PREAMBLE (NOT PART OF THE STANDARD)In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know andspeak the laws that govern them.END OF PREAMBLE (NOT PART OF THE STANDARD)STANDARD METHODS: FOR THE EXAMINATION OF WATER AND WASTEWATER18TH EDITION 1992Prepared and published jointly by:AMERICAN PUBLIC HEALTH ASSOCIATIONAMERICAN WATER WORKS ASSOCIATIONWATER ENVIRONMENT FEDERATIONJoint Editorial BoardArnold E. Greenberg APHA ChairmanLenore S. !le"#er$ WEFAndre% D. E&'on AWWAManaging EditorMary Ann H. FransnPublication OfficeA!"r#$an P%&'#$ H"a'() Ass$#a(#n1*1+ F#,(""n() S(r""(- NWWas)#n.(n- DC 2***+3-16Copyright !", !#$, !#%, and !#& by 'merican (ublic )ealth 'ssociationCopyright !%%, !%*, and !+* by 'merican (ublic )ealth 'ssociation 'merican ,ater ,orks 'ssociationCopyright !&&, !*$, and !*& by 'merican (ublic )ealth 'ssociation 'merican ,ater ,orks 'ssociation ,ater (ollution Control -ederationCopyright !" by 'merican (ublic )ealth 'ssociation 'merican ,ater ,orks 'ssociation ,ater (ollution Control -ederationCopyright !"* by 'merican (ublic )ealth 'ssociation 'merican ,ater ,orks 'ssociation ,ater (ollution Control -ederationCopyright !. by 'merican (ublic )ealth 'ssociation 'merican ,ater ,orks 'ssociation ,ater (ollution Control -ederationCopyright !.& by 'merican (ublic )ealth 'ssociation 'merican ,ater ,orks 'ssociation ,ater (ollution Control -ederationCopyright !.! by 'merican (ublic )ealth 'ssociation 'merican ,ater ,orks 'ssociation ,ater (ollution Control -ederationCopyright !!# by 'merican (ublic )ealth 'ssociation 'merican ,ater ,orks 'ssociation ,ater /nvironment -ederationAll rights reserved. 0o part of this publication may be reproduced, graphically or electronically, including entering in storage or retrieval systems, without the prior written permission of the publishers.%$1"2!#3he 4ibrary of Congress has catalogued this work as follows5'merican (ublic )ealth 'ssociation.6tandard methods for the e7amination of water and wastewater.I680 $9."&&%9#$"9Printed and bound in the United States of America. Composition5 /(6 :roup, Inc., )anover, 1aryland Set in5 3imes ;oman Printing5 'pproved by 6tandard 1ethods Committee, !..3-18())* B. !old,-&.or A'o/$# Ab"or.'$on S.e#'ro/e'r$# Me'0od). Gener&l D$"#+""$on3his method is applicable to the determination of mercury.*. A..&r&'+",hen possible, dedicate glassware for use in )g analysis. 'void using glassware previously e7posed to high levels of )g, such as those used in C?=, 3@0, or Cl analysis.a. Atomic absorption spectrometer and associated equipment5 6ee 6ection %'.*. Instruments and accessories specifically designed for measurement of mercury by the cold vapor technique are available commercially and may be substituted.b. Absorption cell, a glass or plastic tube appro7imately #.&cm in diameter. 'n .+9cm9long tube has been found satisfactory but a &9cm9long tube is preferred. :rind tube endsperpendicular to the longitudinal a7is and cement quartz windows in place. 'ttach gas inlet and outlet ports A*.+ mm diamB .% cm from each end.c. Cell support5 6trap cell to the flat nitrous9o7ide burner head or other suitable support and align in light beam to give ma7imum transmittance.d. Air pumps5 Cse any peristaltic pump with electronic speed control capable of delivering # 4. air2min. 'ny other regulated compressed air system or air cylinder also is satisfactory.e. Flowmeter, capable of measuring an air flow of # 42min.f. Aeration tubing, a straight glass frit having a coarse porosity for use in reaction flask.g. eaction flas!, #&$9m4 erlenmeyer flask or a 8?= bottle, fitted with a rubber stopper to hold aeration tube.h. Dr"ing tube, &$9mm D .9mm9diam, containing #$ g 1g ACl?+B#. ' *$9, light bulb with a suitable shade may be substituted to prevent condensation of moisture inside theabsorption cell. (osition bulb to maintain cell temperature at $EC above ambient.i. Connecting tubing, glass tubing to pass mercury vapor from reaction flask to absorption cell and to interconnect all other components. Clear vinyl plastic> tubing may be substituted for glass.(. Re&gen'"1a. #etal$free water5 6ee %8.%c.b. Stoc! mercur" solution5 =issolve $.%&+g mercuric chloride, )gCl#, in about "$ m4 water, addm4 conc )0?%, and dilute to $$ m4 with water5 .$$ m4 F .$$ mg )g.c. Standard mercur" solutions5 (repare a series of standard mercury solutions containing $ to & Gg24 by appropriate dilution of stock mercury solution with water containing $ m4 cone )0?%24. (repare standards daily.d. %itric acid, )0?%, conc.e. Potassium permanganate solution5 =issolve &$ g @1n?+ in water and dilute to4.f. Potassium persulfate solution5 =issolve &$ g @#6#?. in water and dilute to4.g. Sodium chloride$h"dro&"lamine sulfate solution5 =issolve #$ g 0aCl and #$ g A0)#?)B#)#6?+ in water and dilute to4. ' $H hydro7ylamine hydrochloride solution may be substituted for the hydro7ylamine sulfate.h. Stannous ion 'Sn()* solution5 Cse either stannous chloride, I B, or stannous sulfate,I #B, to prepare this solution containing about ".$ g 6n#J2$$ m4.B =issolve $ g 6nCl# in water containing #$ m4 conc )Cl and dilute to $$ m4.#B =issolveg 6n6?+ in water containing " m4 conc )#6?+ and dilute to $$ m4.8oth solutions decompose with aging. If a suspension forms, stir reagent continuouslyduring use. ;eagent volume is sufficient to process about #$ samples5 adjust volumes prepared to accommodate number of samples processed.i. Sulfuric acid, )#6?+, conc.2. Pro#ed+rea. +nstrument operation5 6ee 6ection %8. +b. 6et wavelength to #&%." nm. Install absorption cell and align in light path to give ma7imum transmission. Connect associated equipment to absorption cell with glass or vinyl plastic tubing as indicated in -igure %#5. 3urn on air and adjust flow rate to # 42min. 'llow air to flow continuously. 'lternatively, follow manufacturerKs directions for operation. 0?3/5 -lourescent lighting may increase baseline noise.b. Standardi,ation5 3ransfer $$ m4 of each of the .$. #.$. and &.$ Gg24 )g standardsolutions and a blank of $$ m4 water to #&$9m4 erlenmeyer reaction flasks. 'dd & m4 conc )#6?+ and #$& m4 conc )0?% to each flask. 'dd & m4 @1n?+ solution to each flask and letstand at least & min. 'dd . m4 @#6#?. solution to each flask and heat for # h in a water bath at !&EC. Cool to room temperature.3reating each flask individually, add enough 0aCl9hydro7ylamine sulfate solution to reduce e7cess @1n?+, then add & m4 6nCl# or 6n6?+ solution and immediately attach flask to aeration apparatus. 's )g is volatilized and carried into the absorption cell, absorbance will increase to a ma7imum within a few seconds. 's soon as recorder returns appro7imately to the base line, remove stopper holding the frit from reaction flask, and replace with a flask containing water. -lush system for a few seconds and run the ne7t standard in the same manner. Construct a standard curve by plotting peak height versus micrograms )g.c. Anal"sis of samples5 3ransfer $$ m4 sample or portion diluted to $$ m4 containing not more than &.$ Gg )g24 to a reaction flask. 3reat as in I +b. 6eawaters, brines, and effluents high in chlorides require as much as an additional #& m4 @1n?+ solution. =uring o7idation step, chlorides are converted to free chlorine, which absorbs at #&% nm. ;emove all free chlorine before the )g is reduced and swept into the cell by using an e7cess A#& m4B of hydro7ylamine sulfate reagent.;emove free chlorine by sparging sample gently with air or nitrogen after adding hydro7ylamine reducing solution. Cse a separate tube and frit to avoid carryover of residual stannous chloride, which could cause reduction and loss of mercury.> 3ygon or equivalent.L Cse specially prepared reagents low in mercury.3-19F#.%r" /11231. S$)"!a(#$ arran."!"n( , "4%#5!"n( ,r !"as%r"!"n( , !"r$%ry &y $'617a5r a(!#$ a&sr5(#n ("$)n#4%".3. !&l#+l&'$on=etermine peak height of sample from recorder chart and read mercury value from standard curve prepared according to I +b.4. Pre#$"$on &nd B$&"=ata on interlaboratory precision and bias for this method are given in 3able %#5.3'84/ %#5. I03/;4'8?;'3?;M (;/CI6I?0 '0= 8I'6 ?- C?4=9