Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Schematic view of the sample concentration methods. Humic acid samples (Wa-HA, Ald-HA, and IH-HA) (10 ml) and a blank (Milli-Q) were concentrated using a flat-type electronegative membrane to obtain 10 ml of concentrates (conc-HA samples). During the process, filt-HA samples and acid-HA samples were collected. Thirty liters of river water samples (R1 to R3) were concentrated using a cartridge-type electronegative membrane to obtain 200 ml of concentrates (conc-river-water samples).
