Ice 3000 series aa spectrometer

The water samples for oxyfluorfen quantification were concentrated via solid phase extraction (SPE) according to [53 (link)]. Moreover, oxyfluorfen was quantified on tissues according to the method described in [54 (link)]. Then, oxyfluorfen concentrations on water and tissue were achieved via gas chromatography equipped with an electron capture detector (GC-ECD), namely Agilent 7890 B (Wilmington, DE, USA); the procedure was based on the method described in [55 (link)]. The detection limit (LOD) was 3.53 μg L⁻¹ and the quantification limit (LOQ) was 10.68 μg L⁻¹.
Regarding Cu quantification, the preparation of water and tissue samples was performed according to the procedure described in [56 (link)]. Briefly, water samples were acidified with supra pure nitric acid Pro Analysis MERCK^® (65%) (Algés, Portugal) to a pH below 2 and stored at 4 °C until the chemical analyses, and the tissues were dried, weighed and digested with nitric acid; after, the organic matter was destroyed with hydrogen peroxide. Cu concentrations were measured via flame atomic absorption spectrophotometry (ICE3000 Series AA Spectrometer—Thermo Scientific—Winsford Cheshire, UK). The LOD was 6.60 μg L⁻¹ and the LOQ was 19.99 μg L⁻¹.
The measured concentrations of each pesticide are presented in Table 1.

We added 5 mL of 0.1 M nitric acid to the honey, and the mixture was stirred on a heating plate until nearly dry. Subsequently, an additional 10 mL of the same acid was added, and the mixture was adjusted to a total volume of 25 mL with ultrapure water [50 (link)]. The mineral components were determined using atomic absorption spectrometry (Thermo Scientific ICE 3000 Series AA Spectrometer, Waltham, MA, USA). Prior to analysis, the instrument was calibrated with known concentrations of K (0.1–5 mg/L), Na (0.1–5 mg/L), Ca (0.1–5 mg/L), Fe (0.1–5 mg/L), Cu (0.5–4 mg/L), Zn (0.1–2 mg/L), Pb (0.1–4 mg/L), Cd (0.1–2 mg/L), and Ni (0.1–5 mg/L).

The cadmium standard curve (Abs = 0.46900C + 0.019858, R² = 0.997) was plotted using the Cd standard solution. B. juncea roots and leaves were prepared and digested according to the approach of Jiang et al. [40 (link)] and the Cd content was determined by Thermo Scientific iCE 3000 Series AA Spectrometers with three biological replicates. Thirty plants were randomly selected from each treatment group to measure the shoot height and root length with a ruler according to Ling et al. [89 (link)]. The dry weights of aboveground and underground parts were measured respectively according to Matse et al. [90 (link)]. Cut off the plant at the base of the stem with a blade and put it into an oven to dry to constant weight. Use an analytical balance to weigh the dry weight of the aboveground part and the underground part, respectively. The cell activity of root tip was determined by Evans blue staining according to Liu and Lin [91 ]. The root tip material was stained with 0.25% (w/v) Evans blue for 24 h, and photo-graphed under stereometric microscope. The data were analyzed by ANOVA using origin 9.1 software. The differences at p < 0.05 were shown to be significant by the LSD test.

B. juncea leaves were digested based on the method of Jiang, et al. [88 (link)], and the Cd content was assayed by iCE 3000 Series AA Spectrometers (Thermo Scientific, USA) with three biological replicates. The Cd standard curve (Abs = 0.46900C + 0.019858, R² = 0.997) was plotted using the Cd standard solution (China national standard sample no. GSB04–1721-2004).