Levels of heavy metals and particularly toxic metals in pharmaceutical and food products are under increasing scrutiny by regulatory bodies such as the European Medicines Agency. Closed Vessel Microwave digestion prepared samples can be analysed by Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) or Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) to give reliable detection results at a parts per billion level.
As analytical techniques get more sensitive, regulatory bodies are able to set lower drug impurity levels. Barbara Mason, European operations manager, Warwick Analytical Service, the analytical division of Exeter Analytical (UK), looks at the ever moving limits.
Heavy metals, toxic metals, trace metals, trace elements, minerals and micro-minerals are all terms that are used interchangeably to describe a group of elements, some of which are essential for biological activity, some of which are toxic at any level and all of which are toxic to some degree.
One definition of ‘heavy metals’ refers to the block of metals belonging to Groups 3 to 16 of the periodic table in periods 4 or greater. Another states that they are metallic elements with a high molecular weight and a density much greater (>5 times) than water. Other definitions rely on various chemical and toxicological properties. In short, there are many definitions for ‘heavy metals’, none of which is derived from an authoritative body.1
The natural background levels of metals are generally controlled by the geological characteristics of their environment, with some being naturally of higher abundance, such as aluminium and iron, compared with mercury or silver. These rarer metals are known collectively as trace metals.2
Some 4% of the human body’s composition is mineral and there are a number of opinions as to how many are essential (cannot be synthesised by the body and must be obtained from food), although there are a number about which there is no debate. These are the macro elements where >100mg/day is required, and the trace elements of which much lower quantities are required.3,4. . .
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