Critical evaluation of SCGD-OES analytical performance in the presence of NaCl

Abstract

The present study deals with the influence of sodium chloride (NaCl) on the analytical response and performance of Solution-Cathode Glow Discharge coupled to Optical Emission Spectroscopy (SCGD-OES). In particular, the...

Concomitant ion matrix effects in SCGD-OES enhanced with formic acid

“…On the other hand, the salts listed in Table 2 are used to prepare simulated matrix solutions. These salts are also dissolved in 1% HNO 3 separately to obtain solutions containing 59.8 mM (consistent with the concentration of our previous work, 3.5 g per L NaCl 33 ) of a cation (Na + , Mg 2+ or Ca 2+ ). K + was an exception since a concentration of 59.8 mM led to unsustainable plasma conditions.…”

“…The analytical performance of SCGD-OES was recently investigated with solutions containing different concentrations of NaCl and HCOOH, demonstrating that the influence of this additive under high NaCl content conditions can be negative. 33 To extend this study to other matrices, the co-presence of HCOOH and different cations and anions is considered. Fig.…”

“…1 illustrates the SCGD conguration applied in this work, which was described in detail elsewhere. 20,33 The discharge zone is composed of a vertically oriented sharpened tungsten electrode (Saf-Fro, 3.2 mm diameter) and a co-axially situated borosilicate glass capillary tube (Hirschmann ringcaps, 20 mL) used for sample introduction, which is surrounded by grounded graphite. A direct current high voltage power supply (Kepco Inc., BHK 2000-01, New York, USA) sustains the discharge in current limited mode (80 mA), providing positive potential to the tungsten electrode and negative (grounded) potential to the graphite.…”

“…In relation to the use of HCOOH (one of the most common additives), previous work from our research group showed that the influence of HCOOH on elemental emission is significantly affected in solutions containing high amounts of NaCl. 33 Specifically, while the HCOOH additive improved the signals of Fe, In, Sr and Li when NaCl was not included in the incoming solution, this was not the case when introducing solutions with 3.5 g L −1 of the salt (one-tenth the total concentration of seawater), In being the exception among the tested elements. Considering that Na + and Cl − are extremely common ions present in many kinds of matrices, understanding how these and other representative ions may alter the influence of HCOOH on the SCGD-OES performance is crucial since it could provide a useful guideline on whether to use it as a sensitivity enhancer in actual analytical methodologies.…”

The spectroscopic study of metallic lines emitted from a pulsed atmospheric pressure gas discharge source with brass and stainless steel cathodes

“…The continuous, pulsed and RF gas discharges in which the excitation/ionization of metal atoms occurs have been studied for analytical purposes and plasma-surface interaction. [1][2][3] The metallic spectral lines are present in spectra as a result of liquid sample treatment in the case of solution-cathode-glowdischarge (SCGD) 4,5 and in the case of a low pressure GD source (e.g. a Grimm-type cell) for the depth proling of conductive thin layered surfaces.…”