Z 5000 atomic absorption spectrometer

Red mature fruit (76 days after anthesis, DAA) along with their stalks (including the pedicle) were sampled randomly from the same bearing shoots in the same tree. The fruit samples were sectioned into the top pericarp (top 1/3 of fruit length, TP), the middle pericarp (central 1/3 of fruit length, MP), the basal pericarp (basal 1/3 of fruit length, BP), fruit base (the knob-like end of the fruit adjoining the calyx and the pericarp base, FB), calyx ring (C), and 5-mm segments of fruit stalk (including the pedicel), which were indicated by S1, S2, S3, and S4 according to their distance from the calyx ring (Figure 1). The corresponding sections from 10 randomly selected fruit were pooled as one replicate and oven dried at 65°C for 48 h, and their dry weights were collected before Ca analysis. The dried tissues were ground into powder. The powder was transferred to a 10 ml melting pot, burnt on an electric stove until smoking stopped, and ashed in an ashing furnace at 550°C for 5 h. The ash was dissolved with 0.1 N HCl solution and set to 25 ml for measuring Ca concentration using a Hitachi Z-5000 atomic absorption spectrometer. The analysis was conducted with five replicates (n = 5).

The release of silver from the AgNPs-PEM-SS/Agar film was measured on a Z-5000 atomic absorption spectrometer (Hitachi, Japan) using the N₂O acetylene flame AAS method. The AgNPs-PEM-SS/Agar films with a dimension of 1.5 cm in length and 1.5 cm in width were immersed into 0.01M PBS buffer (pH 7.4) at 37 °C. The PBS solution was collected for ICPAAS measurement at regular intervals. Then fresh PBS buffer was added after each measurement. Different AgNO₃ concentrations (0.5–10 mg/L) were prepared for the calibration curve. All experiments were carried out in triplicate.