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oaila~e2 ia::a aaor ash 6420 ASCI VAKCOtJVER »». P Y H65 ®ooeioi~ <br />A S C 1 <br />3.3 Absence of ifltratfon <br />3.3.t General pnctlcs <br />It Is normal Oractica to filter aqueous samples through a 0.45 micron filter H the amourtt of a <br />spaeiea in solutlon la being datem+ined. This procedure will not rsmova day sits psrtielaa <br />and colloids leas than 0.46 micron In dlamanr. <br />However, if the 'total' amount of a species is required, the sample is not filtered, Thls <br />protoeot is predicated on the feet that The tolids !n tlw aampla era relatively small and that <br />particulate matter not dissolved when the sample Is preserved does not effect the anelytlcal <br />method for the epeeles being determined. <br />3.3.Z Lyelmeter L3 sample <br />The lyslmeter samples tolleaetl from L3 were not filtered, presumably on the belie that <br />'total', tool cyanide was to ba determined on the samples. As has been noted In section <br />3. t and 3.2, the lyslmster samples will likely Carry relatively higher amounts of paRleulate <br />matter Inetudinp clay sl:e material and eolloide, due to their small volume than would <br />normally be expected In a one Ilue aqueous sample collected for cyanide analysle. Non <br />filtration of the lyslmeter samples will mean that there Is an enhanced potential Tor <br />interference In the eutoanalyaer analytleal metnotl as compared with normal aqueous <br />samples. <br />3.4 Anatytiesl method for total cyanide <br />3.4. t Autoanalyser method for total eyanlde <br />The autoanalyser method for total eyanlde, (USEPA Method 9072 / APHA-AydWA Standard <br />Methotl, Method 335.3 involves degradation of cyanide complexes in phosphoric acid and <br />UV light and measurement of the reaultlnp eyanlde complex with pyridine end barbiturlc acid <br />eolourimeuieally at 6800 ^npetroma. The lower IImIt for detection of cyanide, Ibut not <br />quantlllcatlonl. under Ideal solutlon conditions u given as 0.005 mp/L with a senaldvltV of <br />0.01 mpA.. The method require Doty 2 mis Of sample par determinatlon. <br />The method Is subject to interferenes by thloeyanates, sulphides or reduced sulphur species <br />which affect the tolourimetry, particulates (Including colloidal in the eemple which cause <br />light scattering In the photometry, sod ionic svenpth of Me sample matrix which can give <br />matrix Interference In the photometry If not matched correctly with the standards aced for <br />callbratlon. <br />