EPA-67Q/2-74-007
March 1974
Environmental Protection Technology Series
        Physical,  Chemical, and  Microbiological
             METHODS  OF  SOLID WASTE  TESTING
                       Four Additional Procedures
                                 National Environmental Reset
                                   Office of Research and Development
                                  U.S. Environmental Protection Agency
                                          Cincinnati, Ohio 45268

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                                    EPA-67012-74-007
                                        March 1974
Physical
Chemical and
Microbiological
METHODS OF
SOLID WASTE TESTING

Four Additional  Procedures
by Nancy S. Ulmer
Program Element No 1OB064
      SOLID AND HAZARDOUS WASTE RESEARCH LABORATORY
         NATIONAL ENVIRONMENTAL RESEARCH CENTER
          OFFICE OF RESEARCH AND DEVELOPMENT
          U.S. ENVIRONMENTAL PROTECTION AGENCY
               CINCINNATI, OHIO 45268

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                       REVIEW NOTICE
         The National Environmental  Research Center,  Cincinnati, U.S.
Environmental Protection Agency, has reviewed this report and approved its
publication.  Mention of trade  names or commercial products does  not
constitute endorsement or recommendation for use.
                                 11

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                           FOREWORD
         Man and his  environment must  be protected  from the adverse
effects of pesticides, radiation, noise and other forms of pollution, and the
unwise  management of solid waste. Efforts to protect the environment
require a focus that recognizes the interplay between the components of our
physical environment - air, water,  and land. The  National Environmental
Research Centers  provide  this multidisciplinary  focus through programs
engaged in
              •    studies on the effects of environmental contaminants on
                   man and the biosphere, and
              •    a search  for  ways  to  prevent contamination and to
                   recycle valuable  resources.
         In  May   1973,  the  Solid   and  Hazardous  Wastes  Research
Laboratory published a  manual  "Physical, Chemical,  and Microbiological
Methods for Solid  Waste Testing" (EPA 6700-73-01). It was not intended to
be a  complete manual,  but  the  first edition of a growing  collection of
methods used to  characterize refuse, compost,  incinerator residues and
wastewaters, landfill leachates, and related water samples. This publication is
the first manual supplement  and  presents for the first  time procedures for
determining (a)  chloride in solid wastes, incinerator  wastewaters, landfill
leachates, and  related water samples; (b) total  phosphate in solid wastes; and
(c) total and orthophosphate in refuse extracts, landfill leachates,  and related
water samples.

                                            A. W. Breidenbach, Ph.D.
                                            Director
                                            National Environmental
                                            Research Center, Cincinnati
                               111

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LABORATORY PROCEDURE FOR DETERMINING THE CHLORIDE
         CONTENT OF INCINERATOR WASTEWATERS,
   LANDFILL LEACHATES, AND RELATED WATER SAMPLES

                        Nancy S. Ulmer*
    DISCUSSION	  2
    EQUIPMENT	  2
    REAGENTS  	  3
    SAFETY PRECAUTIONS  	  3
    STANDARDIZATION	  3
    SAMPLE PREPARATION  	  4
    PROCEDURE   	  5
    CALCULATIONS  	  5
    METHOD EVALUATION  	  6
    ACKNOWLEDGMENTS  	10
    REFERENCES	10
    •"Research Chemist, Criteria Development Branch, Water Supply Research Laboratory,
    National Environmental Research Center - Cincinnati; Miss Ulmer was formerly with
    the Solid and Hazardous Waste Research Laboratory of NERC - Cincinnati.

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 METHODS OF SOLID WASTE TESTING


                                      DISCUSSION


  The significance of  chloride ion as a solid  waste  characteristic becomes apparent when one
considers the  impact  of the discharge of highly reactive incinerator waters and landfill leachates to
the environment. The direct effect of chloride  on  the  receiving medium  is, of course, a chemical
degradation. Indirect  effects, biological in nature, may also occur. Thus, a knowledge of the chloride
content  of incinerator  scrubber, quench, and clarifier  wastewaters; landfill leachates; and  related
water samples is of value to those persons developing and evaluating water treatment processes in
solid waste management systems.
  Chemists have employed a variety of titrimetric, potentiometric, and colonmetric methods for the
determination of chloride  in water and  wastewater (1,2). The procedure recommended  here is a
mercuric nitrate titration. In the pH range of 2.3 to 2.8, diphenylcarbazone indicates the end point of
the titration by  forming a deep purple complex with excess mercuric ion. The error in the titration is
about 1 percent of the titrant volume used per change of 0.1 pH unit, in the pH range of 2.1 to 2.8.
                                      EQUIPMENT


1.   Balance, analytical, 0.1 -mg readability
2.   Bar, magnetic stirring, approximately 14 mm (9/16 inch) long
3.   Beakers, Pyrex, 250-ml
4.   Blender, e.g., Waring® no. 700
5.   Bottles, liquid storage, Pyrex, amber, 1-gal (~ 3.8-hters), with screw-cap lid
6.   Bottles, reagent, Pyrex, amber, 500-ml
7.   Bottles, reagent, Pyrex, 250-ml and 1-liter
8.   Bottle, weighing;  low  form; cylindrical with  standard  taper  cap; height, 30mm; inside
     diameter, 60 mm
9.   Buret, 50-ml, with a fine tip, dispensing drops 0.025 ml or less in volume
10.  Buret, micro, 5-ml, with a fine tip, dispensing drops 0.01 ml or less in volume
11.  Desiccator, either Pyrex or small stainless-steel cabinet-type
12.  Filters, cellulose ester, 0.45ju-pore size, 47-mm-diameter (e.g., Millipore Corp. type HA)
13.  Filter holders, hydrosol stainless, (e.g.,  Millipore Corp. no. XX20-047-20)
14.  Flasks, filtering, Erlenmeyer form with side arm, 250-ml
15.  Flasks, volumetric, 500-ml,  l-liter, and  2-liter
16.  Meter,  pH (e.g., Corning, Model 7 with Corning  pH electrode no. 476022 with triple-purpose
     glass  membrane and Corning reference calomel electrode no.  476002 with asbestos junction; a
     silver electrode, Corning no. 476065, is suggested if the chloride concentration of the unknown
     solution is low)
17.  Pipets,  Pyrex, serological, 1-ml and 5-ml
18.  Pipets,  Pyrex, volumetric, 5-, 10-, 15-, and 20-ml
19.  Spatula, stainless-steel (e.g., Scoopula,® Fisher Scientific Co. no. 14-357)
20.  Stirrer, magnetic, round (e.g., Fisher Scientific Co. no. 14-511-1)
21.  Support, buret
22.  Tubing, vacuum (with internal diameter to fit both the side  arm  of the filtering flask and the
     vacuum source)
23.  Vacuum source

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                                                                         Chloride in Solutions


                                      REAGENTS

1.   Chloride-free water- If necessary, redistill or deionize distilled water to remove chloride and any
     interferring ion, such as iron.
2.   Diphenylcarbazone bromphenol  blue indicator: Dissolve 2.5 g diphenylcarbazone and 0.25 g
     bromphenol blue in 375 ml 95 percent ethyl  alcohol and dilute with same to 500 ml. Store in
     an amber reagent  bottle. (Note:  Some analysts  employ  a  diphenylcarbazone   indicator
     containing xylene  cyanol  FF  (l,p. 98).  The author prefers the bromphenol  blue  indicator
     because its color change (at pH 3) serves as a guide in the pH adjustment of the sample prior to
     titration,  thus,  the routine use of  a  pH  meter is eliminated. The  final yellow-pink-deep
     purple color change is generally easier to discern than the blue-purple change of the  indicator
     containing xylene cyanol FF).
3.   Nitric acid solution,   approximately 3.9 N:  To  375 ml chloride-free water, slowly add
     125 ml concentrated nitric acid. Cool and store in a 1-liter reagent bottle. (Note: Some analysts
     recommend a less concentrated nitric acid solution. The use of a 3.9 N acid solution, however,
     minimizes the dilution of the sample during pH adjustment.)
4.   Standard  sodium chloride solution, 0.0141 N:  Dissolve  0.8241 g analytical reagent grade
     NaCl (previously  dried  at HOC for 1 hour) in  chloride-free water and dilute with same  to
     1  liter.
5.   Standard  mercuric acid  solution no.  1, (0.1410 N): Dissolve 50 g Hg(NO3)2-H2O in 1800 ml
     chloride-free water containing 5 ml concentrated nitric acid. Dilute with chloride-free water to
     2  liters. Determine the normality of the solution as directed in the Standardization section  of
     this Procedure.
6.   Standard  mercuric nitrate solution  no. 2, (0.0141 N): Dissolve 5 g Hg(NO3)2-H2O  in 200  ml
     chloride-free water containing 0.5 ml concentrated  nitric  acid, and dilute with  chloride-free
     water to  2 liters. Determine the normality of the solution  as directed in the Standardization
     section of this Procedure.
7.   Buffer solution, pH 2.0 ± 0.02 at 25 C (e.g., Fisher Scientific Co. no. SO-B-96.)
8.   Potassium chloride solution, saturated (e.g., Corning no. 477000).


                               SAFETY PRECAUTIONS

  To avoid hazards associated with the titration
1.   Wear safety glasses when handling concentrated nitric acid and mixtures thereof.
2.   Exercise  care  in weighing, transferring, and disposing mercuric nitrate solutions because
     inhalation, ingestion, or contact with the compound may cause mercurial poisoning.


                                 STANDARDIZATION

   The normality of a mercuric nitrate solution is determined  after titrating triplicate samples of
both a  water blank and a standard sodium chloride  solution, as follows:

                  Procedure                                      Comments

 1.  Place  100ml of the sample to be  titrated    1.  a)  If titrating a water blank, use  100ml of
    with mercuric nitrate solution  in a 250-ml          chloride-free water.
    beaker.                                         b) If  titrating  a standard  NaCl solution

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METHODS OF SOLID WASTE TESTING
2.  While gently stirring the  contents of the
    beaker with  a magnetic  stirrer, add 1 ml
    diphenylcarbazone bromphenol  blue indica-
    tor.
3.  Slowly add 3.9 N nitric acid dropwise  until a
    yellow color forms.
4.  Using the mercuric nitrate solution that is  to
    be standardized,  titrate the contents  of the
    beaker to a deep purple end point.
5.  Calculate and record  the average volume of
    titrant   required    to    titrate    100 ml
    chloride-free water.
6.  Calculate  the  normality of  the  mercuric
    nitrate   solution   as   directed   in    the
    Calculations section of this Procedure. Aver-
    age the calculations.
                                                        with  mercuric  nitrate solution no.  1
                                                        (approximately  0.1410  N),  use 25  ml
                                                        0.0141  N NaCl diluted to 100 ml with
                                                        chloride-free water.
                                                    c)  If  titrating  a  standard  NaCl solution
                                                        with  mercuric  nitrate solution no. 2
                                                        (approximately  0.0141  N),  use  5  ml
                                                        0.0141  N NaCl diluted to 100 ml with
                                                        chloride-free water.
4. a)  Use a 50-ml buret with mercuric nitrate
       solution  no. 1 and  a  S-ml micro buret
       with mercuric nitrate solution no. 2.
   b)  The  pH  of  the  solution  should  be
       2.5 ± 0.1 at the end point.
5. In  our  laboratory,   100ml  chloride-free
   water  usually requires 0.02 ml 0.141 ON or
   0.2 ml 0.0141 N mercuric nitrate.
6. The deviation of each individual observation
   of  normality  from the average should not
   exceed 0.0002.
                                SAMPLE PREPARATION

                                            Physical

   Process or  tap water, well water, and other groundwater samples are generally analyzed directly
without any  physical preparation; however,  landfill leachates containing soil particles are usually
filtered through a Millipore® HA filter using  a hydrosol filter holder. In this manner, iron particles,
which can interfere with the titration, can be removed without loss of soluble chloride. Incinerator
quench, scrubber,  and clarifier  waters containing insoluble  particles  of various sizes are usually
homogenized  in a Waring Blender® prior to analysis. (Filtration of incinerator wastewaters may be
applicable, but has not been evaluated in our laboratory.)
                                          Chemical

   If a sample contains more than 10 mg sulfite or chromate or 20 mg ferric ion per liter (even after
dilution  with chloride-free water to an appropriate range of chloride concentration), the analyst
should also chemically pretreat the samples as suggested by the American  Society for Testing and
Materials in Referee Method A of standard D512-67 (2, p. 26-27).

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                                                                         Chloride in Solutions
                                     PROCEDURE

   Duplicate determinations of a water blank; a standard solution; and an incinerator wastewater, or
landfill leachate, or related water sample  will be required. The chloride content of two 100-ml
aliquots of chloride-free water should  be determined as outlined in the Standardization section. The
procedure, presented herein, is  applicable  for the determination of 250 mg (or less) chloride in
100-ml aliquots of a standard or aqueous solution. Smaller aliquots (5 to 50 ml) are generally used to
attain  measurable chloride concentrations and to  avoid color and ionic interferences during titration.
(See Method Evaluation section of this Procedure.)
   Mercuric nitrate solution no. 1 (approximately  0.1410 N) can be used for titrating 100-ml aliquots
containing up  to 250 mg chloride. Those aliquots, containing less than 5.0 mg chloride,  are  best
titrated, however, with mercuric nitrate solution no. 2 (approximately 0.0141 N).
                 Procedure

1.  Place  an  appropriate  aliquot  of  sample
    (100 ml or less) in a 250 ml beaker.
2.  Dilute the sample to  100 ml, if necessary,
    with chloride-free water.
3.  While  carefully stirring the contents of the
    beaker with a magnetic  stirrer, add  1  ml
    diphenylcarbazone bromphenol   blue  indi-
    cator.
4.  Slowly add 3.9 N nitric acid dropwise until
    a yellow color forms.
5.  Using  the appropriate mercuric nitrate solu-
    tion, titrate the contents of the  beaker to a
    deep purple end  point.  Record  the volume
    of titrant used.
                                                        Comments

                                       1.  The aliquot must contain less than 250 mg
                                          chloride.
                                       5.  a) Use mercuric nitrate solution no. 1, con-
                                             tained in a 50-ml buret, for 100-ml sam-
                                             ples containing 5.0 to 250 mg chloride.
                                          b) Use mercuric nitrate solution no. 2, con-
                                             tained in a 5-ml micro buret for 100-ml
                                             samples containing less than 5.0 mg chlo-
                                             ride.
6.  Calculate the concentration of chloride as
    instructed in the Calculations  section im-
    mediately below.
                                   CALCULATIONS

  The normality, (N), of either mercuric nitrate solution is calculated as follows:
where
   N,
   V,
   A
   B
normality of the standard sodium chloride solution
ml of standard sodium chloride solution diluted to 100 ml
ml of mercuric nitrate solution used to titrate the sodium chloride solution
ml of mercuric nitrate solution used to titrate 100 ml chloride-free water.

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METHODS OF SOLID WASTE TESTING


  The concentration of chloride (mg Cl/1) in a sample is calculated as follows:

                                     _N(A-.01BC) (35.45) (1000)
where
   N  = normality of the mercuric nitrate solution used in the titration
   A  = ml of mercuric nitrate solution used in the titration
   B  = ml of mercuric nitrate solution used to titrate 1 00 ml of chloride-free water
   C  = ml of chloride-free water used to dilute the sample aliquot to 1 00 ml
   S  = ml undiluted sample titrated


                               METHOD  EVALUATION

                                        Interferences

  Iodide and bromide  are titrated with mercuric nitrate  in the same manner as chloride. Zinc, lead,
nickel, ferrous, and  chromous ions affect the solution and end point colors but not the accuracy
unless their  individual  concentrations exceed lOmg per 100-ml sample. Only 5 mg copper can be
tolerated in  a similar volume of sample. Interferences will also occur when more than 1 mg of sulfite
or chromate or 2 mg ferric ion is present in a 100-ml sample.


                                        Accuracy

  The accuracy of the method was first evaluated by determining the chloride concentration of two
aqueous samples,  which were provided by  the  Analytical Quality Control Laboratory, National
Environmental  Research Center-Cincinnati,  U.S.  Environmental Protection Agency. The average
percent  recovery of the chloride concentration of these samples was 100. (See Table 1 .) The chloride
content of 1  0-ml aliquots of 13 wastewater samples was also determined before and after adding 5 ml
0.0141 N  NaCl. The percent chloride recovery from the Winston Salem, North Carolina, and Boone
County, Kentucky, landfill  leachates was  96.8 and 1 00, respectively. The average percent chloride
recovery from the  1 1 Boone County, Kentucky, refuse extracts was 97.9.
                                          Precision

  The reproducibility of the observations  of the chloride content  of incinerator tap water and
wastewater samples  has  been evaluated  by calculating the standard deviation and  coefficient of
variation of the triplicate determinations of each of  20 samples (see Table 2). In each case, the
coefficient of variation was 0.02 or less.
  The reproducibility of the observations of the chloride  content of the refuse extracts, landfill
leachates, and related well-water samples  was evaluated by calculating the pooled standard deviation
and coefficient of variation of groups of duplicate observations. The groupings were based on sample
type,  and the subgroupings on range of chloride concentration. A review  of the data, presented in
Table 3, similarly reveals that the coefficient of variation never exceeded 0.02.

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                                  TABLE 1
                       ACCURACY OF THE METHOD
                                                               Chloride in Solutions
   Sample type
   Sample source
Lab. No.
% Recovery of added
     chloride
Aqueous solutions
Analytical
Quality Control
Min. 1
Min. 2
100
100.1
Landfill leachates
Refuse extracts
Lab. (NERC-
Cincinnati, U.S.
EPA)

Winston Salem,
N.C.
Boone County, Ky.
(Cell 2D)

Boone County, Ky.
(Cell 1)
 70-204
                                           73-8
 71-120
 71-173
 71-125
 71-128
 71-130
 71-133
 71-135
 71-138
 71-140
 71-145
 71-160
       96.8

      100
       96.4
       96.4
       98.0
       96.8
      100.4
       96.4
       96.8
      100.4
       97.6
       97.6
      100

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METHODS OF SOLID WASTE TESTING
                                TABLE 2
           PRECISION OF TRIPLICATE CHLORIDE DETERMINATIONS OF
    WATER SAMPLES FROM INCINERATOR NO. 3, DELAWARE CO , PENNSYLVANIA
Type of
sample
Tap or process
water



Quench water




Scrubber water




Clarifier
water



Lab. No.
70-56
70-64
70-72
70-80
70-88
70-54
70-62
70-70
70-78
70-86
70-52
70-60
70-68
70-76
70-84
70-50
70-58
70-66
70-74
70-82
Observed mean,
mgCl/1
(M)
63.83
83.68
75.05
87.48
88.16
512.4
1045
1169
729.8
780.5
1399
1606
1816
1868
2573
1348
1386
1621
1683
2345
Standard
deviation
(S)
1.20
0.30
1.36
0.52
1.50
1.38
2.30
2.65
1.79
1.79
1.15
0.00
1.73
3.46
2.87
1.15
1.53
0.00
0.60
2.65
Coefficient of
variation
(S/M)
0.02
0.00
0.02
0.01
0.02
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
                                  8

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                                                                       Chloride in Solutions
                                          TABLE 3
     PRECISION OF DUPLICATE CHLORIDE DETERMINATIONS OF REFUSE EXTRACTS
 LEACHATES, AND WELL-WATER SAMPLES FROM THE RESEARCH LANDFILL OPERATION
                             IN BOONE COUNTY, KENTUCKY
Type of
sample

Refuse
extracts*


Leachates



Leachates


Sample
source

Cell no. 1
refuse


Cell no. 1
upper
pipe

Cell no. 1
lower
pipe
Group

Total
Subgroup A
Subgroup B
Subgroup C
Total
Subgroup A
Subgroup B
Subgroup C
Total


No. of
samples
in
group
14
1
11
2
48
1
44
3
38


Range of chloride
concentration
in me/1
(»
1
1
10
100
10
10
100
1000
100


(<)
1000
10
100
1000
10000
100
1000
10000
1000


... Pooled
Mean . . .
_., „ standard
mgCl/1 ,
deviation
(M)
64.86
5.90
52.74
161.0
694.8
90.00
678.8
1123.
495.8


(Sp)
0.39
0.14
0.39
0.50
4.35
0.00
4.01
8.16
3.95

•
Coefficient
of variation
(Sp/M)
0.01
0.02
0.01
0.00
0.01
0.00
0.01
0.01
0.01


  Well water    Well no. 1
  Total
Subgroup A
Subgroup B
Subgroup C
18
 3
 7
 8
10
10
100
1000
10000
100
1000
10000
1621.
83.93
417.0
3619.
7.74
0.40
4.31
10.89
0.00
0.00
0.01
0.00
Well water


Well no. 2A Total
Subgroup A
Subgroup B
20
14
6
1000
1000
10000
100000
10000
100000
8458.
3936.
16800.
15.04
7.07
31.62
0.00
0.00
0.00
  *Each extract was prepared in the laboratory by suspending 50 g ground, mixed refuse (particles 2 mm or less in
diameter) in 750 ml distilled  water. After occasional stirring over a 15-hour penod, the mixture was filtered. The
remaining solid was washed with several 200-ml portions of distilled water and the mixture refiltered each time. The
combined filtrates were diluted to 2 liters with distilled water.

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METHODS OF SOLID WASTE TESTING
                               ACKNOWLEDGMENTS

  The author wishes to thank the staffs of the Process and Disposal Division, Office of Solid Waste
Management Programs, and the  Landfill Disposal Project, Solid  and  Hazardous Waste Research
Laboratory, NERC-Cincinnati, for supplying the incinerator and landfill water samples, respectively.
Special thanks are  also extended to Israel Cohen, Monitoring and Analysis  Project, for preparing
some of the incinerator water samples.


                                    REFERENCES

1.   American Public Health Association, American Water Works Association, and Water Pollution
    Control  Federation. Chloride.  In:  Standard  methods  for  the examination of  water and
    wastewater. 13th ed. Washington, D. C., American Public Health Association, 1971. p. 95-99,
    376-380.
2.   American Society for Testing and Materials. Standard  methods  of test  for chloride ion in
    industrial water  and  wastewater.  In: 1969 Book  of ASTM  standards,  pt. 23. D512-67.
    Philadelphia, 1969. p. 24-31.
                                             10

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    LABORATORY PROCEDURE FOR DETERMINING
               THE CHLORIDE CONTENT
                   OF SOLID WASTES


                      Nancy S. Ulmer*
DISCUSSION	   2
EQUIPMENT	   2
REAGENTS  	   3
SAFETY PRECAUTIONS  	   4
STANDARDIZATION	   5
SOLID WASTE SAMPLE PREPARATION	   5
PROCEDURE   	   5
CALCULATIONS   	   9
METHOD EVALUATION  	10
ACKNOWLEDGMENTS  	10
REFERENCES	12
*Research Chemist, Criteria Development Branch, Water Supply Research Laboratory,
 National Environmental Research Center — Cincinnati; Miss Ulmer was formerly with
 the Solid and Hazardous Waste Research Laboratory of NERC-dncinnati.

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METHODS OF SOLID WASTE TESTING


                                       DISCUSSION

   The  significance  of  chloride ion as a solid  waste characteristic becomes apparent when one
considers the impact it  may have upon processing equipment and on the environment surrounding a
processing or  disposal site. P. D. Miller et al. have studied  the corrosion, pitting, and cracking of
incinerator  boiler tubes,  probes, and  wet scrubbers (1). Their analyses clearly  demonstrated  the
presence  of ferrous chloride  (FeCl2), sodium chloride  (NaCl), and potassium  chloride  (KC1) in
boiler-tube deposits  and up to  16 percent chloride in the scrubber fan deposits. Their investigations
also revealed that the most corrosive salts at 600 F (~316 C) are potassium bisulfate (KHSO4) and
potassium pyrosulfate (K2S2O7), whereas at 800 to 1000 F (~427 to 538 C) zinc chloride (ZnCl2)
and lead chloride (PbCl2 ) accelerate the  corrosion.  Since chloride appears to enhance the  corrosive
action of sulfates, a knowledge of the concentration and distribution of chloride in solid  wastes is
important to the  engineers and scientists responsible for the design, maintenance, and control of
incinerator equipment.
   The emission of hydrogen chloride gas from incinerator stacks and the leaching of highly reactive
chloride  ion  from  municipal  refuse  and  residue  in  incinerators  or landfills  may  result  in
environmental pollution. The  direct effect of chloride is, or course, a chemical degradation of the
receiving medium, but indirect effects, biological in nature, may also occur. Thus, a knowledge of the
chloride content  of municipal refuse, incinerator residue, wastewaters, stack emissions, and landfill
leachates  is also  important to those persons developing and evaluating  gaseous  pollutant control
measures and water treatment processes in solid waste management systems.
   Chemists have  employed a variety of analytical procedures to determine  the chloride content of
the individual components of solid wastes (2-13).  Most of the methods recommend that first  a
sample be oxidized by either (a) wet digestion or (b) combustion in a muffle furnace, Parr Bomb, or
Schoniger,  Thompson-Oakdale, or similar  glass  apparatus.   A  potentiometric, titrimetric,  or
gravimetric determination of the chloride content then follows after absorption and solution of the
products of oxidation.
   Since paper is the primary component of solid wastes, the ASTM procedure for chloride in paper
was considered (7). Briefly, it consists of ashing a dried sample at 600 C in  a muffle furnace. After
aqueous solution  and  dilution of  the ash, the  chloride content is determined  by titration using
AgNO3  as titrant and K2Cr2O7  as indicator. Since the sensitivity of this procedure is limited to 150
ppm (0.15 mg Cl/g sample) however, the technique is not applicable to solid wastes.
   The procedure presented  here,  developed and  evaluated in the  Solid and  Hazardous Waste
Research  Laboratory, represents a modification  of the techniques  used  for the  determination of
chloride in mineral oils  (14), epoxy resins (15), and wastewater (16). Briefly, it recommends that a
0.25- to 0.5-g solid waste  sample, layered with mineral oil, be combusted under 30 atmospheres O2
in a combustion cup suspended in a Parr Bomb that contains a carbonate solution. The products of
combustion are absorbed  by or dissolved in the  carbonate  solution, transferred  with  rinsing to  a
beaker,  diluted to 200  ml with distilled water,  treated with diphenylcarbazone  bromphenol blue
indicator, and acidified  with dilute1 nitric acid until a yellow color (pH  3.0) forms. The chloride
content is then determined by titrating with 0.0141 N mercuric nitrate until excess mercuric ions are
indicated by the formation of a deep purple color (pH 2.5 ± 0.1).


                                       EQUIPMENT

1.   Balance, analytical, 0.1 -mg read ability
2.   Bar, magnetic stirring, approximately 14 mm (9/16 inch) long
3.   Beakers, Pyrex, 600-ml

-------
                                                                             Chloride in Solids


 4.   Bottle, liquid storage, Pyrex, amber, 1-gal (3.8-liters), with screw-cap lid
 5.   Bottle, reagent, Pyrex, amber, 500-ml
 6.   Bottles, reagent, Pyrex, 1-liter
 7.   Bottle, washing-dispensing, polyethylene, 500-ml
 8.   Bottle, weighing; low form; cylindrical with standard taper cap, height, 30 mm; inside diameter,
     60 mm
 9.   Buret, 25-ml, with fine tip, dispensing drops 0.025 ml (or less) in volume
 10.  Calorimeter, Parr Adiabatic, Series 1200; with a self-sealing, 360-ml stainless-steel, oxygen bomb
     with double valve (Parr  no. 1101); an oxygen-filling connection (Parr no.  1823); stainless-steel
     capsules (Parr no. 43AS); and 26-gauge platinum fusion wire (Parr no. 43A); a platinum-lined or
     tantalum-lined bomb and nickel capsules are suggested if numerous determinations are to be
     performed over a long period of time.
 11.  Cloth, aluminum oxide, fine (e.g., Norton Alox®cloth, no. 120 or 150)
 12.  Cylinder, graduate, Pyrex, 25-ml
 13.  Desiccator, either Pyrex  or small stainless-steel cabinet-type
 14.  Dishes, aluminum, moisture, 89- x 50-mm, with tightly fitting lids (e.g., Arthur H. Thomas Co.,
     no. 3840-F30)
 15.  Flasks, volumetric, Pyrex, 2-liter, 1-liter, and 500-ml
 16.  Forceps, dissecting, with straight sharp points  (e.g., Fisher Scientific Co., no. 8-880)
 17.  Meter, pH (e.g., Corning, Model 7, with Corning pH electrode no.  476022 with triple-purpose
     glass membrane  and  Corning reference calomel electrode no. 476002 with asbestos junction; a
     silver electrode,  Corning no. 476065, is suggested if the chloride concentration  of the unknown
     solution is low)
 18.  Oven, forced draft, capable of maintaining a set temperature within the 75- to 105-C range over
     a 4-hour period (e.g., Precision  Scientific Co., Model 18)
 19.  Pipets, Pyrex, serological, 1-ml  and 5-ml
 20.  Policemen, rubber, for glass rods, 4.8 mm (3/16 inch) in diameter
 21.  Press, pellet, with a 12- to 19-mm-(l/2- to 3/4-inch) diameter punch and dye set (e.g., Parr press
     no.  2811   with  punch and   dye  set  no.  A33PR or Carver Lab  Press, Model  B, and  a
     19-mm-diameter punch and dye set, made in machine stop)
 22.  Rods, stirring, glass, 4.8 mm (3/16 inch) in diameter
 23.  Spatula, stainless-steel (e.g., Scoopula,® Fisher Scientific Co. no. 14-357)
 24.  Stirrer, magnetic, round (e.g., Fisher Scientific Co. no.  14-511-1)
 25.  Support, buret
 26.  Support, gas cylinder, safety (e.g., Fisher Scientific Co. no. 10-595)
 27.  Support, ringstand, with a cast-iron support ring having a 60-mm (2-3/8 inch) I.D.
 28.  Syringe, Luer, Tuberculin, Pyrex, 1-ml, with 1/100-ml subdivisions
 29.  Wool, steel, fine (gauge no. 0000)
 30.  Wrench, for opening hand wheel on oxygen tank


                                       REAGENTS

 1.   p-Chlorobenzoic acid, M.  P. 239-241 C, 22.64 percent chloride by weight: Dry  the solid at
     105 C for 1 hour and store in a desiccator until used as a standard in the evaluation of the entire
     procedure.
2.   Squibb mineral oil, extra heavy
3.   Chloride-free  water: If necessary, redistill or deionize distilled water to remove chloride and any
     interferring ion, such  as iron.

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METHODS OF SOLID WASTE TESTING


4.   Sodium carbonate solution, 2 percent: Dissolve 40 g anhydrous Na2CO3 in chloride-free water
     and dilute with same to 2 liters. Store in two 1-liter reagent bottles.
5.   Oxygen, produced by rectification of air, cylinder size 1A (244 cu. ft.)
6.   Nitric acid  solution, approximately  3.9 N: To 375 ml chloride-free water, slowly add  125 ml
     concentrated  nitric  acid. Cool and store in a  l-liter reagent  bottle. (Note: Other procedures
     recommend a less concentrated  nitric acid. The use of  a 3.9 N acid  solution will, however,
     minimize sample dilution during pH adjustment.)
7.   Diphenylcarbazone  bromphenol  blue indicator: Dissolve 2.5  g diphenylcarbazone and 0.25 g
     bromphenol blue in  375 ml of 95  percent ethyl alcohol and dilute with same to 500 ml. Store in
     an  amber  reagent  bottle.  (Note:  Some  analysts  employ  an  indicator containing  0.25 g
     s-diphenylcarbazone and 0.03 g xylene cyanol FF in 100 ml of 95 percent ethyl alcohol. The
     author prefers the indicator with bromphenol  blue because the color change (at pH 3) serves as
     a guide in the pH adjustment of the sample before titration; thus, the routine use of a pH meter
     is eliminated. The final yellow-pink-deep purple color change  (during the titration) is generally
     easier to discern than the blue-purple change of the indicator containing xylene-cyanol FF).
8.   Standard sodium chloride solution, 0.0141 N:  Dissolve 0.8241 g analytical reagent grade NaCl
     (previously dried at  140 C for  1 hour) in chloride-free water and dilute with same to 1 liter.
9.   Standard mercuric  nitrate solution,  0.0141  N: Dissolve  5g Hg(NO3)2.H2O  in  200  ml
     chloride-free  water containing 0.5 ml concentrated HNO3, and dilute with chloride-free water
     to 2 liters. Store in  a 1-gal amber bottle. Determine the normality of the solution as directed in
     the Standardization  section of this Procedure.
10.  Buffer solution, pH 2.0 ± 0.02 at 25 C (e.g., Fisher Scientific Co., no. SO-B-96).
11.  Potassium chloride solution, saturated (e.g., Corning No. 477000).
                               SAFETY PRECAUTIONS
  The high pressure and explosive reaction employed in the combustion of the sample need not be
hazardous if the analyst observes the following precautions:

1.    Limit the  total sample weight (solid waste plus oil) to 1 g; i.e., do not use a quantity of sample
     that  will liberate  more than 10,000  calories of heat. If the calorific value of a solid waste is
     unknown, determine the value before proceeding with the chloride determination.

2.    Do not  charge the  bomb  with more than 30 atmospheres of oxygen. If overcharging occurs,
     release the bomb pressure gently and recharge. Never fire an overcharged bomb.

3.    Keep all parts of the bomb, especially the insulated electrode  assembly, clean and in good
     repair. Do not  fire a bomb if gas is leaking from the bomb  when submerged in water.

4.    Stand away from the calorimeter during and  immediately after (15 seconds) firing the bomb.

  To avoid the chemical hazards associated with the titration:

1.    Wear safety glasses when handling concentrated nitric acid and  mixtures thereof.

2.    Exercise  care  in weighing,  transferring, and  disposing mercuric nitrate  solutions because
     inhalation, ingestion, or contact with the compound may cause mercurial poisoning.

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                                                                            Chloride in Solids
                                 STANDARDIZATION

   The normality of the mercuric nitrate solution is determined after titrating triplicate samples of
 both a water blank and a standard NaCl solution as follows:
                  Procedure

 1.  Place 200  ml of the sample to be titrated
    with mercuric nitrate solution  in a 600-ml
    beaker.
 2.  While gently stirring the solution with a
    magnetic stirrer, add 1 ml of the diphenyl-
    carbazone bromphenol blue indicator.
 3.  Slowly add 3.9 N nitric acid dropwise until a
    yellow color forms.
 4.  Using the mercuric nitrate solution, titrate
    the contents of  the beaker to a purple end
    point. Record the volume of titrant used.
 5.  Calculate and record the average volume  of
    titrant required  to  titrate 200 ml  chlonde-
    free water.
 6.  Calculate  the  normality of  the  mercuric
    nitrate solution  as directed in the Calcula-
    tions section of this Procedure. Average the
    three calculations.
                 Comments

1.  a)  Use 200 ml of chloride-free water fora
       water blank.
    b)  For the standard solution, use 5 ml stock
       0.0141 N NaCl   solution   diluted  to
       200 ml with chloride-free water.
4. The pH of the solution should be 2.5 ± 0.1
   at the end point.

5. In  our laboratory,  this volume is  usually
   0.04 ml.

6. The deviation of each individual observation
   of  normality  from the average should  not
   exceed 0.0002.
                     SOLID WASTE SAMPLE PREPARATION

   A solid waste sample  must undergo physical preparation before its characterization is initiated in
the  laboratory.  The  sample must  be dried to  constant  weight,  preferably  in a  forced-air  or
mechanically-convected oven. A temperature of 70 to 75 C should be used to dry municipal refuse or
compost; incinerator residue may be dried at 100 to 105 C. The particle size of the dried sample
should then be reduced to 0.5 mm (or less) using a hammermill, pulverizer, and laboratory mill. Since
samples may absorb moisture during the grinding and mixing process, they should be redried for 4
hours at the previously specified temperature and then stored in a desiccator.
   Immediately  before initiating an  analysis, prepare  several 1.0-g pellets of  the  standard or solid
waste sample. (A punch  and dye set, 12 to 19 mm in diameter, can  be used with  a Model B, Carver
Laboratory Press, capable of exerting a 7000-lb or 3175 kg load). Store the pellets in a desiccator and
remove as required  for the determinations.
                                      PROCEDURE

  Duplicate determinations of a water blank, an oil blank, and a standard or solid waste sample will
be required. The volume  of mercuric nitrate solution required to titrate two 200-ml aliquots of

-------
METHODS OF SOLID WASTE TESTING
chloride-free water should be determined, as outlined in the Standardization section, steps 1-5. The
chloride  content  of  the oil blank and the standard or solid waste sample should be determined as
follows:
1.
2.
5.
6.
7.
                 Procedure

   Carefully weigh a steel combustion capsule
   to the nearest 0.0001 g.
   If  performing a  standard  or  solid waste
   analysis, add an  appropriate portion of a
   pelletized sample  to the capsule and then
   proceed to step 3.
   Weigh the capsule and solid sample to  the
   nearest 0.0001 g.  Determine and record  the
   weight of the solid sample.
   Using a  1-ml,  Pryex, Tuberculin  syringe,
   flow  approximately  0.5  to  0.7 ml extra
   heavy Squibb  mineral  oil directly into  the
   capsule, wetting any solid sample present.

   Weigh  the  capsule and  sample(s)  to  the
   nearest 0.0001 g.  Determine and record  the
   weight of the oil.
   Rinse the inner surfaces of the stainless-steel
   bomb with the 2  percent Na2 CO3  solution.
   Place 25ml fresh  2 percent Na2CO3 solu-
   tion in the bomb cylinder.
8. Attach  the  fuse  wire  to the  4A  and  5A
   electrodes of the bomb head.
9. Place the  capsule containing the sample in
   the base of the 5 A electrode.
10. Bend the  fuse  wire loop so that it either
   barely touches  the oil-soaked pellet or  lies
   just above the free oil (e.g., in the blank).
11. Place the bomb  head in the cylinder.
 12. Screw the bomb cap  down thoroughly by
    hand.
                 Comments

1.  a)  A capsule should have been previously
       cleaned with fine steel wool, then rinsed
       with  chloride-free  water,  dried,  and
       stored in a desiccator until used.
   b)  Use  nickel capsules if many chloride
       determinations are planned over a period
       of time.
2.  a)  Use  0.015  to 0.020 g p-chlorobenzoic
       acid  (standard) or 0.25 to 0.50 g solid
       waste.
   b)  If performing an oil blank analysis, omit
       steps 2  and 3 and  proceed directly  to
       step 4.
                                                4.  If performing  a standard  or  solid  waste
                                                   analysis, limit the total weight of the sample
                                                   plus oil to 1 g; i.e., do not use sample and oil
                                                   quantities  that  will  liberate  more   than
                                                   10,000 calories of heat.
6.  a)  Use  25 ml of solution  for the bomb
       cylinder and 15 ml for the bomb head.
    b)  Support the rinsed bomb head on a ring
       stand.
                                                8.  Detailed instructions are provided in the Parr
                                                    Instrument Company Manual (17).
                                                11. a)
       Keep the cylinder upright to prevent any
       sample loss from the capsule.
       Make sure  the  sealing ring is in good
       condition.
 12. The  outlet  needle  valve should be open
    dunng this step.
                                                    b)

-------
                                                                           Chloride in Solids
13. Close the outlet needle valve.
14. Remove the inlet valve thumb nut.
15. Attach  the  union  nut of the oxygen-filling
   tube firmly by hand.
16. Open the oxygen-filling connection control
   valve slowly.
17. Allow the oxygen pressure to rise slowly
    until the gauge reads 30 atmospheres.
18. Close the oxygen-filling connection control
    valve.
19. Push the ball knob under  the  relief knob
    sideways.
20. Disconnect the oxygen-filling tube.
21. Replace the thumb nut in the inlet valve.
22. Place the bomb  in the bucket so that its feet
    span the  boss at the bottom of the bucket.
23. Attach  the  thrust terminal to  the  bomb
    head.
24. Lower the bucket into the jacket.

25. Add  2000ml  distilled  water, at  room
    temperature, to the bucket.
26. Swing the calorimeter cover to  the right and
    lower it using the cam lever.
27. Check to see if the pump and stirrer drive
    shafts are seated properly.
28. With the water inlet tube attached to a cold
   water source and the discharge tube draining
   to  a sink, open  the appropriate valves  and
   turn on the cold water.
29. After the  water begins to drain  from the
   discharge tube, start the stirring motor.
30. WHILE STANDING TO THE SIDE OF THE
   CALORIMETER, press the ignition button.
15. a)  Use   Parr  no.   1823  oxygen-filling
       connection.
   b)  Detailed instructions are provided in the
       Parr  Instrument  Company manual (17,
       p. 20-22).
16. a)  The oxygen  tank valve must have been
       opened previously with a special wrench.
   b)  If the oxygen-filling connection valve is
       opened too quickly, some of the sample
       may  be blown  from  the capsule  and,
       thus, prevent complete combustion.
19. This  relieves  the  gas  pressure in the con-
   necting tube.
23. The lead  wire should not extend above the
   bucket.
24. Position the bucket so that  the stirrer and
   handle are in the rear.
27. a)
                                                   b)
       The pump  and stirrer shafts should be
       lowered as far as possible and the pulleys
       should move freely.
       The calorimeter's  thermometers  are not
       used in this test and can be removed.
28. Excessive water pressure will cause seepage
   through  the stirring shaft journal into the
   bucket chamber.
30. a)  If ignition occurs,  a  red  light near  the
       ignition button will flash on briefly.
    b)  If ignition fails to occur (no  red light
       seen),  proceed immediately   to  steps
       32-35, 38-40, and then begin  the deter-
       mination again at step 8.

-------
 METHODS OF SOLID WASTE TESTING
 31. Allow the bomb to stand in the calorimeter
    for 10 minutes after ignition.
 32. Turn off the stirring  motor and allow the
    water to drain from the calorimeter cover.
 33. Lift the  cam  lever,  then the  calorimeter
    cover, and swing the latter to the left.
 34. Lift  the bucket  out  of the  jacket  and
    disconnect the thrust terminal wire.
 35. Remove the  bomb  and  gently  dry  the
    exterior with a towel.
 36. Tilt the bomb 75 to 80 degrees and rotate to
    wash the inner surfaces with the Na2CO3
    solution.
 37. Stand  the bomb upright on a table  for 10
    minutes to  allow  the  Na2CO3  solution to
    dram to the  bottom of the cylinder.
 38. Gently  and  slowly open  the outlet  needle
    valve to relieve the pressure.
 39. Remove the  screw cap.
 40. Lift the bomb head and capsule slowly from
    the cylinder.

 41. Inspect  the  capsule and  cylinder for  un-
    combusted sample.

 42. Inspect  the  inner  bomb  head  surface  for
    formation of iron oxide.
43. Wash  all  interior  bomb  surfaces and all
    capsule  surfaces  with  a  fine  stream of
    chloride-free water. Collect all washings in a
    600-ml beaker.
44. While gently stirring the combined  washings
    in the beaker, add 1.0 ml diphenylcarbazone
    bromphenol blue indicator.
45. Slowly add 3.9 N nitric acid dropwise until a
    yellow color forms.
46. Using 0.0141  N mercuric nitrate, contained
    in a 25-ml buret with a fine  tip, titrate the
    contents of the beaker to a deep purple end
    point. Record the volume of titrant  used.
47. Calculate the concentration of chloride as
    instructed  in the Calculations section of this
    Procedure.
 32. The flow from the discharge tube will return
    to normal when the cover is drained.
40. If the capsule fell down into  the cylinder
    during step 36, do not remove it until step
    43.
41. If the combustion was-incomplete, discard
    the test and proceed to step 48. Repeat the
    determination beginning at step  1.
42. If a  red  color is noticeable,  the analyst
    should suspect a high cloride concentration.
    The test may  have  to  be  repeated with a
    smaller sample.
43. a)  A rubber  policeman is  useful in rinsing
       the surfaces of the cylinder.
    b)  The total  volume of all washings should
       be 200 ml.
44. Use a magnetic stirring device.
46. a)  The buret should deliver 0.025-ml drops.
    b)  The  pH of  the  solution  should  be
       2.5 ±0.1 at the end point.

-------
                                                                            Chloride in Solids
48. Rinse the interior surface of the bomb head   48. a)  Occasionally clean the inner surfaces of
    and  cylinder with  additional chloride-free          the  bomb  head with  fine  steel wool
    water and set them aside to drain.                    (gauge no.  0000) and  then rinse  with
                                                       chloride-free water and  place  in a ring
                                                       stand support to drain.
                                                    b)  If the inner surface of the stainless-steel
                                                       cylinder becomes pitted over a  period of
                                                       time, clean  the  surface  with  a  fine
                                                       aluminum  cloth  (e.g.,  Alox®cloth  no
                                                       120  or 150).  Rinse  surface well  with
                                                       chloride-free water and drain.
49. For each determination, repeat  steps  1-48.
50. At  the end of a  day  (or  a series  of
    determinations), turn off the cold water.


                                    CALCULATIONS

  The normality (N) of the mercuric nitrate solution is calculated as follows:
                                          "    A-B
where
  N,     = normality of the standard sodium chloride solution
  V,     = ml of standard sodium chloride solution diluted to 200 ml
  A      = ml of mercuric nitrate solution used to titrate the sodium chloride solution
  B      = ml of mercuric nitrate solution used to titrate 200 ml chloride-free water
  The percent chloride (%C10) in the oil blank sample is calculated as follows:
                               a r,  - 100 (N)(C-B) (0.03545)
                               /O \-r\Q             \\r
                                                 W0
where
  N      = normality of the mercuric nitrate solution
  B      = ml of mercuric nitrate solution used to titrate 200 ml of chloride-free water
  C      = ml of mercuric nitrate solution used to titrate the total washings from the combusted
            oil sample
  W0     = grams of oil sample used in this test
  The percent chloride (% Cls) of a standard or solid waste sample is calculated as follows:
                               ^ 100 N (D-B) (0.03545) - % C10 (W0)
                                                Ws
where
  N      = normality of the mercuric nitrate solution
  B      = ml of mercuric nitrate solution used to titrate 200 ml of chloride-free water
  D      = ml of mercuric nitrate used to titrate  the total washings  from the combined oil and
            standard or solid waste sample
  % C10   = percent chloride in the oil
  W0     = grams of oil used in the test
  Ws     = grams of standard or solid waste used in the test

-------
METHODS OF SOLID WASTE TESTING


                               METHOD EVALUATION

                                        Interferences

  Iodide and bromide are titrated with mercuric nitrate in the same manner as chloride. Chromate
and sulfite ions interfere when present in excess of 10 mg/1 (16, p. 97-98). Concentrations of ferric
ions up to 20  mg/1 can usually be tolerated.  Above that level, ferric ions interfere with the indicator
and cause a sliding or delayed endpoint in the titration.

                                          Accuracy

  Five p-chlorobenzoic acid samples, ranging in weight from  12 to 25 mgand containing 3 to 6 mg
chloride, respectively, were analyzed by using this procedure. The mean percent recovery of the
theoretical chloride content was 98.1. Three aliquots of a Boone County, Kentucky, refuse sample
(no. 71-130) were also analyzed  before and after the addition of 15 to 23 mg p-chlorobenzoic acid.
The mean percent recovery of the added chloride was 97.4.

                                          Precision

  The reproducibility of the method has been  determined by calculating the standard deviation of
the replicate determinations of the  chloride content of a number of refuse samples. The data are
presented in Table 1.


                                ACKNOWLEDGMENTS

  The author wishes to thank  Dirk  Brunner  and the staff of the Landfill Disposal Project for
providing the Boone County, Kentucky, refuse samples. Special thanks are extended to Israel Cohen,
Monitoring  and  Analysis Project, for preparing these samples.
   Raymond Loebker, Thermal Degradation Project, kindly provided and prepared the Troy, Ohio,
refuse samples for analyses.
                                             10

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                                        Chloride in Solids
            TABLE I
REPRODUCIBILITY OF THE METHOD
Source of
refuse sample
Boone County,
Kentucky












Troy, Ohio






Lab. No.
71-120
71-123
71-125
71-128
71-130
71-133
71-135
71-138
71-140
71-142
71-145
71-155
71-158
71-160
72-668
72-669
72-670
72-671
72-672
73-19
73-20
Number of
replicate
determinations
per sample
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
2
6
2
2
2
2
Observed
mean
%
chloride
0.43
4.48
0.28
0.12
0.29
1.16
0.25
0.36
0.30
0.20
0.62
0.92
0.76
0.49
0.54
0.44
0.78
0.70
0.32
0.37
0.38
Standard
deviation
0.01
0.17
0.03
0.03
0.01
0.01
0.00
0.01
0.03
0.03
0.02
0.03
0.03
0.01
0.04
0.01
0.02
0.01
0.04
0.01
0.01
                11

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METHODS OF SOLID WASTE TESTING
                                      REFERENCES

 1.  Miller, P. D., et al. Corrosion studies in municipal incinerators. A report prepared for the Solid
    Waste  Research  Laboratory  under  Research Grants EP-00325  and EP-00325-S1. Cincinnati,
    National   Environmental  Research  Center,  Office   of   Research   and  Monitoring,  U.S.
    Environmental Protection Agency, 1972. 120 p.
2.  Horwitz, W., ed. Cereal foods: macaroni, egg noodles, and similar products. In: Official methods
    of the Association  of Official Analytical Chemists,  llth ed. sect. 14.129. Washington,  D.C.,
    Association of Official Analytical Chemists, 1970. p. 230.
3.  Horwitz, W., ed. Plants. In: Official  methods of the Association of Official Analytical Chemists.
    11th ed. sect.  3.067-3.072. Washington, D.C., Association of Official Analytical Chemists, 1970.
    p. 45.
4.  Horwitz, W., ed. Fish and other marine products. In: Official methods of the Association of
    Official Analytical Chemists,  llth  ed. sect.  18.014-18.015. Washington,  D.C., Association of
    Official Analytical Chemists,  1970. p. 296.
5.  Horwitz, W., ed. Meats and  meat products.  In: Official methods of the Association of Official
    Analytical Chemists. 11th ed. sect. 24.038. Washington, D.C., Association of Official Analytical
    Chemists,  1970. p. 398.
6.  Steyermark, A.,  R. A.  Lalancute,  and E. M.  Contereas. Collaborative  study of microanalytical
    determination of bromine and chlorine by oxygen flask combustion. Journal Association Official
    Analytical Chemists, 55(4):680-683, 1972.
7.  American  Society for Testing and  Materials.  Standard method of test for total  chloride content
    of paper and paper products. In: 1969 book of ASTM standards, pt.  15.  Dl 161-60. sect. 1-9.
    Philadelphia, 1969. p. 416-419.
8.  American  Society for Testing and Materials. Standard method of test for chlorine in cellulose. In:
    1960 book of ASTM standards, pt. 15. D2641-67T. sect. 1-13. Philadelphia,  1969.  p. 814-816.
9.  Colman, D. M., Determination of chlorine  concentration in plastics.  University of California
    method 5346. Livermore, California, University of California,  1958. p. 3-5.
 10. American  Society for Testing and  Materials.  Standard method of test for total  chlorine in vinyl
    chloride polymers and  copolymers. In:  1969 book of ASTM standards, pt.  27. D1303-55. sect.
    1-9. Philadelphia, 1969. p. 486-488.
 11. American  Society for Testing and Materials. Standard method of test for chloride content in
    polyvinylchloride polymers and copolymers  used in surface coatings. In:  1969 book of ASTM
    standards,  pt. 20. Dl 156-52.  sect. 1-6. Philadelphia, 1969. p. 540-542.
 12. American  Society for Testing and Materials. Standard method  of test for chlorine in  organic
    compounds  by sodium peroxide  bomb ignition. In:  1969  book of ASTM standards,  pt. 22.
    E256-67. sect. 1-8. Philadelphia, 1969. p. 586-592.
 13. American  Society for Testing and Materials. Standard method of test for chlorine in new and
    used petroleum products (bomb method).  In: 1969 book of ASTM standards, pt. 17. D808-63.
    sect. 1-7. Philadelphia, 1969. p. 232-235.
 14. Agruss, M. S., G. W. Ayers,  Jr., and H. Schindler. Organic halogen compounds in mineral oils.
    Industrial  and Engineering Chemistry, 13(2):69-70, 1941.
 15. American  Society for Testing and Materials.  Standard method of test for total  chlorine content
    of epoxy  resins. In: 1969 book of ASTM standards, pt. 20. D1847-67. sect. 1-8. Philadelphia,
    1969, p. 864-866.


                                              12

-------
                                                                          Chloride in Solids
16. American Public Health Association, American Water Works Association, and Water Pollution
   Control  Federation.  Chloride.  In:  Standard  methods  for  the  examination  of water and
   wastewater. 13th ed. Washington, D.C., American Public Health Association, 1971. p. 97-99.
17. Parr Instrument Company.  Oxygen bomb calorimetry  and combustion  methods.  Technical
   Manual no. 130. Moline, Illinois, 1966. 56 p.
                                             13

-------
 LABORATORY PROCEDURE FOR DETERMINING THE
 TOTAL PHOSPHATE AND TOTAL ORTHOPHOSPHATE
    CONTENTS OF REFUSE EXTRACTS, LANDFILL
    LEACHATES, AND RELATED WATER SAMPLES

                     Nancy S. Ulmer*
DISCUSSION	   2
SAFETY PRECAUTIONS  	   2
EQUIPMENT	   3
REAGENTS  	   3
STANDARDIZATION	   4
SAMPLE PREPARATION  	   5
PROCEDURES 	   5
    Determination of Total Phosphate  	   5
    Determination of Total Orthophosphate  	   7
CALCULATIONS  	   8
METHOD EVALUATION  	   9
ACKNOWLEDGMENTS   	  10
REFERENCES	  12
*Research Chemist, Criteria Development Branch, Water Supply Research Laboratory,
 National Environmental Research Center-Cincinnati; Miss Ulmer was formerly with the
 Solid and Hazardous Waste Research Laboratory of NERC-Cmcinnati

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 METHODS OF SOLID WASTE TESTING


                                      DISCUSSION

   Orthophosphates,  condensed  (pyro-,  meta-,  and  poly-)  phosphates,  and  organically-bound
 phosphorus may  occur in natural water and wastewaters. Since phosphorus  promotes the growth of
 algae,  its discharge into receiving streams  may contribute to the  deterioration of water quality and
 the eutrophication of lakes. A knowledge of the form and concentration of phosphorus in solid waste
 leachates and other water samples,  associated with landfill operations, is therefore important to the
 scientists and  engineers  responsible for developing and evaluating solid waste and water quality
 management systems.
   Chemists have  employed numerous methods to determine the various phosphorus forms present in
 water  and wastewater (1-10). In general, the procedures are characterized by (1) a conversion of the
 phosphorus  forms of  interest to orthophosphate and (2),the determination  of the  latter by
 colonmetnc, gravimetric, or atomic absorption techniques.
   The  amino  reduction  method (2 [sect.  13-21,  p. 46-50]; 11)  is recommended here  for  the
 determination  of the orthophosphate content of water and wastewater samples. An aliquot of an
 unfiltered but  appropriately  diluted sample is first  treated with a sulfuric  acid reagent containing
 bismuth. Ammonium molybdate is then added to form molybdophosphate. The subsequent addition
 of l-amino-2-naphthol-4-sulfomc acid results in the  formation of  molybdenum blue. The absorbance
 of the latter is measured at 650 nm against the absorbance of a similarly treated distilled  water blank.
The bismuth in the acid reagent increases the intensity of the blue  color fourfold.
   When a total phosphate determination is desired, an unfiltered but appropriately diluted sample,
contained in an Erlenmeyer  flask, is similarly treated with the sulfuric acid bismuth reagent. After
the addition  of potassium persulfate, the sample is heated to convert the condensed phosphates and
organically-bound phosphorus  to orthophosphate.  The molybdenum blue color of the cooled and
appropriately diluted  digest is then developed after the addition of ammonium molybdate and amino
solutions as  previously described.  The absorbance  of the solution  is measured against that of a
similarly processed distilled water blank. The observed total orthophosphate concentration serves as a
measurement of the total phosphate.
                               SAFETY PRECAUTIONS

  To avoid hazards associated with the maintenance of the glassware and the performance of each
analysis:

1.   Wear safety glasses when handling concentrated acids or mixtures thereof.

2.   Perform all acid digestions in a hood to avoid inhaling acid fumes.

3.   Wear asbestos glove while handling hot digestion flasks.

4.   Place hot digestion flasks on asbestos mats while cooling their contents.

5.   Exercise care in weighing, transferring, and disposing l-ammo-2-naphthoI-4-sulfomc acid as its
     toxological properties have not been fully evaluated.

6.   Avoid inhalation of  SO2 vapors during disposal of the final color-reaction mixtures. The sink
     area should be well ventilated and the tap water running during disposal of the solutions.

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                                           Total Phosphate and Total Orthophosphate in Liquids


                                      EQUIPMENT

                                       Requirements

1.    Balance, analytical, 0.0001-g readability
2.    Bottles, reagent, 250-ml and 1-liter
3.    Bottle, reagent, Pyrex, amber,  1-liter
4.    Bottle, washing-dispensing, polyethylene, 500-ml
5.    Bottle, weighing;  low form; cylindrical with standard taper  cap; 30mm high and 60mm in
     diameter
6.    Cuvettes, spectrophotometer, matched with 1-cm pathlength
7.    Cylinders, graduate, Pyrex, 100-ml, with standard taper stopper; A 105-ml volume mark should
     be etched on each cylinder with a glass-marking pencil.
8.    Desiccator, Pyrex or small stainless-steel cabinet-type
9.    Filler, pipet (e.g., Will Scientific Co. no 22105)
10.  Flasks, Erlenmeyer, Kimax or Pyrex, 250-ml, with wide mouth
11.  Flasks, volumetric, 100-ml and 2-liter
12.  Foil, aluminum
13.  Gloves, asbestos
14.  Hood, capable of removing acid fumes
15.  Hot  plate,  electric (230  volts), rectangular,  12 x  20 inches (~  30x51  cm),  with input
     proportioner and 79- to 510-C temperature range (e.g., Lindberg Hevi-duty hot plate, type H-2,
     Matheson Scientific Co. no. 28650-20)
16.  Mats, asbestos, 12x12 inches  (~  30 x 30 cm)
17.  Meter, pH (e.g.,  Corning Model  7,  with  Corning pH electrode no. 476022 with triple-purpose
     glass membrane and Corning reference calomel electrode no. 476002 with asbestos junction)
18.  Pencil, diamond,  for marking glass
19.  Pipets, serological, class A accuracy, 5-ml
20.  Pipets, volumetric, Pyrex; 1-, 5-, and 10-ml
21.  Spatula, stainless-steel (e.g., Scoopula®, Fisher Scientific Co. no. 14-357)
22.  Spectrophotometer, operative at  650 nm, with matched cuvettes having a 1-cm pathlength (e.g.,
     Beckman model B spectrophotometer)

                                         Preparation

   Soak all glassware in the special cleaning solution (See Reagents section below). Rinse well with
distilled  water, and dry before using. Avoid  contact  of glassware with soaps or detergents as they
contain phosphates.
                                       REAGENTS

 1.   Cleaning solution for glassware: Slowly add 250 ml concentrated hydrochloric acid to 750 ml
     distilled water. Cool before using.
 2.   Stock organic phosphate solution(21.98 mgPO4/l): As needed, dissolve 0.1 g anhydrous beta
     sodium  glycerophosphate (e.g., C3H7Na2O6P'51/2  H2O, Fisher Scientific  Co. no. 314,  pre-
     viously heated for 1  hour at 105 C to drive off water) in distilled water and dilute with same to
     2 liters.

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 METHODS OF SOLID WASTE TESTING
3.   Stock  inorganic  phosphate  solution  no.  1  (lOOOmg  PO4/1):  Dissolve  1.433g KH2PO4
     (previously dried  for 1 hour at 105 C) in distilled water and dilute with same to 1 liter. Store in
     a 1-liter reagent bottle.
4.   Stock inorganic phosphate solution no.  2 (10 mgPO4/l): Prepare as needed by diluting 10 ml
     stock inorganic phosphate solution no. 1 to 1 liter with distilled water.
5.   Sulfunc  acid  solution  containing  bismuth: Slowly add  370ml concentrated  sulfunc  acid
     (S.G. 1.84) to 600 ml  distilled water. While the solution is warm, add 4.8 g Bi(NO3)3-5H2O.
     Cool the solution to room temperature,  and dilute with distilled water to 1 liter. Store in a
     1-liter reagent bottle.
6.   Potassium persulfate, A.C.S., anhydrous (K2 S2 O8).
7.   Ammonium  molybdate  solution: Dissolve 48 g (NH4)6MO,O24 -4H2O  in  800ml distilled
     water. Add 2.5 ml concentrated NH4OH (S.G. 0.90), and dilute with distilled water to 1 liter.
8.   Amino solution:  In  500 ml distilled  water, dissolve (in order specified) 18.5g sodium sulfite
     (Na2SO3), 0.500  g l-amino-2-naphthol-4-sulfomc acid, and  31 g sodium  metabisulfite (sodium
     pyrosulfite, Na2 S2 Os).  Store in an amber reagent bottle, wrapped in aluminum foil to exclude
     light. Prepare fresh once a month.
9.   Buffer solution, pH 2.0 ± 0.02 at 25 C (e.g., Fisher Scientific Co. no. SO-B-96).
10.  Potassium chloride solution, saturated (e.g., Corning no. 477000).


                                  STANDARDIZATION

  The calibration of  the method is initiated by developing the molybdenum  blue color in  eight
standard inorganic phosphate solutions that range in concentration from 0.5 to 5.0 mgPO4/l. After
measuring the absorbance of each standard solution against that of a similarly treated water blank, a
calibration graph is prepared.
  The steps of the calibration procedure are as follows:
                  Procedure

1.  Prepare  a  blank  sample  by  transferring
    100ml  distilled water  to  a  100-ml glass-
    stoppered cylinder.
2.  Prepare eight calibration standards by indi-
    vidually transferring a 2-, 5-,  10-,  15-,  20-,
    25-, 30-, 40-, and 50-ml aliquot of standard
    inorganic solution no. 2 to an appropriately
    labelled  100-ml  glass-stoppered  cylinder.
    Then  dilute each with  distilled  water to
    100ml.
3.  Add  5 ml sulfuric  acid  reagent containing
    bismuth  to  each of the  nine cylinders.
    Stopper and invert several times to mix the
    contents.
4.  Add  5 ml ammonium molybdate reagent to
    each  cylinder. Restopper  and  invert to  mix
    the contents.
                 Comments
2. The calibration standards contain 0.2, 0.5,
    1.0,  1.5,  2.0,  2.5,  3.0, 4.0, and  5.0 mg
   PO4/1, respectively.
3. Use a pipet filler and  a  clean serological
   pipet to add each reagent m steps 3-5.
4.  A yellowish color forms.

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                                           Total Phosphate and Total Orthophosphate in Liquids
 5.  Without delay, add 5 ml amino solution to
    each cylinder. Restopper and invert to mix
    the contents. Note the time.
 6.  Fifteen minutes after mixing the samples in
    step 5, transfer an  aliquot of each solution
    to  a spectrophotometer  cuvette having  a
    1-cm pathlength.
 7.  Measure at 650 nm the absorbance of each
    standard solution against that of the  water
    blank, set at zero.
 8.  Prepare a calibration graph (i.e., on regular
    graph paper plot the absorbance values as
    ordinates and  the phosphate concentrations
    as abscissas; connect the points).
5.  Molybdenum  blue  begins  to  form directly
    upon  the addition of  this  reagent  to a
    standard  solution.  The  color  intensity in-
    creases within the  first  few minutes  and
    appears stable after 15 minutes.
6.  The color remains  stable for at least 25
    minutes  (i.e.  from 15 to 40  minutes after
    mixing the samples in step 5).

7.  The final  pH  of each developed solution
    should be 0.65 ± 0.05.

8.  The graph should be linear.
                                SAMPLE PREPARATION

   Since the total phosphate and total orthophosphate determinations are performed on aliquots of
the total aqueous sample, no sample preparation is required. It is advantageous, however, to minimize
the oxidation of a sample (particularly its ferrous iron content) during its collection and delivery to
the laboratory. If the collection vessel is quickly and completely filled and then tightly sealed, sample
oxidation will be minimized. In this way, the ferric iron concentration may be prevented from rising
to the level of interference. (See Method Evaluation Section of this Procedure.)


                                     PROCEDURES

   The procedures  recommended  here are  applicable for the direct determination of  the  total
phosphate and total orthophosphate contents of refuse extracts, landfill leachates, and related water
samples containing  up to 5  mg PO4/1. The range  of applicability  has routinely been extended to
100 mg PO4/1 by  diluting  an appropriate aliquot of the sample to 100  ml  before initiating the
analysis.
   Duplicate determinations of the total phosphate  and total orthophosphate contents of a standard
or wastewater sample should  be performed. A reagent blank should also be processed with each set of
samples.  The  blank for the  total phosphate analysis (reagent blank  no. 1)  measures the color
produced  by  all the reagents and  is therefore subjected  to both the digestion and  the color
development. The blank for the total orthophosphate analysis  (reagent blank no. 2)  measures only
the color produced by the reagents used in the color development.
                              Determination of Total Phosphate
                 Procedure
                Comments
1.  Prepare reagent blank  no. 1 by transferring
   100ml distilled  water to  a labelled,  wide
   mouth 250-ml Erlenmeyer flask.

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METHODS OF SOLID WASTE TESTING
2. Transfer an appropriate aliquot of a standard
   solution or  wastewater to a labelled wide-
   mouth 250-ml Erlenmeyer flask.
3.  If necessary, dilute the sample aliquot in the
    flask to  100 ml with distilled water.
4.  Process  a  second  aliquot  of the standard
    solution or wastewater as directed in steps 2
    and 3.
5.  Add 5  ml sulfuric acid reagent  containing
    bismuth to each flask.  Mix the contents of
    the flask by swirling.
6.  Add 0.8 g potassium persulfate to each flask.
    Mix the contents of the flask by swirling.
 7.  Place each flask on a previously heated hot
    plate.
 8.  Using  maximum heating, boil the contents
    of each flask for 40 minutes.
 9.   After  digestion is  completed, remove each
     flask from the hot plate.

 10. Wash down the inner surface of each flask
     with a fine stream  (10 ml) of distilled water.
 11. Cool the  contents of each  flask  to  room
     temperature (25 C  ±5 C).
 12. Transfer  the  contents of  each flask to a
     correspondingly  labelled,  105-ml  marked,
     glass-stoppered cylinder.
2.  a)

   b)
                                                    c)
7.
       An appropriate aliquot contains less than
       0.5mgPO4.
       A  10-ml  aliquot  of the stock organic
       phosphate solution can be used for the
       standard analysis.
       A pipet filler and clean volumetric pipet
       should be used to transfer each sample.
5.  a)
    b)

    c)
                                                    b)
       Wear safety glasses while handling acids
       and mixtures thereof.
       Use a pipet filler and  clean serological
       pipet to add the reagent.
       A  sample, containing sulfide,  will turn
       brown on addition of this reagent. If this
       occurs, modify the procedure as suggest-
       ed by  ASTM. (See Method Evaluation
       section of this procedure.)
6. Previously  weighed  glassine  paper may be
   used  as support  while  weighing and trans-
   ferring the potassium  persulfate  to  each
   flask.
   a)  Turn hot plate  on to maximum  heating
       position 30 minutes prior to use.
       The directions concerning the  hot plate
       apply to the apparatus specified in the
       Equipment section of this procedure.
       The sample volume normally  decreases
       to  about  10   to   15ml  during  the
       40-minute digestion. A white precipitate
       forms if the volume falls below 10 ml.
       If the  sample volume falls  below 25 ml
       dunng the first 35 minutes  of  the diges-
       tion, add distilled water to the  sample to
       maintain  a  volume  between  25  and
       100 ml.
       Wear asbestos gloves while  handling hot
       flasks.
       Support hot flasks on asbestos mats.
 10. A  dispensing-washing bottle  can be used to
    dispense the distilled water.
 11. Cooling is usually completed after 45 to 60
    minutes.
 8.  a)
                                                     b)
 9.  a)

    b)

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                                            Total Phosphate and Total Orthophosphate in Liquids
13. Using a  fine  stream  (10ml)  of  distilled
    water,  rinse each flask several times.  Add
    each rinse to its corresponding sample, con-
    tained in a cylinder.
14. Dilute  the  contents  of each  cylinder  to
    105 ml with distilled  water.  Stopper and
    invert to mix the contents.

15. Add 5 ml  ammonium molybdate solution to
    each cylinder.  Restopper and invert to mix
    the contents.
16. Without delay, add  5 ml amino addition to
    each cylinder.  Restopper and invert to mix
    the contents. Note the time.
17. Fifteen minutes after mixing the samples in
    step 16, transfer an aliquot of each solution
    to a spectrophotometer cuvette with a 1-cm
    pathlength.
18. Measure at 650 nm the absorbance of each
    standard solution or wastewater against that
    of reagent blank no. 1, set at zero.
19. Obtain the  Orthophosphate concentration
    (mgPO4/l) of each solution from the cali-
    bration graph.
20. If the sample aliquot (used in step  2) was
    less  than  100 ml,  calculate the phosphate
    concentration of  the  original (undiluted)
    standard solution or wastewater as directed
    in the Calculations section of this Procedure.
21. Report the observed  total  Orthophosphate
    concentration as the total phosphate.
14. Mixing of insufficiently cooled samples may
    result in excessive generation of heat, expan-
    sion of flask contents, and expulsion of both
    the stopper and acidic solution.
15. a)  Use  a pipet filler  and clean serological
       pipet to add each reagent  in  steps  15
       and 16.
    b)  A yellowish color forms on addition of
       this reagent.
16. Molybdenum blue begins  to form  upon the
    addition  of this reagent  to the  standard
    solution or wastewater. The color intensity
    increases within the first few minutes and
    appears stable after 15 minutes.
17. The  color  remains stable for  at  least  25
    minutes (i.e., from 15 to 40 minutes after
    mixing the samples in step 16.)

18. The  final pH   of  each developed solution
    should be 0.65 ± 0.05.
                            Determination of Total Orthophosphate
                  Procedure

1.  Prepare reagent blank no. 2 by transferring
    100 ml distilled water to a labelled,  100-ml
    glass-stoppered cylinder.
2.  Transfer an appropriate  aliquot of the stan-
    dard solution  of  wastewater to a labelled,
    100-ml glass-stoppered cylinder.
                 Comments
2.  a)  An appropriate aliquot contains less than
       0.5 mgPO4.
   b)  A  10-ml aliquot of stock inorganic phos-
       phate solution no. 2 can be used for the
       standard analysis.
   c)  A  pipet filler and clean volumetric pipet
       should be used  to transfer each sample.

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 METHODS OF SOLID WASTE TESTING
3.
4.
5.
6.
7.
8.
9.
    Dilute  the  contents  of each  cylinder, if
    necessary, to  100 ml  with  distilled water.
    Stopper and invert to mix the contents.
    Process  a second  aliquot of the standard
    solution or wastewater as directed in steps 2
    and 3.
    Add 5 ml sulfuric  acid reagent  containing
    bismuth to each cylinder. Stopper and invert
    to mix the contents.
    Add 5 ml ammonium molybdate solution to
    each  cylinder. Restopper and  invert to mix
    the contents.
    Without delay,  add 5 ml amino solution to
    each  cylinder. Restopper and  invert to mix
    the contents. Note the time.
5. a)  Wear safety glasses while handling acids
       or mixtures thereof.
   b)  Use a pipet filler and a clean serological
       pipet to add each reagent in steps 5-7.
   c)  A sample, containing sulfide,  will  turn
       brown on addition of this reagent. If this
       occurs, modify the procedure as suggest-
       ed by the American Society for Testing
       and  Materials (ASTM).  (See  Method
       Evaluation section of this Procedure).
6. A yellowish color forms when this reagent is
   added.

7. Molybdenum blue begins to form  upon the
   addition of  this reagent  to  the  standard
   solution or wastewater. The color intensity
   increases within the first few minutes  and
   appears stable after 15 minutes.
8. The color remains stable  for at  least  25
   minutes (i.e.,  from 15 to 40  minutes after
   mixing the samples in step 7).

9. The final pH of  each developed solution
   should be 0.65 ± 0.05.
    Fifteen  minutes after mixing the samples in
    step 7, transfer an aliquot of each solution
    to a spectrophotometer cuvette with a 1-cm
    pathlength.
    Measure at 650 nm the absorbance of each
    standard solution or wastewater against that
    of reagent blank no. 2, set at zero.
1 0. Obtain the  orthophosphate concentration
    (mgPO4/l) of each solution from the cali-
    bration graph.
    If the sample  aliquot (used in step  2) was
    less   than  1 00 ml,  calculate  the  ortho-
    phosphate concentration of the original (un-
    diluted)  standard solution or  wastewater
    sample as directed in  the following section.

                                    CALCULATIONS

  Since the total phosphate concentration is reported in terms of the total orthophosphate concentra-
tion of a sample, the following formula suffices for the calculation of either the total phosphate or total
orthophosphate concentration of the original (undiluted) standard solution or wastewater sample.
11
where:
  C = mg PO4/1 obtained from the calibration graph
  V = ml of sample used in the test

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                                           Total Phosphate and Total Orthophosphate in Liquids


                               METHOD EVALUATION

                                        interferences

  Studies performed in the Solid and Hazardous Waste Research Laboratory have demonstrated that
the color development of a 100-ml sample is not affected by the presence of 100 mg chloride or
50 mg calcium. Ferric iron may delay the  color development for a few minutes, but the maximum
color intensity is always attained within 15 minutes  in the presence of 20 mg ferric iron. The ASTM
has reported only a 2 percent error in the  analyses of solutions containing silica concentrations fifty
times larger than their phosphate concentrations (2,  sect.  15, p. 47). Nitrite, several mgsulfide, and
>75 mg  chromate  per liter, however,  will interfere with the test. The  analyst should  use the
modifications proposed by ASTM to overcome these interferences (13).

                                         Accuracy

Total phosphate method.
  The accuracy of the total phosphate procedure was first evaluated by  analyzing four  aliquots of
three standard solutions of organic phosphates: beta sodium glycerophosphate, 3-adenylic acid, and
barium   fructose  6-phosphate.  The  average  percent recoveries  of the  theoretical  phosphate
concentrations of the three solutions were  99.6, 91.3, and  86.3, respectively (See Table 1). Although
the phosphate recoveries  from the 3-adenylic acid and barium fructose 6-phosphate solutions were
lower than the recovery from the beta sodium glycerophosphate solution, the observations compare
favorably with those of Gales, Julian and Kroner (4).
  Four diluted leachate samples were also analyzed before and after the addition of an aliquot of
one of the organic phosphate solutions. The percent recovery of phosphate added as 3-adenylic acid
(3AA) to two landfill leachates was 92.6 whereas the percent recovery of phosphate added as barium
fructose  6-phosphate (BF6P) to the same leachates  was  86.7. When aliquots of the beta sodium
glycerophosphate (BSG)  solution were  added to four leachates, the percent phosphate  recovery
varied  from 97.1  to 99.1; the average  was 98.6. The excellent  recovery of phosphate from two
leachates, (namely,  nos.   71-303  and  73-49) was  particularly significant  because  these  samples
contained substances that  prevented  the  determination  of their total phosphate content by the
vanadomolybdophosphoric acid and stannous chloride methods (7, p. 78-93).

Total Orthophosphate method.
  The accuracy of the total Orthophosphate  method was first evaluated by analyzing an inorganic
phosphate  standard  obtained from the  Analytical Quality Control Laboratory, National  Environ-
mental Research Center-Cincinnati, U.S. Environmental Protection Agency. The percent recovery of
the theoretical phosphate  concentration was 102. (See Table 2.)
  Two diluted leachate samples were also  analyzed before and after adding an aliquot of a standard
solution  of monobasic potassium phosphate (KH2PO4). The percent phosphate recovery was 100 in
each case. The excellent phosphate recovery from leachate no. 73-49 was particularly significant in
view of the 290 mg iron (ferrous and ferric) present in the aliquot analyzed.

                                         Precision

  The reproducibility of  the observations  of the total phosphate and total Orthophosphate contents
of refuse extracts and landfill leachates  was evaluated by  calculating the pooled standard deviation
and coefficient  of variation of groups of duplicate observations. The groupings were based on sample
type and source, and the  subgroupings, on range of phosphate  concentration. A  review of the data,
presented in Tables 3 and  4, reveals that the coefficient of variation never exceeded 0.03.

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METHODS OF SOLID WASTE TESTING
                              ACKNOWLEDGMENTS

  The author wishes to thank Dirk Brunner and the staff of the Landfill Disposal Project, Solid and
Hazardous Waste Research Laboratory, for supplying the refuse and landfill leachate samples. Special
thanks are also extended to Israel Cohen, Monitoring and Analysis Project, for preparing the refuse
extracts.
                                      TABLE 1
                   ACCURACY OF THE TOTAL PHOSPHATE METHOD
               Sample
              Identity
mgP04/l
 diluted
 sample
 Added
 standard
mgP04/l
% Recovery
 standard
                                                       Observed
          Avg.
       Standards
       Beta sodium
        glycerophosphate
        (BSG)
      3-Aden ylie acid
        (3AA)
      Barium fructose
        6-phosphate
        (BF6P)
  2.198
  2.198
  2.198
  1.099
   .367
   .367
   .367
  0.684
   .200
   .200
  1.200
  0.600
      Boone Co., Ky., Landfill Leachates
      no. 71-303               2.10
        with BSG
        with BSG
      no. 72-125
        with BSG
        with 3AA
        with BF6P

      no. 72-126
        with BSG
        with 3AA
        with BF6P

      no. 73-49
         with BSG
 2.59
 1.40
 1.01
               1.099
               1.099
               1.099
              0.684
              0.600
              1.099
              0.684
              0.600
              2.198
               100.0
                99.1
               100.0
                99.1

                91.4
                91.4
                91.4
                91.2
                85.6
                88.3
                84.9
                86.6
                99.1
               100.0
               99.1
               92.6
               86.7
               97.3
               92.6
               86.7
               99.1
                                                                      99.6
                                                                      91.3
                                                                      86.4
          99.6
                                         10

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                                       Total Phosphate and Total Orthophosphate in Liquids
                                     TABLE 2
               ACCURACY OF THE TOTAL ORTHOPHOSPHATE METHOD
                    Sample
                    Identity
mgP04/l
 diluted
 sample
 Added
 standard
mgP04/l
%Recovery
 standard
             Standard
             Analytical Quality
              Control Lab.
              nutrient soln.
              no. 2
  0.975
               102
Boone Co., Ky.,
no. 73-9
with KH2 PO4
no. 73-49
with KH2 PO4
Landfill Leach ates
0.170

0.645



1.100

1.100


100

100
                                     TABLE 3
         PRECISION OF DUPLICATE TOTAL PHOSPHATE DETERMINATIONS OF
        REFUSE EXTRACTS AND LEACHATES FROM THE RESEARCH LANDFILL
                     OPERATION IN BOONE COUNTY, KENTUCKY
Type of
sample
Refuse
extracts*

Leachates


Leach ates


Sample
source
Cell no. 1
refuse

Cell no. 1
upper
pipe
Cell no. 1
lower
pipe
No. of
Group samples
in group
Total
Subgroup A
Subgroup B
Total
Subgroup A
Subgroup B
Total
Subgroup A
Subgroup B
14
4
10
39
3
36
33
9
24
Range of total
PO4 cone, in
mg/1
>
1
1
10
1
1
10
1
1
10
<
100
10
100
100
10
100
100
10
100
Mean
mgP04/l
(M)
20.66
7.30
26.00
29.94
8.43
31.73
14.41
6.87
17.25
Pooled
standard
deviation

-------
   METHODS OF SOLID WASTE TESTING
                                        TABLE 4
       PRECISION OF DUPLICATE TOTAL ORTHOPHOSPHATE DETERMINATIONS OF
LEACHATES FROM THE RESEARCH LANDFILL OPERATION IN BOONE COUNTY, KENTUCKY
Sample
source
Cell no. 1
upper
pipe
Cell no. 1
lower
pipe
Group
Total


Total
Subgroup A
Subgroup B
No. of
samples
in group
23


18
10
8
Range of total
PO4 cone, in
mg/1
>
10


1
1
10
<_
100


100
10
100
Mean
mgP04/l
(M)
31.50


11.53
6.26
18.12
Pooled
standard
deviation

-------
   LABORATORY PROCEDURE FOR DETERMINING
          THE TOTAL PHOSPHATE CONTENT
                  OF SOLID WASTES


                      Nancy S. Ulmer*

 DISCUSSION	   2
 SAFETY PRECAUTIONS  	          2
 EQUIPMENT	   2
 REAGENTS  	   3
 STANDARDIZATION	   4
 SOLID WASTE PREPARATION	   5
 PROCEDURE   	   5
 CALCULATIONS  	   9
 METHOD EVALUATION  	   9
 ACKNOWLEDGMENTS  	  10
 REFERENCES	  11
'Research Chemist, Criteria Development Branch, Water Supply Research Laboratory,
 National Environmental Research Center - Cincinnati, Miss Ulmer was formerly with
 the Solid and Hazardous Waste Research Laboratory of NERC-Cincinnati

-------
METHODS OF SOLID WASTE TESTING
                                       DISCUSSION

   The significance of  phosphorus  as  a solid  waste  characteristic  becomes apparent when one
considers that it is an essential nutrient. Along with nitrogen, phosphorus promotes the growth of
algae in streams. Discharging incinerator wastewater and landfill leachates containing phosphorus into
receiving streams will contribute to the deterioration of stream water quality and the eutrophication
of lakes.  A knowledge of the concentration and distribution of phosphorus in solid  wastes and
related water  samples is, therefore, important to the engineers and scientists responsible for the
development and evaluation of solid waste and water quality management systems.
   Analysts have employed a variety of methods to determine the phosphorus content of solid wastes
and related materials (1-11). The condensed phosphates and organically bound phosphorus present in
a sample  must first be  converted  to orthophosphate by either ashing or digesting the sample. The
total orthophosphate  content of the treated and diluted sample is then  determined  with the use of
volumetric, gravimetric,  colorimetric, or atomic absorption technique.
   The technique outlined here recommends the digestion of 1-g solid waste samples with sulfuric and
nitric acids. After the  digestion is completed, the sample is cooled, filtered, and carefully diluted. The
orthophosphate  concentration of an appropriate aliquot of solution  is  then determined colorimet-
rically using the  amino reduction  method  (2, p. 46-50). The solution  is therefore treated  with a
sulfuric  acid  reagent containing  bismuth.  Ammonium  molybdate is  added  to form  molyb-
dophosphate. The latter, in turn, is reduced to molybdenum blue with 1-amino-2-naphthol-4-sulfonic
acid. The bismuth salt  in the acid reagent provides a fourfold increase  in the intensity  of the blue
color.


                               SAFETY PRECAUTIONS

   To avoid the physical and chemical hazards associated with the maintenance of the glassware and
the performance of each analysis:

1.   Wear safety glasses  when handling concentrated acids and mixtures thereof.
2.   Perform all acid digestions in a hood to avoid inhalation of fumes.
3.   Wear asbestos gloves while handling hot flasks.
4.   Avoid contact of skin, clothing, metal, and painted surfaces with the molybdate reagent as it is
     corrosive.
5.   Exercise care in weighing, transferring, and disposing l-amino-2-naphthol-4-sulfonic acid as its
     toxicological properties have not been fully evaluated.
6.   Avoid inhalation of SO2 vapors when disposing of the final  color-reaction  mixtures. The sink
     area should be well ventilated and tap water should be running during disposal of the solutions.


                                       EQUIPMENT

                                        Requirements

\.   Apparatus,  digestion, micro-Kjeldahl, with six individual heaters and controls (e.g., Fisher
     Scientific Co. no. 21-131-5)
2.   Balance, analytical, 0.0001 -g readability
3.   Bottles, reagent, Pyrex, 250-ml and 1-liter

-------
                                                                     Total Phosphate in Solids


 4.   Bottle, reagent, Pyrex, amber, 1-liter
 5.   Bottle, washing-dispensing, polyethylene, 500-ml
 6.   Bottle,  weighing, low form, cylindrical with standard taper cap, 30 mm high and  60 mm in
     diameter
 7.   Cuvettes, spectrophotometer, matched, with  1-cm pathlength
 8.   Cylinders, graduate, Pyrex, with standard taper stopper, 100-mI
 9.   Desiccator, Pyrex or small, stainless-steel, cabinet-type
 10.  Dishes, aluminum, moisture, 89- x 50-mm, with tightly fitting lids (e.g., Arthur H. Thomas Co.,
     no. 3840-F30)
 11.  Dispenser, tilting, with 25-ml reservoir, for use with 500-ml Erlenmeyer flask (e.g., Lab. Glass,
     Inc., no. LG-7915)
 12.  Filler, pipet (e.g., Will Scientific Co. no. 22105)
 13.  Flask, Erlenmeyer, 500-ml, with 20/40 ground glass neck to receive tilting dispenser
 14.  Flasks, Kjeldahl, micro, 100-ml (e.g., Scientific Glass Blowing Co. no. SGB-16350)
 15.  Flasks, volumetric, 100-ml and  1-liter
 16.  Foil, aluminum
 17.  Funnel, filtering, Pyrex, 65 mm in diameter, with 60° angle and short stem
 18.  Gloves, asbestos
 19.  Hood, capable of removing acid fumes
 20.  Meter,  pH (e.g., Corning Model  7 with Corning pH electrode  no. 476022 with triple-purpose
     glass membrane and Corning reference calomel electrode no. 476002 with asbestos junction)
 21.  Oven, forced-draft, capable of maintaining a 70- to 75-C temperature over a 4-hour period
 22.  Paper, filter, Whatman no. 7, 12.5-cm diameter
 23.  Paper, glassine
 24.  Pipets, serological, Pyrex, class A accuracy, 5-ml
 25.  Pipets, volumetric, Pyrex, 1-, 5-, and 10-ml
 26.  Spatula, stainless-steel (e.g., Scoopula®, Fisher Scientific Co. no. 14-357)
 27.  Spectrophotometer,  operative at 650 nm; with  cuvettes having  a  1-cm  pathlength  (e.g.,
     Beckman model B spectrophotometer)
 28.  Support for funnels, 65 mm in top diameter

                                         Preparation

   Soak all glassware  in the special cleaning solution (see Reagent section in this Procedure). Rinse
well  with distilled  water, and dry before using. Avoid contact of glassware with soaps and detergents
as they contain phosphates.


                                       REAGENTS

 1.   Cleaning solution for glassware:  Slowly add  250 ml concentrated hydrochloric acid to 750 ml
     distilled water. Cool before using.
2.   Beta sodium glycerophosphate, ACS. Heat C3 H7 Na2 O6 P.5-1/2 H2 O (e.g., Fisher Scientific Co.
     no.  S-314) for 1  hour at 105 C to drive off water. Store in a desiccator. The dried solid contains
     43.96 percent phosphate (PO4 ) by weight.

-------
METHODS OF SOLID WASTE TESTING


 3.   Stock inorganic  phosphate  solution  no.  1  (1000 mg PO4/1):  Dissolve  1.433gKH2PO4
     (previously dried for 1 hour at 105 C) in distilled water and dilute with same to 1 liter. Store in
     a 1-liter reagent bottle.
4.   Stock inorganic phosphate solution no. 2 (10 mg PO4/1): Prepare as needed by diluting 10 ml
     stock inorganic phosphate solution no. 1 to 1 liter with distilled water.
5.   Sulfuric acid, concentrated, ACS. (S.G. 1.84).
6.   Nitric acid, concentrated, ACS.
7.   Sulfuric  acid  reagent containing bismuth:  Slowly  add 370 ml  concentrated sulfuric  acid
     (S.G. 1.84) to 600 ml distilled water. While the solution is warm,  add 4.8 gBi(NO3)3-5H2O.
     Then cool the solution to room temperature and dilute with distilled water to 1 liter. Store in a
     1-liter reagent bottle.
8.   Ammonium molybdate  solution: Dissolve 48 g (NH4)6MO7O24 -4H2O in 800ml distilled
     water. Add 2 5 ml concentrated NH4OH (S.G. 0.90), and dilute with distilled water to  1 liter.
9.   Amino solution:  In 500 ml distilled  water, dissolve (in order specified) 18.5 g sodium  sulfite
     (NaaSO3), 0.500 g l-amino-2-naphthol-4-sulfonic acid, and  31  g sodium metabisulfite (sodium
     pyrosulfite, Na2 S2 O5). Store  in an amber reagent bottle that has been wrapped in aluminum
     foil to exclude light. Prepare fresh once a month.
10.  Buffer solution, pH 2.0 ± 0.02  at 25 C (e.g., Fisher Scientific Co. no. SO-B-96).
11.  Potassium chloride solution, saturated (e.g., Corning no. 477000).


                                  STANDARDIZATION

   The calibration of the method  is initiated by developing the molybdenum  blue color in eight
standard inorganic phosphate solutions, ranging in concentration from 0.5  to 5.0 mg PO4/1. After
measuring'the absorbance of each standard solution against that of a similarly treated water blank, a
calibration graph is prepared.
   The steps of the calibration  procedure are as follows:

                  Procedure                                     Comments

1.  Prepare a  blank  sample  by   transferring
    100ml distilled  water to a 100-ml  glass-
    stoppered cylinder.
2.  Prepare eight  calibration  standards by  in-   2.   The calibration standards contain 0.2, 0.5,
    dividually transferring a 2-, 5-,  10-,  15-, 20-,       1.0, 1.5,2.0,2.5,3.0,4.0, and 5.0mgPO4/l,
    25-, 30-, 40-, and 50-ml aliquot of standard       respectively.
    inorganic phosphate  solution  no.  2  to an
    appropriately   labelled   100-ml   glass-
    stoppered  cylinder.  Then dilute each with
    distilled water to 100 ml.
3.   Add  5 ml sulfuric  acid reagent containing   3.   Use a  pipet filler  and  a clean serological
    bismuth  to each  of the  nine cylinders.       plpet for each of the three reagents added in
    Stopper and invert several times to mix the       steps 3-5.
    contents.
4.   Add  5 ml ammonium molybdate reagent to   4   A yellowish color forms.
    each cylinder.  Restopper  and invert to mix
    the contents.

-------
                                                                     Total Phosphate in Solids
5.  Without delay, add  5 ml  ammo solution to
    each cylinder. Restopper, invert to mix, and
    note the time.
6.  Fifteen minutes after  mixing the  sample in
    step 5, transfer an aliquot of each solution
    to  a  spectrophotometer cuvette  having a
    1-cm pathlength.
7.  Measure at  650 nm  the  absorbance of each
    standard solution  against that of  the water
    blank, set at zero.
8.  Prepare a calibration graph (i.e., on regular
    graph  paper,  plot the absorbance values as
    ordinates and the phosphate concentrations
    as abscissas. Connect the  points.)
7.
Molybdenum blue begins  to form upon the
addition of this reagent to a standard solu-
tion. The color intensity increases within the
first few minutes and appears stable after 15
minutes.
The color  remains  stable for at least  25
minutes  (i.e.,  from  15 to 40  minutes after
mixing the  sample in step 5).

The final  pH  of each developed  solution
should be 0.65 ± 0.05.
8.  The graph should be linear.
                            SOLID WASTE PREPARATION

  A solid waste sample must undergo physical preparation before its characterization is initiated.
First, most of the glass and the metallic and magnetic iron particles are removed manually. Then the
waste is dried to a constant weight in a forced-air or mechanically convected oven. A temperature of
70 to 75 C is used to dry municipal refuse or compost. The particle size of the dried sample is then
reduced to 2 mm (or less) using a hammermill, pulverizer, and laboratory mill. Finally, since samples
may absorb moisture during  the  grinding and mixing process, they are redned for 4 hours at the
previously specified temperature and stored in a desiccator until the analyses are completed.

                                      PROCEDURE

  Duplicate determinations  of the total phosphate content of a solid standard  or  waste sample
should be performed. Initially, two different reagent blanks should  also be processed. Reagent blank
no. 1  measures the color produced by all the reagents and is therefore subjected to both the digestion
and the color development (steps 1-34). Reagent blank no. 2 measures only the color produced by
the three reagents used in  the  final color development  (steps  28-34).  If  the initial  analyses
demonstrate  that the absorbance  of reagent  blank no. 1  equals that of blank no. 2, the analyst can
conclude that phosphate is not present in  the sulfuric and nitric acids used to digest the samples.
Thereafter the preparation of reagent blank  no. 1 can  be omitted and blank no. 2 used as the
reference solution.
  The steps of the analytical procedure are as follows1
                 Procedure

    Label   a   100-ml  micro-Kjeldahl  flask  as
    reagent blank no. 1, and place on a cold-
    heater  unit  of  a micro-Kjeldahl digestion
    apparatus located  in a well-ventilated hood.
    Transfer an appropriate quantity of a solid
    sample to a  preweighed  piece of glassine
    paper  and determine the sample weight  to
    the nearest 0.0001 g.
                 Comments
2.
Use 0.025 g dried beta sodium glycerophos-
phate (organic standard) or 1  g of prepared
solid waste

-------
METHODS OF SOLID WASTE TESTING
3.  Quantitatively transfer  the solid to  an ap-
    propriately  labelled  micro-Kjeldahl   flask.
    Place  the latter on a cold-heater unit  of the
    micro-Kjeldahl digestion apparatus.
4.  Select  and process  a  second aliquot  of the
    solid sample as directed in steps 2 and  3.
5.  Carefully flow  10ml concentrated sulfunc
    acid  down the side of  each micro-Kjeldahl
    flask.

6.  Gently swirl each flask to wet the solid and
    mix the contents.

7.  Carefully add 5 ml  concentrated nitric acid
    to each flask.
8.  Gently swirl the contents of each flask and
    return the latter to a cold heater unit.
9.  Turn  the  control  knob of each heater to
    position 1.

10. After  the brown fumes have evolved from
    each flask, turn each heater control knob to
    position 3.
11. As the heat increases, swirl each flask to mix
    its contents.
12. After  heating  5 to  10 minutes at control
    knob position  3, turn each  control knob to
    position 5 and digest each sample for 1-1/2
    to 2 hours.
13. Turn off heater units and cool samples.
14. Examine each sample for completeness of
    digestion.
15. If the sample is completely digested, proceed
    to step 17.
16. If the sample is incompletely digested, care-
    fully add 1 ml concentrated nitric acid, and
    continue digestion until  the solution clears.
    Then  turn  off  the  heater  and  cool the
    sample.
17. After the contents of each flask have cooled,
    carefully flow  25 ml distilled  water down
    the side  of each flask.
    a)  Wear safety glasses when handling acids
       and mixtures thereof.
    b)  Use a pipet filler with a serological pipet
       to add the acid to each flask.
    Wear asbestos  gloves  while  handling the
    flasks in steps 6-8; heat will be generated as
    the acids react with the sample.
    Avoid inhaling  the brown  fumes that will
    evolve from samples.
9. The directions concerning the heater control
   knobs apply only to the apparatus specified
   in the Equipment section of this Procedure.
10. Samples, containing organic matter will turn
   dark brown.

11. Wear  asbestos gloves  while  handling hot
   flasks.
12. Do  not allow  the  sample volume  to drop
   below 3 ml.
14. a)  The  solution of  a  completely digested
       solid  sample will  appear  colorless  on
       cooling.  A  white  precipitate  may  be
       present in a flask containing a digested
       solid waste.
   b)  An incompletely digested sample will be
       brown or tan in color.
16. a)  Continue digestion using heater control
       knob position 5.
   b)  This additional step is required for only
       an occasional sample.
                                     t
17. a)  Use a 25-ml tilting dispenser attached to
       a 500-ml Erlenmeyer to add the water.
   b)  Minimize  the  spattering of  acid while
       adding water to each  flask.

-------
                                                                       Total Phosphate in Solids
18. Return each flask to a heater unit and boil
    its contents for 10 minutes

19. After boiling  is  completed, turn off each
    heater. While waiting for the digested sam-
    ples to cool to room temperature, proceed
    to step 20.
20. Set up a  filtering  apparatus for each sample,
    including reagent blank, no. 1, as follows:
    Place  a clean,  100-ml volumetric flask, con-
    taining  25 ml  distilled  water,  beneath a
    supported funnel  containing Whatman no. 7
    filter paper recently washed with four 20-ml
    portions of distilled water.
21. Quantitatively  transfer the cooled contents
    of each micro-Kjeldahl flask to  its respective
    filtering apparatus.
18. a)  Use heater control knob position 5.
   b)  This treatment helps to drive off excess
       nitric acid.
22. Rinse each micro-Kjeldahl flask several times
    with 5- to 10-ml portions of distilled  water.
    Add the  rinsings to  the appropriate funnel.
23. After the material in  each funnel is com-
    pletely filtered, rinse the  filter paper down
    with  a  gentle  stream (10ml) of distilled
    water.
24. Allow  the contents  of each  100-ml volu-
    metric flask to cool to  room temperature
    (25 ± 5 C).
25. Carefully  dilute the  contents  of each volu-
    metric flask to 100ml with distilled  water.
    Stopper  tightly and invert to mix.  Each
    solution, thus prepared is labelled SolutionA.
26. Dilute a 10-ml aliquot of each solution A to
    100 ml with distilled water. Each  new solu-
    tion is labelled Solution B.
27. To initiate the color development, transfer a
    10-ml  aliquot  of each  Solution  B  to an
    appropriately  labelled,  100-ml  glass-stop-
    pered cylinder.
28. Similarly prepare reagent blank  no. 2 by
    transferring  10ml distilled water  to  an ap-
    propriately  labelled  100-ml glass-stoppered
    cylinder.
20. a)  At  least  30  minutes are required  for
       sample cooling.
   b)  Discard the filtrate from  the four wash-
       ings of each filter paper.
21. a)  If the filter paper  is  wet, it  will not
       rupture when the acidic sample  is slowly
       added.
   b)  Filtering the sample into a volumetric
       flask  containing distilled water reduces
       the generation  of heat on  further dilu-
       tion in step 25.
22. A washing-dispensing bottle can be used to
   dispense the rinses in steps 22 and 23.

23. Allow the rinse  to filter through the paper
   into the flask.
25. BEWARE1  Mixing of  insufficiently cooled
    samples may result in excessive generation of
    heat, expansion of flask contents, and expul-
    sion of both the stopper and acidic solution.
26. The specified dilution of Solution A suffices
    for  the  analysis of  0.025-g beta  sodium
    glycerophosphate samples and for  1-g solid
    waste samples  containing  up to 5 percent
    total phosphate (PO4).

-------
 METHODS OF SOLID WASTE TESTING
29. Dilute each cylinder to 100 ml with distilled
    water. Each solution, thus prepared, is iden-
    tified as Solution C.

30. Add  5 ml  sulfuric acid reagent  containing
    bismuth  to each of the cylinders. Stopper
    each cylinder and invert several times to mix
    the contents.
31. Add 5 ml ammonium molybdate reagent to
    each  cylinder.  Restopper  and  mix  the
    contents.

32. With delay, add 5 ml amino solution to each
    cylinder. Restopper and mix the contents.
    Note the time.
33. Fifteen minutes after mixing the samples in
    step 32, transfer an aliquot of each solution
    to a spectrophotometer cuvette with a 1-cm
    pathlength.

34. Measure  at  650 nm  the  absorbance  of
    reagent blank no. 2  and each standard and
    solid waste solution  against that of reagent
    blank  no. 1, set at zero. Record the  obser-
    vations.
35. Obtain  the  orthophosphate  concentration
    (mgPO4/l)  of each  C  solution from the
    calibration graph.

36. Calculate the percent  total phosphate in the
    original  solid  standard  or  waste  sample
    according to the instructions in the Calcula-
    tions section below.
30. a)  Use a pipet filler and a clean serological
       pipet  for  each  of  the  three  reagents
       added in steps 30-32.
    b)  Although 10-ml  ahquots of the B solu-
       tions  may theoretically  contain up to
       0.1 ml  residual   concentrated   sulfuric
       acid (from the digestion), an adjustment
       in the added volume of the sulfuric acid
       - bismuth  reagent  does  not appear
       necessary.  The  final  pH of developed
       solutions  of digested  samples  has not
       varied  significantly from those of un-
       digested inorganic standards.

31. A yellowish color forms
32. Molybdenum  blue  begins  to  form directly
    upon  the  addition  of this reagent to the
    standard  or waste solution. The color in-
    tensity increases within the first few minutes
    and appears stable after 15 minutes.

33. The color  remains  stable for at least 25
    minutes (i.e., from  15 to  40  minutes after
    mixing the sample in Step 32).
34. a)  If the initial analyses reveal that the two
       blanks have  equal  absorbance, reagent
       blank no. 2 can henceforth be used as a
       reference solution.
    b)  The final pH  of each developed solution
       should be 0.65 ± 0.05.

-------
                                                                    Total Phosphate in Solids
                                   CALCULATIONS
  The percent  total phosphate (% total PO4) of a solid standard or waste sample, analyzed as
recommended in the Procedure section, is calculated as follows:

                                      % total PO4 =*j-

where
     M = mg orthophosphate (PO4 ) observed per liter of solution C of the digested sample
and  W = g of standard or solid waste digested in the test

  This formula is  based on the presence of 1  ml of solution A  (or 1/100 of the solid sample) in
100 ml solution C. When any other volume of solution  A is diluted to  100ml  and the color is
developed as outlined, the formula must be modified as follows:
                                           PCX,  =
where
     M = mg orthophosphate (PO4) observed per liter of the developed solution
     V = ml of solution A in the 100 ml of developed solution
     W = g standard or solid waste digested in the test
                              METHOD EVALUATION


                                       Interferences


  Studies performed in the Solid and Hazardous Waste Research Laboratory have demonstrated that
the color  development of a 100-ml sample is not affected by the presence of 100 mg chloride or
50 mg calcium. Ferric iron may delay the color development  for a few minutes, but the maximum
color intensity is always  attained  within  15 minutes in the presence of 20 mg ferric iron. The
American  Society  for Testing and  Materials (ASTM) has reported only a 2 percent error in the
analyses  of solutions  containing  silica concentrations  fifty times larger than  their  phosphate
concentrations (1,  p. 47). Nitrite, several mg sulfide, and 75 mg chromate per liter, however, will
interfere  with  the  test. The analyst should use the modifications proposed by ASTM to overcome
these interferences (1, p. 47).


                                         Accuracy

  Duplicate 0.025-g samples of beta sodium glycerophosphate, 0.1-g samples of 3-adenylic acid, and
0.1-g samples of barium fructose-6-phosphate were all analyzed using the recommended procedure.
The  average percent recoveries of the theoretical total phosphate  of the three standards were 99.1,
94.0, and 89.8, respectively. Although the average  percent  recoveries from 3-adenylic acid and
barium fructose-6-phosphate were less than  the average recovery from  the beta sodium glycerophos-
phate, the observations compare favorably with the data reported  by Gales, Julian, and Kroner (12).

-------
METHODS OF SOLID WASTE TESTING
  The concentration of total phosphate in duplicate aliquots of a Boone County, Kentucky, refuse
sample (no. 71-142) was also determined  before and after the addition of 0.025 g beta sodium
glycerophosphate. The average percent recovery of the added phosphate was 99.1. Additional studies
also revealed that the chloride, calcium, and iron concentrations in the C solutions of the 14 analyzed
Boone County refuse samples were all very low and, hence, noninterfenng.

                                        Precision

  The reproducibility  of the method has been determined by calculating the standard deviation of
the duplicate determinations of 14 Boone County, Kentucky, refuse samples. The data are presented
in Table 1.
                                        TABLE I
                   PRECISION OF THE DUPLICATE TOTAL PHOSPHATE
                         DETERMINATIONS OF BOONE COUNTY,
                             KENTUCKY, REFUSE SAMPLES
Sample No.
71-120
71-123
71-125
71-128
71-130
71-133
71-135
71-138
71-140
71-142
71-145
71-155
71-158
71-160
Observed mean %
total phosphate
2.22
0.51
0.44
0.34
0.50
1.02
0.24
0.26
0.18
0.20
0.44
0.44
0.58
0.20
Standard
deviation
0.09
0.02
0.01
0.04
0.04
0.02
0.02
0.01
0.02
0.01
0.00
0.01
0.03
0.00
                               ACKNOWLEDGMENTS

  The author wishes to thank Dirk Brunner and the staff of the Landfill Disposal Project, Solid and
Hazardous Waste Research Laboratory, for providing the Boone County, Kentucky, refuse samples.
Special thanks are extended to Israel Cohen, Monitoring & Analysis Project, Solid and Hazardous
Waste Research Laboratory, for preparing these samples. The calcium and iron analyses, mentioned
in the Method Evaluation section, were kindly performed by Michael Fluharty while he was
associated with the Laboratory.


                                           10

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                                                                    Total Phosphate in Solids
                                     REFERENCES
 1.  American Society for Testing and Materials. Standard method of test for phosphate in industrial
    water.  In:  1969 Book of ASTM  standards, pt. 23. D515-68.  sect.  1-39. Philadelphia  1969
    p. 43-53.
 2.  Boltz, D. F. Phosphorus. In: Colonmetnc determination of nonmetals New York, Interscience
    Publishers, Inc., 1958. p. 29-46.
 3.  Click, D., ed.  Determination  of organic  phosphorus compounds  by  phosphate analyses. In
    Methods of biochemical analyses, v. 3. New York, Interscience Publishers, 1954  p. 1-22.
4.  Horwitz, W., ed. Official methods of analyses of the Association of Official Analytical Chemists.
    llth ed. Washington, D.C., Association of Official Analytical Chemists, 1970. 1015 p.
 5.  Jackson, M. L.  Phosphorus determinations for soils. In. Soil chemical analysis. Englewood Cliffs,
    New Jersey, Prentice-Hall, Inc., 1958. p. 134-182.
6.  Scott, W. W. Gravimetric methods for the determination of phosphorus. In. Standard methods of
    chemical  analysis, v. 1. The elements. 5th  ed. New York, D. Van Nostrand Co.,  Inc   1939
    p. 694-696.
7.  Scott, W. W. Volumetric methods for the determination of phosphorus In- Standard methods of
    chemical  analysis, v. 1. The elements. 5th  ed. New York, D. Van Nostrand Co.,  Inc., 1939
    p. 697-699.
8.  Snell. F. D. and C. T. Snell. Phosphorus. In: Colonmetnc methods  of analysis, v. 2. 3d ed. New
    York, D. Van Nostrand Co., Inc., 1948. p. 630-681.
9.  Treadwell, F. P. Gravimetric determination of acid constituents—phosphoric acid. In: Analytical
    chemistry, v. 2. Quantitative analysis. 7th ed. New York, J. Wiley & Sons, Inc., 1937. p. 380-390.
10. Woodman, A. G. Food analyses. 4th ed. New York, McGraw-Hill Book Co., Inc., 1941. 607 p.
11. Zaugg, W.  S., and R. J. Knox. Determination of phosphate in biological materials and reaction
    mixtures by atomic absorption spectrophotometry. Analytical Biochem., 20:282-293, 1969.
12. Gales, Jr., M. E., E. C.  Julian, and R. C. Kroner. A method for the quantitative determination of
    total phosphorus in filtered and unfiltered water. Journal American Water Works Association,
    58(10): 1363-1368, Oct. 1966.
                                                                -It US GOVERNMENT PRINTING OFFICE. 1974— 757-581/5308

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