Selective extraction and determination of beryllium in real samples using amino-5,8-dihydroxy-1,4-naphthoquinone functionalized magnetic MIL-53 as a novel nanoadsorbent.

Herein, a magnetic MOF for preconcentration of Be(ii) was synthesized. The material is obtained from magnetite (Fe3O4) nanoparticles that were modified with 2-amino-5,8-dihydroxy-1,4-naphthoquinone (ADHNQ) and then reacted with terephthalic acid and iron(iii) chloride to form a metal-organic framework of the type MIL-53(Fe) capable of extracting Be(ii). The extraction parameters were optimized by employing design of experiments methodology. Beryllium concentration was determined by flame atomic absorption spectrometry (FAAS). The detection limit was as low as 0.07 ng mL-1 and the quantification limit is 0.2 ng mL-1. Linearity extends from 0.2 to 100 ng mL-1, and the precision of the method (intra and inter-day assay) is <9.5%. The recoveries of real sample analysis were in the range of 89-101%. The method was successfully applied to the analysis of various real water samples and an alloy sample.

Speciation analysis of Tl(I) and Tl(III) after magnetic solid phase extraction using a magnetite nanoparticle composite modified with aminodibenzo-18-crown-6 functionalized MIL-101(Cr).

The authors describe a magnetic metal-organic framework nanocomposite consisting of aminodibenzo-18-crown-6 magnetite nanoparticles and MIL-101(Cr). It was employed to the speciation analysis of Tl(I) and Tl(III) ions. The sorbent is capable of selectively extracting Tl(I) while Tl(III) remains in solution. The total amount of thallium was then determined by reducing Tl(III) to Tl(I) by hydroxylamine hydrochloride and also extracting it. The extraction parameters were optimized by employing design of experiments methodology. Thallium was quantified by ET-AAS. Under optimized conditions, the detection limit is as low as 1.5 ng L-1, the quantification limit is 5.0 ng L-1, the linear range extends from 5 to 400 ng L-1, and the relative standard deviation is <12% (for n = 5 at levels of 5, 50 and 250 ng L-1). The recoveries of real samples analysis were in the range of 90-106%. The method was successfully applied to the analysis of a certified reference material (NIST SRM 1643d water sample) and to various real water samples. Graphical abstract A novel metal-organic framework nanocomposite consisting of aminodibenzo-18-crwon-6 magnetite nanoparticles (Fe3O4@ADB18C6) and MIL-101(Cr) was synthesized, characterized and employed to speciation analysis of Tl(I) and Tl(III).

4-[(4-Bromo-phen-yl)diazen-yl]-2-eth-oxy-aniline.

The title compound, C(14)H(14)BrN(3)O, exhibits a trans geometry about the -N=N- double bond. The dihedral angle between the benzene rings is 24.01 (5)°. An intra-molecular N-H⋯O hydrogen bond occurs. In the crystal, inter-molecular N-H⋯N hydrogen bonds between the amine groups lead to the formation of a C(8) polymeric chain along [101].