Determination of Ultra-Trace Cobalt in Water Samples Using Dispersive Liquid-Liquid Microextraction Followed by Graphite Furnace Atomic Absorption Spectrometry
A novel method for the determination of ultra-trace cobalt by dispersive liquid–liquid microextraction (DLLME) coupled with graphite furnace atomic absorption spectrometry has been developed. It is based on the color reaction of Co<sup>2+</sup> with 2-(5-bromo-2-pyridylazo)-5-dimethylami...
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MDPI AG
2022-04-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/27/9/2694 |
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| author | Quan Han Yaqi Liu Yanyan Huo Dan Li Xiaohui Yang |
| author_facet | Quan Han Yaqi Liu Yanyan Huo Dan Li Xiaohui Yang |
| author_sort | Quan Han |
| collection | DOAJ |
| description | A novel method for the determination of ultra-trace cobalt by dispersive liquid–liquid microextraction (DLLME) coupled with graphite furnace atomic absorption spectrometry has been developed. It is based on the color reaction of Co<sup>2+</sup> with 2-(5-bromo-2-pyridylazo)-5-dimethylaminoaniline (5-Br-PADMA) in a Britton–Robinson buffer solution at pH 6.0 to form stable hydrophobic chelates, which were separated and enriched by DLLME with 1,2-dichloroethane (CH<sub>2</sub>ClCH<sub>2</sub>Cl) as extraction and acetonitrile (CH<sub>3</sub>CN) as a dispersive solvent. The sedimented phase containing the chelates is then determined with GFAAS. Parameters that affect extraction efficiency, such as types and volumes of extraction and disperser solvents, pH of sample solution, extraction time, concentration of the chelating agent 5-Br-PADMA, and salt effect, were investigated. Under optimal conditions, the calibration graph was linear over the range 0.05–1.0 ng/mL, with a correlation coefficient of 0.9922 and a detection limit of 0.03 ng/mL. Preconcentration factor (PF) is calculated as the ratio of the aqueous solution volume (5 mL) to that of the organic phase volume (40 μL), and enrichment factor (EF) is calculated as the ratio of the slopes of the calibration graphs obtained with and without DLLME for 5.0 mL of sample solution, which were 120 and 112.5, respectively. The extraction efficiency, calculated by EF/PF·100, was 93.8%. The relative standard deviation (RSD) at the 0.5 ng/mL Co<sup>2+</sup> level was 3.8% (<i>n</i> = 6). The method has been applied to the determination of trace cobalt in water samples with satisfactory results. |
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| last_indexed | 2024-03-10T03:54:25Z |
| publishDate | 2022-04-01 |
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| series | Molecules |
| spelling | doaj.art-313995dcf8c94c6caa3f9956185666052023-11-23T08:48:15ZengMDPI AGMolecules1420-30492022-04-01279269410.3390/molecules27092694Determination of Ultra-Trace Cobalt in Water Samples Using Dispersive Liquid-Liquid Microextraction Followed by Graphite Furnace Atomic Absorption SpectrometryQuan Han0Yaqi Liu1Yanyan Huo2Dan Li3Xiaohui Yang4School of Chemical Engineering, Xi’an University, Xi’an 710065, ChinaSchool of Chemistry and Chemical Engineering, Yan′an University, Xi’an 716061, ChinaSchool of Chemical Engineering, Xi’an University, Xi’an 710065, ChinaSchool of Chemical Engineering, Xi’an University, Xi’an 710065, ChinaSchool of Chemical Engineering, Xi’an University, Xi’an 710065, ChinaA novel method for the determination of ultra-trace cobalt by dispersive liquid–liquid microextraction (DLLME) coupled with graphite furnace atomic absorption spectrometry has been developed. It is based on the color reaction of Co<sup>2+</sup> with 2-(5-bromo-2-pyridylazo)-5-dimethylaminoaniline (5-Br-PADMA) in a Britton–Robinson buffer solution at pH 6.0 to form stable hydrophobic chelates, which were separated and enriched by DLLME with 1,2-dichloroethane (CH<sub>2</sub>ClCH<sub>2</sub>Cl) as extraction and acetonitrile (CH<sub>3</sub>CN) as a dispersive solvent. The sedimented phase containing the chelates is then determined with GFAAS. Parameters that affect extraction efficiency, such as types and volumes of extraction and disperser solvents, pH of sample solution, extraction time, concentration of the chelating agent 5-Br-PADMA, and salt effect, were investigated. Under optimal conditions, the calibration graph was linear over the range 0.05–1.0 ng/mL, with a correlation coefficient of 0.9922 and a detection limit of 0.03 ng/mL. Preconcentration factor (PF) is calculated as the ratio of the aqueous solution volume (5 mL) to that of the organic phase volume (40 μL), and enrichment factor (EF) is calculated as the ratio of the slopes of the calibration graphs obtained with and without DLLME for 5.0 mL of sample solution, which were 120 and 112.5, respectively. The extraction efficiency, calculated by EF/PF·100, was 93.8%. The relative standard deviation (RSD) at the 0.5 ng/mL Co<sup>2+</sup> level was 3.8% (<i>n</i> = 6). The method has been applied to the determination of trace cobalt in water samples with satisfactory results.https://www.mdpi.com/1420-3049/27/9/2694dispersive liquid–liquid microextractiongraphite furnace atomic absorptionspectrometrycobalt2-(5-bromopyridyazo)-5-dimethylaminoanline1,2-dichloroethanacetonitrile |
| spellingShingle | Quan Han Yaqi Liu Yanyan Huo Dan Li Xiaohui Yang Determination of Ultra-Trace Cobalt in Water Samples Using Dispersive Liquid-Liquid Microextraction Followed by Graphite Furnace Atomic Absorption Spectrometry Molecules dispersive liquid–liquid microextraction graphite furnace atomic absorptionspectrometry cobalt 2-(5-bromopyridyazo)-5-dimethylaminoanline 1,2-dichloroethan acetonitrile |
| title | Determination of Ultra-Trace Cobalt in Water Samples Using Dispersive Liquid-Liquid Microextraction Followed by Graphite Furnace Atomic Absorption Spectrometry |
| title_full | Determination of Ultra-Trace Cobalt in Water Samples Using Dispersive Liquid-Liquid Microextraction Followed by Graphite Furnace Atomic Absorption Spectrometry |
| title_fullStr | Determination of Ultra-Trace Cobalt in Water Samples Using Dispersive Liquid-Liquid Microextraction Followed by Graphite Furnace Atomic Absorption Spectrometry |
| title_full_unstemmed | Determination of Ultra-Trace Cobalt in Water Samples Using Dispersive Liquid-Liquid Microextraction Followed by Graphite Furnace Atomic Absorption Spectrometry |
| title_short | Determination of Ultra-Trace Cobalt in Water Samples Using Dispersive Liquid-Liquid Microextraction Followed by Graphite Furnace Atomic Absorption Spectrometry |
| title_sort | determination of ultra trace cobalt in water samples using dispersive liquid liquid microextraction followed by graphite furnace atomic absorption spectrometry |
| topic | dispersive liquid–liquid microextraction graphite furnace atomic absorptionspectrometry cobalt 2-(5-bromopyridyazo)-5-dimethylaminoanline 1,2-dichloroethan acetonitrile |
| url | https://www.mdpi.com/1420-3049/27/9/2694 |
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