Versatile Flow Injection System for Spectrophotometric Determination of Silicon in Agronomic Samples

Abstract

A versatile flow injection system for spectrophotometric determination of silicon (Si) in agronomic samples is proposed. For plant and slag analysis (1.0-10.0 mg L 21 Si), the method involves monitoring the yellowish molybdosilicic acid at 410 nm. Soil, fertilizer, water, and sugarcane juice analysis (0.5-5.0 mg L 21 Si) were accomplished by adding a reducing agent, and the molybdenum blue compound that formed was monitored at 735 nm. Flexibility of the method allows determination in a variety of matrices involving a wide range of concentrations. Beer's law is followed up to 20.0 mg L 21 Si (r , 0.9997; n ¼ 6) for analysis at 410 nm and up to 10.0 mg L 21 Si (r , 0.9998; n ¼ 6) at 735 nm. For the yellow-color and blue-color methods, the detection limits were estimated as 0.5 and 0.1 mg L 21 Si. Measurement frequency for both methods is approximately 75 h 21 using 48 mg of ammonium heptamolybdate, 80 mg of oxalic acid, and 24 mg of ascorbic acid per determination. Results are precise (r.s.d. . 0.1%, n ¼ 10) and in agreement with inductively coupled plasma-optical emission spectroscopy (ICP-OES). Statistical differences between data sets were not confirmed after applying the Student's ttest at the 95% confidence level (t exp ¼ 0.195 . t tab ¼ 2.57) related to n ¼ 6.

Root traits predict decomposition across a landscape‐scale grazing experiment

“…C and N concentrations were determined by elemental analysis (NA 1500 Series 2; Carlo-Erba, Stanford, CA, USA). Ca, P and K concentrations were determined by sulphuric acid/hydrogen peroxide digestion, followed by ammonium molybdate/ascorbic acid colorimetric determination using flow injection analysis (FIAstar spectrophotometer 5023; Tecator, H€ oganas, Sweden) for P, and flame atomic absorbance spectrometry (Atomic Absorption Spectrophotometer Analyst 100; Perkin Elmer, Waltham, MA, USA) for Ca and K. Silica concentrations were assessed using an alkaline sodium hydroxide/hydrogen peroxide digest followed by determination of concentrations using flow injection analysis (Carneiro et al, 2007). Root lignin and lignin-like substances were assessed using a sulphuric acid digestion method with the remaining oven-dried, acid-insoluble residue operationally defined as the root lignin and lignin-like fraction (Woodin et al, 2009).…”

Genetic mapping of the rice ionome in leaves and grain: identification of QTLs for 17 elements including arsenic, cadmium, iron and selenium

“…Leaf sample preparation for silicon analysis by FIA Samples were prepared for silicon (Si) analysis as described by Carneiro et al (2007). Briefly, dried ground leaf (0.02 g) was weighed into polyethylene centrifuge tubes and 0.6 ml of hydrogen peroxide and 1.5 ml of 50% sodium hydroxide were added.…”

Genotypic differences in shoot silicon concentration and the impact on grain arsenic concentration in rice

“…Plant material and certified reference material (CRM) were prepared for silicon analysis as described by Carneiro et al. (). A total of 1.5 g shoot material from each sample were sub‐sampled at random and powderised using a ball mill (Retsch, MM200, Germany).…”

“…Prior to analysis, samples were diluted 1 : 5 with Milli‐Q water. Silicon concentration was measured using an FIA spectrophotometer (Tecator FIAstar 5010) at a wavelength of 410 nm ( Carneiro et al., ; Norton et al., ; ).…”