**2. Arsenic content in food and beverages**

Arsenic is a chemically active, toxic, and carcinogenic element (Moore & Ramamoorthy, 1984). It is among the 129 priority pollutants of the environment and among the 25 hazardous substances representing a significant potential threat to human health (EPA: Toxic and priority pollutants). It occurs naturally in soil and groundwater, but additionally enters the environment in a large quantity because of the human industrial and agricultural activities. The most affected by arsenic pollution are fishes and other aquatic organisms, since they accumulate it. High arsenic concentrations in plants are registered when using for irrigation arsenic-rich groundwater or contaminated water because of the industrial discharges and the treatment of soils with fertilizers and pesticides. Lead arsenate insecticides were extensively used in some countries until 1981 (Peryea, 1998). Arsenic content in food from plant and animal origin, with the exceptions of seafood and animal and poultry offal, does not habitually exceed 0.25 mg kg-1, according to WHO data (Arsenic.

Lettuce, leaf, raw 0.002 Beef w/vegetables in sauce, from Chinese carry-out 0.004 Potato, baked (w/peel) 0.002 Chili con carne w/beans, canned 0.003 Quarter-pound hamburger on bun, fast-food 0.001 Meatloaf, beef, homemade 0.001 Chicken potpie, frozen, heated 0.001 Soup, tomato, canned, cond., prepared w/water 0.003 Cake, chocolate w/ icing 0.013 Sweet roll/Danish pastry 0.001 Gelatine dessert, any flavour 0.001 Wine, dry table, red/white 0.010 BF, beef and broth/gravy 0.001 BF, macaroni, tomato and beef 0.002 BF, peaches 0.001 BF, juice, apple 0.022 BF, vanilla custard/pudding 0.002 BF, fruit dessert/pudding 0.003 Chicken breast, oven-roasted (skin removed) 0.004 Shrimp, boiled 0.265 Bread, cracked wheat 0.003 Bagel, plain, toasted 0.001 English muffin, plain, toasted 0.001 Crackers, graham 0.004 Grape juice, frozen conc., reconstituted 0.007 Mushrooms, raw 0.073 Eggplant, fresh, peeled, boiled 0.001 Okra, fresh/frozen, boiled 0.001 Beef stroganoff w/noodles, homemade 0.012 Tuna noodle casserole, homemade 0.164 Fish sandwich on bun, fast-food 0.380 Egg, cheese, and ham on English muffin, fast-food 0.002 Clam chowder, New England, canned, cond., prepared w/ whole milk 0.128 Coffee, from ground 0.0002 BF, teething biscuits 0.004 Salmon, steaks/fillets, baked 0.288 BF, cereal, rice w/apples, dry, prepared w/water 0.033 Chicken breast, fried, fast-food (w/skin) 0.013 Chicken leg, fried, fast-food (w/skin) 0.013 Tuna, canned in water, drained 1.00 Cranberry juice cocktail, canned/bottled 0.004 Sweet potatoes, canned 0.001

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Table 1. Arsenic occurence in food (US Food & Drug Administration - Total Diet Study -

Market Baskets 2006-1 through 2008-4).

WHO Food Additives Series 18). The average daily arsenic intakes for various countries are summarized in Fig. 1. Arsenic concentration in food and beverages, as evaluated by the US Food and Drug Administration (FAD, 2010) in its annual Total Diet Study, is shown in Table 1.


WHO Food Additives Series 18). The average daily arsenic intakes for various countries are summarized in Fig. 1. Arsenic concentration in food and beverages, as evaluated by the US Food and Drug Administration (FAD, 2010) in its annual Total Diet Study, is shown in Table 1.

Cheese, American, processed 0.002 Beef roast, chuck, oven-roasted 0.001 Turkey breast, oven-roasted 0.004 Liver (beef/calf), pan-cooked w/oil 0.001 Fish sticks or patty, frozen, oven cooked 0.527 Peanut butter, creamy 0.013 Peanuts, dry roasted, salted 0.014 Rice, white, enriched, cooked 0.065 Oatmeal, plain, cooked 0.002 Cream of wheat (farina), enriched, cooked 0.001 Corn, fresh/frozen, boiled 0.001 Bread, white, enriched 0.001 Bread, whole wheat 0.002 Muffin, fruit or plain 0.007 Corn/tortilla chips 0.001 Fruit-flavoured cereal, presweetened 0.013 Raisin bran cereal 0.006 Crisped rice cereal 0.135 Granola w/raisins 0.021 Oat ring cereal 0.028 Pear, raw (w/peel) 0.001 Strawberries, raw/frozen 0.001 Fruit cocktail, canned in light syrup 0.002 Grapes (red/green), raw 0.003 Cantaloupe, raw/frozen 0.008 Raisins 0.014 Avocado, raw 0.001 Apple juice, bottled 0.005 Prune juice, bottled 0.004 Spinach, fresh/frozen, boiled 0.001 Collards, fresh/frozen, boiled 0.003 Tomato, raw 0.001 Tomato sauce, plain, bottled 0.001 Cucumber, peeled, raw 0.011 Brownie 0.006 Syrup, chocolate 0.001 Jelly, any flavour 0.002 BF, cereal, rice, dry, prepared w/water 0.041 Beef steak, loin/sirloin, broiled 0.001 Chicken thigh, oven-roasted (skin removed) 0.009 Catfish, pan-cooked w/oil 0.012 Fruit juice blend (100% juice), canned/bottled 0.005

**Product As, mg kg-1**


Table 1. Arsenic occurence in food (US Food & Drug Administration - Total Diet Study - Market Baskets 2006-1 through 2008-4).

fluorescence permit the determination of arsenic at trace levels, but they require expensive and sophisticated equipment. The spectrophotometric methods, although simple and cost

217

The electrochemical methods for inorganic arsenic determination (Cavicchioli et al., 2004), including mainly anodic stripping voltammetry and differential pulse polarography, in spite of their limited application in food quality control, could be considered as an alternative to the above mentioned analytical techniques. For instance, their sensitivity is similar to this of mass spectrometry and NAA, but they are much more simple, require low costing equipment, and allow distinguishing the electro-active As(III) and the electroinactive As(V), in contrast to the enumerated techniques. As(III) and As(V) have different toxicity, biological activity, and physiological action. The toxicity of As(III) is known to be greater of that of As(V). Thus, the distinction between the two forms is of primary

The further development of the electrochemical methods is associated with the appearance, during the 1960s, of the so-called electrochemical biosensors. They combine the high sensitivity, accuracy and reproducibility of the electrochemical analysis with the substrate specificity and catalytic activity of the biological molecules. A number of them found an application in food industry, namely in food safety and quality control, and in the control of the fermentation processes (Mutlu, 2010; Scott, 1998; Prodromidis & Karayannis, 2002;

Arsenic determination in wine, using the suggested in this work acetylcholinesterase

thiocholine → dithio-bis-choline + 2H+ + 2e-The acetylcholinesterase Ach (EC 3.1.1.7) catalysed hydrolysis of acetylcholine generates the electroactive product thiocholine. The current of its oxidation is recorded amperometrically at a potential of +0.80 V/SCE. In the presence of As(III), because of the enzyme inhibition that it provokes, the quantity of the produced thiocholine decreases. Thus, the current of its oxidation also decreases as a function of As(III) concentration under similar conditions. The acetylcholinesterase based electrochemical sensor was prepared as described in our previous works (Stoytcheva et al., 1998a, 1998b), i. e.: acetylcholinesterase was covalently immobilized onto the surface of a rotating disc electrode elaborated from spectrally pure graphite (Ringsdorf Werke, Germany). The analysis was carried out in an electrolysis cell of conventional type, at a temperature of 25oC, with a rotation speed of the working electrode of 1000 rpm. The auxiliary electrode was a glassy carbon electrode. A saturated calomel

The response of the biosensor was measured for various acetylthiocholine iodide concentrations in the presence of different amounts of As(III) in the form of AsO33- in a Britton-Robinson buffer solution with pH 7. The obtained results are presented in Fig. 2, where I is the difference between the registered steady-state currents of thiocholine oxidation in the absence and in the presence of inhibitor (to note that iodide oxidation to

thiocholine + CH3COOH

**5. Acylcholinesterase based sensor for arsenic determination in wine** 

electrochemical sensor, is based on the following reactions:

acetylthiocholine + H2O *ACh*

effective, do not provide the required sensitivity.

importance.

Wagner & Guilbault, 1994).

electrode was used as a reference.

iodine occurs, too).

Fig. 1. Average daily arsenic intakes for various countries (Arsenic. WHO Food Additives Series 18)
