Fig. 1From: Optimized sampling protocol for mass spectrometry-based metabolomics in StreptomycesSchematic representation of rapid sampling, quenching, and extraction procedures for Streptomyces. The three extraction procedures were (1) boiling ethanol: 75% (v/v) ethanol in 95 °C 4 min; (2) thawing–freezing in − 30 °C and liquid nitrogen in 50% (v/v) methanol, and (3) grinding liquid nitrogen in 50% (v/v) methanolBack to article page