Inductively coupled plasma with optical emission spectroscopy (ICP-OES; model 720 ES, Varian, Inc., US) was used to measure the levels of titanium, chromium, manganese, iron, copper, and zinc in each of the three selected nonwoven textiles. As described in detail by Mudunkotuwa et al.(17 (link)), a sample of textile (~ 200 – 400 mg) was inserted into a digestion vessel containing concentrated H2SO4 (4 mL) and concentrated HNO3 (2 mL). The vessel was then placed in a microwave digestion system (MARS 6, CEM Corporation, USA). The temperature was ramped to 210°C, held for 45 minutes, and allowed to cool to room temperature. The resulting clear solution was then topped to 25 mL with water and analyzed. All measurements were conducted in triplicate.
Once the number of layers of each of the selected nonwoven textiles were verified by experimental collection efficiency, the LOD of each of the nonwoven textiles and each element were calculated. The LOD was calculated by calculating the value three standard deviations of metal in the blank above the mean ICP-OES determined metal value in the pristine nonwoven textiles.(6 (link))
Once the number of layers of each of the selected nonwoven textiles were verified by experimental collection efficiency, the LOD of each of the nonwoven textiles and each element were calculated. The LOD was calculated by calculating the value three standard deviations of metal in the blank above the mean ICP-OES determined metal value in the pristine nonwoven textiles.(6 (link))
