Automatic flow system for simultaneous determination of iron and chromium in steel alloys employing photometers based on LEDs as radiation source

Abstract

A multicommutated flow system for simultaneous determination of iron and chromium in steel alloys by photometry is described. The flow network consisted of an automatic injector and four solenoid valves assembled to form two independent analytical pathways, each one comprising reaction coils and a flow cell. The light source (LED) and detector (photodiode) were attached to the flow cells to form a compact unit. The flow system was microcomputer controlled by Quick BASIC 4.5 software, which carried out all steps of the analytical procedure. The feasibility of the system was proved by the determination of iron and chromium in steel alloys and its accuracy was accessed by comparing results with those obtained by plasma atomic emission spectrometry (ICP-AES). No significant difference at the 95% confidence level was observed.Other profitable features such as low reagent consumption (0.33 mg 1,10-phenantroline and 0.03 mg 1,5-diphenylcarbazide per determination); relative standard deviations (n ¼ 5) of 0.4% for iron and 1.2% for chromium; and an analytical throughput of 160 determinations per h were also achieved.

Multi‐commutation in Flow Analysis: A Versatile Tool for the Development of the Automatic Analytical Procedure Focused on the Reduction of Reagent Consumption

“…[48,49] Employing these facilities, the photometer and the flow system manifold were designed to comprise a compact instrument with little dimension, which could be housed in a metallic box with dimension of 30 Â 20 Â 15 cm. [50,51] Most works based on the multi-commutation process employed peristaltic pump for fluid propelling, however it was proved that gravity acceleration could be also employed.…”