Heavy metal speciation: why and how?

Transcription

1 eavy metal speciation: why and how? Rikke V. edegaard, Erik. Larsen, Marianne ansen and Jens. J. Sloth National Food Institute (DTU Food) Technical University of Denmark

2 Today's agenda The National Food Institute Definition of speciation Toxicity and speciation Speciation and legislation (EFSA) Analytical methodologies for speciation Examples of speciation Projects: EN standard NffIDENE Developing of new methods speciation (PL- IPMS and SPE) Summary and onclusion

3 Total of 60 employees Externally funded research projects Research-based advise to authorities National reference lab for food analysis Mass spectrometry!! Pesticides Vet drug residues Biotoxins Bioactive compounds PPs Vitamins Trace elements

4 Speciation - definition (IUPA definition: Templeton et al., Pure and Appl. hem., 2000, 72, 143) hemical species: specific form of an element defined as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure. Speciation of an element: distribution of an element amongst defined chemical species in a system. Speciation analysis: analytical activities of identifying and/or measuring the quantities of one or more individual chemical species in a sample.

5 Speciation some historical milestones Fish arsenic (hapman 1926) a different (and non-toxic) compound than 2 3? Minamata, mercury, Japan (1950 ies) Meg + emissions from industry into fish man Archachon Bay, TBT, France (1980 ies) TBT from antifouling agents -> oysters EU Tematic network speciation 21 ( ) Participants from research, industry og authorities EVISA (European Virtual Institute for Speciation Analysis)(2003) Information and technology transfer in the framework of speciation See more info at the EVISA homepage:

6 Pollutants in formulated feed Fish meal eavy metals such as Mercury Arsenic Effect on Food safety Fish oil Dioxins Dioxin-like PBs Brominated flame retardant =PPs (Persistent rganic Pollutants) Vegetable meal GM ingredients (Gene Modified) Metals e.g. cadmium Vegetable oils Pesticides

7 Arsenic - occurrence Arsenic alchemical symbol igh concentrations of arsenic has been found in samples from the marine environment. Seawater 1-2 µg/l Marine fish 0,2 - >100 mg/kg Marine invertebrates 0,2 - >100 mg/kg Marine algae 0,02-40 mg/kg Freshwater fish <0,01-2 mg/kg Terrestrial biota <0,2 mg/kg All results on wet weight basis Marine organisms can bioaccumulate arsenic by a factor of up to compared with seawater!!!

8 Analysis of total content vs. speciation analysis Analysis of total concentration Aim: get information on e.g.: biological activity toxicity mobility bioavailability lifetime, fate and metabolism chemical and physical activity Arsenic Tin Mercury Lead hromium Selenium Iodine these characteristics are species related

9 Arsenic species in the marine environment (V) (III) MA DMA TMA TETRA A AB DMAA DMAE TMAP P 3 Dimethylarsinoylriboside -sugar 2 AB2 R (7) 3 + S 3 Dimethyl -sugar 4 N R (8) Trimethylarsonioriboside R R = 1,2,3,4,5 More than 50 different arsenic species have been found in the marine environment inclusive lipid-soluble compounds. P Dimethyl -sugar 1 Dimethyl -sugar 2 S 3 Dimethyl -sugar 3 Dimethyl -sugar 4 Me (5) (6) (7) S 3 N (8)

10 Arsenic compounds in the marine environment (V) (III) MA DMA TMA TETRA A More than 50 different arsenic species have been found in the marine environment AB DMAA DMAE TMAP 2 AB2 2 2 R R P 3 P 3 Dimethyl -sugar 1 Dimethyl -sugar 2 Dimethylarsinoylriboside -sugar 2 S 3 S 3 S 3 Dimethyl -sugar 3 Dimethyl -sugar 4 Dimethyl -sugar 4 Me (7) 3 + (5) (6) (7) Arsenous N R N acid Arsenic 3 acid (8) (8) (III) (V) R = 1,2,3,4,5 Trimethylarsonioriboside Inorganic arsenic

11 Arsenic compounds in the marine environment (V) (III) MA DMA TMA TETRA rganoarsenic compounds - trimethylated species 2 2 AB DMAA DMAE AB R More than 25 different 2 Arsenobetaine R TMAP P 3 arsenic Arsenocholine 3 2 species have been AB P 3 3 A found Dimethyl in -sugar the 1 marine + 2 Dimethyl -sugar 2 Dimethylarsinoylriboside -sugar 2 environment S 3 S 3 2 S 3 Dimethyl -sugar 3 Dimethyl -sugar 4 Dimethyl -sugar 4 Me (7) 3 + (5) (6) (7) Trimethylarsoniopropionic N R N acid 3 (8) TMAP (8) R = 1,2,3,4,5 Trimethylarsonioriboside More than 50 different arsenic species have been found in the marine environment + 2

12 Arsenic - toxicity Toxicity: (III) > (V) > TETRA > MA > DMA > A/AB Inorganic arsenic LD 50 - values (mg/kg) (III) (V) TETRA 890 MA DMA A 6500 AB >10000 Values for mice and rats Kaise & Fukui (1992); Shiomi (1994); Donohue & Abernathy (1999)

13 Arsenic chronic toxicity Long term exposure => skin diseases Keratosis, gangrene, melatosis Skin cancer and also lung, kidney, liver, bladder cancers ancer slope factor: 1.5 (mg kg -1 day -1 ) -1 (US EPA 2005) W PTWI for inorganic arsenic: 15 µg/kg bw/week (Provisional Tolerable Weekly Intake) For a 70 kg person => 150 µg / day

14 ommission Directive 2003/100/E on animal feed Max levels for total arsenic Footnote in the ommission directive

15 Total arsenic in fish feed products Sloth et al, Aquaculture Nutr., 2005, 11, % > ML Product N Median Mean SD Range omplete feedingstuffs omplete feedingstuffs Fish meal Fish meal % > ML Fish oils Results in mg kg -1 ML = 15 ML mg = 6 /kg mg /kg Marine feed omplete ingredients feedingstuffs

16 Inorganic arsenic in fish feed products Sloth et al, Aquaculture Nutr., 2005, 11, Product N Range % of total omplete Feedingstuffs Fish meal 10 All < 7 - Results in µg kg -1

17 Total arsenic in fish feed products Sloth et al, Aquaculture Nutr., 2005, 11, Product N Median Mean SD Range omplete Feedingstuffs Fish meal Fish oils Fish oils Results in mg kg -1

18 Sloth et al, J.Agric.Food hem., 2005, 53, Sample identification Inorganic arsenic Total arsenic Salmon (Salmo salar) < ± 0.2 od (Gadus morhua) < ± 2 od (Gadus morhua) < ± 2 Wolffish (Anarhichas lupus) < ± 0.5 Wolffish (Anarhichas lupus) < ± 4 Anglerfish (Lophius piscatorius) < ± 2 Fish muscle Anglerfish (Lophius piscatorius) < ± 6 Atlantic halibut (ippoglossus hippoglossus) < ± 1 Mackerel (Scomber scombrus) < ± 0.2 Mackerel (Scomber scombrus) < ± 0.4 erring (lupea harengus) < ± 0.2 erring (lupea harengus) < ± 0.2 erring (lupea harengus) < ± 0.2 Tuna fish (Thunnus alalunga) ± ± 0.1 Lobster, tail meat (omarus gammarus) < ± 2 Lobster, head and thorax meat (omarus gammarus) ± ± 3 rab, white meat (ancer pagurus) ± ± 4 rab, head and thorax meat (ancer pagurus) ± ± 3 King crab, white meat (Paralithodes camschaticus) ± ± 3 rustaceans & bivalves Norway lobster (Nephrops norvegicus) ± ± 3 Shrimp (Pandalus borealis) < ± 0.5 Shrimp (Pandalus borealis) < ± 8 Shrimp (Pandalus borealis) < ± 8 orse mussel (Modilous modiolus) ± ± 0.4 Scallop muscle (Pecten maximus) ± ± 0.3 yster (strea edulis) ± ± 0.2 Mink whale (Balaenoptera Acutorostrata) < ± 0.08 Marine mammals arp seal (Pagophilus groenlandicus) < ± 0.1 ooded seal (ystophora cristata) < ±0.03

19 Inorganic / mg kg Total = 13.8 mg/kg Inorg = 5.8 mg/kg Fraction = 42 % y = 0.51x R 2 = Data from 175 blue mussel (Mytilus edulis) samples collected along the Norwegian oastline in Total / mg kg -1 NRWAY Sloth and Julshamn 2008, J. Agri.Food hem.

20 Mercury speciation Sea water 0,005 µg/l (2% Meg) Effects the central nerve system Learning ability for children Bioaccumulation in the food chain Toxicity: Meg > inorganic g Biomethylation: Inorganic g -> Meg Plankton/algae 11 ppb (25% Meg) Zooplankton 11 ppb (25% Meg) Anchovy 40 ppb (90% Meg) Ref: Bjerregaard, 1988

21 Mercury accumulates in food chain Seafood Feral fish Industrial fish Fish meal + feed additives Fish feed Fish oil Farmed fish onsumer

22 Mercury intake from food Milk and milk products heese Icecream Bread and cereals Vegetables Fruit Meats Fish Poultry FIS Eggs Fats Sugar and condiments Beverages Spices Snacks 0,0 0,2 0,4 0,6 0,8 1,0 1,2 Intake, µg/day Data fra FVST/DFVF s overvågningssystem

23 Directive No (E) 2002/32 of the European Parliament and of the ouncil of 7 May 2002 on undesirable substances in animal feed. Feed materials -feedingstuffs of fish/marine animals 0.1 mg/kg 0.5 mg/kg Scientific ommittee on Animal Nutrition (SAN) in 2003 concluded that a more detailed risk assessment of the presence of mercury in animal feed and the possible effects for animal health and public health is necessary and that this detailed assessment should address the risks related to the organic forms of mercury. PTWI = 5 µg / kg bodyweight (Total g) PTWI = 1.6 µg/kg bodyweight (Meg)

24 There is a need for methods for future monitoring and control with heavy metals speciation for feed The demand is: Simplification of existing method Inexpensive instrumentation Semi-automated Robust Easy-to-use Applicable in routine control laboratories

25 Speciation analysis nline separation: PL IP-MS ff line separation: SPE-AAS Screening methods: Biosensors

26 PL-IPMS the speciation workhorse PL Sample introduction olumn Separation IPMS Element specific detection Result hromatogram Simple coupling from column outlet to IPMS PL flow rate 0,2-2 ml/min matches IP-MS demands Vintermøte Røros 2003

27 Analysis of inorganic arsenic by SPE-GAAS Microwave assisted hydrolysis: Freeze drying of sample (Addition of solvent) Microwave treatment 20 min, 90 in slightly acetic conditions and 2 2 I: Solubilisation of sample matrix II:onversion of (III) T (V) by 2 2 III: Insure no degradation of other arsenic species to (V) Adjust p of sample to p 6

28 Extraction of inorganic arsenic by SPE SAX (strong anionic exchange) 1. Wash of the column with methanol 2. ondition the cartridges with solvent 3. Addition of sample. Inorganic arsenic in the form of (V) is retained on the cartridges 4. Elute interferences from other arsenic species with acetic acid 5. Elution of inorganic arsenic as (V) with l (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) (V) ~ ther arsenic compounds

29 Solid phase extraction (SPE): Silica versus polymer % (V) standard retained on SPE 120,0 100,0 100 % retention with SAX Silica columns at p ~ 6 % retained 80,0 60,0 40,0 Polymer Silica 20,0 0, , p SPE column important only about 80 % retention on polymer based

30 PRE-REDUTIN AND DETETIN Electrically heated cell Prereduced to (III)

31 AAS compared to IP-MS Preliminary Results- not published Tort-2 (Lobster hepatopancreas) AAS (ppm) IP (ppm) 0,94 0,95 Blue mussel 0,38 0,37 Shrimp 0,22 0,20 - Detection limits AAS: below 0.2 ppm - ngoing test of several different marine matrices - In-house validation - ollaborative trial with 5-6 laboratories participation early Towards a European standard on 2011

32 Summary Total concentration of trace elements does not always provide adequate information on bioavailability and toxicity Speciation analysis is required PL- and G-IPMS are versatile tools for trace element speciation analysis Arsenic speciation analysis by PL-IPMS - inorganic arsenic is the most toxic form -Alternatively by SPE-G-AAS Mercury speciation analysis by G-IPMS/LP-IPMS - seafood are potential sources of exposure - Alternatively by SPE-G-AAS

33 Thanks for your attention!!!