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In this paper, a method of ultrasound-assisted low-pressure closed acid digestion followed by inductively coupled plasma mass spectrometry (ICP-MS) analysis was proposed for trace element quantification in rock samples. By using 1.5 mL of a binary acid mixture of HNO3–HF with a ratio of 2:1, rock powder samples of 50 mg were completely decomposed in 12 h at 140 °C after 4 h of ultrasonic treatment with or without pressure relief procedure. The element extraction efficiency of this method was evaluated via the yielded relative errors (REs) of the trace elements in a series of geological standard reference materials (SRMs) with compositions from basic to acidic. It was found that the contents of trace elements (i.e., 36 metal elements from Li to U) in basalt BCR-2, diabase W-2a, andesite AGV-2, granodiorite GSP-2, and granite GSR-1 were comparable with the reported reference values, giving REs with absolute values less than 10%. It was also found that clear solutions without sample powder residues by naked-eye observation can be obtained when using the low-pressure closed decomposition method without ultrasonic pretreatment. The quantification results, however, were found to be negatively biased for most of the studied trace elements, and, in particular, the content bias of Zr in SRM GSP-2 was down to −86.28% due to the low extraction efficiency of refractory minerals of the low-pressure closed digestion method. By applying this proposed digestion strategy, the decomposition property of the ternary combination of HNO3–HF–mannitol in terms of trace element quantification accuracy was also investigated. Results showed that the concentrations of trace elements in the studied SRMs were consistent with the reference values, giving REs within ±6.94%, which revealed that there was no deterioration of extraction efficiencies of trace elements and neglected mass interferences from mannitol. This study demonstrated the essential role of ultrasound irradiation in rock sample decomposition to achieve the high extraction efficiency of trace elements under a low-pressure environment, and the developed approach with promising future applications in geoscience exhibited considerable merits, including a high extraction efficiency, feasible digestion process, less time consumption, and lower safety associated risks. [ABSTRACT FROM AUTHOR]

• Ultrasound synthesis of polysubstituted imidazole based benzoxazole derivatives A rapid and efficient synthesis of novel hybrid imidazole-benzoxazole derivatives is described under ultrasound irradiation. These reactions were carried out through a cyclization reaction of polysubstituted imidazole-based o -aminophenols and various benzoic acids in polyphosphoric acid. The starting o -amiophenols were synthesized from corresponding o -nitrophenols using Fe powder in EtOH and acetic acid. o -Nitrophenol derivatives were synthesized from related phenols by employing HNO 3 in acetic acid. Structures of the newly obtained products were confirmed by spectral and analytical data. The optical properties of the products were investigated via UV–Vis absorption and fluorescent emission spectroscopy in dilute ethanol solution. [ABSTRACT FROM AUTHOR]

In this study, various benzothiazoles, benzoxazoles, and benzo[1,3]-dithiols derivatives with good yields were obtained using the Ullmann coupling reaction of dihalobenzenes and malononitrile-heterocumulene adducts in the vicinity of copper catalyst, Cs 2 CO 3 as a base under ultrasound irradiation. The use of the popular sonochemical method, short reaction time, simple and available raw materials, mild catalytic copper reaction conditions, simple purification, and good efficiency are some of the notable characteristics of this protocol. [Display omitted] • Novel protocols synthesis of various benzothiazoles, benzoxazoles, and benzo[1,3]-dithiols. • CuI catalyzed and efficient sonochemical method in the synthesis of benzothiazoles, benzoxazoles and benzo[1,3]-dithiols. • Ullmann coupling reaction of dihalobenzene and malononitrile-heterocumulene adducts. [ABSTRACT FROM AUTHOR]