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MERCURY IN SEDIMENT Method 245.5 (Manual Cold Vapor Technique) I Scope and ApphcatIOn I I ThIS procedure(!) measures total mercury (organIc t InorganIc) In sOlIs, sedIments, bottom depOSIts and sludge type materials I 2 The range of the method IS 0 2 to 5 ug/g The range may be extended above or below the normal range by IncreaSIng or decreaSIng sample SIze or through Instrument and recorder control 2 Summary ofMethod 2 I A weIghed portIOn of the sample IS dIgested In aqua regIa for 2 mInutes at 95°C, followed by oXIdatIOn wIth potaSSIUm permanganate Mercury In the dIgested sample IS then measured by the conventIOnal cold vapor technIque 2 2 An alternate digestIOn(2) InvolVIng the use ofan autoclave IS descnbed In (8 2) 3 Sample Handhng and Preservation 3I 32 Because of the extreme senSItIVIty of the analytical procedure and the omnIpresence of mercury, care must be taken to aVOId extraneous contamInatIOn Samphng deVIces and sample contaIners should be ascertaIned to be free of mercury, the sample should not be exposed to any condItion In the laboratory that may result In contact or aIr-borne mercury contamInatIOn WhIle the sample may be analyzed WIthout dryIng, It has been found to be more convenIent to analyze a dry sample MOIsture may be driven off In a dryIng oven at a temperature of 60°C No mercury losses have been observed by USIng thIS drymg step The dry sample should be pulverized and thoroughly mIxed before the ahquot IS weIghed 4 Interferences 4 I The same types of Interferences that may occur In water samples are also pOSSIble WIth sedIments, 1 e , sulfides, hIgh copper, hIgh chlOrides, etc 4 2 Volatile materials whIch absorb at 253 7 nm WIll cause a pOSItIve Interference In order to remove any Interfenng volatIle materials, the dead aIr space In the BOD bottle should be purged before the addItion ofstannous sulfate 5 Apparatus 51 AtomIC AbsorptIOn Spectrophotometer (See Note 1) Any atomIC absorptIOn UnIt haVIng an open sample presentatIOn area In whIch to mount the absorptIOn cell IS SUItable Instrument settIngs recommended by the partIcular manufacturer should be followed NOTE 1 Instruments deSIgned speCIfically for the measurement of mercury USIng the cold vapor technIque are commerCIally avaIlable and may be substItuted for the atomIC absorptIOn spectrophotometer Issued 1974 2455-1PDF Image | Methods for Chemical Analysis of Water and Wastes
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