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In order to determine metal ions in aqueous solution, a millisecond pulsed solution cathode glow discharge (SCGD) source coupled with a portable spectrometer was developed for atomic emission spectrometry (AES). The millisecond pulsed SCGD source was operated with two high-voltage DC power supplies and a high-voltage pulse switch, specifically boosting the analyte excitation and sustain the glow discharge. The method to excite the plasma discharge contrasts with traditional approaches that employ a single power source. The influence of operating parameters, including pulsed voltage, pulsed frequency, duty ratio, and sample flow rate, were optimized to construct a system having good stability and improved excitation of metal ions. The optimum detection limits for Na, K, Li, Mg, Ag, Cs, Rb, and Sr were 0.17, 0.32, 0.38, 0.50, 2.65, 1.30, 0.22, and 74.02 µg·L−1, respectively. Furthermore, mountain spring, Yangtze River, and reservoir water were spiked with Ag, Rb, and Cs; the recoveries ranged from 105% to 106%, 106% to 107%, and 107% to 108% indicating that the developed system has favorable analytical performance. [ABSTRACT FROM AUTHOR]

This study reports a syringe injection pump for sample introduction for solution cathode glow discharge (SCGD) atomic emission spectroscopy (AES). The experimental conditions are optimized at 60 mA discharge current, 2.5 mm gap spacing, 2.0 mm distance from the glass capillary to cathode, 1.60 mL/min flow rate, and pH 1.0 based on the detection limits (DLs) obtained for Li, Cd, Cu, Ag, Mn, Pb, Cr, and Zn. The detection limits for Li, Cd, Cu, Ag, Mn, Pb, Cr, and Zn were 0.24, 12.26, 12.08, 1.09, 46.42, 25.81, 183.05, and 29.01 µg/L, respectively, significantly lower than using the traditional peristaltic pump. The detection limits decreased by 1.4, 1.8, 2.2, 5.0, 1.4, 1.4, 1.4, 1.6, and 2.2-fold for these elements. The flow rate and the solution consumed per unit time were significantly reduced using this design. The spectral detection revealed stable and practical operation of the system with relative standard deviations <0.85%. Water samples from Yangtze River, Baixi River, and Baiyun Reservoir are analyzed using the modified SCGD system and its evaluation is based upon comparison to inductively coupled plasma—optical emission spectroscopy (ICP-OES). The modified device operates at atmospheric pressure without inert gas and integrates a syringe injection pump and a compact spectrometer to optimize solution utility, analytical performance, and operation size for industrial and environmental monitoring applications. [ABSTRACT FROM AUTHOR]

Solution cathode glow discharge-atomic emission spectrometry (SCGD-AES) has attracted increasing attention in recent years in water and environmental analysis. In this article, the traditional spectrometer was replaced by an interference filter wheel for spectral discrimination using SCGD-AES. The aforementioned interference filters selected the spectral lines of Na, K, Ca, Li, Sr, Rb, and Cs. These spectral signals were transferred to weak currents using a photomultiplier tube and amplified by a picoammeter. The solution flow rate, discharge current and slit width were optimized individually. The analytical performance of SCGD coupled with an interference filter wheel was studied for atomic emission (SCGD-IFW-AES). The results show that the limits of detection for Na, K, Ca, Li, Sr, Rb, and Cs were 0.16, 0.36, 107, 0.53, 330, 1.93, and 13.58 µg/L, respectively. The relative standard deviations of the spectral intensities for the seven elements were 0.58, 0.94, 0.69, 0.70, 0.63, 0.67, and 0.65%, which indicated that the system operated stably. Matrix effect experiments were performed to study the effect of different concentrations of Na on the spectral intensities of K and Ca. Based on these measurements, the concentration of K in physiological saline was determined to be 0.534 mg/L by SCGD-IFW-AES. [ABSTRACT FROM AUTHOR]

In sample measurements, matrix effects are unavoidable. The matrix effects are one of the main factors affecting the accuracy of the pulsed electrolyte cathode atmospheric pressure discharge detection system. The stability of sodium, potassium, and magnesium, under optimized parameters is measured; the relative standard deviation of spectral intensity is found to be no more than 2%; and the relative standard deviation of background intensity is less than 2%. The matrix effects on the elements potassium, sodium, and magnesium were studied, and the experiments showed that high concentrations of sodium and potassium interfere with each other. A concentration of 200 mg L−1K+affected the sodium signal with an enhancement of more than 120%; and the K+intensity increased 20% in the presence of a high concentration of 200 mL−1Na+. In high concentrations of sodium or potassium, the elemental signal for magnesium enhancement was approximately 8%. Sodium, potassium, and magnesium were quantitatively determined using a mixed calibration sample. When sodium, potassium, and magnesium are present at low concentrations in solution, there were no obvious matrix effects. The sodium, potassium, and magnesium in the calibration samples are quantitatively determined. The relative error and precision are less than 3%, and the recoveries are less than 105%. The detection limits for sodium, potassium, and magnesium were found to be 2.1, 3.4, and 92.6 µg L−1, respectively. [ABSTRACT FROM AUTHOR]

Solution-cathode glow discharge-atomic emission spectrometry (SCGD-AES) with a portable spectrometer was used to detect metal elements in solution. A modified pulsation damper was designed and optimized to improve discharge plasma stability. The effects of pulsation damper parameters as well as the discharge current and solution flow rate were investigated. The plasma stability of Na, K and Li elements under optimized parameters with the modified pulsation damper was discussed and they showed good stability over a long time. The standard deviation (SD) of background intensity was low, and the detection limits for Zn, Mg, Ag, Pb, Sr, Na, Li, K, Rb and Cs were 72, 2.1, 1.2, 35, 86, 0.04, 0.16, 0.14, 0.38 and 1.1 μg L−1, respectively. Ag, Zn and Pb elements in a certified reference material were quantitatively analyzed, and the measurement results obtained by SCGD-AES agreed well with the reference values. Specifically, the precision (relative standard deviation of 10 measured values) of detection was lower than 1.85%. The results show that the SCGD-AES system with the modified pulsation damper can accurately and stably detect the content of metal elements in water. [ABSTRACT FROM AUTHOR]

A solution-cathode glow discharge was used for atomic emission spectrometry. The acidic reagent, discharge current, and flow rate were optimized. The detection limits for sodium, potassium, calcium, and magnesium were 1.51, 4.13, 131, and 54.9 µg L−1, respectively. The relative standard deviation for five replicates was from 0.52 to 3.00%. Sodium, potassium, calcium, and magnesium were determined in mineral water by solution-cathode glow discharge–atomic emission spectrometry. The results demonstrate that the protocol is suitable for the elemental analysis of mineral water. [ABSTRACT FROM AUTHOR]