The Analysis of Disinfection By-Products in Drinking Water

Gavin Mills Principal Scientist Gavin.mills@severntrent.co.uk 6th February 2014

Content

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Introduction to Drinking Water Analysis

Regulatory monitoring of DBPs

Techniques used in routine analysis

More advanced techniques and potential interest in DBPs in the future

Severn Trent Water

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Regulated water company – division of Severn Trent plc

Chemical Analysis in Severn Trent Water

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STW – Chemistry Laboratory, Bridgend

Drinking Water Regulations

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The Water Supply (Water Quality) Regulations 2000 (England & Wales)

Enforcement by Drinking Water Inspectorate (DWI)

Monitoring of Water Supplies as stated in part V of the regulations and specifically Regulation 16 i.e. “Collection and Analysis of Samples”

Prescribed concentrations or values for a range of physical, chemical and microbiological parameters

Techniques Employed - Organics

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THMs – headspace GCMS

PAHS – HPLC fluorescence

Unknowns – GCMS.......

Pesticides – GCMS, GCQQQ, LCMS, LCQQQ, LC-HRMS

Techniques Employed (Triple Quadrupole)QQQ

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Quad Mass Filter (Q3) Quad Mass Filter (Q1)

Collision Cell

Spectrum with background ions

170 210 250 290

210

222

268 280 165

Q1 lets only target ion 210 pass through

190 210

210

Collision cell breaks ion 210 apart

150 170 190 210

210 158

191

Q3 monitors only characteristic fragments 158 and 191 from ion 210 for quant and qual.

160

158

190

191

no chemical background

Drinking Water Regulations - DBPs

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Trihalomethanes THMs

Bromate

Any other DBPs of interest or that may affect the “wholesomeness” of drinking water

CHCl3 Chloroform CHBrCl2 Bromodichloromethane CHBr2Cl Dibromochloromethane CHBr3 Bromoform

BrO3-

NDMA Nitrosodimethylamine Chlorite, Chlorate – Disinfection with Chlorine Dioxide Halophenols, Haloanisoles, Haloacetonitriles etc.

Trihalomethanes - THMs

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PCV (Prescribed Concentration or Value) in Drinking Water of 100 mg/l Total THMs

CHCl3 Chloromethane CHBrCl2 Bromodichloromethane CHBr2Cl Dibromochloromethane CHBr3 Bromomethane

Formed by chlorination of organic matter – humic acids, NOM

Problems with PCV in various locations, times of the year, raw water types

Water companies seek to minimise THMs formation whilst maintaining disinfection – e.g., Reduction in THM formation potential(Optimisation of coagulation, MIEX, Electro-osmosis etc), blending raw water, chloramination.....

Analysis of THMs – Headspace GCMS “Dual Rail”

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Syringe on left spikes samples with standards, AQCs and internal standard.

15 ml de-chlorinated sample and approx 3g NaCl matrix modifier added to headspace vials

Syringe on the right - headspace

Analysis of THMs

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Analysis of THMs – Analytical Quality Control

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Analysis of THMs – Online Monitoring

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Online monitoring can reduce costs by minimisation of additional treatment processes

Bromate

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Bromate formed by ozone treatment of raw water containing bromide - 10 mg/l PCV

Analysis by anion exchange chromatography – bromate, bromide, chlorite, chlorate

BrO3- Detection by post-column derivatisation and uv

Br- ClO2

- ClO3- Detection by conductivity

NDMA

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N-Nitroso dimethylamine, CAS No 62-75-9

DBP linked to chloramination

By product of ozonolysis of water containing certain pesticides

Present in certain foods and industrial waste – may be found in raw water

Linked to contaminated coagulants

Action taken at various levels in drinking water 1, 10 and 200 ng/l

NDMA

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Small molecule, water soluble & subject to interference by GCMS

Alternate approaches include GCMSMS, GCMSMS (-ve CI), LCMSMS and automation of sample preparation

10.40 10.60 10.80 11.00 11.20 11.40 11.600

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

Time-->

Abundance

Ion 74.00 (73.70 to 74.70): NDMA10.D\DATASIM.MS

NDMA in Brecon

10 ng/l

Ion 80.00 (79.70 to 80.70): NDMA10.D\DATASIM.MS

30 35 40 45 50 55 60 65 70 75 80 85 90 950

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

60000

65000

70000

75000

80000

85000

90000

95000

m/z-->

Abundance

Average of 6.411 to 6.441 min.: T9A9017.D (-)42 74

4044

5938 804648 76 8653 936735 63 69 8450 88 9655

NDMA - GCQQQ

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Confirmation of positive results from single quad GCMS

Confirmation of NDMA in sample @ 4.6 ng/l

Other DBPs

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Haloacetics acids – HAAs

Other GCMS amenable DBPS determined in full scan analysis:

Determination by GCMS following derivatisation (pentafluorobenzoyl derivatives or methyl esters). Alternatively by IC, ICMSMS etc...

1,1-dichloro-2-propanone Dichloroacetonitrile Dibromoacetonitrile

Other DBPs

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Halophenols, anisoles. Included with the analysis of other “tasty” compounds such as geosmin, MIB etc

11.35 11.40 11.45 11.50 11.55 11.60 11.65 11.70 11.75 11.80 11.85 11.90 11.95

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

320

340

360

380

Time-->

Abundance

Ion 252.00 (251.70 to 252.70): TASTE012.D\data.ms

11.643|

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Ion 250.00 (249.70 to 250.70): TASTE012.D\data.ms

GCMS detection 2,6-dibromophenol @ 6.2 ng/l

Automation of Halophenols Analysis – ITSP GCQQQ

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Specificity and sensitivity of GCQQQ allows for reduced sample volumes & automation

ITSP GCQQQ

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Automation of sample prep

ITSP GCQQQ

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Duplicate analyses - 2,3 dichlorophenol and 2,4-dichlorophenol

Other DBPs – “Unknowns”

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“Routine” unknown not present in the NIST library and is a suspected brominated disinfection by-product

Candidate for further investigation by GC-QTOF ?

Other Taste & Odour Detection Technologies

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Odour port & GCMS

ARISTOT & “Twister” Research carried out by Veolia P Roche & D Benanou

Summary

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DBPs are routinely monitored by water companies for the purposes of compliance monitoring and also to assess wholesomeness

Analytical methods have been developed to allow high throughput with minimal sample preparation

The use of highly selective and sensitive techniques is increasing in order to detect low level contaminants in raw water as well as treated drinking water

Technologies are improving that allow the identification of “unknown” DBPs