Mili q iq 7000

Analytical and trace-metal grade reagents were utilized throughout. The Mili-Q IQ-7000 (Merck KGaA, Darmstadt, Germany) water purification system was used to provide high quality deionized water (resistivity > 18.2 M). Prior to use, all glassware and plasticware were cleaned by soaking for 48 h in a 10% (v/v) HNO3 solution, then rinsing with ultrapure water and drying. The dilution of 10 µg/mL (Bi²⁰⁹, Tb¹⁵⁹, In¹¹⁵, Y⁸⁹, Ge⁷⁴, Ge⁷², Sc⁴⁵, Li⁶) Internal Standard Mix solution (Agilent Technologies, Santa Clara, CA, USA) was required for the internal standard solution. The calibration curves were made using a 10 µg/mL and 100 µg/mL custom mix multi-element ICP-MS standard (HPS, North Charleston, SC, USA), as well as a 1000 µg/mL mineral element ICP-MS standard solution (HPS, North Charleston, SC, USA) (ICP-AM-17 Mineral Calibration Standard, HPS, North Charleston, SC, USA).

High purity HNO₃ (≥70% w/w, TRACEMETAL™ Grade, Fisher Scientific, Waltham, MA, USA) and HCl (≥38% w/w TRACEMETAL™ Grade, Fisher Scientific, Waltham, MA, USA) were used as received. The internal standard solution was prepared by appropriate dilution of the Internal Standard Mix solution (Agilent Technologies, Santa Clara, CA, USA). Calibration standards were prepared from 10 µg/mL and 100 µg/mL custom mix multi-element ICP-MS standard (HPS, North Charleston, SC, USA), and from the 1000 µg/mL mineral element ICP-MS standard solution (ICP-AM-17 Mineral Calibration Standard, HPS, North Charleston, SC, USA). All solutions were prepared by using ultrapure water (>18.2 MΩ·cm at 25 °C) from a Mili-Q IQ-7000 (Merck KGaA, Darmstadt, Germany) water purification system. All the glassware and plastic materials were decontaminated with a 10% (v/v) HNO3 solution for 48 h and rinsed with ultrapure water prior to use.

The internal standard solution was prepared by dissolving 200 mg of methyl undecanoate (C11:0 FAME, Sigma Aldrich, Singapore) in 1 mL of n-hexane (Merck, KGaA, Darmstadt, Germany). The fatty acid methyl esters (FAMEs) standard solution was prepared by diluting the stock standard (GLC 36, Nu-Chek-Prep, Elysian, MN, USA) in n-hexane (Merck, KGaA, Darmstadt, Germany). Lipid extraction was performed using petroleum spirit (40 °C–60 °C, Avantor VWR, Radnor, PA, USA). For the determination of fatty acids profile, sodium hydroxide (Merck, KGaA, Darmstadt, Germany), boron trifluoride (BF3) (Merck, KGaA, Darmstadt, Germany), methanol (Merck, KGaA, Darmstadt, Germany), n-hexane (Merck, KGaA, Darmstadt, Germany) and ultrapure water (>18.2 MΩ·cm at 25 °C) from a Mili-Q IQ-7000 (Merck KGaA, Darmstadt, Germany) water purification system was used.