Be-10, C-14, Cl-36 and I-129 test measurements have been made with a new Pelletron-based accelerator mass spectrometer operating at up to 5.2 MV. All ion detection was with a versatile gas ionization detector. Low-background radiocarbon measurements with 2% scatter of identical samples was performed with both spectrometer ion sources. Be-10/Be backgrounds of 3 x 10(-15) were achieved using a gas cell adjoining the detector for B-10 suppression. High sample-throughput Cl AMS with Cl-36/Cl backgrounds of 4 x 10(-15) was accomplished. (C) 2004 Elsevier B.V. All rights reserved.