Thermo Scientific iCE 3500 atomic absorption spectrometer

The iCE 3500 atomic absorption spectrometer allows simple analysis of cadmium in chocolate, while SOLAAR software enables easy method development.

The Graphite Furnace TeleVision (GFTV) capability of the iCE 3500 also aids method development as sample deposition and sample drying can be viewed in real time inside the cuvette. The method is detailed in an application note entitled ‘The Analysis of Cadmium in Chocolate by Graphite Furnace Atomic Absorption Spectrometry’, which is available to download at www.thermoscientific.com/App-Note-43034.

Cadmium is a heavy metal used in a number of applications, including the production of batteries, steel plating and as a pigment in plastics and glasses. These industrial activities can release cadmium into the environment where it accumulates in water and soil and enters plants, animals and fish through uptake and ingestion. As a result, humans can be exposed to cadmium through the consumption of foodstuffs. This poses health risks as excessive cadmium consumption can cause nausea, gastrointestinal pain, softening of bones and kidney damage.

The main ingredients in chocolate include milk, cocoa and fats, and each is a potential source of cadmium, so chocolate samples should be analysed accurately to ensure consumer safety. The provisional tolerable weekly intake (PTWI) of cadmium is 7 µg/kg body weight. The recommendation, however, is to limit cadmium intake as much as possible because it offers no nutritional benefit. Typical maximum levels of cadmium in foodstuffs are currently between 0.05 and 0.2 mg/kg wet weight.

Samples were analysed following a simple digestion procedure and matrix matched standards were used to accurately determine cadmium concentration. The unique GFTV enabled easy optimisation of the position of the injection capillary and allowed visualisation of the deposition of the sample into the cuvette, ensuring accuracy and repeatability. In addition, the wizard-driven SOLAAR software enabled quick and easy furnace optimisation and method development. Experimental results revealed that cadmium was accurately detected in all analysed chocolate samples at concentration levels well below recommended limits for cadmium in foodstuffs.