Processing contaminants are generated during the processing cycle of a product. They are formed when a chemical reaction takes place between the food and processing (e.g. disinfection, fermentation, heating, canning, or grilling). Examples of these contaminants include acrylamide, PAHs, oxyhalides, and haloacetic acids.

Pork contaminated with polychlorinated biphenyls (PCBs) has been discovered in Ireland. Allegedly, an animal feed manufacturer dumped machine oil containing PCBs into the foodstuff, which was supplied to 10 pig farms. PCBs accumulated in the animal tissue, contaminating the meat.

Before they were banned in most countries, PCBs were used in numerous industrial and commercial applications including electronics, plastics, rubber, dyes, lubricants, and many others. PCBs are persistent environmental pollutants that are both toxic and carcinogenic to humans and animals. Government agencies, universities, contract laboratories, and businesses can simplify the extraction of PCB’s from meat by using the Dionex Accelerated Solvent Extraction (ASE^®) systems. With an ASE system, PCBs can be extracted from meat samples or other foodstuffs in minutes, using only a fraction of the solvent required by other methods.

Application

AN 359: Extraction of Contaminants, Pollutants, and Poisons from Animal Tissue Using Accelerated Solvent Extraction (ASE)

Acrylamide is a genotoxic compound found in fried or baked goods. It is produced when asparagine reacts with reducing sugars such as fructose or glucose, or carbonyl compounds. Browning while cooking and overcooking can produce acylamide. The acrylamide content in some samples such as hash browns or French fries can be particularly high, as much as several mg/kg. 

Sample preparation methods for acrylamide determination often use multiple cleanup steps, such as liquid extraction, centrifugation, and solid-phase extraction (SPE). Automated extraction using an ASE^® system decreases the time, labor, and solvent required to prepare samples for analysis. Acrylamide can be separated using ion-exclusion chromatography or reversed-phase LC, and determined by UV or mass spectrometric detection.

Acrylamide extracted from potato chips using an ASE system. Sample extract was separated using the IonPac^® ICE-AS1 column and determined using UV detection.

Mass spectrometry can be used to detect far lower levels of acrylamide in extracts from foods.

Acrylamide extracted from a crisp bread sample using an ASE system. Sample extract was separated using ion-exclusion chromatography and determined using ESI+ MS detection.

Polycyclic Aromatic Hydrocarbons in Edible Oils

Numerous polycyclic aromatic hydrocarbons (PAHs) are carcinogenic, making their presence in foods and the environment a health concern. PAHs occur in charbroiled and dried foods, and may form in edible oils by pyrolytic processes, such as incomplete combustion of organic substances. PAHs in foods can also result from environmental contamination.

Oils are difficult to analyze, because the matrix quickly clogs columns and equipment. Most methods for PAH determination in oils require complex liquid-liquid extractions, cleanup columns, evaporation, and/or solid-phase extraction (SPE). These manual steps are time, labor, and solvent intensive. The dual capabilities of the UltiMate^® 3000 system allow automation of SPE and matrix elimination, greatly reducing the effort and resources required to analyze these carcinogens while increasing the recovery and reproducibility of the method.

Overlay of chromatograms of seven serial injections of an olive oil sample spiked with a PAH standard mixture (20 µg/kg): The method is highly reproducible.

Oxyhalides and Bromate in Bottled Water

In the United States, bottled water safety is regulated by the US FDA. Bottled water must be disinfected to remove pathogenic microorganisms and ensure it is safe for human consumption. Ozone is favored by bottlers because it does not remain in the water and leaves no taste, but it can react with naturally occurring bromide to produce bromate, a suspected carcinogen. Chlorination of drinking water can produce trihalomethanes, haloacetic acids, and chlorate. While chlorine dioxide treatment generates the inorganic oxyhalide DBPs chlorite and chlorate, and the presence of chloramine has also been known to generate chlorate.

Chromatogram of mineral water A spiked with 1 µg/L each chlorite and chlorate and 0.5 µg/L bromate, separated using the high capacity IonPac AS19 column.

Drinking water often has high concentrations of common anions, such as chloride, nitrate, and sulfate, which can overload columns and mask trace-level contaminants. Bottled mineral waters have even higher ionic strength matrices. Dionex high-capacity columns and dual IC capabilities make determinations of very low levels of contaminants in high strength matrices routine.