Comparisons of real versus synthetic proficiency testing items

Both real and synthetic materials are regularly used by providers of external quality assessment and proficiency testing schemes, and there are, in most cases, justifiable reasons for the choice made. This article focusses on the field of clinical biochemistry and discusses the different properties of a material and the benefits and limitations of using real or synthetic material. However, the overarching principles should be able to be applied to all sectors within the laboratory. Whilst genuine/real material would appear to be the preferred matrix, this is not always practicable, and synthetic material may be a suitable alternative. Synthetic material covers a wide range of material, be it that the material is 100% artificial to real material being used as a ‘base’ item, which is manipulated either by the addition of further real material from a different source or by the addition of exogenous analyte. A number of real-life cases are presented to demonstrate the impact of material matrix, storage conditions, volume, and interferences.