The Varian UltraMass ICP-MS system was used to determine the concentrations of a suite of trace and toxic elements (arsenic, cadmium, mercury, manganese, lead and selenium) in whole blood samples.
The blood samples were retained from distributions of Quality Control Technologies Australia and New Zealand Trace Element Quality Assurance Program (TEQAP) and a commercial source (Nycomed Pharma AS Oslo, Norway).
Element concentrations ascribed to the TEQAP samples are the means of the survey distribution for lead and cadmium, and medians for the remaining elements where less than ten laboratories contributed to the results. The targets for the Nycomed products were developed in Europe.
Blood samples were diluted twenty-fold in a solution containing 0.1% TritonX-100 and 0.1% ammonium EDTA by mass in ASTM type 1 water. This solution has been used to efficiently lyse red blood cells, reduce the size of remnant membrane fragments and reduce inter sample rinse-out times. Aliquots of bulk porcine blood diluted in this fashion were spiked with 5 and 50 ppb of As, Se, Cd, Mn and Pb and 0.5 and 5 ppb of Hg. The porcine blood used was known to have near zero Pb, Cd and As content. The Mn and Se content was assigned a value by repeated GFAAS analysis at RNSH. The Hg content was assumed to be zero.
The UltraMass was in the standard configuration. The mass spectrum was scanned in peak-hop mode with the resolution set to 0.7 amu (5% peak height definition). Data were obtained at three points/peak and later reprocessed at one point/peak. Three replicates were measured for each sample with at a dwell of 20 msec/point and 50 scans/replicate. The internal standards (approximately 100 ppb) were introduced via a tee prior to the nebulizer. This effectively dilutes the sample by a further fifty percent but avoids the contamination prone external spiking which would otherwise be required.
Two confounding factors in the achievement of trueness in this experiment were
Data will be presented which demonstrate the linearity of the calibrations and the very good to excellent agreement with the certified whole bloods obtained using this technique. It was especially pleasing to achieve good data for Mn in this high concentration iron matrix.
The use of the UltraMass for this suite of elements has the potential to improve laboratory efficiency and more importantly, improve the turnaround times. Using three point/peak determinations sample time was approximately 5 minutes. This may be compared with the hours which are typically required to perform digestions and cold vapour atomic absorption or 3-5 minutes per sample per element for direct graphite furnace determinations.
These determinations were made as part of a prepurchase evaluation. The samples were presented as low volume unknowns to an operator with only minimal experience with biological matrices. As such it may be expected that routine data will be of an even better quality than the acceptable results already obtained.