I recently viewed a Pittcon 2015 video (you can start the video below by click the Play button) that reminded me of the time-saving advantages of a fully automated combustion ion chromatography analytical system that measures total halogens (F, Cl, Br, and I) and speciates sulfur in solid, gas, and liquid samples. The technique provides accurate and reproducible results for pharmaceutical raw materials and finished products, polymers, wood, petrochemicals, ores, inks, metals, polishing agents, lubricating oil, and electronic components, often in less than 12 minutes with minimal method development.
Interest in halogens and sulfur is of importance because they are corrosive and can damage industrial equipment, poison catalysts, and damage sensitive electronic components. Many countries also regulate the amount of halogens released into the environment. The Restriction of the Use of Certain Hazardous Substances (RoHS) compliance requires the elimination of brominated flame retardant compounds (BFRs) which were formerly widely used in polymer formulations, such as those used in printed circuit boards. The demonstrated lack of bromide in a sample proves that the material is in compliance with the RoHS prohibition of BFRs.
Sample preparation needed to extract analytes or remove interfering matrices can be performed directly by automated combustion IC, saving time and labor for determination of halogens and sulfur in difficult matrices – intractable solids, semisolids, liquids, and gases. Under high temperature, halogens are pyrolized in an oxidizing atmosphere and converted to volatile HX and X2 and the sulfur to SOx. These volatile products are trapped in an aqueous solution which can subsequently be analyzed by ion chromatography to give the concentrations of individual halides and sulfur species (e.g., sulfite, sulfate, and thiosulfate). A total sulfate can be measurement can be determined by further oxidizing the sulfur species using hydrogen peroxide.
Below are results of the technique using a standard mixture of fluoride, chloride, carbonate, and sulfate prepared in xylene and absorbed into aqueous hydrogen peroxide. Analysis was performed on an integrated ion chromatography system (Thermo Scientific Dionex ICS-2100 system with suppressed conductivity detection) and an ion chromatography column (Thermo Scientific Dionex IonPac AS15 anion exchange column).
Figure 1 shows results of overlaid standards: 0, 10, 50, and 100 µg/L (ppb). Figure 2 shows run-to-run reproducibility of 0.08% RSD for the method where consecutive, repeat injections of a low concentration sample (approximately 50 ppb) are compared. Click the images to display in separate browser window.