Certified reference materials for electrolytes

International science service company LGC has produced four new certified reference materials (CRMs) containing creatinine and electrolytes in frozen human serum.

International science service company LGC has produced four new certified reference materials (CRMs) containing creatinine and electrolytes in frozen human serum in its capacity as the designated National Measurement Institute for chemical and biochemical analysis in the UK.

Available for sale as ERMs (European Reference Materials) from LGC Promochem, they are novel in that they are whole frozen serum materials.

Previously only freeze dried serum materials have been available containing these analytes.

LGC developed the CRMs in response to the demand from clinical laboratories that carry out the determination of creatinine in serum as an indicator of renal function.

The number of these determinations has increased markedly in the last few years.

Additionally, in April 2006, new legislation was introduced in the UK under which doctors are paid for all patients over the age of 55 to have their creatinine levels annually tested and monitored.

Measurements of electrolytes in human serum are usually carried out at the same time, as analysis of renal function significantly aids the interpretation of electrolyte measurements.

To be confident in the quality of the results of analysis of such samples, it is important to validate and monitor procedures using a CRM close in matrix composition to the test samples.

Two of LGC's new CRMs have been certified for creatinine and the electrolytes calcium, lithium, magnesium, potassium and sodium, and the remaining two have been certified for creatinine only, but indicative values for the electrolytes are also provided.

These materials are intended for use in validating methods, and for monitoring the performance of methods commonly used in clinical laboratories.

Dr John Marriott, LGC's Director of Analytical Technology, said: "Our new CRMs will help laboratories overcome the challenges of modern clinical analysis, by helping them achieve accurate and traceable measurements.

This is a confirmation of LGC's commitment to setting the standards in analytical science through innovation and provision of the highest quality products." These CRMs have been produced in collaboration with the University Hospital of Wales (UHW) and were prepared from two native human serum pools.

The pools were thoroughly mixed in different proportions to give four materials covering a range of clinically relevant creatinine and electrolyte levels, sterile filtered and 1 mL aliquots sub-sampled into plastic screw-cap 3 mL vials.

The materials were certified by LGC using isotope dilution mass spectrometry (IDMS) for creatinine, and a mixture of IDMS, ICP-MS and ICP-OES for the electrolytes.

The data were corroborated by measurements carried out by UHW and by data from the Wales External Quality Assessment Scheme (WEQAS), and were accepted as complying with the principles laid down in the Technical Guidelines of the European Reference Materials (ERM) co-operation agreement between BAM-LGC-IRMM.

Information on these guidelines is available at www.erm-crm.org.

The materials were produced by LGC under the DTI's Valid Analytical Measurement (VAM) programme.

LGC is accredited by UKAS to ISO Guide 34:2000 for the production of reference materials.

The materials are numbered ERM-DA250a and ERM-DA251a (creatinine and electrolytes in serum), and ERM-DA252a and ERM-DA253a (creatinine in serum).

Back to top