Solaar m6

Seeds were grown on 1/2 MS medium with or without 50 μM CdCl₂ for two weeks and their seedlings were then sampled for analysis of Cd content. Cd content was carried out according to the method described by Lee et al. [14 (link)] (2003). Digested samples were measured using an atomic absorption spectrometer (Solaar M6;Thermo Fisher). Two-week-old seedlings grown on 1/2 MS medium were treated with or without 50 μM CdCl₂ for 24 h and then sampled for analysis of GSH/GSSG/PC contents. GSH/GSSG/PC contents were quantitated as described by Chen et al. [37 (link)].

The content of zinc in soil fractions was determined by means of an atomic absorption spectrometry with a flame (air-acetylene) atomization (Solaar M6, Thermo Scientific, UK). A zinc hollow cathode lamp (LabHut, UK) was operated at 10 mA current. The integrated absorbance signal of zinc was measured at 213.9 nm with a slit width of 0.2 nm using deuterium background correction.
The external calibration technique based on reagent-matched standard solutions was used for zinc quantification by FAAS.
An ultrasound probe, VCX 130 model (Sonics and Materials, USA) (max. power 130 W, max. frequency 20 kHz) was used in pulsed mode (on/off, 15 s/15 s) in USE procedure. The system during sonication was cooled down with flowing tap water. A centrifuge, MPW 250 model (Med. Instruments, Poland), was used for the centrifugation of extracts of soil samples.

After 20 days of Cd treatment, Cd content, plant height, root length, leaf width, leaf length, biomass, and chlorophyll content were measured. For determination of Cd content, plants were dried and used to estimate Cd content using a SOLAAR M6 atomic absorption spectrometer (Thermo Fisher Scientific, MA, USA), according to the methods described by She et al. [10 ].
The top fourth leaf was used for chlorophyll content determination. Fresh leaves (0.01–0.02 g) were collected and immediately soaked in 95% ethanol, under dark conditions. The chlorophyll content was determined according to the methods described by Sales et al. [21 (link)].

The WT, PSE1-OE, and pse1-1 mutant plants were grown on 1/2 MS medium in the absence or presence of 0.5mM Pb(NO₃)₂ for 2 weeks and then sampled to determine the Pb content, which was analysed using the method described by Kim et al. (2006) (link). Digested samples were analysed using an atomic absorption spectrometer (Solaar M6, Thermo Fisher, Waltham, MA, USA). A standard reference material was not used to assess the efficiency of the acid digestion procedure; therefore, while the relative concentrations of Pb in WT, PSE1-OE, and pse1-1 mutant plants are reliable, the actual concentrations reported may be less than the true values.

In the batch adsorption experiments, a weighed quantity of the silica-based adsorbent was mixed with 3.0 M HNO₃ solution containing 15 mM Pd(II). The ratio of solid phase to liquid phase was 0.1 g to 5 cm³. Then the mixture was shaken at 160 rpm for different contact time. After the phase separation by vacuum filtration, concentrations of Pd(II) in the separated solution were analyzed by AAS (Thermo Scientific SOLAAR.M6). The distribution coefficient (K_d, cm³/g) in the adsorption process was calculated as follows: $${\mathit{K}}_d=\frac{{\mathit{C}}_0-{\mathit{C}}_t}{{\mathit{C}}_{\mathit{t}}}\times \frac{\mathit{V}}{\mathit{m}}$$ where C₀ and C_t are initial and residual metal ion concentrations in liquid phase in mg/dm³ (ppm). V is the volume of solution in cm³ and m is the weight of adsorbent in g.

Sediment samples were freeze-dried for at least 24 h and then ground to pass through a 160 mesh sieve using an agate mortar and pestle. For metal analysis, samples were digested with the mixture of HNO₃ and HClO₄ as described by Cai [27 (link)]. Samples were then examined for Cu, Pb, Zn, Cd and Cr concentrations using an atomic absorption spectrophotometer (SOLAAR M6, Thermo Fisher Scientific, Waltham, MA, USA). Redox potential (Eh) was recorded in situ using a potentiometer. Granulometry was determined using a Mastersizer 2000 laser particle size analyzer. Organic carbon was measured based on potassium dichromate oxidation–ferrous sulphate titrimetry and sulfide was measured by iodimetry.