Advances in the Identification of Tastes and Odours in. Drinking Water. Gavin Mills CChem FRSC Principal Scientist

Transcription

1 Advances in the Identification of Tastes and Odours in Drinking Water Gavin Mills CChem FRSC Principal Scientist 3 rd March 2017

2 Content Taste & Odour Determination in Regulatory Drinking Water Analysis Techniques used in Organics Analysis Application of GCMS, including GC-QTOF with ITSP & ODP Case studies Summary and further work 2

3 Severn Trent Water Regulated water company division of Severn Trent plc 3

4 Monitoring & Analytical Services STW Chemistry Laboratory, Bridgend 4

5 Drinking Water Regulations 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 Taste and Odour is a regulatory parameter. 5

6 Taste & Odour Panel 5 Panellists perform qualitative analysis 6

7 Sensory Standards ALMOND (CYANIDE) AMMONIACAL BITTER CHEMICAL CHLORINE DAIRY DECAYED VEG DISINFECTANT EARTHY FARMY FRUITY GAS METALLIC MUSTY OILY PENCIL PETROL PLASTIC POLISH OR CLEANING FLUID RUBBER SALINE RUBBER SALINE SEWAGE SILAGE (DMS) SOAPY SOLVENT SOUR SULPHUR SWEET TCP VEGETATION 7 What about quantitative chemical analysis?

8 Techniques Employed - Organics GCMS single quad SIM/scan Headspace GCMS 5975 MSD and dual rail MPS GCQQQ & ITSP 7000C system 8

9 Techniques Employed - Organics LCQQQ e.g LC-HRAM 9

10 GCMS Liquid/Liquid extraction and full scan GCMS for determination of unknowns & quantitative screen Targeted SIM analysis for tasty substances such as geosmin, MIB, halophenols/anisoles etc. Abundance Ion ( to ): TASTE003.D\data.ms Ion (97.00 to 98.00): TASTE003.D\data.ms Ion ( to ): TASTE003.D\data.ms ng/l Geosmin Time-->

11 GCMS Typical T&O Problems e.g. Petrol Abundance TIC: SCAN_003.D\data.ms 5e e+07 4e+07 TIC Total Ion Chromatogram 3.5e+07 3e+07 Abundance Scan 1529 ( min): SCAN_003.D\data.ms e e e e+07 m/z--> Time--> Abundance Time--> Ion ( to ): SCAN_003.D\data.ms Ion ( to ): SCAN_003.D\data.ms Many components in petrol include substituted benzene & naphthalene Extracted Ion Chromatogram m/z 120 &

12 GCMS Typical T&O Problems e.g. Petrol 12

13 GCMS & In-house Database Substance CAS No Potential Source Comment 2-t-butyl-5-methyl-1-4 benzoquinone Plastic Pipe Leachate "Pencil Shavings" taste phenol Unknown 1-Hexanol, 2-ethyl Plastic Pipe Leachate Precursor to plasticizers. PVC-C pipes 1-octanol Plastic Pipe Leachate PE-Xb pipes - also Fragrance 7-octen-2-ol, 2,6-dimethyl Unknown Fragrance Phenol, 2-(1-methylethyl) Unknown Fragrance Phenol, 4-(1-methylethyl) Unknown Fragrance Benzothiazole Unknown On Norman list (fragrance) Propanoic acid, 2-methyl-, 2,2-dimethyl-1-(2-hydroxy Unknown Texanol A (acrylic paints?) 1-methylethyl)propyl ester Propanoic acid, 2-methyl-,3-hydroxy-2,4, Unknown Texanol B (acrylic paints?) trimethylpentyl ester Benzophenone Unknown Norman list (Personal Care Product) Cyclopentaneacetic acid, 3-oxo-2-pentyl, methyl ester Unknown Known as methyl jasmonate (a fragrance) - on Norman list etc... In-house database of compounds detected by GCMS with flags if associated with a known issue such as taste & odour provides added information to WQ & Public Health & Standards to identify genuine problems 13

14 Automated Prep & Analysis - ITSP GCQQQ Automation of sample prep 14

15 ITSP & GCQQQ 15

16 ITSP & GCQQQ in Routine Production Calibration up to 500 ng/l (10 ng/l standard highlighted) 1.3 ng/l metaldehyde in raw water 16

17 Supplementary Techniques Odour port (ODP), linked to chromatograph to produce olfactogram ARISTOT & Twister Research carried out by Veolia P Roche & D Benanou 17

18 GC QTOF Agilent 7200 Sensitivity and selectivity of the QTOF enables simultaneous determination of unknowns and targeted compounds. High Resolution and Accurate mass of Q-TOF provides additional identification capabilities 18

19 GC QTOF Single Quad (Unit mass) ToF M Resolution = Mass/ Mass =100/0.01 =10,000 Mass Accuracy= (Measured Mass- Theoretical)/ (Theoretical / ) = ( )/( / ) = 5 ppm Typical MS Resolution High Low

20 GC-GTOF Nominal mass extracted ion Calculated s/n 15.9 Accurate mass (20ppm) extracted ion Calculated s/n 58.8 Detection of vanillin (4-Hydroxy-3-methoxybenzaldehyde) 20

21 The Ultimate! ITSP, GC-QTOF & ODP ITSP automation of sample preparation GC QTOF sensitive, selective detection of target compounds and identification of unknowns ODP flagging of compounds that may produce a taint in drinking water and worthy of further investigation 21

22 GC QTOF Initial work with targeted analytes 10 mg/l (in extract) 2-chlorophenol 22

23 GC QTOF Initial work with targeted analytes 10 mg/l (in extract) 2-bromophenol 23

24 GC QTOF Initial work with targeted analytes 1 mg/l (in extract) 2-chlorophenol 24

25 GC QTOF Initial work with targeted analytes 25

26 GC QTOF Pencil taste compound 2-tert-butyl-5-methyl-1,4 benzoquinone C 11 H 14 O 2 CAS#: Breakdown product of santonox (4,4 -thiobis(6-t-butyl-m-cresol). CAS# :

27 GC QTOF Pencil taste compound 27

28 Pencil taste compound NIST Searching 28

29 Pencil taste compound NIST Searching 29 Exact Mass, (M+) C 12 H 18 0 = , fragments C 12 H 15 O= , C 9 H 11 O= :

30 Generation of Formula from MassHunter Empirical formula C 11 H 14 O 2 30

31 MS/MS 31

32 Floral Medicinal Sweet Floral Fruity Burnt Perfume Floral Green Acrid, acid Acrid, acid Perfume Burnt Pencils Woody Burnt Phenol Phenol, 2-(1-methylethyl)- Phenol, 3-(1-methylethyl)- 3,5-Diisopropylphenol Mono-2-ethylhexyl adipate Substituted Adipic acid Substituted Adipic acid Taints in Drinking Water from Flooring Material 32

33 Taints in Drinking Water from Flooring Material ,5-Diisopropylphenol C12H18 O Perceived to have pencil odour in extract OH tert-butyl-5-methyl-1,4 benzoquinone C 11 H 14 O 2 CAS#: (mainlib) Phenol, 3,5-bis(1-methylethyl)- 33

34 EDD & EMD 2-Ethyl-5,5-dimethyl-1,3-dioxane (2-EDD) 2-Ethyl-4-methyl-1,3-dioxolane (2-EMD) 1992 New Jersey 1994 Wem Incident (Worcester) 2010 North East London See the following DWI report Objectionable taste and odour in water supplies in North-East London between January and March

35 cooked fruit, plum Strong, fruity, (sickly) EDD & EMD EDD EMD 35

36 EMD 2-ethyl-4-methyl-1,3-dioxolane (2EMD) CAS now present in NIST MS libraries 36

37 EDD 2-ethyl-5, 5 dimethyl-1,3-dioxane (2EDD) CAS not in NIST libraries and note loss of proton from molecular ion 37

38 EDD Formula C 8 H 16 O 2 mw (M ) 38

39 Summary Taste and Odour monitoring of drinking water is a regulatory requirement linked to acceptable wholesomeness of potable water Positive detections by customers, Quality Inspectors or the Taste Panel require chemical analysis to identify the cause and quantify taints Improvements in technologies in the area of organics analysis allows for low level determination of tasty compounds and identification of unknowns, with minimal sample preparation The ITSP GC QTOF with ODP provides the ultimate in the identification and detection of odiferous organic compounds in samples of drinking water 39

40 Acknowledgements Kathy Ridgway Dan Carrier Phine Banks Jeff Stubbs Adrian Thomas Alison MacArthur Roland Matthews Anatune Severn Trent Water 40