ASTM D5544-94(1999)e1
(Test Method)Standard Test Method for On-Line Measurement of Residue After Evaporation of High-Purity Water
Standard Test Method for On-Line Measurement of Residue After Evaporation of High-Purity Water
SCOPE
1.1 This test method covers the determination of dissolved organic and inorganic matter and colloidal material found in high-purity water used in the semiconductor, aerospace, and other industries. This material is referred to as residue after evaporation (RAE). The range of the test method is from 0.1 [mu]g/L(ppb) to 20 mg/L (ppm).
1.2 This test method uses a continuous, real time monitoring technique to measure the concentration of RAE. A pressurized sample of high-purity water is supplied to the test method's apparatus continuously through ultra-clean fittings and tubing. Contaminants from the atmosphere are therefore prevented from entering the sample. General information on the test method and a literature review on the continuous measurement of RAE has been published.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazards statements, see Section 8.
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An American National Standard
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Designation: D 5544 – 94 (Reapproved 1999)
Standard Test Method for
On-Line Measurement of Residue After Evaporation of High-
Purity Water
This standard is issued under the fixed designation D 5544; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Footnotes were editorially removed in June 1999.
1. Scope D 3864 Practice for Continual On-line Monitoring Systems
for Water Analysis
1.1 This test method covers the determination of dissolved
D 3919 Practice for Measuring Trace Elements in Water by
organic and inorganic matter and colloidal material found in
Graphite Furnace Atomic Absorption Spectrophotometry
high-purity water used in the semiconductor, aerospace, and
E 1184 Practice for Electrothermal (Graphite Furnace)
other industries. This material is referred to as residue after
Atomic Absorption Analysis
evaporation (RAE). The range of the test method is from 0.1
μg/L(ppb) to 20 mg/L (ppm).
3. Terminology
1.2 This test method uses a continuous, real time monitoring
3.1 Definitions—For definitions of terms used in this test
technique to measure the concentration of RAE. A pressurized
method, refer to Terminology D 1129.
sample of high-purity water is supplied to the test method’s
3.2 Definitions of Terms Specific to This Standard:
apparatus continuously through ultra-clean fittings and tubing.
3.2.1 aerosol, n—any solid or liquid particles, with a
Contaminants from the atmosphere are therefore prevented
nominal size range from 10 nm to 100 μm, suspended in a gas
from entering the sample. General information on the test
(usually air).
method and a literature review on the continuous measurement
2 3.2.2 colloidal suspension, n— any material in suspension
of RAE has been published.
(for example, silica) with a nominal particle size less than 100
1.3 The values stated in SI units are to be regarded as the
nm.
standard. The values given in parentheses are for information
3.2.3 condensation nucleus counter (CNC), n—instrument
only.
for detecting very small aerosol particles in a size range from
1.4 This standard does not purport to address all of the
approximately 10 nm to 2 to 3 μm. The CNC cannot differen-
safety concerns, if any, associated with its use. It is the
tiate between particles of varying size within this size range; it
responsibility of the user of this standard to establish appro-
reports the number of particles with a size greater than that
priate safety and health practices and determine the applica-
defined by its detection efficiency curve. Detection is indepen-
bility of regulatory limitations prior to use. For specific hazards
dent of particle composition.
statements, see Section 8.
3.2.4 detection effıciency, n— in this test method, detection
2. Referenced Documents efficiency represents a curve relating particle size to a counter’s
ability to detect that size.
2.1 ASTM Standards:
3 3.2.5 diffusion screen, n—a fine mesh screen used to filter
D 1129 Terminology Relating to Water
residue particles of a particular size.
D 1193 Specification for Reagent Water
3.2.6 high-purity water, n—within the context of this test
D 2777 Practice for Determination of Precision and Bias of
method, high-purity water is defined as water containing
Applicable Methods of Committee D-19 on Water
residue after evaporation in the range from 0.1 μg/L to 20
D 3370 Practices for Sampling Water from Closed Con-
mg/L.
duits
3.2.7 polydisperse, adj—a size population, in this case of
aerosol particles, composed of many different sizes; the oppo-
site of monodisperse, a distribution of just one size.
This test method is under the jurisdiction of ASTM Committee D19 on Water
3.2.8 realtime, n—the time that an event is occurring plus
and is the direct responsibility of Subcommittee D19.03 on Sampling of Water and
Water-Formed Deposits, Surveillance of Water, and Flow Measurement of Water.
the response time; in this case, the response time is 3 to 5 min.
Current edition approved Sept. 15, 1994. Published November 1994.
Therefore, contamination is recorded 3 to 5 min after it occurs.
Blackford, D. B., and Kerrick, T. A., Proceeding of Microcontamination ’91,
San Jose, CA, 1991, pp. 39–51. Published by Canon Communications Inc., 3340
Ocean Park Blvd., Suite 1000, Santa Monica, CA 90405.
3 4
Annual Book of ASTM Standards, Vol 11.01. Annual Book of ASTM Standards, Vol 03.06.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D 5544 – 94 (1999)
3.2.9 residue after evaporation, n—contaminants remaining manganese, ammonium, bicarbonates, sulfates, nitrates, chlo-
after all water is evaporated; sometimes known as nonvolatile ride and fluoride ions, ferric and ferrous ions, and silicates;
residue or total dissolved and suspended solids. dissolved organic substances such as pesticides, herbicides,
plasticizers, styrene monomers, deionization resin material;
4. Summary of Test Method
and colloidal suspensions such as silica. While this test method
4.1 This test method consists of continuously removing a
facilitates the monitoring of these contaminants in high-purity
representative sample of high-purity water from a pressurized
water, in real time, with one instrument, this test method is not
supply line (refer to Practices D 3370, Practice C on Continual
capable of identifying the various sources of residue contami-
Sampling, and Practice D 3864). The temperature of the
nation or detecting dissolved gases or suspended particles.
incoming high-purity water should ideally be at room tempera-
5.2 This test method is calibrated using weighed amounts of
ture, but not more than 50°C. The high-purity water is
an artificial contaminant (potassium chloride). The density of
subsequently cooled to a constant temperature of 18°C. An
potassium chloride is reasonably typical of contaminants found
atomizer is supplied with the cooled high-purity water at a
in high-purity water; however, the response of this test method
constant flow rate, and a source of compressed air, or nitrogen,
is clearly based on a response to potassium chloride. The
at a constant flow rate and pressure, to generate a stable aerosol
response to actual contaminants found in high-purity water
of high-purity water droplets. Under these conditions, the may differ from the test method’s calibration. This test method
atomizer produces a polydisperse size distribution of droplets
is not different from many other analytical test methods in this
with a median size of approximately 1 μm, and a concentration respect.
7 12
of approximately 10 droplets/s, or 10 droplets/mL
5.3 Together with other monitoring methods, this test
4.2 The droplets enter a drying column; are rapidly mixed method is useful for diagnosing sources of RAE in ultra-pure
with dried, filtered, heated (normally at 120°C) compressed air,
water systems. In particular, this test method can be used to
or nitrogen; and dried within the first few centimetres of the detect leakages such as colloidal silica breakthrough from the
drying column. The temperature of the drying column can be
effluent of a primary anion or mixed-bed deionizer. In addition,
set at lower temperatures (95, 70, or 45°C) if information
this test method has been used to measure the rinse-up time for
concerning the dissolved organic fraction of residue is re-
new liquid filters and has been adapted for batch-type sampling
quired. Each atomizer droplet produces a particle of nonvola-
(this adaptation is not described in this test method).
tile residue. As the residue particles emerge from the drying
5.4 Obtaining an immediate indication of contamination in
column, a small percentage is removed and passed through a
high-purity water has significance to those industries using
diffusion screen before being counted by a condensation
high-purity water for manufacturing components; production
nucleus counter (CNC). Different combinations of diffusion
can be halted immediately to correct a contamination problem.
screens modify the detection efficiency of the CNC, allowing
The biomedical and power-generating industries will also
detection in the 0.1-μg/L to 20-mg/L range.
benefit from this information.
4.3 The CNC works as follows: The residue particles enter
6. Apparatus
a saturator and pass through a heated, volatile liquid-soaked
6.1 The schematic arrangement of the system is shown in
wick. The wick dips into the liquid reservoir and continually
Fig. 1. The apparatus is available as a complete instrument, or
draws up liquid through an inclined tube. The liquid evaporates
the individual components described in 6.4, 6.6, and 6.7 can
and saturates the aerosol stream with vapor. N-butyl alcohol
be purchased separately.
has been used successfully as the volatile liquid in this test
6.2 Flow Controller, made of a non-contaminating material
method. The vapor-saturated aerosol passes into a vertical
such as perfluoroalkoxy (PFA), necessary to supply the atom-
condenser tube, cooled by a thermoelectric device. The vapor
izer with high-purity water at the desired flow rate. The flow
cools, becomes super-saturated, and begins to condense on the
controller must contain a pressure regulator to ensure that
particle nuclei to form large droplets that can then be counted
water is delivered to the atomizer at a stable flow rate, despite
with a relatively simple optical particle counter. A more
external fluctuations. High-purity water must be delivered to
elaborate description of the CNC’s method for distinguishing
the flow controller and atomizer through ultra-clean tubes and
between clean and dirty water is described in Appendix X1.
fittings made from PFA polytetrafluor-oethylene. Atomizers
4.4 A calibration technique (described in detail in Section
usually require a very low flow rate, approximately 1 mL/min,
10) uses concentration standards of high-purity potassium
for efficient operation. However, such a low flow rate is
chloride (KCl) to convert the CNC count concentration in
inadequate for routine monitoring because it results in a long
particles per cubic centimetre into RAE concentration in
response time. This test method is designed to overcome the
micrograms per litre or milligrams per litre. A graphite furnace
problem of long response times by using a flow controller to
atomic absorption spectrometer (GFAAS) can be used to check
deliver approximately 70 mL/min of high-purity water to the
the concentration of KCl in this test method standard (see
monitoring site and then to divert 1 mL/min of the flow to the
Practices D 3919 and E 1184).
atomizer through a short tube. This short tube facilitates a short
5. Significance and Use
response time.
5.1 Even so-called high-purity water will contain contami-
nants. While not always present, these contaminants may
Available from TSI Inc., P.O. Box 64394, St. Paul, MN 55164.
contribute one or more of the following: dissolved active ionic
Available from Particle Measuring Systems, 5475 Airport Blvd., Boulder, CO
substances such as calcium, magnesium, sodium, potassium, 80301.
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D 5544 – 94 (1999)
FIG. 1 Schematic Diagram of Apparatus Required for This Test Method
6.3 Cooling Block, necessary to cool the water and maintain (referred to as a 400 mesh in the Tyler equivalent designation)
it at a stable temperature before it enters the atomizer (18°C is
has worked well in this test method.
adequate). The cooling block incorporates a thermoelectric
6.7 Condensation Nucleus Counter (CNC), containing a
device capable of maintaining the cooling block at the required
saturator, condenser, and optical particle counter to enlarge the
temperature.
particles to a uniform size and count them in particles per cubic
6.4 Atomizer, required to produce a polydisperse size dis-
centimetre. The flow rate through the CNC is 2.8 L/min.
tribution of droplets with a median size of approximately 1 μm
7 6.7.1 Inside the saturator is a wick soaked in a volatile
and a concentration of approximately 10 droplets/s. The
liquid. The wick dips into a liquid reservoir and draws up liquid
atomizer must be supplied with clean, dried filtered com-
continually through an inclined tube. The liquid evaporates and
pressed air or nitrogen and must be machined from a material
saturates the aerosol stream with vapor.
that will not contaminate the high-purity water. Passivated 316
stainless steel has been used successfully in this test method. 6.7.2 The vapor-saturated aerosol passes into a vertical
Details of how to passivate stainless steel can be found in the
condenser tube, cooled by a thermoelectric device. Aerosol
Metal Finishing Guidebook.
particles of a certain size and above (nominally 10-nm diam-
6.5 Mixing Chamber and Drying Column, for mixing the
eter) act as nucleation sites upon which the vapor can condense
water droplets from the atomizer with dried, heated (at 120°C
to form droplets (nominally 10-μm diameter). Droplets pass
or, if required, 95, 70, or 45°C) dilution air or nitrogen. The
from the condenser tube through a nozzle into the optical
water droplets and dilution air pass through a drying column
detector.
that evaporates all of the water from the droplets. The residue
6.7.3 The CNC’s focusing optics consist of a laser diode and
from each droplet is left as a particle. A drying column
beam-shaping optics. This combination forms a beam of laser
approximately 2.5 cm in diameter and 30 cm in length has
light above the aerosol exit nozzle. The sensor’s collecting
worked well in this test method, with a ratio of dilution air to
optics collect the light scattered by the droplets and focus this
atomizer air of approximately 10:1.
light onto a low-noise photo-detector.
6.6 Diffusion Screens—Fifty-millimetre diameter diffusion
screens made of a fine stainless steel wire cloth used to shift the
7. Reagents and Materials
detection efficiency of the CNC to larger sizes. Wire cloth with
a wire diameter of 25 μm and a square weave opening of 38 μm
7.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
all reagents conform to the specifications of the Committee on
Metal Finishing Guidebook, Elsevier Science, New York, NY, 60th ed., 1992. Analytical Reagents of the American Chemical Society where
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D 5544 – 94 (1999)
such specifications are available. Other grades may be used, fluctuations will affect the size of water drop
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