1 C15H20O2 117.0804 (Su et al., 2013)

2 C15H20O3 125.0779 (Su et al., 2013)

3 C15H20O4 133.0754 (Su et al., 2013)

4 C16H24O6 157.0859 (Fotiou et al., 2013)

5 C17H32N6O6 209.1264 (Fotiou et al., 2013)

6 C20H33NO5 184.6252 (Fotiou et al., 2013)

7 C20H36N6O6 229.1421 (Fotiou et al., 2013)

8 C21H37N7O8 258.6425 (Fotiou et al., 2013)

9 C22H38N2O5 206.1463 (Fotiou et al., 2013)

10 C23H41N7O8 272.6581 (Fotiou et al., 2013)

11 C26H43N5O9 285.6603 (Yang et al., 2011)

12 C31H48N6O7 309.1865 (Liu et al., 2003)

13 C31H50N6O9 326.1892 (Liu et al., 2003) (Liu et al., 2003;

14 C33H54N10O12 392.2034 Antoniou et al., 2008a; Zong et al., 2013)

15 C34H54N10O12 398.2034 (Liu et al., 2003; Antoniou et al., 2008a;

14 Antoniou et al., 2008b; Zong et al., 2013) (Liu et al., 2003; 16 C34H54N10O13 406.2009 Fotiou et al., 2013)

17 C34H56N10O11 391.2138 (Fotiou et al., 2013)

18 C36H56N10O13 419.2087 (Fotiou et al., 2013) (Liu et al., 2003;

19 C37H58N10O12 418.2191 Antoniou et al., 2008a; Antoniou et al., 2008b) (Antoniou et al., 2008a; Antoniou et al., 20 C48H72N10O11 483.2764 2008b; Fotiou et al., 2013) (Liu et al., 2003; 21 C48H74N10O13 500.2791 Fotiou et al., 2013)

22 C48H74N10O14 508.2766 (Fotiou et al., 2013)

23 C48H75N11O11 491.7897 (Fotiou et al., 2013) (Antoniou et al.,

24 C49H72N10O13 505.2713 2008a; Antoniou et al., 2008b)

15 25 C49H74N10O12 498.2817 (Andersen et al., 2014) (Antoniou et al., 2008a; Antoniou et al., 26 C49H74N10O13 506.2791 2008b; Zong et al., 2013) (Antoniou et al.,

27 C49H74N10O14 514.2766 2008a; Antoniou et al., 2008b) (Liu et al., 2003;

28 C49H76N10O14 515.2844 Antoniou et al., 2008a; Antoniou et al., 2008b) (Fotiou et al., 2013; 29 C49H76N10O15 523.2819 Zong et al., 2013)

30 C49H78N10O14 516.2922 (Fotiou et al., 2013) (Antoniou et al., 2008a; Antoniou et al., 31 C49H78N10O16 532.2871 2008b; Zong et al., 2013)

16 Table S5 Structure elucidation of stable intermediates. Average Mass Average Isotope Identified Molecular Exact Extraction Mass(Da) Error Ratio Difference Name MaS (%) Fragment Formula Mass(Da) (×10-3 Da) (%) Number [M+H] + [M+2H]2+/2 [M+2H] 2+ [M+2H] 2+

MC-LR C49H74N10O12 994.5487 995.5560 498.2817 2.36 3.6 92.5 85

H C33H54N10O12 782.3923 783.3995 392.2034 0.86 2.8 77.2 27

G C34H54N10O12 794.3923 795.3995 398.2034 1.94 5.9 80.7 47

C C33H54N10O14* 814.3821 815.3894 408.1983 0.76 4.3 82.5 21

F C37H58N10O12 834.4236 835.4308 418.2191 1.34 3.7 86.8 51

B C36H58N10O14* 854.4134 855.4207 428.2140 5.12 7.7 88.3 12 E1 84.4 147 C49H74N10O13 1010.5437 1011.551 506.2791 0.34 6.1 E2 80.2 147 D1 93.0 90 D2 C49H76N10O14 1028.5542 1029.562 515.2844 -1.64 3.1 94.5 90 D3 93.4 90 A1 90.9 35 C48H74N10O15* 1030.5335 1031.541 516.2740 0.58 3.6 A2 90.9 35 MaS represents the Matching Score, which indicated the percentage of intensity in regard to MS2 fragments which can be directly matched with the given .mol file

(seen in Intermediate Screening Method).

The intermediates with “*” symbol were the novel ones that were observed for the first time in the current study.

17 2 2+ Table S6 MS ions observed in the spectrum of [MC-LR+2H] . m/z Intensity (%) Error (Da) Assigned molecular formula 862.487 + 32.29 0.005 [C42H68N7O12] 1 861.484 + 39.03 0.001 [C40H65N10O11] 4 850.449 + 5.28 0.033 [C43H64N9O9] 6 593.378 + 6.19 0.074 [C26H41N8O8] 2 570.337 + 9.03 0.001 [C24H44N9O7] 7 487.300 + 12.50 0.001 [C20H39N8O6] 4 482.270 6.16 -- -- 9 470.274 + 7.38 0.002 [C20H36N7O6] 3 303.178 + 11.29 0.001 [C11H23N6O4] 7 286.152 + 5.43 0.001 [C11H20N5O4] 6 265.159 9.43 -- -- 6 226.157 + 7.62 0.039 [C10H16N3O3] 5 213.087 + 19.04 0.002 [C9H13N2O4] 7 174.134 + 8.06 0.001 [C6H16N5O] 8 155.081 + 8.51 0.003 [C7H11N2O2] 8 135.079 + 100.00 0.001 [C9H11O] 9

18 127.086 + 17.74 0.005 [C6H11N2O] 6

+ 117.0699 9.50 0.015 [C5H9O3] 105.070 + 20.00 0.002 [C8H9] 2 103.054 + 40.75 0.001 [C8H7] 6 Only the top 20 fragments in intensity were presented. The intensity of m/z 135.0799 was set as

100.00, and the intensities of other fragments were normalized based on it. Two fragments cannot be assigned.

19 Table S7 EE/O values for 265 nm UV-LED/H2O2 systems. -1 3 MC-LR P (kW) kobs (h ) t (h) Pt (kWh) V (m ) EE/O-e EE/O-c EE/O concentratio n (μg L-1) 100 5.0 × 10-6 0.2077 0.18 9.24 × 10-7 2.0 × 10-5 0.00077 0.00371 0.00447 500 5.0 × 10-6 0.1567 0.24 1.22 × 10-6 2.0 × 10-5 0.00102 0.00371 0.00473 1000 5.0 × 10-6 0.0811 0.47 2.36 × 10-6 2.0 × 10-5 0.00197 0.00371 0.00568 5000 5.0 × 10-6 0.0663 0.58 2.89 × 10-6 2.0 × 10-5 0.00241 0.00371 0.00612  P is the total electrical power or flux entering the reactor (kW), t the time (h) and V the volume (m3) of water treated.

3  The unit of EE/O is kWh/m /order. EE/O-e is the cost associated with electricity consumption. EE/O-c is equivalent to the cost for H2O2 consumption, which is

regarded as part of electrical consumption. EE/O= EE/O-e + EE/O-c.

-3  The prices of electricity and H2O2 are $0.1/KWh and $2.18×10 /g, respectively (Tan et al., 2014).

References

Andersen, J., Han, C., O'Shea, K., Dionysiou, D.D., 2014. Revealing the degradation intermediates and pathways of visible light-induced NF-

TiO2 photocatalysis of microcystin-LR. Applied Catalysis B: Environmental 154, 259-266.

Antoniou, M.G., Shoemaker, J.A., Armah, A., Dionysiou, D.D., 2008a. LC/MS/MS structure elucidation of reaction intermediates formed during

the TiO2 photocatalysis of microcystin-LR. Toxicon 51, 1103-1118.

Antoniou, M.G., Shoemaker, J.A., Cruz, A.A.d.l., Dionysiou, D.D., 2008b. Unveiling new degradation intermediates/pathways from the

photocatalytic degradation of microcystin-LR. Environmental Science & Technology 42, 8877-8883.

20 Fotiou, T., Triantis, T.M., Kaloudis, T., Pastrana-Martínez, L.M., Likodimos, V., Falaras, P., Silva, A.n.M., Hiskia, A., 2013. Photocatalytic

degradation of microcystin-LR and off-odor compounds in water under UV-A and solar light with a nanostructured photocatalyst based on

reduced graphene oxide–TiO2 composite. Identification of intermediate products. Industrial & Engineering Chemistry Research 52, 13991-

14000.

Liu, I., Lawton, L.A., Robertson, P.K., 2003. Mechanistic studies of the photocatalytic oxidation of microcystin-LR: an investigation of

byproducts of the decomposition process. Environmental Science & Technology 37, 3214-3219.

Su, Y., Deng, Y., Du, Y., 2013. Alternative pathways for photocatalytic degradation of microcystin-LR revealed by TiO 2 nanotubes. Journal of

Molecular Catalysis A: Chemical 373, 18-24.

Tan, C., Gao, N., Zhou, S., Xiao, Y., Zhuang, Z., 2014. Kinetic study of acetaminophen degradation by UV-based advanced oxidation processes.

Chemical Engineering Journal 253, 229-236.

Yang, J., Chen, D., Deng, A., Huang, Y., Chen, C., 2011. Visible-light-driven photocatalytic degradation of microcystin-LR by Bi-doped TiO 2.

Research on Chemical Intermediates 37, 47-60.

Zong, W., Sun, F., Sun, X., 2013. Oxidation by-products formation of microcystin-LR exposed to UV/H2O2: Toward the generative mechanism

and biological toxicity. Water Research 47, 3211-3219.