AWPA A5: Standard Methods for Analysis of Oil-Borne Preservatives

17 Pages·1991·2.2 MB·English

by  American Wood Preservers Association

By Authority Of
THE UNITED STATES OF AMERICA
Legally Binding Document
By the Authority Vested By Part 5 of the United States Code § 552(a) and
Part 1 of the Code of Regulations § 51 the attached document has been duly
INCORPORATED BY REFERENCE and shall be considered legally
binding upon all citizens and residents of the United States of America.
HEED THIS NOTICE: Criminal penalties may apply for noncompliance.
e
Document Name:
CFR Section(s):
Standards Body:
Official Incorporator:
THE EXECUTIVE DIRECTOR
OFFICE OF THE FEDERAL REGISTER
WASHINGTON, D.C.

AMERICAN WOOD-PRESERVERS' ASSOCIATION STANDARD
(This Standard is under the jurisdiction of AWPA Committee P-S)
AS--91
STANDARD METHODS fOR ANALYSIS Of Oil-BORNE PRESERVATIVES
Note: Standard A5-90 consists of 15 pages dated 1990. the burette to the nearest estimated 0.01 m!. Record
the volume of NaOH used for each replicate.
1. DETERMINATION OF TOTAL ACIDITY FOR
3. Sample Preparation
CALCULATING PENTACHLOROPHENOL
IN DRY CHEMICAL a. Weigh from 4 to 6 grams of oven-dry sample
to be analyzed to the nearest mg.
Scope
b. Quantitatively transfer to a 500 ml volumetric
This method covers the determination of the to flask.
tal acidity of a dry chemical sample expressed as the c. Add methanol exactly to mark. Mix weI!.
pentachlorophenol content of the sample. It does not
distinguish between pentachlorophenol and other 4. Analytical Procedure
chlorinated phenols. All phenols, as well as other a. Transfer four replicates of the sample dis
acidic compounds present, will be included as pen solved in methanol each of 100.00 ml volume into
tachlorophenol in the determination. 250 ml flasks.
b. Add 3 to 5 drops m-cresol purple indicator.
1. Reagents c. Titrate each replicate from a yellow color to
a. Reagent grade water (non-referee grade) con a faint purple color with 0.1 normal sodium hydrox
forming to ASTM D 1193 "Standard Specifications for ide. Read the burette to the nearest estimated 0.01
Reagent Grade Water." m!. Record the ml sodium hydroxide used for each
b. O.J normal sodium hydroxide-Dissolve 4.0 replicate.
gm reagent grade NaOH in 1000 ml water (see Note d. Determine the reagent blank of four repli
1). cates of 100 ml methanol plus 25 ml water placed
c. 0.1 normal potassiuh1 acid phthlate-Weigh in 250 ml Erlenmeyer flasks. Follow Step c of this
from 18 to 22 grams oven-dry primary standard paragraph.
grade potassium acid phthalate to the nearest mg.
Quantitatively transfer to a 1 liter volumetric flask. 5. Calculations
Add water exactly to mark. Mix well (see Note 1). a. Potassium acid phthalate normality
d. Meta-cresol purple indicator solution-Trans A = (0.004897) X (B)
fer 0.1 gm m-cresol purple to a small mortar. Add Where
2.5 ml 0.1 normal NaOH and complete solution with A = normality of potassium acid phthalate
the aid of a pestle. Transfer to a flask and add 100 (expressed to the nearest 0.0001 units)
ml water. (see Note 1). B = gm potassium acid phthalate from Par
e. 0.5% phenolphthalein indicator solution agraph lc
Dissolve 0.5 gm phenolphthalein in 50 ml ethanol b. Sodium hydroxide normality
plus 50 ml water (see Note 1).
C = (A) X (25.00)
f. Methanol, reagent grade.
D
Note 1: Suitable solutions are commercially avail
able from several chemical supply companies. Where
C = normality of sodium hydroxide (ex
2. Standardization of Sodium Hydroxide pressed to the nearest 0.0001 units)
A = normality of potassium acid phthalate
a. Transfer four 0.1 normal potassium acid
from Paragraph 5a
phthalate replicates (from lc) each of 25.00 ml vol
ume into 125 ml Erlenmeyer flasks. D = ml sodium hydroxide used from Para
graph 2c
b. Add 3 to .5 drops phenolphthalein indicator
c. Percent pentachlorophenol
to each replicate.
c. Titrate to a permanent faint pink end point E = (F-G) X (C) X (133.2)
with 0.1 normal sodium hydroxide (from Ib). Read W
2 AS-Analysis of Oil-Borne Preservatives 1990
Where 3. As the freezing point is reached, heat of crys
E = total acidity calculated as percent pen tallization usually causes the temperature to increase
tachlorophenol by weight (expressed to the slightly. Read the freezing point as the highest point
nearest 0.1 units) at which the temperature remains constant for at
F = ml 0.1 normal sodium hydroxide from least 15 seconds.
Paragraph 4c
4. DETERMINATION OF PENTACHLORO
G = ml 0.1 normal sodium hydroxide reagent
PHENOL SOLVENCY
blank from Paragraph 4d (average of four de
terminations)
Scope
C = normality of sodium hydroxide from Par
This procedure is used to determine if a partic
agraph 5b (average of four determinations)
ular Hydrocarbon Solvent Type A has sufficient sol
W = gm sample from Paragraph 3a
vency for pentachlorophenol to be used as part of
6. Repeatability (95% Confidence Limits) the oil-borne formulation.
1. Add ten grams (:': 0.1 gram) of technical pen
Individual values within a set of determinations
tachlorophenol (A WPA P8) to 90 grams (:': 1.0 gram)
should be no less than (0.9955) X (average for the
of Hydrocarbon Solvent Type A (AWPA P9) and
set) and no greater than (1.0045) X (average for
maintain the mixture at 150' F. with constant stirring
the set). The range of values (highest minus low
for 30 minutes. If there is visual evidence of undis
est) within a replicate set of four determinations
solved pentachlorophenol remaining at the end of
should not exceed (0.0070) X (average for the
the heating period, the solvent shall be regarded as
set).
non-conforming. The solution shall be cooled to 75'
F. for at least four hours. During the first two hours,
2. DETERMINATION OF ALKALI INSOLUBLE the solution shall be stirred at intervals of 15 minutes.
MATERIAL IN PENTACHLOROPHENOL During the last two hours, it shall be permitted to
stand undisturbed to allow any undissolved penta
Scope
cholorphenol to settle to the bottom. If there is evi
This procedure is used to determine the amount dence of undissolved pentachlorophenol, the solvent
of alkali insoluble material present in a sample of shall be regarded as non-conforming. If there is no
dry pentachlorophenol. evidence of undissolved pentachlorophenol and in
1. Dissolve a I-gram sample weighed to the cases of doubt, a sample of the solution shall be re
nearest mg, in 100 ml. of 4 percent (:': 0.1 percent) moved from the supernatant liquid and analyzed by
NaOH solution, warming to about 60' C. and crush the method in Paragraph 5 below.
ing larger particles with a flattened glass rod. 2. Add six grams (:': 0.1 gram) of technical pen
2. Filter through a tared Gooch crucible with a tachlorophenol (A WPA P8) to the Hydrocarbon Sol
fiberglass filter mat, weighed to the nearest mg, wash vent Type A (A WPA P9) fraction undistilled above
free from alkali with distilled water, and dry at 100' 500' F. from a 100 ml ASTM Standard D-86 distil
C. to constant weight. Weigh to the nearest mg. The lation and maintain the mixture at 150' F. with con
increase in weight represents alkali-insoluble matter. stant stirring for 30 minutes. After mixing, continue
Calculation with the test procedure as in (1) above.
Gm. residue X 100 3. When it is desired to test the maximum sol
Percent alkali insoluble
Gm. of sample vency of a Hydrocarbon Solvent Type A prepare a
gradient series of penta solutions in one percent con
centration intervals spanning the range of antici
3. DETERMINATION OF FREEZING POINT OF
pated solvency. When the approximate solvency is
PENTACHLOROPHENOL
estimated using the method in (1) above, if desired,
Scope prepare another series to determine the solvency to
the nearest 0.1 percent by preparing solutions in 0.1
This method covers the determination of the
percent concentration intervals and proceed as in
freezing point of dry pentachlorophenol.
(1) above.
1. Fill an enameled cup or a nickel tube of at
least 1 inch diameter with sample. Melt in the direct 5. DETERMINATION OF CHLORIDE FOR
flame of a burner, in a hood, stirring constantly with CALCULATING PENTA CHOLOROPHE-
a standardized 160' to 195' C. thermometer to avoid NOL IN SOLUTION OR WOOD
overheating.
2. When the molten material has a temperature 1. Scope
about 10' above its expected freezing point, allow it 1.1 The following Volhard Chloride procedure,
to cool while maintaining constant stirring. commonly called the "lime ignition" method de-
1990 AS-Analysis of Oil-Borne Preservatives 3
scribes the chemical analysis of treating solutions 3.4 Potassium nitrate-KN0 crystals contain
3
which contain pentachlorophenol, of pentachloro ing 0.002 percent or less chloride. Grind and powder
phenol concentrates, and of wood treated with pen the KN0 using an agate or porcelain mortar and
3
tachlorophenol. The method as described is pestle or food blender sufficiently to pass through a
specifically suitable for the determination of the fol 40-mesh screen.
lowing: 3.5 Lime-nitrate mixture-Thoroughly mix 10
parts of Ca(OH)2 with one part of the powdered
* Solutions which contain less than 10 percent KN03•
by weight pentachlorophenol (refer to paragraph 3.6 Nitric acid-Concentrated HNO), specific
5) gravity 1.42, containing 0.00005 percent or less chlo
* Solutions which contain more than 10 percent ride.
by weight pentachlorophenol (refer to paragraph 3.7 Silver nitrate solution-0.l00 AgNO, solu
6) tion (standard)-Dissolve 16.99 g AgN0 crystals
3
* Wood volumes of less than 0.25 cubic inches containing 0.005% chloride or less in water. Quan
which contain less than 0.75 pounds per cubic foot titatively transfer to a one-liter volumetric flask and
pentachlorophenol (refer to paragraph 7) add water exactly to mark. Mix well and store in a
* Wood volumes of less than 2.0 cubic inches dark place. (Hint: It is a good idea to transfer the
which contain less than 0.50 pounds per cubic foot above prepared O.lOON AgNO. into five (5) 200 ml
3
pentachlorophenol (refer to paragraph 8) amber bottles and store under refrigeration, rather
1.2 This method is not applicable to samples con than to continually use the 1 liter container). Cer
taining halogens other than chlorine unless appro tified, commercially-prepared AgN0 solutions are
1
priate correction can be made because the suitable. (Note: It is very important that the AgN0
1
pentachlorophenol concentration is calculated from be as close to 0.100N as practical. The analysis can
the total (excluding fluorine) halogen content. be performed and standardized at Normalities
greater or lesser than 0.100N, however the results
2. Apparatus
will be in error).
2.1 Crucibles, iron, nickel, or porcelain.
3.8 Ferric ammonium sulfate solution (Volhard
2.2 Ignition sources (either).
indicator)-Dissolve 10 grams FeNH" (SO")2,12H 0
2.2.1 High temperature gas burner of the 2
crystals containing 0.001 percent or less chloride in
Meeker type.
a dilute nitric acid solution prepared by adding 10
2.2.2 Electric muffle.
ml concentrated HNO:) to 100 ml water.
2.3 Analytical balance, sensitive to 0.001 g.
3.9 Ammonium thiocyanate solution (approxi
2.4 Magnetic stirrer, with stirring bars (optional).
mately O.lN)-Dissolve 7.6 g NH.,SCN crystals con
2.5 Buchner funnel.
taining 0.005 percent or less chloride in water.
2.6 Suction flask.
Quantitatively transfer to a one-liter volumetric flask
2.7 Vacuum source.
and add water exactly to mark. Mix well. Certified,
2.8 Food blender, equipped with a detachable
commercially-prepared NH.,SCN solutions are suit
lid and blade assembly that will fit a one-half pint
able.
fruit jar threaded top (Hamilton Beach Model 215
or equivalent). 4. Standardization of NH4 SeN Solution
2.9 Fruit jar, one-half pint with smooth inside
4.1 Transfer 10.00 m!. of 0.1 OON AgN0 to a 400
walls and equipped with a protective cover over the ml. beaker. Dilute to approximately 150 1m l. with
assembly in case of breakage during blending. water. Add 5 ml. concentrated HNo. and 5 m!. Vol
3
(Spraying the inside wall of the jar with silicone resin
hard indicator. Titrate to a permanent (5 minutes or
will prevent sticking of the lime-boring mixture.) longer) pinkish-brown end-point with O.lN NH.,SCN
2.10 Miscellaneous glassware, as required. solution.
The NH., SCN should be added from a burette
3. Reagents
whose smallest subdivisions are 0.05 m!. Estimate
3.1 Purity of reagents-All chemicals used shall
the amount of NH SCN required to the nearest 0.01
meet the requirements of the American Chemical 4
m!. Record the standardization volume used as quan
Society Committee on Analytical Reagents (or equiv
tity "S."
alent promulgating agencies).
4.2 Calculate the Standardization Equivalence
3.2 Purity of water-Reagent grade water (non
Factor (F) for NH.,SCN according to the following:
referee grade) conforming to ASTM D 1193 shall be
10.00
used. F = NH SCN Factor = -S-
4
3.3 Calcium hydroxide-Powdered Ca(OH)2
containing 0.025 percent chloride or less. Where: S = ml. NH., SCN per paragraph 4.1.
4 AS-Analysis of Oil-Borne Preservatives 1990
5. Procedure for Treating Solutions or Other Solu hole of a center hole watch glass covering the beaker.
tions Containing Not More Than 10.0 Percent Addition of HN0 should be in small increments
3
Pentachlorophenol by Weight because of the vigor of the reaction. The use of an
acid dispensing burette or automatic filling pipette
5.1 Place 10 g of lime-nitrate mixture in a 100
and a magnetic stirrer have been found useful in
m!. or number 3 crucible, gently tapping the crucible
dissolving the sample. A cold water bath is not ab
on a hard surface to settle the contents. Add the
solutely required when using an acid dispensing bur
sample of treating solution (filtered if necessary)
ette or automatic filling pipet as long as a one hole
drop-wise to little wells in the lime-nitrate mixture
cover glass is used and the condensate is recovered.
in such a manner as to give even distribution of the
After the addition of HN0 the beaker may be re
sample without having any sample touch the sides 3,
moved from the cold water bath and gently heated
of the crucible. The sample should contain approx
(contents not boiled) to promote the solution of the
imately 0.04 g pentachlorophenol. The sample size
lime-nitrate mixture. The solution should be acid to
should approximately fit the following schedule:
Congo red paper and all lime should be in solution.
If not, additions in 5 ml. increments of concentrated
Nominal % Pentachlorophenol
by \Veigh! Sample Size in g HN0 are to be added until these conditions are met.
2.R 1.4 3
.0.0 0.6 5.4 Pipet 10.00 m!. of O.lOON AgN0 into the
7.'s 0.4 1
111.0 0.2 beaker. Cover with a watch glass and boil several
Determine the size of the sample to the nearest minutes to coagulate the precipitate. Cool and filter
0.001 grams by the weight difference in a weighing the solution through a soft, rapid paper (Whatman
bottle containing the treating solution before and 41 or equivalent) into a 500 ml. Erlenmeyer suction
after sampling. Record the weight of sample in grams flask by use of an appropriately sized Buchner funnel
as quantity "Ws." and a vacuum source (water aspirator source is ade
5.2 Cover the sample with an additional 20 g of quate). Rinse the beaker with a small quantity of
lime-nitrate mixture and tap the crucible gently on water and add rinsings to precipitate on the filter
a hard surface. Ignite the sample by either using an paper. Rinse the precipitate thoroughly with water
electric mume or a gas burner. If an electric mume permitting the rinsings to be added to the contents
is used, place the sample in the mume and maintain of the suction flask. Test a few drops of the wash
at 800 C for 30 minutes (the mume may be preheated water with O.lN NH SCN. An absence of turbidity
4
if desired). If a gas burner is used, place the crucible in this test indicates that the washing is complete.
on a supported nichrome triangle. Light the burner 5.5 Add 5 m!. Volhard indicator to the contents
and adjust the gas and air so that a quiet flame is of the suction flask. Titrate to a permanent (5 minutes
obtained and small cones of flame rise from II" in. to or longer) pinkish-brown end-point with O.lN
lit inch (3 to 6 mm) above the grid of the burner. NR,SCN. The coloration is faint and occurs at the
Place the lighted burner under the supported cru point where Ferric Thiocyanate is formed. Fading
cible and adjust the height of the crucible so that of the end-point color prior to the end of 5 minutes
the distance from the burner grid to the bottom of is a common occurrence. Care should be taken not
the crucible is one to two inches (25 to 50 mm). Heat to add excessive NH SCN. The NHtSCN should be
4
in this position for two to three minutes. Readjust added from a burette whose smallest subdivisions
the distance between the burner grid and the bot are 0.05 ml. Estimate the amount of NH.,SCN used
tom of the crucible to approximately 1/2 inch (12 to to the nearest 0.01 m!. Record the volume titrant
1.3 mm). Heat in this position for an additional 20 to used for the sample as quantity "Ts."
30 minutes. The ignited sample should be free of 5.6 Calculate the Equivalent Sample (Es) vol
carbon, but no appreciable error will be introduced ume of O.lOON NH,SCN used according to the fol
unless large amounts of unburned carbon remain. lowing:
5.3 Allow the crucible to cool and empty its con
Es = m!. O.lOON NRtSCN (sample) = Ts X F
tents into a 600 ml. beaker by gently tapping the
Where: Ts = m!. O.lOON NH<jSCN per para
crucible. Rapidly add 150 ml. of water to the beaker
graph 5.5
and immediately place a watch glass on the beaker.
F = NH.,SCN factor per paragraph 4.2
Scrub the crucible with water (or 2 percent HNO'l
if desired) using a stirring rod equipped with a rub 5.7 Determine a correction for the pentachlo
ber policeman to loosen any remaining residue. Add rophenol carrier if it contains halogens other than
the scrubbings to the beaker. The total aqueous vol those due solely to the presence of pentachloro
ume at this point should be approximately 200 ml. phenol, unless it is known that the carrier being
Place the beaker in a cold water bath. Add 50 ml. analyzed is free of additional halogens. Follow the
of concentrated HNO, either down the side of the procedures of paragraph 5.1 to 5.6 inclusive, using
beaker covered with a watch glass or through the carrier without pentachlorophenol except that the
1990 AS-Analysis of Oil-Borne Preservatives S
weight of the sample should be approximately 2 6. Procedure for Treating Solutions or Other Solu
grams (determined to the nearest 0.001 gram). Rec tions Containing More than 10.0 Percent Pen
ord the sample weight of the carrier as "Wc." tachlorophenol by Weight.
5.8 Calculate the equivalent carrier (Ec) volume 6.1 Weigh approximately 4 g of the original sam
of 0.1 OON NR,SCN used according to the following: ple into a tared weighing bottle. Dilute with ap
proximately four times its weight of heavy mineral
Ec = ml. O.lOON NH"SCN (carrier) = Tc X F
oil (1), and weigh again. Determine weights to the
Where: Tc = ml O.lOON NR,SCN per paragraph nearest 0.001 gram.
5.7 6.2 Mix diluted solution thoroughly and transfer
F = NR, SCN factor per paragraph 4.2 portions for analysis to crucible containing lime ni
trate mixture as set forth in paragraph 5.1. Follow
5.9 Determine a reagent blank by following the
the analytical procedures as set forth in paragraphs
procedures of paragraphs 5.1 to 5.6, inclusive, but
5.2 through 5.8 substituting for "Ws" as follows:
using no sample and 10.00 m!. of O.lOON AgNO,.
Record the volume of NH.,SCN titrant in paragraph Ws = Os X Ds
5.5 as quantity "Tb." Dt
5.10 Calculate the equivalent blank volume (Eb) Where: Os = Weight of original sample
of 0.1 OON NH.,SCN used according to the following: Dt = Weight of the diluted total (sample +
Eb = ml. O.lOON NR,SCN (blank) = Tb X F diluent)
Ds = Weight of the diluted sample used for
Where: Tb = m!. O.lOON NH"SCN per para
analysis
graph 5.9
F = NR, SCN factor per paragraph 4.2 (1) Heavy mineral oil is described in National For
5.11 Calculate the Reagent Blank (R) according mulary and is available locally.
to the following:
R = ml. O.lOON AgNO] Reagent Blank = 10.00 7. Procedure for Wood Samples 0.25 Cubic Inches
- Eb (4cc) or Less in Volume
5.12 Calculations (Samples involving wood volumes greater than
0.25 cubic inches should be subdivided into approx
Ptotal = Total (uncorrected) percent pentach
imately equal parts and the results averaged. Sam
lorophenol by weight
ples involving wood samples greater than 1.0 cubic
P = (10 - R - Es) 0.5327 inch should be determined using the procedures of
Ws paragraph 8.)
Plotal
7.1 Place 10 g of lime-nitrate mixture in a 100
m!. or number 3 crucible, gently tapping the crucible
Pcarrier Percent pentachlorophenol by on a hard surface to settle the contents. Add the
weight blank of carrier wood sample to be assayed to the surface of the lime
nitrate mixture in such a manner that the sample
does not contact the sides of the crucible. Record
Pcarrier = _(1 _0_-_R_-=-:-E_c_)_0_.5_3_2_7
the volume of the sample in cubic inches as quantity
Wc
"Vs." (Optional: If the results are desired in terms
of weight percent, the weight of the sample should
Pcorrected = percent pentachlorophenol by be determined to the nearest 0.001 grams and re
weight corrected for carrier blank
corded as "Ws.")
7.2 Cover the sample with an additional 20 g of
_ (Ptotal - Pcarrier) X 100
Pcorrecte d - (100 P .) lime-nitrate mixture and tap the crucible gently on
- carner a hard surface. Ignite the sample by either using an
electric muffle or a gas burner. If an electric muffle
Where: 1.00 ml of O.lOON AgNO, = 0.005327 is used, place the sample in the muffle and maintain
grams of pentachlorophenol. at 800 C for 30 minutes (the muffle may be preheated
if desired). If a gas burner is used, place the crucible
R = as defined in paragraph 5.11 on a supported nichrome triangle. Light the burner
As = as defined in paragraph 5.6 and adjust the gas and air so that a quiet flame is
Ac = as defined in paragraph 5.8 obtained and small cones of flame rise from /,; to ;;
Ws = as defined in paragraph 5.1 inch (3 to 6 mm) above the grid of the burner. Place
Wc = as defined in paragraph 5.7 the lighted burner under the supported crucible and
6 AS-Analysis of Oil-Borne Preservatives 1990
adjust the height of the crucible so that the distance of the end-point color prior to the end of 5 minutes
from the burner grid to the bottom of the crucible is a common occurrence. Care should be taken not
in one to two inches (25 to 50 mm). Heat in this to add excessive NR,SCN. The NH,SCN should be
position for two to three minutes. Readjust the dis added from a burette whose smallest subdivisions
tance between the burner grid and the bottom of are 0.05 ml. Estimate the amount of NR,SCN used
the crucible to approximately Yz inch (12 to 13 mm). to the nearest 0.01 ml. Record the volume titrant
Heat in this position for an additional 20 to 30 min used for the sample as quantity "Ts".
utes. The ignited sample should be free of carbon, 7.6 Calculate the equivalent sample volume (Es)
but no appreciable error will be introduced unless of O.lOON NR,SCN used according to the following:
large amounts of unburned carbon remain. Es = m!. O.lOON NH1SCN (sample) = Ts X F
7.3 Allow the crucible to cool and empty its con Where: Ts = m!. O.lOON NR,SCN per paragraph
tents into a 600 ml beaker by gently tapping the 7.5
crucible. Rapidly add 150 ml of water to the beaker
F = NR, SCN factor per paragraph 4.2
and immediately place a watch glass on the beaker.
7.7 Determine a correction for wood if it con
Scrub the crucible with water (or 2% HNO) if de
tains halogens other than those due solely to the
sired) using a stirring rod equipped with a rubber
presence of pentachlorophenol, unless it is known
policeman to loosen any remaining residue. Add the
that the sample being analyzed is free of additional
scrubbings to the beaker. The total aqueous volume
halogens. Follow the procedures of paragraph 7.1 to
at this point should be approximately 200 ml. Place
7.6 inclusive using untreated wood. Record the vol
the beaker in a cold water bath. Add 50 ml of con
ume of wood used as "Vc." (Optional: If the results
centrated HNO, either down the side of the beaker
are desired in terms of weight percent, the weight
covered with a watch glass or through the hold of a
of the sample should be determined to the nearest
center hole watch glass covering the beaker. Addi
0.001 grams and recorded as "Wc.")
tion of HNO) should be in small increments because
7.8 Calculate the equivalent correction volume
of the vigor of the reaction. The use of an acid dis
(Ec) of O.lOON NR,SCN according to the following:
pensing burette or automatic filling pipette and a
magnetic stirrer have been found useful in dissolving Ec = ml O.lOON NR,SCN (carrier) = Tc X F
the sample. A cold water bath is not absolutely re Where: Tc = ml 0.1 OON NH, SCN per paragraph
quired when using an acid dispensing burette or 7.5
automatic filling pipette as long as a one hole cover F = NR,SCN factor per paragraph 4.2
glass is used and the condensate is recovered. After 7.9 Determine a reagent blank by following the
the addition of HN03, the beaker may be removed procedures of paragraphs 7.1 to 7.6, inclusive, but
from the cold water bath and gently heated (contents using no sample and 10.00 ml of O.lOON AgN0
1•
not boiled) to promote the solution of the lime-ni Record the volume of NH SCN titrant in paragraph
4
trate mixture. The solution should be acid to Congo 7.5 as quantity "Tb".
red paper and all lime should be in solution. If not, 7.10 Calculate the equivalent blank (Eb) volume
additions in 5 ml increments of concentrated HN0 of O.lOON NR,SCN used according to the following:
3
are to be added until these conditions are met.
Eb = ml O.lOON NR,SCN (blank) = Tb X F
7.4 Pipette 10.00 ml of O.lOON AgNO: into the
J Where: Tb = ml O.lOON :'IJR,SCN per paragraph
beaker. Cover with a watch glass and boil several 7.9
minutes to coagulate the precipitate. Cool and filter
F = NH1 SCN factor per paragraph 4.2
the solution through a soft, rapid paper (Whatman
7.11 Calculate the Reagent Blank (R) according
41 or equivalent) into a 500 ml Erlenmeyer suction
to the following:
flask by use of an appropriately sized Buchner funnel
and a vacuum source (water aspirator source is ad R = ml O.lOON AgNO, Reagent Blank = 10.00
equate). Rinse the beaker with a small quantity of Eb
water and add rinsings to precipitate on the filter 7.12 Calculations
paper. Rinse the precipitate thoroughly with water
PCF I PPtotal = Total (uncorrected)
permitting the rinsings to be added to the contents
pentachlorophenol
of the suction flask. Test a few drops of the water
water with O.lN NR,SCN. An absence of turbidity (10 - R - Es) 0.02029
by volume: PCFtotal
in this test indicates that the washing is complete. Vs
7.5 Add 5 ml Volhard indicator to the contents
(10 - R - Es) 0.5327
of the suction flask. Titrate to a permanent (5 minutes by weight: PPtotal
Ws
or longer) pinkish-brown end-point with O.lN
NR,SCN. The coloration is faint and occurs at the PCF/PPwood Correction for wood if it contains
point where Ferric Thiocyanate is formed. Fading halogens other than those due
1990 AS-Analysis of Oil-Borne Preservatives 7
solely to the presence of penta adjust the height of the crucible so that the distance
chlorophenol from the burner grid to the bottom of the crucible
is one to two inches (25 to 50 mm). Heat in this
(10 - R - Ec) 0.02029
by volume: PCFwood = Vc position for two to three minutes. Readjust the dis
tance between the burner grid and the bottom of
(10 - R - Ec) 0.5327 the crucible to approximately Yz inch (12 to 13 mm).
by weight: PPwood = Wc Heat in this position for an additional 50 to 60 min
PCF I PPcorrected = Corrected pounds per cubic utes. The ignited sample should be free of carbon,
but no appreciable error will be introduced unless
foot or percent by weight
large amounts of unburned carbon remain.
pentachlorophenol corrected
8.3 Allow the crucible to cool and empty its con
for the wood blank.
tents into a 600 ml beaker by gently tapping the
by volume: PCFcorrected PCFtotal
crucible. Rapidly add 250 ml of water to the beaker
PCFwood
and immediately place a watch glass on the beaker.
by weight: PPcorrected = PPtotal - PPwood Scrub the crucible with water (or 2% HNO, if de
Where: R = as defined in paragraph 7.8 sired) using a stirring rod equipped with a rubber
Es = as defined in paragraph 7.6 policeman to loosen any remaining residue. Add the
Ec = as defined in paragraph 7.8 scrubbings to the beaker. The total aqueous volume
Vs = as defined in paragraph 7.1 at this point should be approximately 300 m!. Place
Ws = as defined in paragraph 7.1 the beaker in a cold water bath. Add 100 ml of
V c = as defined in paragraph 7.7 concentrated HNO) either down the side of the
Wc = as defined in paragraph 7.7 beaker covered with a watch glass or through the
hold of a center hole watch glass covering the
8. Procedure for Wood Samples up to 2.0 Cubic
beaker. Addition of HN0 should be in small incre
Inches (33cc) in Volume 3
ments because of the vigor of the reaction. The use
(Samples involving wood volumes greater than of an acid dispensing burette or automatic filling
2.0 cubic inches should be subdivided into approx pipette and a magnetic stirrer have been found use
imately equal parts and the results averaged. Sam ful in dissolving the sample. A cold water bath is not
ples involving wood samples less than 1.0 cubic inch absolutely required when using an acid dispensing
should be determined using the procedures of par burette or automatic filling pipette as long as a one
agraph 7. hole cover glass is used and the condensate is re
8.1 Record the volume of wood sample in cubic covered. After the addition ofHNO" the beaker may
inches as quantity "Vs". (Optional: If the results are be removed from the cold water bath and gently
desired in terms of weight percent, the weight of heated (contents not boiled) to promote the solution
the sample should be determined to the nearest of the lime-nitrate mixture. The solution should be
0.001 grams and recorded as "Ws"). Place the sample acid to Congo red paper and all lime should be in
in a dry, half-pint fruit jar, attach a clean, dry lid solution. If not, additions in 5 ml increments of con
assembly and, using the food blender, grind for one centrated HNO, are to be added until these condi
half to one minute. Add 30 g of lime-nitrate mixture tions are met.
to the fruit jar, replace the lid assembly, and grind 8.4 Cool the sample to room temperature and
(blend) for an additional 2 to four minutes. quantitatively transfer to a 500 ml volumetric flask.
8.2 Transfer the contents of the fruit jar to a 200 Rinse the beaker and cover glass with water, adding
ml, 250 ml, or number 5 crucible. Clean the re the rinsings to the volumetric flask. Add water ex
maining mixture from the fruit jar with a fine brush, actly to the mark and mix well. Transfer 100 ml of
adding these cleanings to the crucible. Add an ad the solution by pipette (do not use a graduated cyl
ditional 30 grams of lime-nitrate mixture to the cru inder as they are too inaccurate) to a 600 ml beaker
cible. Gently tap the crucible on a hard surface to and add 150 ml of water. Pipette 10.00 ml of O.lOON
settle the contents. Ignite the sample by either using AgNO, into the beaker. Cover with a watch glass
an electric muffle or a gas burner. If an electric muffle and boil several minutes to coagulate the precipitate.
is used, place the sample in the muffle and maintain Cool and filter the solution through a soft, rapid pa
at 800 C for 60 minutes (the muffle may be preheated per (Whatman 41 or equivalent) into a 500 ml Er
if desired). If a gas burner is used, place the crucible lenmeyer suction flask by use of an appropriately
on a supported nichrome triangle. Light the burner sized Buchner funnel and a vacuum source (water
and adjust the gas and air so that a quiet flame is aspirator source is adequate). Rinse the beaker with
obtained and small cones of flame rise from ;;" to /,; a small quantity of water and add rinsings to pre
inch (3 to 6 mm) above the grid of the burner. Place cipitate on the filter paper. Rinse the precipitate
the lighted burner under the supported crucible and thoroughly with water permitting the rinsings to be
8 AS-Analysis of Oil-Borne Preservatives 1990
added to the contents of the suction flask. Test a few 8.12 Calculations
drops of the wash water with O.lN NH.,SCN. An
PCF/PPtotal = Total (uncorrected) pentachloro
absence of turbidity in this test indicates that the
phenol
washing is complete.
8.5 Add 5 ml Volhard indicator to the contents (10 R - Es) 0.10145
by volume: PCFtotal = -----=-c---'---
of the suction Hask. Titrate to a permanent (5 minutes Vs
or longer) pinkish-brown end-point with O.lN (10 - R -Es) 2.6635
NH,SCN. The coloration is faint and occurs at the b y weig h t: PP totaI = -----=-=-----
Ws
point where Ferric Thiocyanate is formed. Fading
of the end-point color prior to the end of 5 minutes PCF I PPwood Correction for wood if it contains
halogens other than those due
is a common occurrence. Care should be taken not
solely to the presence of pentach
to add excessive NH.,SCN. The NH.,SCN should be
lorophenol
added from a burette whose smallest subdivisions
are 0.05 m!. Estimate the amount of NH.,SCN used PCFwood = (10 - R - Ec) 0.10145
by volume:
to the nearest 0.01 m!. Record the volume used for Vc
the sample as quantity "Ts".
. h PP d (10 - R - Ec) 2.6635
8.6 Calculate the equivalent sample volume (Es) b y welg t: woo = --'-----:::;:---'----
Wc
of 0.1 OON NH,SCN used according to the following:
8.12 Calculations continued
Es = ml O.lOON NH,SCN (sample) = Ts X F PCF/PPcorrected = Corrected pounds per cubic
Where: Ts = ml O.lOON NH,SCN per paragraph foot or percent by weight
8 ..5
pentachlorophenol corrected
F = NH, SCN factor per paragraph 4.2 for the wood blank.
8.7 Determine a correction for wood if it contains by volume: PCFcorrected PCFtotal
halogens other than those due solely to the presence PCFwood
of pentachlorophenol, unless it is known that the
by weight: PPcorrected = PPtotal - PPwood
sample being analyzed is free of additional halogens.
Where: R = as defined in paragraph 8.11
Follow the procedures of paragraph 8.1 to 8.6 inclu
Es = as defined in paragraph 8.6
sive using untreated wood. Record the volume of
wood used as "Vc". (Optional: If the results are de Ec = as defined in paragraph 8.8
sired in terms of weight percent, the weight of the Vs = as defined in paragraph 8.1
Ws = as defined in paragraph 8.1
sample should be determined to the nearest 0.001
grams and recorded as "Wc .) V c = as defined in paragraph 8.7
W c = as defined in paragraph 8.7
8.8 Calculate the equivalent correction volume
(Ec) of O.lOON NH"SCN according to the following:
Es = m!. O.lOON NH,SCN (carrier) = Tc X F 9. Precision
Where: Tc = ml O.lOON NH,SCN per paragraph The following criteria should be used for judging
8.5 the acceptability of the results.
F = NH4SCN factor per paragraph 4.2 9.1 Pentachlorophenol in Solution Repeatability:
8.9 Determine a reagent blank by following the Duplicate determinations on the same sample by the
procedures of paragraphs 8.1 to 8.6, inclusive, but same operator using the same equipment should not
using no sample and 10.00 ml of O.lOON AgN01. be considered suspect at the 95% confidence level
Record the volume of titrant NH,SCN in paragraph if they differ by 0.089% or less.
8.5 as quantity "Tb". Reproducibility: Duplicate determinations on the
same sample by different operators in different lab
8.10 Calculate the equivalent blank volume (Eb)
oratories should not be considered suspect at the
of O.lOON NH.,SCN used according to the following:
95% confidence level if they differ by 0.152% or
Eb = ml O.lOON NH4SCN (blank) = Tb X F less.
Where: Tb = ml O.lOON NH SCN per paragraph
4 9.2 Lime Ignition Method-Pentachlorophenol
8.9
in Wood
F = NH,SCN factor per paragraph 4.2
Repeatability: Duplicate results from runs on the
8.11 Calculate the Reagent Blank (R) according
same sample by the same operator in the same lab
to the following:
oratory should not be considered suspect at the 95%
R = m!. O.lOON AgNO, Reagent Blank = 10.00 confidence level unless they differ by more than 0.02
- Eb pcf.