Determination of gold at trace levels in gold plating wastewater samples by vortex-assisted amidosulfonic acid-coated magnetic nanoparticle-based solid-phase microextraction method prior to slotted quartz tube flame atomic absorption spectrometric measurements

In the present study, an analytical method was developed for the sensitive determination of gold at trace levels by a slotted quartz tube flame atomic absorption spectrometry (SQT-FAAS) system after magnetic nanoparticle-assisted solid-phase microextraction (MNP-SPME). Amidosulfonic acid (ASA)-coated magnetic nanoparticles were used as adsorbent material in the extraction experiments. Parameters affecting the extraction efficiency of gold, including amount of magnetic nanoparticles, pH/volume of buffer solution, mixing type/period, volume of eluent and volume of sample were optimized with the univariate optimization approach to achieve the highest extraction efficiency. A neodymium magnet was used to separate the analyte-adsorbed MNPs from the liquid phase. Under the optimum experimental conditions, the limit of detection (LOD) and limit of quantitation (LOQ) values were found to be 0.3 and 1.1 µg L−1, respectively. In order to investigate the matrix effects on the proposed method, spike recovery experiments were carried out in gold coating wastewater samples. Using the matrix matching calibration strategy, percent recoveries were obtained between 99 and 105% with low percent relative standard deviations. The detection power of traditional FAAS system was improved by about 162-fold; thanks to ASA-MNP-SPME-SQT-FAAS method. All experimental results of the study demonstrated the applicability of the method for the determination of trace levels of gold in complex matrices with high accuracy and precision.