The Analysis of Disinfection By-Products in Drinking Water
Gavin Mills Principal Scientist [email protected] 6th February 2014
Content
2
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
3
Regulated water company – division of Severn Trent plc
Chemical Analysis in Severn Trent Water
4
STW – Chemistry Laboratory, Bridgend
Drinking Water Regulations
5
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
6
THMs – headspace GCMS
PAHS – HPLC fluorescence
Unknowns – GCMS.......
Pesticides – GCMS, GCQQQ, LCMS, LCQQQ, LC-HRMS
Techniques Employed (Triple Quadrupole)QQQ
7
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
9
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”
10
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
11
Analysis of THMs – Analytical Quality Control
12
Analysis of THMs – Online Monitoring
13
Online monitoring can reduce costs by minimisation of additional treatment processes
Bromate
14
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
15
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
16
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
17
Confirmation of positive results from single quad GCMS
Confirmation of NDMA in sample @ 4.6 ng/l
Other DBPs
18
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
19
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
20
Specificity and sensitivity of GCQQQ allows for reduced sample volumes & automation
ITSP GCQQQ
21
Automation of sample prep
ITSP GCQQQ
22
Duplicate analyses - 2,3 dichlorophenol and 2,4-dichlorophenol
Other DBPs – “Unknowns”
23
“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
24
Odour port & GCMS
ARISTOT & “Twister” Research carried out by Veolia P Roche & D Benanou
Summary
25
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