Dicyandiamide (DCD) Contamination Analysis

Dicyandiamide (scientific name: cyanoguanidine) is a dimer of cyanamide. It is a white crystalline and soluble in alcohol and water with no color.

Figure 1. Chemical structure of DCD and related food products

Dicyandiamide has been widely used in the production of melamine as an intermediate. It is also the basic ingredient to produce resins and plastics which has a wide range of industrial uses.

Dicyandiamide was reported to be unexpectedly detected in low levels in some dairy products from New Zealand. Dicyandiamide is often used to reduce the negative effects of leaching of nitrate to waters and greenhouse gas emission on farm land. Dicyandiamide has been used to improve the growth of pastures for cows grazing. It is also used in the formulation of fertilizer in order to slow down the release of nitrogen source. The dicyandiamide residue can remain in milk products when they are on pastures when dicyandiamide has been applied. The trace dicyandiamide detected in milk products were found to be associated with the grass that contaminated by dicyandiamide from fertilizers. Animals can produce milk with trace dicyandiamide after eating the contaminated grass. In addition, dicyandiamide is a nitrogen-rich compound like melamine and may be a potential economic food adulterant in foods to artificially enhance the protein content of food products.

Dicyandiamide has lower toxicity compared with other chemical contaminants in foods. Large amount of dicyandiamide can also be toxic.

There are currently no standards that has been set for the level of dicyandiamide contamination in foods and no agreed safe limit for dicyandiamide in foods. The manufactures of dicyandiamide have voluntarily minimized their sales to the chemical use on the farm. The European Commission has published a recommendation on the acceptable daily intake for dicyandiamide. Based on the record of the highest level of dicyandiamide contamination in foods, the daily intake was set as 1kg milk powder/kg of body weight per day. The discovery of this chemical residue has become a concern in the dairy products.

The procedure for the analysis of dicyandiamide in foods includes the sample preparation and extraction, clean-ups, and detection/quantification. We control sample preparation factors and have extensive steps for sample clean-up step. 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 that have been widely applied in the determination of dicyandiamide in food samples to meet customers' needs.

Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS)

LC-MS/MS is a fast, sensitive and relatively easy method for the analysis of dicyandiamide in milk products and other protein-rich foods. The limit of quantification typically can in the range of μg/kg. The minimal sample preparation is needed allowing maximum throughput for the analysis of many samples in a short period of time.

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.