Preconcentration procedure using vortex agitator system for determination of trace levels of cadmium by flame atomic absorption spectrometry

Abstract

Um procedimento simples e rápido de microextração líquido-líquido com líquido iônico e agitação vortex (VALLME) foi usado na determinação de quantidades traço de cádmio por espectrometria de absorção atômica com chama (FAAS). O líquido iônico (IL), hexafluorato de 1-hexil-3-metilimidazólio ([Hmim][PF 6 ]), foi usado como solvente extractor. Os íons Cd 2+ foram complexados com pirrolidina ditiocarbamato de amônia (APDC), e então confinados em pequenas gotas de IL pela intervenção do sistema de agitação vortex. Alguns fatores que influenciam na extração tais como pH, concentração de ligante, quantidade de líquido iônico, tempo de extração e efeito da força iônica foram completamente investigados e otimizados. Sob condições ideais, o limite de detecção foi de 1,1 ng mL -1 . O desvio padrão relativo (RSD) foi 4,3% para 20 ng mL -1 de cádmio (n = 10), e o gráfico de calibração usando o método de preconcentração foi linear de 5 a 150 µg L -1 , com um coeficiente de correlação de 0,998. O método proposto foi aplicado com sucesso na determinação de cádmio em amostras de água e folhas de espinafre.A simple and rapid vortex-assisted ionic liquid based liquid-liquid microextraction (VALLME) procedure was used for the determination of trace amounts of cadmium by flame atomic absorption spectrometry (FAAS). Ionic liquid (IL), 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF 6 ]), was used as an extractant solvent. Cd 2+ was complexed with ammonium pyrrolidinedithiocarbamate (APDC) and then entered into the fine IL droplets by the assistance of vortex agitator system. Some effective factors that influence the extraction efficiency such as pH, ligand concentration, amount of ionic liquid, extraction time and ionic strength effect were completely investigated and optimized. Under the optimum conditions, the limit of detection (LOD) was 1.1 ng mL -1 . The relative standard deviation (RSD) was 4.3% for 20 ng mL -1 of cadmium (n = 10), and the calibration graph using the preconcentration method was linear from 5 to 150 µg L -1 , with a correlation coefficient of 0.998. The proposed method was successfully applied for determination of cadmium in water samples and spinach leaves.

Vortex Assisted Liquid–Liquid Microextraction Using Triton X‐114 for Ultratrace Cadmium Prior to Analysis

“…The limit of detection (LOD) and quantification were calculated on the basis of 3 S b /m and 10 S b /m (n ¼ 10) (S b is the standard deviation of the blank and m is the slope of calibration curve after extraction), were 0.5 and 1.7 mg/L, respectively. The obtained LOD value for Cd was sufficiently low as compared to a reported work [37] and to be valuable for detecting Cd in different types of water samples.…”

Metal applications of liquid-phase microextraction

“…In this study, FAAS was selected as a determination method and samples were diluted to a certain volume before injecting into the detection system. About vortex agitation, Chamsaz et al [29] firstly employed VALLME for the determination of trace amounts of cadmium by FAAS. In this research, the IL 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF 6 ]), was used as an extractant solvent, Cd 2+ was complexed with APDC, and then extracted into fine IL droplets by the assistance of vortex agitator system.…”

Ionic liquid-based microextraction techniques for trace-element analysis

“…These techniques are termed temperatureassisted DLLME (TA-DLLME) or cold-induced aggregation microextraction (CIAME), ultrasound-assisted DLLME (USA-DLLME) and IL-based microwave-assisted dispersive LLME (IL-MA-DLLME), respectively. The use of vortex stirring is a simple alternative to avoid the need for a third component or solvent (vortex-assisted DLLME) [15,39,84]. Temperature in TA-DLLME increases solubility of the IL phase, so full contact between the two phases is obtained.…”

“…Using the VA-LLME technique, Chamsaz et al developed analytical methods for Pb and Cd determination in samples of spinach leaves, apple and rice. In addition to the simplicity of this microextraction technique, TX-100 was used as dispersant solvent, which avoided the application of volatile organic solvents [15,39]. Another method aimed to determine trace amounts of Mo(VI) in three plant samples (mint, black pepper and fenugreek leaves) was developed using the IL [C6mim][Tf2N] in a DLLME procedure.…”