Microwave-assisted digestion methods: towards greener approaches for plasma-based analytical techniques

Bizzi, Cezar A.; Pedrotti, Matheus F.; Silva, Jussiane S.; Barin, Juliano Smanioto; Nóbrega, Joaquim A.; Flores, Érico M.M.

doi:10.1039/c7ja00108h

Cited by 96 publications

(33 citation statements)

References 121 publications

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“…In the present study, microwave energy was explored as a tool to enhance the extraction of PAC as well as to increase the generation of monomers through depolymerization of PAC. Microwave-assisted extraction (MAE) is a fast and efficient bioactive extraction method that is based on the direct impact on polar compounds [15,16]. Electromagnetic energy, in the frequency range of 300 MHz to 300 GHz, is transferred to heat following ionic conduction and dipole rotation.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Catechin and Proanthocyanidin Recovery from Grape Seeds Using Microwave-Assisted Extraction

et al. 2020

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Grape seed extract (GSE) is a rich source of condensed flavonoid tannins, also called proanthocyanidins (PACs). The high molecular weight of polymeric PAC limits their biological activity due to poor bioavailability. The present study was undertaken to explore the potential applicability of microwave-assisted extraction (MAE) to convert GSE-PAC into monomeric catechins. A central composite design (CCD) was used to optimize the processing conditions for the MAE. The maximum total yield of monomeric catechins (catechin, epicatechin, and epicatechin gallate) and PAC were 8.2 mg/g dry weight (DW) and 56.4 mg catechin equivalence (CE)/g DW, respectively. The optimized MAE condition was 94% ethanol, 170 °C temperature, and a duration of 55 min. Compared to the results for PACs extracted via conventional extraction (Con) (94% ethanol; shaking at 25 °C for 55 min), MAE yielded 3.9-fold more monomeric catechins and 5.5-fold more PACs. The MAE showed higher antioxidant capacity and α-glucosidase inhibitory activity than that of the conventional extract, suggesting the potential use of the MAE products of grape seeds as a functional food ingredient and nutraceutical.

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Section: Introductionmentioning

confidence: 99%

Optimization of Catechin and Proanthocyanidin Recovery from Grape Seeds Using Microwave-Assisted Extraction

et al. 2020

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“…Sample preparation in this case was also time‐consuming and required several steps, using HF, HNO 3 and HClO 4 . These examples demonstrate that the results are prone to interferences and that sample preparation must contribute to avoid this, being as simple as possible and in agreement with green sample preparation in analytical chemistry …”

Section: Introductionmentioning

confidence: 72%

An ultrasound‐assisted sample preparation method of carbonatite rock for determination of rare earth elements by inductively coupled plasma mass spectrometry

Gatiboni

Iop

Diehl

et al. 2020

Rapid Comm Mass Spectrometry

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Rationale A method for the determination of rare earth elements in carbonatite rocks by inductively coupled plasma mass spectrometry (ICP‐MS) was developed. Methods An alkaline rock, carbonatite, was submitted to ultrasound‐assisted extraction (USAE) using an ultrasound bath, a cup horn system or an ultrasound probe. The main USAE parameters were evaluated, such as extraction time (1 to 30 min), extraction temperature (20 to 100°C) and ultrasound amplitude (10 to 100%). For ICP‐MS, a desolvation system (APEX‐Q) was used to reduce interference in lanthanide determination. To evaluate if the effect of ultrasound improved extraction, experiments were carried out using magnetic stirring (500 rpm) for comparison. Results The temperature and ultrasound amplitude optimized for the method were 70°C and 40%, respectively, using dilute nitric acid (3% v/v). Quantitative analyte recoveries were obtained using an ultrasound bath (25 kHz/100 W) which allowed for the simultaneous extraction of twelve replicates. Conclusions All the results obtained with the use of ultrasound systems were better than those obtained with mechanical stirring. The extracts were suitable for ICP‐MS analysis and the results were in agreement with those obtained by the reference method (using wet acid digestion). Based on the results, the use of USAE can be considered an alternative method for sample preparation of carbonatite rocks, under milder conditions, for further ICP‐MS analysis.

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“…The sample preparation step plays an important role in the analytical sequence, as it should guarantee the quality of digests and avoid interferences or instrument damage. [102][103][104][105] In this sense, it is imperative that a sample preparation method be implemented to provide suitable solutions to be analyzed by ICP-MS. 106 ignition is performed by microwave radiation and the sample is burnt, generally reaching temperatures higher than 1200 C. There is also the possibility of adding a short reflux step (e.g. 5 min) to improve analyte absorption into the absorbing solution.…”

Section: Sample Preparation Methods For Further Halogen Determinatimentioning

confidence: 99%

Challenges and trends for halogen determination by inductively coupled plasma mass spectrometry: A review

Flores

Mello

Krzyzaniak

et al. 2020

Rapid Comm Mass Spectrometry

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Rationale In this review, works published in the past 25 years for fluorine, chlorine, bromine, and iodine determination in several matrices by inductively coupled plasma mass spectrometry (ICP‐MS) were covered. Usually, the determination of halogens has been performed by ICP‐MS using a previous sample preparation step or, more recently, by direct analysis of solid or liquid samples. Methods Methods based on combustion, extraction, pyrohydrolysis, sample dilution in organic or aqueous medium, and wet digestion, among others, are discussed. Moreover, the recent applications of methods based on laser ablation (LA) and electrothermal vaporization (ETV) coupled to ICP‐MS are discussed. Results The main challenge for methods using sample preparation has been to obtain a final solution compatible with ICP‐MS, as well as to overcome problems related to analyte losses and contamination. Interferences due to the presence of dissolved organic compounds in solution, enhancement or suppression of ionization of analytes, and related matrix effects have been of concern when using ICP‐MS. For the determination of halogens by ICP‐MS using LA and ETV systems, some limitations related to the difficulty of calibration are pointed out, impairing the widespread use of this approach. Conclusions A critical view is presented for further halogen determination by ICP‐MS, mainly for matrices considered difficult to digest using conventional protocols.

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Microwave-assisted digestion methods: towards greener approaches for plasma-based analytical techniques

Abstract: With the development of new materials and recent requirements of green chemistry, digestion remains a challenging step in many analytical procedures.

Cited by 96 publications

References 121 publications

Optimization of Catechin and Proanthocyanidin Recovery from Grape Seeds Using Microwave-Assisted Extraction

Optimization of Catechin and Proanthocyanidin Recovery from Grape Seeds Using Microwave-Assisted Extraction

An ultrasound‐assisted sample preparation method of carbonatite rock for determination of rare earth elements by inductively coupled plasma mass spectrometry

Challenges and trends for halogen determination by inductively coupled plasma mass spectrometry: A review

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