The EXPEC 520 is heated by a water bath and uses the rapid flow of nitrogen to break the gas-liquid balance above the liquid, acceler­ate the volatilization speed of the liquid and achieve the effect of rapidly concentrating the solvent. It has the characteristics of processing large batches of samples, no need for personnel to guard, safety, etc. It improves the efficiency of laboratory personnel, reduces nitrogen loss and saves laboratory costs. And it reduces the harm of toxic and harmful solvents to experimenters, it is an essential sample pretreatment device in the laboratory.