Application of a screening method for cyanobacterial toxins in natural samples S. Hiller

(1)

Application of a screening method for cyanobacterial toxins in natural samples

S. Hiller

¹

, B. Krock

²

, A. Cembella

²

, B. Luckas

¹

1Friedrich Schiller University, Institute of Nutrition, D-07743 Jena, Germany

2Alfred Wegener Institute for Polar and Marine Research, Dpt. Ecological Chemistry, D-27570 Bremerhaven, Germany

bernd.luckas@uni-jena.de

Introduction

Cyanobacterial toxins as microcystins (MCs), nodularins (NODs), Paralytic Shellfish Poisoning (PSP) toxins, anatoxins (ANAs), and cylindrospermopsins (CYNs) with over 100 known varieties, occur worldwide associated with human and animal lethal poisoning.

In contrast to all analytical methods for toxin determination are based on LC/MS-MS measurements with Multiple Reaction Monitoring (MRM) the application of Precursor Ion mode allows the coverage of all these structural variants. Although in MRM mode enables a higher sensitivity, a lot of information regarding structural changes is missed. The new generation of Q- TRAPs combines the advantages of quadrupoles having a high selectivity with the high sensitivity of ion-trap systems.

Here we published results, showing the suitability of Precursor Ion mode for detection of cyanobacterial toxins extracted from phytoplankton.

Material and Methods

Lyophilised phytoplankton samples of Aphanizomenon flos-aquae[Fig 1], Lyngbya wollei[Fig 2], Nodularia spumigena[Fig 3] and Microcystis aeruginosa [Fig 4] were extracted with a methanol - 0.1 M acetic acid (1:1) solution using ultrasonic bath and ultrasonic stick. An HPLC system equipped with Agilent 1100 series components was applied for the separation. LC/MS- MS experiments were performed using a 4000 Q Trap (ABI Sciex, Darmstadt, Germany) equipped with a turbo ion-spray source. The chromatographic separation was carried out with a Luna column (3 µm, 150 mm x 3.0 mm; Phenomenex, USA) using two eluents containing 50 mM formic acid and 2 mM ammonia formate in water (eluent A) or methanol / water (95/5, eluent B) and gradient elution.

Based on the retention times [Table 1], three time periods with different detection modes and parameters [Table 2-5] were generated for the different toxin classes. Only PSP toxins were detected in MRM mode, due to no known daughter ion usable in Precursor Ion mode. For ANAs, CYNs, MCs and NODs a fragment characteristic for each toxin group was utilized to analyse the compounds in Precursor Ion mode [Table 1].

tRRetention time; LOD: S/N = 3

Conclusions

It could be shown, that a qualitative screening method using Precursor Ion mode is well suited for detection cyanobacterial toxin variants, which allows a very rapid screening of putatively toxic cyanobacterial samples of uncertain taxonomic composition and unknown toxin profile.

period 1 period 2 period 3

Toxin tR(min)

mass transition

(m/z) LOD

(pg) Toxin tR(min) Precursor ion (m/z)

LOD

(pg) Toxin tR(min) Precursor ion (m/z)

LOD (pg)

NEO 1.4 316 > 298 1.0 ANA 5.2 91.0 700 MC-RR 12.3 135.0 20

dcSTX 1.4 257 > 239 9.0 CYN 5.4 194.0 9 MC-YR 14.9 135.0 15

STX 1.4 300 > 282 10.0 MC-LR 15.5 135.0 15

B 1 1.5 380 > 300 3.0 MC-LA 19.7 135.0 18

dcGTX 2/3 1.6 353 > 273 25.0 MC-LW 21.0 135.0 100

GTX 2/3 1.6 396 > 316 12.0 MC-LF 22.0 135.0 100

GTX 1/4 1.7 412 > 332 6.0 NOD 14.6 135.0 6

doCYN 5.5 194.0 no standa

rd

Table 1: Retention times, MRMs, precursor ions and LOD of cyanobacterial toxins

40 eV DP:

35 eV CE:

15 L h^-1 CUR:

70 L h^-1 Gas 2:

50 L h^-1 Gas 1:

550 °C Temp.:

high level CAD:

5500 V IS:

400-550 amu scan range (m/z):

135.0 precursor ion (m/z):

[M+2H]²⁺

protonated ion:

Precursor Ion mode MS parameters

175 eV DP:

90 eV CE:

15 L h^-1 CUR:

70 L h^-1 Gas 2:

50 L h^-1 Gas 1:

550 °C Temp.:

high level CAD:

5500 V IS:

[M+H]⁺ protonated ion:

Precursor Ion mode MS parameters

80 eV DP:

50 eV CE:

25 L h^-1 CUR:

70 L h^-1 Gas 2:

50 L h^-1 Gas 1:

550 °C Temp.:

high level CAD:

5200 V IS:

[M+H]⁺ protonated ion:

Precursor Ion mode MS parameters Fig 1: MRM chromatogram of STX and NEO at tR1.43 min from Aphanizomenon flos-aquaeextract

Table 2: MS parameter for detection of PSP toxins

Fig 2: Precursor Ion spectrum of total run (a); of time period 2 (b) containing CYN at tR5.40 min and doCYN at t_R5.55 min; Precursor Ion chromatogram of doCYN (c) and CYN (d) from Lyngbya wolleiextract

Table 3: MS parameter for detection of CYNs

Fig 3: Precursor Ion spectrum of total run (a), of time period 3 with experiment for NODs containing dmNOD at t_R14.10 min and NOD at t_R14.76 min (b), Precursor Ion chromatogram of NOD (c) and dmNOD (d) from Nodularia spumigenaextract

Table 4: MS parameter for detection of NODs

Table 5: MS parameter for detection of MCs

Fig 4: Precursor Ion spectrum of total run (a); of time period 3 with experiment for MCs containing dmMC- LR at tR14.79 min and MC-YR at tR15.56 min (b); Precursor Ion chromatogram of dmMC-LR (c) and MC-YR (d) from Microcystis aeruginosaextract

40 eV DP:

30 eV CE:

25 L h^-1 CUR:

70 L h^-1 Gas 2:

50 L h^-1 Gas 1:

550 °C Temp.:

high level CAD:

5000 V IS:

NEO 316 / 298

STX 300 / 282

[M+H]⁺/ [M+H - H2O]⁺ transition:

MRM mode MS parameters

0 5 10 15 20 25 30

Intensity (cps)

0 5e+7 1e+8

m/z (amu)

350 375 400 425 450

0 5e+4 1e+5

Time (min)

3 4 5 6 7 8 9 10

0 5e+7 1e+8

0,0 2,5e+6

prec. of m/z 194

416.5 CYN

doCYN Time (min)

Intensity (cps)

400.4

Intensity (cps)

x 25

[M+H]⁺

[M+H]⁺ a)

b)

c)

d)

5.55

5.40

Intensity (cps)

0 10000

200000Tim e (m in) 5 10 15 20 25 30

Intensity (cps)

0,0 5,0e+5 1,0e+6 1,5e+6

0 2500 5000

Time (min)

0,0 0,5 1,0 1,5 2,0 2,5 3,0

0 5000 10000 15000

TIC MRM

300 > 282

316 > 298 NEO

STX 1.43

0 5 10 15 20 25 30

Intensity (cps)

0 1e+7 2e+7

m/z (amu)

400 450 500 550

0 2e+5 4e+5

Time (min)

10 15 20 25 30

0 5e+6 1e+7

0 1e+5 2e+5

prec. of m/z 135

dmMC-LR Time (min)

Intensity (cps)

492.2

Intensity (cps)

524.3 [M+2H]²⁺

MC-YR[M+2H]²⁺

a)

b)

c)

d)

14.79

15.56

0 5 10 15 20 25 30

Intensity (cps)

0 5e+7

m/z (amu)

800 810 820 830 840 850

0 5e+4 1e+5

Time (min)

10 15 20 25 30

0 5e+7

0,0 2,5e+6

prec. of m/z 135

dmNOD NOD Time (min)

Intensity (cps)

825.8

Intensity (cps)

x 20

826.8 827.8 811.9

812.8 813.8 [M+H]⁺

[M+H]⁺ a)

b)

c)

d)

14.76

14.10