When exporting grain and grain co-products there are a variety of hurdles and regulations to navigate. Phytosanitary requirements can vary not only by the product but the country of origin and destination. All export shipments require inspection by FGIS (Federal Grain Inspection Service) in order to obtain an official Phytosanitary Certificate, but additional quality parameters above and beyond the minimum requirements in particular for chemical contaminants are often requested. SGS provides analysis for all categories of contaminants using official methods that are widely accepted across the globe.
Mycotoxins: Although total Aflatoxins in corn is the only grain requiring testing by USDA/GIPSA*, mycotoxins are the most commonly required contaminants across a variety of products.
- Corn and co-products (such as DDG): Aflatoxins (B1, B2, G1, G2), Fumonisins B1 and B2, Deoxynivalenol (Vomitoxin), and Zearalenone
- Soybean and products: Aflatoxins ((B1, B2, G1, G2)
- Wheat, Barley, Oats and their products: Deoxynivalenol (Vomitoxin), Zearalenone, and Ochratoxin A, (also ergot).
- Rice and by-products: Zearalenone, Fumonisins B1 and B2, and Aflatoxins (B1, B2, G1, G2)
- Cottonseed, nuts, sorghum, and products: Aflatoxins (B1, B2, G1, G2)
*Ergot, found in cereals in grasses also has maximum levels allowed by USDA/GIPSA
Analysis methods for mycotoxins are diverse ranging from qualitative visual exam with a black light to highly sensitive LC/MSMS. Laboratory analysis for official quantitation generally falls in some category of chromatography (LC, GC, or TLC).
Pesticide Residues: The requirement of pesticide residue testing continues to grow on many products as people continue to become more aware of chemical contaminants in our environment. Pesticides are particularly diverse group which vary widely in their usage and application by geographic region. Common categories of pesticides requiring testing are listed below. The individual compounds within each group and the Maximum Residue Limit (MRL) allowed varies widely and should be confirmed for the specific commodity, country of origin and country of destination.
- Organophosphorus (OP) insecticides act as nerve agents by inhibiting acetylcholinesterase irreversibly although they degrade rapidly when exposed to sunlight, air, and water. These compounds work not only on insects but also animals and have been largely removed from household products due to their acute toxicity but are still widely used in agricultural applications.
- Organochlorine (OC) insecticides once widely used worldwide have largely been banned due to their acute toxicity, slow degradation, and bioaccumulation. Like OP’s, OC’s also act as nerve agents but as stimulants.
- Carbamates and methyl carbamates like OP’s inhibit acetylcholinesterase but by a different mechanism that is transient in mammals but toxic against a wide range of insects making them a popular option for insect control. They are also used as fungicides.
- Dithiocarbamates although related in chemical structure to carbamates have very different neuropathy and are primarily used as fungicides.
- Diquat and paraquat are non-selective herbicides that are widely used for weed control in some countries including the US. Both are also highly toxic to all animals and therefore has restricted use in the US and although paraquat was briefly approved for use in the EU in 2004 was banned again in 2007.
- Glyphosate a broad spectrum systemic herbicide which inhibits amino acid synthesis in plants. Glyphosate does not affect amino acid synthesis in mammals and breaks down rapidly in the environment to aminomethylphosphonic acid (AMPA) therefore little there is little direct impact to human and animal food safety from residue. Although may be required in residue test, most controversy centers on its role in affecting biodiversity, and the emerging threat of glyphosate resistance in weeds.
Analysis of pesticides is traditionally done by GC with MS or element specific detector (such as NPD or FPD) and HPLC methods. Advances in both GC/MSMS and LC/MSMS have resulted in development of more sensitive detection along with large multi-residue screens that span across the different pesticide classes.
Veterinary Drug Residues: Antimicrobials have been a hot topic as resistant strains of microbes have become serious threats to humans. Antimicrobials use solely for growth promotion has been banned in many countries and legislation governing more prudent use of antimicrobials for legitimate therapeutic use continues to be enacted. Like other chemicals veterinary drugs are categorized by chemical structure and activity.
|Beta-lactams||penicillin, amoxicillin, ceftiofur, cephapirin||Inhibits cell wall systhesis in bacteria|
|Fluoroquinolones||enrofloxacin, danofloxacin||Inhibit DNA synthesis in bacteria|
|Sulfonamides||sulfadimethoxine||interferes with metabolic process in bacteria|
|Phenicol||florfenicol||Inhibits protein systhesis in bacteria|
|Lincosamides||lincomycin, clindamycin, pirlimycin|
|Nitrofurans||furazolidone (AOZ), furaltadone (AMOZ)||damage bacterial DNA|
Methods for detecting drug residues generally fall into two categories: Bioassays or instrumental methods. Instrumental methods (GC and HPLC) are most commonly used for routine analysis and are generally preferred over bioassays due to higher specificity and sensitivity.
Heavy Metal Residues: As countries become more industrialized there are increasing levels of metals dispersed from their natural deposits. There are 60 metals that are considered “Heavy” metals (density > 5g/cm3) but only a few have been identified as having high potential as hazards toward humans.
- Lead: produced by industrial production processes and their emissions, and historically from leaded gasoline emissions. Lead accumulates overtime so chronic exposure is of particular concern.
- Cadmium: Naturally exist in all soil and also produced by industrial production processes and their emissions. Like lead it accumulates so chronic exposure is again the primary concern.
- Mercury: Mercury is generally introduced in the environment in its inorganic form from mining and other industrial activities. Previous to 1970 mercuric compounds were also used as pesticides and disinfectants but have been banned in most countries. In aquatic systems is converted to the organic methylmercury form which can accumulate over time making it a concern in fish and fishmeal. All forms of mercury are toxic to animals. Most importantly to human health consumption of contaminated fish can results in serious central nervous system defects in developing fetus’ and young children.
- Arsenic: Is not a true heavy metal, but highly toxic metal. Produced by chemical processing plants, but more importantly contained in a number of feed additives/antimicrobials that are used to increase weight gain and improve meat appearance in poultry and swine. Arsenic is a potent carcinogen.
Heavy metals, like normal minerals are analyzed by spectrophotometry. Methodology ranges from simple AAS to newer, more sensitive techniques like ICP-MS.
Melamine: Melamine is a nitrogen rich, organic base that has been around since the 1930’s when it was widely used in plastics and laminates to create stylish dinnerware. Melamine and other related analogs (cyanuric acid, ammeline, ammelide) have numerous other industrial uses as in glues, polymers, and fire retardants. Because of its nitrogen rich chemical structure its also been used as an adulterant in a number of cases. By adding melamine to feed and food products, the added nitrogen will artificially elevate the protein levels in standard laboratory testing. In 2007 a Chinese melamine product labeled as wheat gluten and rice protein was used by a Canadian company in their petfood products resulting in thousands of pets deaths. In 2008 it was again found, but this time in infant formula. Although melamine is not directly toxic, when ingested it collects in the kidneys renal microtubules and crystallizes, damaging them and leading to kidney failure. Although there are numerous methods available, official methods from the FDA for testing of melamine and its analogs utilize LC/MSMS. ELISA kits similar to the kits available for mycotoxins are also useful tools for screening of products.
Gas Chromatograph - GC
High Performance Liquid Chromatograph - HPLC or simply LC
Mass spectrophotometry – MS, Tandem MS – MSMS
Flame photometric detector – FPD
Nitrogen-phosphorus detector - NPD
Thin Layer Chromatography – TLC
Enzyme Linked Immunoabsorbent Assay – ELISA
Inductively Coupled Plasma – Mass Spectrometry - ICP-MS
Atomic Absorption Spectrophotometry - AAS
Analytical Lab Manager
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