In situ matrix evaporation of high-purity acids based on isothermal distillation was achieved in a high-density polyethylene (HDPE) container on a water bath, to avoid contamination from the laboratory environment. The solubility of water and acid vapours in glycerol due to co-association was utilized to achieve complete evaporation. All major sources which contribute to the process blank were taken care of in a simple and effective way. A 50-fold preconcentration with >99.9% matrix removal was achieved for the analysis of low-boiling acids, HCl, HF, HNO₃ and H₂O₂. The non-volatile ions NH₄⁺, Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺, SO₄²⁻ and PO₄³⁻ were determined by ion chromatograph with conductivity detection. The detection limits were 6–130 ng/l with recoveries of 85–110% for all ions studied.