ASTM: D5544: Residue in Water

Summary
Analytes
Revision
Data and Sites

Official Method Name

Standard Test Method for On-Line Measurement of Residue After Evaporation of High-Purity Water

Current Revision

Reapproved 1999. Current edition approved Sept. 15, 1994. Published November 1994.

Media

WATER

Instrumentation

CNC (Condensation Nucleus Counter)

Method Subcategory

Inorganic

Method Source

ASTM

Citation

Annual Book of ASTM Standards, Section 11, Water and Environmental Technology, Volume 11.01, Water (I)

Brief Method Summary

This test method consists of continuously removing a representative sample of high-purity water from a pressurized supply line. The temperature of the incoming high-purity water should ideally be at room temperature, but not more than 50^oC. The high-purity water is subsequently cooled to a constant temperature of 18^oC. An atomizer is supplied with the cooled high-purity water at a constant flow rate, and a source of compressed air, or nitrogen, at a constant flow rate and pressure, to generate a stable aerosol of high-purity water droplets. Under these conditions, the atomizer produces a polydisperse size distribution of droplets with a median size of approximately 1 um, and a concentration of approximately 10⁷ droplets/s, or 10¹² droplets/mL.
The droplets enter a drying column; are rapidly mixed with dried, filtered, heated (normally at 120^oC) compressed air, or nitrogen; and dried within the first few centimetres of the drying column. The temperature of the drying column can be set at lower temperatures (95, 70, or 45^oC) if information concerning the dissolved organic fraction of residue is required. Each atomizer droplet produces a particle of nonvolatile residue. As the residue particles emerge from the drying column, a small percentage is removed and passed through a diffusion screen before being counted by a condensation nucleus counter (CNC).

Scope and Application

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 ug/L(ppb) to 20 mg/L (ppm). 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.

Applicable Concentration Range

0.1-20,000 ug/L

Interferences

None indicated.

Quality Control Requirements

Sample Handling

High-purity water must be supplied through ultra-clean fittings made of a material that will not contaminate the water. Perfluoroalkoxy (PFA) has been used successfully with this test method. PFA is a fully fluorinated, translucent polymer of exceptional purity. It does not release a gas and is resistant to virtually all chemicals and solvents.
High-purity water should not be exposed to the atmosphere because it picks up contamination readily. This test method requires a continuous flow of high-purity water through a sealed, on-line installation to prevent such contamination.
This test method requires a non-contaminating pressure regulator because high-purity water must be supplied to the atomizer at a constant flow rate. Pressure fluctuations in the high-purity water supply must not be allowed to affect the flow rate of water supplied to the atomizer because pressure fluctuations will affect the size of water droplets produced by the atomizer, making the calibration inaccurate.
The atomizer requires a source of high-pressure compressed air, or nitrogen, regulated at a constant pressure to generate a stable aerosol of high-purity water droplets with a median size of approximately 1 um.
Water entering the atomizer must be at a temperature of 18 +/- 1^oC, to control surface tension in the high-purity water. Changes in surface tension affect the size distribution of water droplets.
Using long sample lines with low sample velocity to divert the flow of high-purity water to the test apparatus is not recommended, as this allows contaminants to accumulate in the sample lines. Sample lines should therefore be less than 2 m long, and line velocity should be greater than 10 cm/s. If the instrumentation for this test method cannot be sited close to the high-purity water supply, a sample line with a velocity of at least 1.8 m/s should bring the high-purity water to a tee connection (to high-purity water and to drain).

Maximum Holding Time

Relative Cost

$51 to $200

Sample Preparation Methods

This method has 1 analyte associated with it.

Analyte	Detection Level	Bias	Precision	Pct False Positive	Pct False Negative	Spiking Level
Solids, dissolved, residue on evaporation, 180deg C(N-55561) RAE Residue - Filterable Residue After Evaporation Solids, dissolved, residue on evaporation, 180deg C	0.100 ug/L	N/A	1.60 % RSD (ML)			50.00 ug/L

Precision Descriptor Notes:	To provide users with information on the stability of this test method's measurement of RAE, the following experiment was performed. A constant source of KCl contaminant was injected into a continuous water supply with the custom-built motorized syringe injection system shown in Fig. 2 of the method. This constant injection of KCl was monitored by this test method's apparatus until the syringe emptied; total injection time was 4 h. The results of this experiment are shown in Fig. 5 of the Method. The median value for this data is 50 ug/L, with a maximum value of 53 ug/L and a minimum value of 48 ug/L. The standard deviation was 0.807 ug/L.
Detection Level Note:	None.

Precision Descriptor Notes:

To provide users with information on the stability of this test method's measurement of RAE, the following experiment was performed. A constant source of KCl contaminant was injected into a continuous water supply with the custom-built motorized syringe injection system shown in Fig. 2 of the method. This constant injection of KCl was monitored by this test method's apparatus until the syringe emptied; total injection time was 4 h. The results of this experiment are shown in Fig. 5 of the Method. The median value for this data is 50 ug/L, with a maximum value of 53 ug/L and a minimum value of 48 ug/L. The standard deviation was 0.807 ug/L.

Detection Level Note:

None.

Revision	PDF/Link
Reapproved 1999. Current edition approved Sept. 15, 1994. Published November 1994.

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ASTM: D5544: Residue in Water

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