Measurement of serum aldosterone is clinically important in the diagnosis of hypertension. While isotope dilution gas chromatography–mass spectrometry (ID-GC–MS) provides reliable results, it requires derivatization and is lengthy and time-consuming. Detection by liquid chromatography–mass spectrometry (LC–MS) is a potentially superior method. The analysis utilizes 0.5mL of serum. The samples were extracted with dichloromethane–ether. The extract was evaporated to dryness and aldosterone was analyzed by LC–MS/MS operating in the negative mode ESI after separation on a reversed-phase column. Aldosterone was also measured by RIA. The calibration curves for analysis of serum aldosterone exhibited consistent linearity and reproducibility in the range of 60–3000pmol/L. Interassay CVs were 4.3–7.5% at aldosterone concentrations of 97–993pmol/L. The lower limit of quantitation (LOQ) was 30pmol/L (signal to noise ratio=10). The mean recovery of the analyte added to serum ranged from 95 to 102%. The regression equation by LC–MS/MS (x) and RIA (y) method was: y=1.33x+185 (r=0.95; n=124). Sensitivity and specificity of the LC–MS/MS method for serum aldosterone offer advantages over GC–MS by eliminating derivatization. The novel method is rapid, reliable and simple to perform with a routine LC–MS/MS spectrometer. The sensitivity is adequate for patient samples. Aldosterone concentrations reported by nonextraction RIA were consistently higher than those produced by LC–MS/MS.

Objective. The concept of boron neutron capture therapy (BNCT) involves infusion of a B-10 containing tracer into the patient's bloodstream followed by local neutron irradiation(s). Accurate estimation of the blood boron level for the treatment field before irradiation is required. Boron concentration can be quantified by inductively coupled plasma atomic emission spectrometry (ICP-AES), mass spectrometry (ICP-MS), spectrofluorometric and direct current atomic emission spectrometry (DCP-AES) or by prompt gamma photon detection methods. Material and methods. The blood boron concentrations were analysed and compared using ICP-AES and ICP-MS to ensure congruency of the results if the analysis had to be changed during the treatment, e.g. for technical reasons. The effect of wet-ashing on the results was studied in addition. Results. The mean of all samples analysed with ICP-MS was 5.8% lower than with ICP-AES coupled to wet-ashing (R-2=0.88). Without wet-ashing, the mean of all samples analysed with ICP-MS was 9.1% higher than with ICP-AES (R-2=0.99). Conclusions. Boron concentration analysed from whole blood samples with ICP-AES correlated well with the values of ICP-MS with wet-ashing of the sample matrix, which is generally considered the reference method. When using these methods in parallel at certain intervals during the treatments, reliability of the blood boron concentration values remains satisfactory, taking into account the required accuracy of dose determination in the irradiation of cancer patients.

The purpose of the QSL-Finland study was to assess the state-of-the-art trueness and precision of serum total-calcium and glucose measurements in Finnish clinical laboratories. For this purpose, 21 hospitals and clinical institutes were selected. They measured six single donation sera, the total-calcium (t-calcium) and glucose content of which had been determined by ion chromatography and isotope dilution-gas chromatography-mass spectrometry (ID-GC-MS) reference methods. The results were interpreted in light of specifications for imprecision, bias and total error of routine methods that have been proposed in the past. The data revealed that the performance of t-calcium and glucose methods is generally acceptable in Finnish clinical laboratories. This study did not lead to a separation of laboratories according to accreditation. In consequence, it seems that accreditation, in its present form, cannot substitute dedicated quality assurance practices.