Double pass glass cyclonic spray chamber

Purified proteins (0.1 – 0.5 mg/ml) were dialyzed three times against 10 mM Tris·HCl pH 8.0 in deionized (mQ) water in the presence of 0.5% Chelex-100 (Bio-Rad) to remove trace metal ions from the buffer. An axial ICP-AES 720-ES spectrometer (Agilent Technologies, USA) was used for measurements with a low flow axial quartz torch with 2.4 mm inner diameter injector tube (Glass Expansion, Australia), a double-pass glass cyclonic spray chamber (Agilent Technologies), a OneNeb nebulizer (Agilent Technologies, USA), and a Trident Internal Standard Kit (Glass Expansion). Samples were introduced manually to reduce washing volume, without preliminary digestion or dilution. A Sc solution (20 ppm) internal standard was added to increase the accuracy of measurements. Results were collected and processed by ICP Expert software 2.0.5 (Agilent Technologies). An ICP-AM-6 standard solution, 1000 ppm (High Purity Standards) was used for calibration in the range 10–200 ppb.

The content of oxaliplatin (weight ratio of the drug to the block copolymer) in the freeze-dried nanoparticles was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). An axial ICP-AES 720-ES spectrometer (Agilent Technologies, USA) was used for measurements with a low flow axial quartz torch with 2.4 mm inner diameter injector tube (Glass Expansion, Australia), a double-pass glass cyclonic spray chamber (Agilent Technologies), a OneNeb nebulizer (Agilent Technologies, USA), and a Trident Internal Standard Kit (Glass Expansion). Samples were introduced manually to reduce washing volume, without preliminary digestion or dilution. A detailed description of the measurement process can be found in the Supplementary Materials. The drug loading content DLC and encapsulation efficacy EE of oxaliplatin-loaded mPEG-b-P(D,L)LA nanoparticles were calculated according to the following equations: $DLC= \frac{m_1^{OxPt}}{m_{NP}}\times 100\%$
$EE= \frac{m_1^{OxPt}}{m_o^{OxPt}}\times 100\%$
where $m_1^{OxPt}$ is amount of incorporated oxaliplatin in nanoparticles, $m_{NP}$ is amount of nanoparticles, and $m_0^{OxPt}$ is initial amount of oxaliplatin.