Heavy Metals Contamination Analysis

Heavy metals are a group of metallic chemical elements with relatively high density. They are poisonous or toxic even at low concentrations. The common heavy metals include arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and lead (Pb).

Figure 1. Foods associated with heavy metals contamination

Heavy meals are natural components and widely exist on the earth. They cannot be destroyed or degraded and remain in the environment for hundreds of years. They can enter human bodies through food, air and drinking water.

The presence of heavy metals in foods has become an ongoing issue for food safety. The contamination of heavy metals in foods can come from different sources, resulting in a wide range of food contamination by heavy metals including fish products and plant products. The major contributions to the heavy metal contamination are from the soil that foods grow, chemical fertilizers and pesticides used in agriculture and the use of other materials. Heavy metals can also bioaccumulate in the food chain. So fish is one of the food products that are most affected by heavy metal contamination, especially mercury. Some other foods such as fruits and vegetables, cereals and nuts may also be associated with the heavy metal contamination.

Heavy metals are harmful to the health of general public. Since heavy metals cannot be biologically or chemically degraded, the danger of heavy metals to humans is more serious. They have negative effects on the metabolism of human bodies. Mercury and lead have toxic effects on the neuro system. Arsenic can cause skin and lungs cancer.

The European Commission specified the maximum levels for different heavy metals in a variety types of foods. The contamination limits of lead range from 0.02 mg/kg for milk products to 3.0 mg/kg for food supplements. The limits for cadmium range from 0.05 mg/kg for vegetables and fruits to 3.0 mg/kg for food supplements. The contamination limits of mercury range from 0.5 mg/kg for fish products to 1.0 mg/kg for other food products. U.S. EPA also established allowable limits for cadmium as 1.0 mg/L, lead as 5.0 mg/L and mercury as 0.2 mg/L.

The procedure for the analysis of heavy metals in foods includes sample preparation and digestion, reconstitution, and detection/quantification. We have expertise in the sample preparation of a variety types of food matrices. The sample preparation has significant effect on the accuracy of the level measured in the food samples.

We offer accurate and validated analytical methods for both identification and quantification that have been widely applied in the determination of different heavy metals in food and water samples to meet customers' needs.

Inductively coupled plasma mass spectrometry (ICP-MS)

ICP-MS is a commonly used method for elemental analysis. It can be used to detect different heavy metals at trace amounts with high sensitivity. The limit of detection is typically at levels of milligram to nanogram per liter. It allows for the simultaneous analysis of various elements in one run to obtain comprehensive information.

We also maintain high quality assurance for the analysis. The recovery of internal standard, the use of blanks and spikes is monitored for each batch of analysis.