How can I evaporate samples with nitrogen without losing labile analytes or contaminating the batch?

Keep the process gentle and controlled.

• Position the needle so the gas stream plays just above the liquid surface — never submerged — which creates a soft vortex without splashing.
• Set the bath or block to the lowest temperature that still gives acceptable evaporation speed (typically 30–60 °C for volatile solvent removal) and monitor the endpoint instead of running to complete dryness. Analytes adsorbed on a dry vessel wall are the most common cause of low recovery.
• Use one needle and one position per sample, replace needles regularly and clean the gas manifold between runs to avoid cross-contamination.

For oxygen- or moisture-sensitive compounds, use high-purity nitrogen from your ANVORE generator and seal the vial immediately after concentration.