Heavy Metals Analysis in Food

Heavy metals are high-density metallic elements that are often toxic to humans in low quantities. It may seem alarming, then, that the metals are present in small quantities in soils all over the world, either through natural deposition or pollution. While dozens of heavy metals can pose harm to consumers, the four most common contaminants are: arsenic, mercury, cadmium and lead. Even in miniscule quantities, all four can lead to concerning health consequences. ARSENIC Health effects Short term Vomiting Abdominal pain Diarrhea Long term Skin lesions Cancers (in the skin, bladder and lungs) LEAD Health effects Short term Convulsions Long term Coma Anemia Hypertension Renal impairment Lower attention span MERCURY Health effects Short term Tremors and insomnia Memory loss Headaches Long term Skin corrosion Damage to gastrointestinal tract BIG FOUR The CERTAIN CROPS, CERTAIN METALS RICE Prone to absorbing arsenic LETTUCE AND ONIONS Accumulate lead more readily SPINACH AND CARROTS have a weakness for cadmium CADMIUM Health effects Short term Chills Fever Muscle pain Long term Cancer Kidney, bone and lung diseases Naturally, there is more to heavy metal analysis than just six easy steps. Rigorous testing requires rigorous training, particularly given ICP-MS’s lower detection capabilities and potential for contamination from multiple lab sources. So, to ensure that the final data are an accurate reflection of the material being sampled, analysts must be suitably trained with the knowledge and expertise to be working in the ultra-trace element environment. Heavy metals can be identified and quantified using several different methods, including flame atomic absorption spectrometry, inductively coupled plasma atomic absorption spectroscopy and graphite furnace atomic absorption spectrometry. But, if they have the money to buy the equipment, labs tend to use inductively coupled plasma mass spectrometry (ICP-MS) because, unlike some other techniques, it can test for multiple metals at once from low sample volumes. HEAVY METALS How to test for SAMPLE PREPARATION ANALYSIS 1 2 3 4 5 6 The food sample is ground up and weighed. The sample is transferred into a microwave digestion vessel. Acids (such as nitric acid) are added, and the vessel is heated and pressurized to aid the breakdown. The vial is then placed into the auto-sampler of an ICP-MS The vessel is placed into a microwave digestor. The sample is then transferred to another vessel and diluted to a fixed volume with deionized water before it is introduced into the ICP-MS for analysis. The more you know All sample matrices must be completely dissolved before undergoing mass spectrometry analysis. The more you know Within the ICP-MS equipment, the liquid sample is pumped through a nebulizer to create an aerosol, which is then introduced into an argon gas plasma. The high temperature of the plasma (~5500-6500 K) is sufficient to atomize and ionize almost all elements in the periodic table. The analyte ions can then be detected and quantified by the mass spectrometer. The whole process can be done in less than five minutes! The more you know A microwave digester excites water molecules to break sample materials apart. The added nitric acid also helps to speed up this digestion process. What is left is a blend of decomposed food material and highly solubilized metal ions with uniform oxidation states, now suitable for analysis. These metallic elements can become a problem when that soil is used to grow crops. On the off chance that a plant has absorbed dangerous amounts of heavy metals – or a livestock animal has consumed such a plant – food suppliers in the US test their products before they hit the shelves to ensure they are safe to eat and comply with US Food and Drug Administration (FDA) regulations. Which heavy metals do they look for, and how do they carry out such tests? Read on to find out more. 74.922 112.411 200.59 33 | As 82 | Pb 48 | Cd 80 | Hg 207.2 Sample Solution Drain Spray Chamber and Nebulizer Signal Conversion Cones Ar Ar Load Torch Coil Vacuum Pumps Detector Quadrupole Lens Solution introduction system Inductively coupled plasma Interface Mass spectrometer