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Od/10/A2 11:22 '680d ABd 8628 ASCI yANCOtJI'ER »»» P >i 11&5 Qj00S/014 <br />A f C 1 <br />The 'normal' amount of sodium hydroxide added to one Titre of aqueous solution, six to <br />•Ipht standard pallets, is about 2 puma In weight. ThIS rstulu In an Increase In the total <br />dissolved solids (TD5) of the aolution by about 2000 mp/L, which la usually Iruuffklem to <br />cause problems with analysts, (see section 9.4 betowl. <br />(Furthermore, an increase of sample pH to above 1I will cause precipitation of such species <br />•s iron, manganese, aluminum and silica H these are prosent in aolution in the sample. Thla <br />will increase the amount of particulate matter in the aample, including the colloidal species <br />which would not ba either necessary visible Or filterable from the aample. <br />3.2.2 Lyclmeter L3 samples <br />The smell sample volumes retrieved from lysimater L3 and the feet that the same amtlunt of <br />sodium hydroxide was atldsd to these samplee as would normally be atldatl to one litre of <br />sample moons that the TDS and ionic svenpth of the lytimeter sample will ba substantially <br />different from that which might be antlclpated by the analytical laboratory and eYrtalnly <br />dlHerent from the analytical standards uced for calibratlnp the aut0analyser used for total <br />cyanide determinations. <br />For the three samples collected from the Ivsimeter L3, the TDS values would Nava increased <br />from perhaps several hundrod mp/L to 17,000 mp/L, 100,000 mp/L end 400,000 mp/L <br />respectively. The letter two samples become essentially brines, (seawater has a TDS Of <br />about 35,000 mp/Ll, and the third aample It syrup at 4096 colids. Such high TOS and Ionic <br />strengths will have an Impact on the analysis of these samples for cyanide. <br />Ths amount of sodium hydroxide added to the aqueous lyaimeter samplee would Increase <br />the sample pH far higher than the pH 12 normally targeted for preservation of Cyanlda <br />samplee, probably to pH 14 or beyond. This would <br />potential eauae major changes in the solubility of many of the major ion species in aolution, <br />with precipltstlon being a common nsuR. For example, at these pH values magnesium will <br />prsclpltate ss a hydroxide, some of which will be colleidel due to the solution ionic strength. <br />Once again, such praclpltatlon will have the potential to effect the autoanalyser method for <br />total cyanide, lase section 3.4 betowl. <br />As concluded by Smitn and Mudder, 119911, • the (mine) operator should aasesi carefully <br />the effect of any end etl preservatives on his particular samplee prior to entering a loop term <br />analytical pro0rem for cyanide', (Pape 24, eectlon 2.2.1. <br />