Microwave digestion for the quantification of inorganic elements in coal and coal ash using ICP-OES

Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler: Part 3 – Partitioning of trace elements

“…As ICP-OES requires the sample to be in the form of a solution, prior acid digestions on the solid samples were performed using a microwave digester (Multiwave 3000, Anton Paar). The conditions adopted for this sample preparation precursor are 0.1 g of a solid sample, 0.2 ml 40 wt% hydrofluoric acid (Fluka), 5 ml 65 wt% nitric acid (Suprapur, Merck), 2 ml 30 wt% analytical-grade hydrogen peroxide (Merck), and a microwave power of 1200 W. The digestion conditions adopted in this study were based on prior parameter optimisation [24]. The bulk samples obtained for quantification analysis were first grinded and mixed thoroughly to ensure that subsequent analysis is representative of the bulk sample.…”

A rapid microwave-assisted acid extraction method based on the use of diluted HNO3-H2O2followed by ICP-MS analysis for simultaneous determination of trace elements in coal samples

“…When comparing the three digestion methods (microwave, ultrasonic bath and hot plate), microwave offers rapid effective digestion processes and also possesses an advantage of reducing analyte losses (closed system) due to volatilisation [15][16][17]. Furthermore, studies were reported where the use of explosive and toxic acids (HClO 4 and HF, respectively) in coal and coal fly ash digestions have been avoided [18][19][20]. In addition, Wang et al [10,21] reported elemental recoveries of 77-186% when coal samples were digested using microwave and concentrated acidic solutions (HNO 3 -H 2 O 2 and HNO 3 only) without HF, HCl and HClO 4 addition.…”

A Straightforward Method for Determination of Al and Na in Aluminosilicates Using ICP OES

“…1 Additionally, detection and quantification limits allow the determination of a diversity of metals and nonmetals in a myriad of sample types such as cements, ceramics, silicates, geological materials, metallosilicates, refractory compounds, aluminophosphates, silicoaluminophosphates, clays, phyllosilicates, and coals. 4,[6][7][8][9][10][11][12][13][14] The chemical analysis of the inorganic solids mentioned above by ICP OES using conventional acid dissolution methods, in open flasks on hot plate, 15 usually involves costly and time-consuming procedures for sample preparation, 3 requiring a long analysis time and large amounts of reagents. Additionally, such conventional procedures do not assure complete dissolution of some solid inorganic samples, especially geological samples 15,16 (including silicates 8,13,17 and aluminosilicates) 14,16 even when a large amount of concentrated acids is used.…”