Laserfiche WebLink
<br />ANALYTICAL -GENERAL <br />The method is highly recommemied for monitoring the effluent of the Inco pn~cess <br />since it is simple to do (once the picric acid reagent has been prepared;) and any <br />procedural errors will result in an assay biased high; whereas, any procedural errors in the <br />distillation methods will bias the assay low. If the Inco Process has lost its catalytic <br />activit}~, an orange colour may develop instantly upon addition of the picric acid reagent <br />due to an SO3 interference (unoxidized SO2 in solution). The interference can be <br />removed by adding CaC12 which will precipitate the SOj as CaSd~. The precipitate must <br />be filtered out prior to using the colorimeter. If the SO,' is not precipitated out of <br />solution the final result may be biased slightly high. <br />IV Safetv Precautions <br />Solutions of picric acid (trinitrophenol) are safe in ordinary laboratory use. <br />However, in dry form the acid and especially some of its salts have explosive properties. <br />This requires that all picric acid solutions be thoroughly washed down a sink with water. <br />Spills must be carefully wiped up. Picric acid has the tendency of staining the skin, and <br />wearing protective hand gloves is therefore recommended. Glass stained by picric; acid <br />is best washed with methanol or acetone. <br />V Direct Colorimetry (8 - 160 ua CN'} <br />Measure the absorbance of solutions more deeply coloured than the reagent blank <br />at 520 nm using the reagent blank as the reference (Note 3). <br />VI Calibration and Samvle Analysis <br />The following pages are self-contained analytical sections that desribe the <br />various tests needed to operate the Inco System effectively. They are located on <br />separate pages so that they may be copied and posted for easy reference. The <br />pages in order of appearance are: <br /> <br />wv~wnumcam fI <br />