Agilent 8800 icp ms ms

The E. coli strains W3110, WC3110, AW3110, AW3110/pTe2854, AW3110/pTe3384, AW3110/pTe3675, WC3110/pTe2854 and WC3110/pTe3384 were pre-cultured overnight. Then, 0.6 ml of each overnight culture was used to inoculate Erlenmeyer flasks (250 ml) containing 60 ml of LB medium supplemented with 1 mM arsenate or 3 mM arsenite. The inoculated flasks were incubated with continuous stirring (200 rpm) for 5 h at 37°C. After incubation, a volume of 15 ml of culture was filtered through nitrocellulose filters (0.45-μm pore diameter; Whatman) and the cells retained on the filters were washed twice with 0.05 M potassium phosphate buffer (pH 7.6). Filtering and washing were performed using a vacuum pump (Millipore 230V). The filters, which contained the retained cells, were treated with 10 ml of 65% Nitric acid at 70°C for 120 min. Nitric acid (Sigma-Aldrich) was doubly distilled from 65% HNO₃ reagent grade with a DST-1000 sub-boiling acid purification system from Savillex (Savillex, Eden Prairie, MN, USA) and diluted with Milli-Q water. Samples were analyzed in an Agilent 8800 ICP-MS/MS (Agilent Technologies) at the General Facilities for Research of the University of Sevilla (http://citius.us.es).

All measurements were conducted using a tandem mass spectrometer with inductively coupled plasma (ICP-MS/MS) using an optimized method for the measurement of TCEs in sediment digests (Klein et al. 2021 (link)). The ICP-MS/MS system consists of an Agilent 8800 ICP-MS/MS (Agilent 8800, Agilent Technologies, Tokyo, Japan) coupled to an ESI SC-4 DX FAST autosampler (Elemental Scientific, Omaha, Nebraska, USA) equipped with an ultra-low penetration air (ULPA) filtration unit (Elemental Scientific, Omaha, Nebraska, USA). For each measurement, the instrument was optimized on a daily basis using a tune solution containing Li, Co, Y, Ce, and Tl (10 μg L⁻¹). Optimal tuning and instrument parameters can be found in the supplemental information Table A.4. An external calibration, covering a concentration range from 0.1 μg L⁻¹ to 100 μg L⁻¹ for all analytes, was used to allow quantification of each element. Each solution for instrument tuning and quantification was prepared from custom-made multielement standards (Inorganic Ventures, Christiansburg, USA) on a daily basis. A solution containing 10 μg L⁻¹ of Ir and Rh was dosed online to the sample solutions to allow for drift correction. To monitor potential carryover effects, wash blanks of 2% (w/w) HNO₃ were measured after each sample triplicate.

Centrifugal ultrafiltration was carried out using Amicon Ultra 0.5-mL centrifugal regenerated cellulose membrane filters, with a 10-kDa molecular weight cut-off (MWCO) (Millipore Co, Carrigtwohill, Co. Cork, Ireland). The samples were ultracentrifuged with a Hermle Z 466 K device with a precooled rotor (4 °C) at a G-force of 12,500g. For preconditioning of the membrane filters and ultracentrifugation of the drug solutions, a centrifugation time of 60 min and 15 min was used, respectively. The filters used for centrifugal ultrafiltration were preconditioned using the solvents with the highest recovery for the drugs, respectively. For KP2156, 50 mM CH₃COONH₄, pH = 6.0 was employed, whereas for KP2157 FCS was used. Flow injection measurements for platinum quantification were performed using an Agilent 1260 Infinity Bio-inert HPLC system (Agilent Technologies, Waldbronn, Germany) coupled to an Agilent 8800 ICP–MS/MS (Agilent Technologies, Tokyo, Japan). The HPLC system was operated with CH₃COONH₄ (50 mM, pH = 6) as eluent, a flow rate of 250 μL/min, and an injection volume of 10 μL. The ICP–MS operation parameters are summarized in Table 1.