posted on 2023-11-15, 16:33authored byRui Yang, Yubin Su, Tian Ren, Yuanyuan Li, Yurong Deng, Chengbin Zheng
Acid–base titration of complex
samples is conducive to the
rapid evaluation of the degree and risk of environmental pollution
to some extent. However, the traditional titration methods usually
suffer from serious interference. Herein, an automatic acid–base
titration method coupling miniature point discharge optical emission
spectrometry (μPD-OES) with CO2 vapor generation
was described for the precise, sensitive, and matrix interference-free
acid–base titration of complex samples, particularly those
with high color intensity, salinity, and turbidity such as wastewater
and soil samples. In this work, acid–base titration was carried
out in a chemical vapor generator where CO2 was generated
through the addition of HCl or NaHCO3, thus enabling efficient
separation of CO2 from a complex matrix. The generated
CO2 was subsequently swept into the miniaturized point
discharge for excitation and further detection by μPD-OES, where
the carbon atomic emission at 193.0 nm was monitored. According to
the consumed volume and concentration of HCl, accurate and automatic
measurements of OH–, CO32–, and HCO3– can be accomplished. The
proposed method possesses a high sensitivity of μPD-OES for
the detection of CO2 with a relative standard deviation
of below 3.0%. Moreover, the proposed system not only retains several
unique advantages of accuracy, simplicity, and elimination of the
use of complicated, expensive, and high power-consumption instruments
but also alleviates the color and turbid interference from complex
samples such as dyeing wastewater samples, oilfield water samples,
and soil samples. It retains a promising potential application for
titration analysis of other samples such as sludge, sediment, and
landfill leachate.