Determination of metal concentrations in certified plastic reference materials after small-size autoclave and microwave-assisted digestion followed with inductively coupled plasma optical emission spectrometry

Abstract

The digestion methods for the determination of As, Cd, Cr, Pb, Sb, Sn and Zn concentrations in plastic samples using microwave-assisted digestion (MW-AD) and small-size autoclave digestion was developed. The certified polyethylene, polypropylene, polyvinyl chloride and acrylonitrile butadiene styrene certified reference materials were used in order to find digestion method working properly for several sample matrices. Efficiency of the digestion methods was evaluated by analyzing the residual carbon in digests by TOC analyzer. MW-AD using a mixture of 7 mL of HNO 3 and 3 ml of H 2 O 2 as a digestion solution resulted in excellent recoveries for As, Cd, Pb, Sb and Zn, and were in the range of 92-107 % for all the analytes except Pb in polyethylene material. Autoclave digestion using 5 mL of concentrated HNO 3 as a digestion solution resulted in similar recoveries with the exception of a higher As recovery (98 %). Tin recovery resulted in low level after both MW-AD and autoclave digestion. Autoclave digestion was further developed resulting in a partially open two-step digestion process especially for the determination of Sn and Cr. The method resulted in higher recoveries of Sn and Cr (87 and 76 %) but with the lower concentration of easily volatile As, Cd and Sb.

Beyond Mechanical Recycling: Giving New Life to Plastic Waste

“…[166] Microwave-assisted digestion has been described for analytical purposes of samples of PE, PP,PVC,and ABS in am ixture of hydrogen peroxide and nitric acid. [167] In addition, breaking up the polymers into oligomers may also improve solubility in different solvents.T his can be achieved through mechanochemical treatment, for example with exploding ultrasonic bubbles (Section 2.1.1). [82] This approach in particular, but also other dissolution/ precipitation techniques,y ields ac rystallized polymer that needs to be upgraded to obtain reliable virgin grade quality.…”

A metrologically traceable protocol for the quantification of trace metals in different types of microplastic

“…The difficulties in recovering Cr from BAM-H010 (compared the other plastic CRMs) can be explained by the nature of the metal species present in the material (Cr 2 O 3 ). Lethimaki and Väisänen (2017) could also only recover a very small percentage of Cr from BAM-H010 (2.9%) in their study [49]. Cr 2 O 3 and also SnO 2 , for instance, are considered virtually not accessible by normal acid digestion methods [74].…”

“…There is already scientific evidence (from polymer testing studies) that shows how challenging the accurate quantification of metals in CRMs of different polymer matrices is [44][45][46][47][48]. Dependent on the polymer type, the metal species and the applied digestion conditions, the recoveries can highly vary from a few percent to a quantitative recovery [47,49].…”

Die nächste Generation des Recyclings – neues Leben für Kunststoffmüll

“…[164] PE, PP,P VC und ABS wurden füra nalytische Zwecke schon in Mikrowellen mit Wasserstoffperoxid und Salpetersäure aufgelçst. [165] Zusätzlich kçnnte das Aufbrechen der Polymere in Oligomere die Lçslichkeit verbessern, z. B. mithilfe der implodierenden Blasen, die beim Ultraschall entstehen (Abschnitt 2.1.1).…”