Chromatographic Analysis of Environmental and Food Toxicants

Takayuki Shibamoto

• Editore: CRC Press
• Anno: 2021
• ISBN:
  9781000447736
• Edizione: 1
• Argomento: Ciencias físicas
• Categoria: Química

Shows how to choose the most effective techniques for assessing the toxicity of chemicals in both food and the environment. examines a wide range of volatile compounds from toxic aldehydes and pesticides to micotoxins and dioxins.

1 Polycyclic Aromatic Hydrocarbons

KENNETH G. FURTON
AND GRETCHEN PENTZKE
Florida International University, Miami, Florida

I. INTRODUCTION

In this chapter, we survey some of the numerous methods available for the chromatographic analysis of PAHs and highlight some of the recent advances. We discuss only chromatographic and related techniques and do not cover methodology focusing on the distribution, biotransformation, flux, and spectroscopic properties of PAHs. The analysis techniques have been grouped into sample preparation (including new extraction techniques and hyphenated techniques), supercritical fluid chromatography and extraction, gas chromatography, liquid chromatography, and miscellaneous techniques including thin layer chromatography and micellar electrokinetic capillary chromatography. Readers are referred to more comprehensive publications, if more thorough background material or historical information is required [1,2], including a recent review of air sampling and analysis of PAHs [3], PAHs comprise the largest class of known chemical carcinogens and are produced during the combustion, pyrolysis, and pyrosynthesis of organic matter. PAHs are ubiquitous in air, water, soil, and food, and their accurate identification and determination continues to be an important analytical problem. In fact, PAHs are even present in outer space and are probably more abundant than all other known interstellar polyatomic molecules combined [4], It has been suggested that interstellar PAHs on meteorites may represent the starting material for the synthesis of complex molecules including amino acids [5] and primitive pigments in the prebiotic environment [6]. Readers interested in the subject of interstellar PAHs are referred to Ref. 7.

The earliest reports of the carcinogenic properties of PAHs were made by Percival Pott in 1775 based on studies of combustion products such as soot [8], The first identification of a specific chemical carcinogen was made by Kennaway and Hieger in 1930 who identified dibenz(a,h)anthracene as the first chemical recognized to have carcinogenic activity [9], Samples typically contain an extremely complex mixture of many different PAHs including isomers, alkylated, and nonalkylated forms of PAHs. The structures of the 16 PAHs identified as priority pollutants by the EPA are shown in Figure 1 and include the first carcinogenic PAH isolated, dibenz(a,h)anthracene. By far, a person’s greatest exposure to carcinogenic PAHs in the environment comes from food. The average estimated intake of carcinogenic PAHs by nonsmokers in the US is 1-5 fxg/day with 96.2% coming from food, 1.9% from soil, 1.6% from air, and 0.2% from water [10], Smokers increase their exposure to carcinogenic PAHs 2-5 fig/day per pack of cigarettes smoked. Additional exposure can also come from occupational environments, cosmetics applied to the skin, and asphalic materials applied to roofs or driveways. The estimated potential doses of carcinogenic PAHs from water, soil, air, and food are shown in Figure 2, and the median concentrations and ranges of PAHs in environmental media are given in Table 1 [10], Exposure risks are greatest from surface waters, indoor air with smokers, and urban soil/road dust. Foods with the greatest average PAH levels tend to be charcoal broiled or smoked meats, green leafy vegetables, and fats and oils, as seen in Figure 3. The average dietary intake of PAHs in Finland is reported to be approximately 18 p.g/day, with the greatest levels found in samples collected from industrialized areas where large-scale manufacturing industries employ fossil fuels [11].

The cooking mode as well as cooking time has been shown to affect greatly the levels of PAHs in foods, as seen in Table 2 [12]. The levels of PAHs increased from pressure cooker to microwave to pan frying and again with cooking time, as seen in Table 2 for the production of benzo[a]pyrene in mutton and chicken as a function of pan frying time. Additionally, many deep-fried South Indian food dishes, particularly those deeply charred, showed high quantities of PAHs and were suggested to play a role in the high incidence of gastric cancers in South India [13]. Although charbroiled and smoked meats generally have the highest reported levels of PAHs, there may be methods to reduce these levels. The use of a vertical barbecue where fat drips away sufficiently distant from the heat source during grilling to prevent its pyrolysis resulted in 10-30 times lower PAHs levels, as shown in Table 3 for sardines [14]. The use of liquid smoke flavors has been

FIGURE 1 Structures of the 16 PAHs identified as priority pollutants by the US EPA.

FIGURE 2 Maximum potential doses of carcinogenic PAHs from water, soil, air, and food.

Table 1 Carcinogenic PAH Concentrations in Environmental Media

Media	Median concentration	Concentration range
Ground water	1.2 ng/L	0.2-6.9
Drinking water	2.8 ng/L	0.1-62
Surface water	8.0 ng/L	0.1-830
Outdoor air	5.7 ng/m^3	0.2-65
Indoor air in homes (Ohio)	8 ng/m^3	0.6-29
Homes with tobacco smoke	13 ng/m^3	7-29
Rural soil	0.07 mg/kg	0.01-1.3
Urban soil	1.10 mg/kg	0.6-5.8
Road dust	137.0 mg/kg	8-336

Source: Data from Ref. 10.

demonstrated to lower PAH concentrations by two orders compared to traditional smoking, possibly due to the sorption process of PAHs into polyethylene packaging materials [15]. Recently, PAH concentrations of 91 p,g/kg in liquid smoke flavor filled into low density polyethylene bottles were observed to decrease to zero in 164 hours, offering a potential solution to the problems caused by the presence of PAHs in foods or food additives [16]. The mutagenicity of wood smoke condensates typically experienced by people in developing nations has been shown to be more mutagenic than cigarette smoke condensate, depending on the type of wood and combustion conditions and allowing for the possibility of minimizing exposure to the more carcinogenic PAHs by careful selection of wood combinations and combustion conditions [17], Gas-fire drying of wheat grain does not appear to increase PAH levels [18].

The mechanisms of action of food-associated PAH carcinogens have become clearer recently, and it appears that they require metabolism to dihydrodiol epoxide metabolites in order to express their biological activities. Each PAHreactive metabolite is unique in its interactions with cells but as sufficient to shif...