Fig. 4: Rapid analysis of salvianolic acids in salvianolate injection.

a The workflow of salvianolate injection analysis. Left: The powder of salvianolate injection was dissolved in Milli-Q water to reach a 5 mg/mL concentration. Center: 4 μL dissolved salvianolate injection was added to the cis chamber of a nanopore device. The measurement was carried out using MspA-90PBA in a buffer of 1.5 M KCl, 100 mM MOPS, pH 7.0 (Methods) and a bias of +100 mV was continually applied. Right: Corresponding nanopore events observed immediately. (b) A representative trace acquired during salvianolate injection analysis. The events were identified by the trained KNN model and are labeled accordingly. (c) The scatter plot of \(\varDelta I/{I}_{o}\) versus \(S.D.\) of events acquired with the salvianolate injection. The events in the scatter plot were taken from a 30 min continually recorded trace and a total of 846 events were collected. The events were labeled according to the prediction results performed by the previously trained KNN model. (d) The proportion of salvianolic acid events in the salvianolate injection. Data were presented as mean ± standard deviation values derived from results of three independent measurements (N = 3) (Supplementary Fig. 20). The error bars represent standard deviation values. Clearly, SalB is the main component of the salvianolate injection. However, other salvianolic acid components were also detected by nanopore. Source data are provided as a Source Data file.