High-Sensitivity Determination of K, Ca, Na, and Mg in Salt Mines Samples by Atomic Emission Spectrometry with a Miniaturized Liquid Cathode Glow Discharge

Abstract

An atomic emission spectrometer (AES) based on a novel atmospheric pressure liquid cathode glow discharge (LCGD) as one of the most promising miniaturized excitation sources has been developed, in which the glow discharge is produced between a needle-like Pt anode and the electrolyte (as cathode) overflowing from a quartz capillary. Lower energy consumption (<50 W) and higher excitation efficiency can be realized by point discharge of the needle-like Pt. The miniaturized LCGD seems particularly well suited to rapid and high-sensitivity determination of K, Ca, Na, and Mg in salt mines samples. The optimized analytical conditions of LCGD-AES were pH = 1 with HNO3 as electrolyte, 650 V discharge voltage, and 3 mL min−1 solution flow rate. The limits of detections (LODs) of K, Ca, Na, and Mg were 0.390, 0.054, 0.048, and 0.032 mg L−1, respectively. Measurement results of the LCGD-AES are in good agreement with the comparison value obtained by inductively coupled plasma (ICP) and ion chromatography (IC). All results suggested that the developed portable analytical instrument can be used for on-site and real-time monitoring of metal elements in field with further improvement.

Liquid Cathode Glow Discharge as an Excitation Source for the Analysis of Complex Water Samples with Atomic Emission Spectrometry

“…The developed LCGD-AES is similar to our previous work − and presented in Figure . Sample solution was introduced into the LCGD excitation source using a peristaltic pump (BT100-02, Baoding Longer Precision Pump Co., Baoding, China).…”

“… 32 In addition, the bands from 315 to 406 nm are attributed to the C 3 Π u → B 3 Π g of N 2 because the discharge is operated in atmospheric air. 33 , 34 …”

“…All these active species are coming from the cathode sputtering of the electrolyte . In addition, the bands from 315 to 406 nm are attributed to the C 3 Π u → B 3 Π g of N 2 because the discharge is operated in atmospheric air. , …”

“…The t test is used for calculating the p value to find the statistical significance of the test. , p < 0.05 suggests that the group means are different; otherwise, p > 0.05 indicates that both groups have identical means. , The statistical results between LCGD-AES and IC are listed in Table . Almost all values of t do not go over t 95% = 2.78 ( t test for a confidence level of 95%).…”

“…Recently, we also established a liquid cathode glow discharge (LCGD, a kind of SCGD) for the detection of metal elements in wastewater, , salt mines, gluconate oral solutions, and blood samples . Herein, to further evaluate the feasibility of the proposed method, the detection of K, Na, Ca, and Mg in water samples from rivers and lakes was investigated.…”