Ultra low-level measurements of actinides by sector field ICP-MS

In the present work, a double-focusing sector field inductively coupled plasma-mass spectrometer was optimised for ultra trace and isotopic analyses of actinide long-lived isotopes in low concentration solutions of the fg ml−1 to the ng ml−1 range. Sensitivities of about 3 GHz/(μg ml−1), with as low a background as 0.1 cps, were obtained for U using a conventional concentric pneumatic nebuliser. Detection limits are below the fg range for 239Pu and 240Pu. With natural U, a precision lower than 0.5% RSD is currently obtained for 235U/238U isotopic ratio at the 200 pg ml−1 level.