Miniaturized heating/ultrasound assisted direct injection - dielectric barrier discharge molecular emission spectrometry for determination of dissolved sulfide in environmental water

•Dissolved sulfide was separated as H2S gas in water samples.•H2S was excited to generate molecular emission signal in dielectric barrier discharge microplasma.•The proposed system continuously monitored the dissolved sulfide in real water sample.Herein, a method based on direct injection-miniaturized dielectric barrier discharge molecular emission spectrometry (DBD-MES) with online heating/ultrasound-assisted blows was developed to determine dissolved sulfide levels in aqueous environmental samples. The samples were continuously acidified on-line using a carrier liquid to release H2S, which was subsequently separated in a gas-liquid separator for direct transfer to DBD tubes. The H2S molecules were excited by the DBD microplasma, emitting a characteristic spectral line at 365.28 nm that was monitored using a miniaturized charge-coupled device spectrometer. The separation of the H2S from the sample was accelerated by heating and ultrasonication. For an injection volume of 2 mL, the linear correlation coefficient (R2) was ˃ 0.99 from 1 to 200 mg L−1 S2− and the limit of detection was 0.10 mg L−1 S2−. Recoveries from spiked samples were 81–105% with relative standard deviations of 1.3–6.5%. The newly developed method is simple, accurate, low-cost, uses miniaturized and compact equipment, and provides an alternative to current techniques for determining dissolved sulfide levels in aqueous environmental samples.