Short-term studies and conclusions

When instability is detected at an earlier stage of the study the material has to be maintained in adequate conditions. In addition, a short-term stability study has to be performed to monitor the behaviour of the material during transport under possibly increased temperature conditions. Short-term and drastic transport conditions may be reproduced by storing the material under temperatures up to 40-45°C for 10 days. This covers the maximum real time transport duration (normal surface transportation for all major European laboratories customer of BCR). The study is performed as above for the long term stability by comparative measurements. 

Stability remains a difficult aspect of the production of CRMs, in particular matrix materials for environmental monitoring. Feasibility studies devoted to the stabilisation of the material must be conducted before any production starts. New materials, such as fresh materials, required by analysts increase the problem of 

Lagarde, M.B. Amran, M.J.F. Leroy, C. Demesmay, M. Olle, A. Lamotte, H. Muntau, P. Michel, P. Thomas, S. Caroli, E. Larsen, P. Bonner, G. Rauret, M. Foulkes, A. Howard, B. Griepink and E.A. Maier, Fresenius J. Anal. Chem. 363 (1999) 5. 

Rauret, J. Alberti and G. Rauret, Intern. J. Environ. Anal. Chem., 52 (1993) 203. 

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