Dissolvable layered double hydroxide as an efficient nanosorbent for centrifugeless air-agitated dispersive solid-phase extraction of potentially toxic metal ions from bio-fluid samples

• Published in: Analytica chimica acta Vol. 957; pp. 1 - 9
• Main Authors: Rajabi, Maryam, Arghavani-Beydokhti, Somayeh, Barfi, Behruz, Asghari, Alireza
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 08-03-2017
• Subjects: Air-agitated; Bio-fluids; Centrifugeless; Dispersive solid-phase extraction; Drinking Water - chemistry; Hair - chemistry; Humans; Hydroxides; Layered double hydroxide; Limit of Detection; Metals - isolation & purification; Micro-sampling; Nails - chemistry; Plasma - chemistry; Saliva - chemistry; Solid Phase Extraction; Spectrophotometry, Atomic; Urine - chemistry; Water Pollutants, Chemical; Centrifugeless; Air-agitated; Dispersive solid-phase extraction; Bio-fluids; Layered double hydroxide; Micro-sampling
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2016.12.041

In the present work, a novel nanosorbent namely layered double hydroxides with 4-amino-5-hydroxyl-2,7-naphthalendisulfonic acid monosodium salt interlayer anion (Mg-Al-AHNDA-LDH) was synthesized and applied as a dissolvable nanosorbent in a centrifugeless ultrasound-enhanced air-agitated dispersive solid-phase extraction (USE-AA-D-SPE) method. This method was used for the separation and preconcentration of some metal ions including Cd2+, Cr6+, Pb2+, Co2+, and Ni2+ prior to their determination using the micro-sampling flame atomic absorption spectrometry (MS-FAAS) technique. The most interesting aspect of this nanosorbent is its immediate dissolvability at pH values lower than 4. This capability drastically eliminates the elution step, leading to a great improvement in the extraction efficiency and a decrease in the extraction time. Also in this method, the use of a syringe nanofilter eliminates the need for the centrifugation step, which is time-consuming and essentially causes the analysis to be off-line. Several effective parameters governing the extraction efficiency including the sample solution pH, amount of nanosorbent, eluent condition, number of air-agitation cycles, and sonication time were investigated and optimized. Under the optimized conditions, the good linear dynamic ranges of 2–70, 6–360, 7–725, 7–370, and 8–450 ng mL−1 for the Cd2+, Cr6+, Pb2+, Co2+and Ni2+ ions, respectively, with the correlation of determinations (R2s) higher than 0.997 were obtained. The limits of detection (LODs) were found to be 0.6, 1.7, 2.0, 2.1, and 2.4 for the Cd2+, Cr6+, Pb2+, Co2+, and Ni2+ ions, respectively. The intra-day and inter-day precisions (percent relative standard deviations (%RSDs) (n = 5)) were below 7.8%. The proposed method was also successfully applied for the extraction and determination of the target ions in different biological fluid and tap water samples.
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•A novel centrifugeless dispersive solid-phase extraction method was developed.•A new functionalized LDH nanosorbent was introduced.•The proposed method extends application of D-SPE in on-line systems.•Some potentially toxic heavy metals were quantified in different biological fluids.•Elimination of centrifugation and elution steps, are most advantages of the method.