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<br />' •' 1 ~~ ~ III I II I II I II IIII III
<br />999
<br />~~ Designation: D 4374 - 90
<br />Standard Test Methods for
<br />Cyanide In Water-Automated Methods For Total Cyanide
<br />And Dissociable Cyanide'
<br />This standard is issued under the fixed deigna[ion D4374; tht number immcdialely following the designation indicates the ?ear of
<br />original adoption or, in the eau of revision, the year of last revision. A number in parentheses indicates she year of last reapprc val. A
<br />superscript epsilon (<) indicates an editorial change sintt the lazt revision or reapproval.
<br />1. Scope
<br />I.I These test methods cover the determination of dif-
<br />ferent species of cyanides in water and waste water, namely,
<br />dissociable cyanide, and total cyanide (1, 2).2
<br />l.l.l Dissociable Cyanide-This test method basically
<br />determines free cyanides, as CN- and HCN, and weak
<br />metal-cyano-complexes such as [Cd(CN)4]~- and
<br />[Mn(CN)4]3-. Iron complexes are not included.
<br />1.1.2 Total Cvanide-This test method determines all the
<br />acid dissociable cyanides and the strong metal-cyano-
<br />complexes, such as ferrocyanide [Fe(CN)6]4-, ferricyanide
<br />[Fe(CN)b]3', hexacyanocobaltate [Co(CN)6]3-, and those of
<br />gold and platinum.
<br />l.2 Cyanide complexes, like those of iron, cobalt, etc„ can
<br />be determined by difference, that is, C anide Com lexes =
<br />Total Cyanides -Dissociable Cyani es.
<br />otal cyanide measurement includes also all the
<br />thiocyanates. However, the thiocyanate could be determined
<br />(3, 4, 5) and subtracted if so desired.
<br />1.4 Cyanates and cyanogen halides are not detected.
<br />cyanogen chloride hydrolyses to cyanate at the pH of sample
<br />preservation (a 12).
<br />I.5 Most of the organo-cyano-complexes are not mea-
<br />sured, with the exception of the weak cyanohydrins.
<br />l.6 These test methods apply to different types of water
<br />samples, namely drinking water, natural surface and ground
<br />water, saline water, raw sewage, treated effluents, and some
<br />industrial wastes. Other sample matrixes should be evaluated
<br />by the user. The reported precision and biaz (see Section 15)
<br />may not apply to other waters.
<br />1.7 This standard does not purport to address all of the
<br />sajefy problems associated with its use. /t is the responsibility
<br />ojt/le user ojthis standard to establish appropriate sajefy and
<br />ltealrh practices and determine flee applicabi(ify ojregulatory
<br />limitations prior to use. Specific precautions are given in
<br />Section 9.
<br />2. Referenced Documents
<br />2.1 ASTM Standards:
<br />D 1 129 Definitions of Terms Relating to Water'
<br />D 1193 Specification far Reagent Water3
<br />These test methods are und<r the jurisdiction of ASTM Committee 619 on
<br />Wamr and are the direr responsibility of Subcommittee D19.06 on Meshods for
<br />Analysis for Orgpnic Subsunces in water.
<br />Current edition approved May 25. 1990. Published November 1990. Originally
<br />published as D 4174 - 84. lass previous edition D 4374 - 86.
<br />-'The boldfatt numbers in parentheses refer to the list of references appended
<br />to this sandard.
<br />a .4ncual BaoA of.4STAf Standards. Vol 11.01.
<br />WX ~~\Y ~Ir~
<br />D 2036 Test Methods for Cyanides in Vlater4
<br />D 3370 Practices for Sampling Water'
<br />D 3856 Guide for Good Laboratory Pra~:tices in Laborato-
<br />ries Engaged in Sampling and Analysis of Water'
<br />D 3864 Guide for Continual On-Line M onitoting Systems
<br />for Water Analysis}
<br />D4193 Test Method for Thiocvanate in Water"
<br />D 4210 Practice for Interlaboratory Quality Control Proce-
<br />dures and a Discussion on Reporting Low-Level Data'
<br />3. Terminology
<br />3.1 Definitions-For definitions of terns, refer to Defini-
<br />tions D 1129.
<br />3.2 Descriptions ojTerms Specific to T his Standard.'
<br />3.2.1 Acid Dissociable Cvanide-Und:r the defined e~-
<br />petimental conditions (Sections 4, 10, and I I), this param-
<br />eter determines the free cyanides, HCN and CN-, and the
<br />weak cyanide complexes. Iron complexes are not included.
<br />3.2.2 Total Cvanide-In addition to all the acid
<br />dissociable cyanides, the strong cyanide complexes are in-
<br />cluded, such as those of iron and cobalt.
<br />3.2.3 Distillation Ratio, % _
<br />Volume of Distilled Portion of Sarr ple x 100
<br />Total Sample Volume
<br />4. Summary of Test Methods
<br />4.1 Some automated continuous flow modules are used
<br />(see Guide D 3864) in addition to the newly developed on-
<br />line Thin Film Distillation (6) and Ultra~riolet Irradiation.
<br />4.2 Three factors control the separation of cyanides from
<br />the samples, namely (a) acidification, (bl air stripping. anal
<br />(c) thin film distillation (7.2 and 7.3). The classic use ai
<br />condensers in distillation units was found to be disadvanu-
<br />geous, and has been eliminated, because a considerable
<br />amount of the liberated HCN gas is reFl axed back with the
<br />condensed water and thus not recovered.
<br />4.3 Acidification is made to pH<I, but the sample
<br />exposure to heat treatment in the continuous thin film
<br />distillation is very short (few seconds). Tt1us the liberation ni
<br />HCN is only from the free cyanides amt the weak cyanide
<br />complexes, that is, the dissociable cyanides, and no[ from the
<br />strong complexes.
<br />4.4 For total cyanides the breakdown of the strong c~3-
<br />nide complexes, prior to the thin film distillation, is achietr'd
<br />by ultraviolet irradiation (7).
<br />4.5 Absorption of the liberated HCl` gas is carried ool
<br />Annual BooA ofASTtif Standards, Vol 11.02.
<br />104
<br />using a gl
<br />(7.4).
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