ASTM E2193-23

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2193 − 16 E2193 − 23
Standard Test Method for
Ultraviolet Transmittance of Monoethylene Glycol (using
Ultraviolet Spectrophotometry)
This standard is issued under the fixed designation E2193; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers a procedure for the determination of the transmittance of monoethylene glycol (1,2-ethanediol; MEG)
at wavelengths in the region 220 to 350 nm. 220 nm to 350 nm. The results provide a measure of the purity of the sample with
respect to ultraviolet (UV) absorbing compounds.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For specific hazard statements, see Section 7.
1.4 Review the current Safety Data Sheets (SDS) for detailed information concerning toxicity, first aid procedures, and safety
precautions for all materials used in this test method.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D6299D6809 Practice for Applying Statistical Quality Assurance and Control Charting Techniques to Evaluate Analytical
Measurement System PerformanceGuide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons
and Related Materials
E131 Terminology Relating to Molecular Spectroscopy
E169 Practices for General Techniques of Ultraviolet-Visible Quantitative Analysis
E180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals
(Withdrawn 2009)
E275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers
2.2 Other Document:
Manufacturer’s Instruction Manual of Spectrophotometer
This test method is under the jurisdiction of ASTM Committee D16 on Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsibility of
Subcommittee D16.14 on Alcohols & Glycols.
Current edition approved Jan. 1, 2016April 1, 2023. Published January 2016April 2023. Originally approved in 2002. Last previous edition approved in 20082016 as
E2193 – 08.E2193 – 16. DOI: 10.1520/E2193-16.10.1520/E2193-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2193 − 23
3. Summary of Test Method
3.1 The product is sampled in such a way as to avoid extraneous contamination and air contact. The absorbancetransmittance of
the sample contained in a 50-mm or 10-mm 10 mm cell is measured against water at a series of wavelengths and the transmittance
over a pathlength of 10 mm is calculated.wavelengths.
3.2 This test method can be performed with two options as to sample preparation prior to UV measurement.
3.2.1 Option A: Nitrogen sparging of the sample (see 4.2).
3.2.2 Option B: No nitrogen sparging.
4. Significance and Use
4.1 Knowledge of the ultravioletUV transmittance of monoethylene glycol MEG is required to establish whether the product meets
the requirements of its quality specifications.
4.2 Dissolved oxygen in organic solvents, such as MEG, forms complexes that shift the solvent absorption from the vacuum
ultravioletUV range into the measurable UV range (near 190 to 250 nm). Monoethylene glycol 190 nm to 250 nm). MEG has a
UV absorption peak at 180 nm. For MEG-oxygen complexes, this peak is shifted to a longer wavelength, thus increasing the
absorbability at 220 nm.
4.2.1 However, this effect is not observed in water. There is no significant measurable effect due to dissolved oxygen in water that
would require nitrogen sparging prior to using for collection of the reference spectrum.
4.2.2 Nitrogen sparging and re-measurement of suspect or borderline glycol samples at 220 nm can be used as a tool to rule out
or confirm the presence of UV affecting contaminants other than oxygen.
5. Apparatus
5.1 Ultraviolet Spectrophotometer, double beam, suitable for measurement at wavelengths in the region 200 to 400 nm, 200 nm
to 400 nm, having a spectral bandwidth of 2.0 nm or less at 220 nm, 220 nm, wavelength accuracy 60.5 nm or less at 220 nm,
220 nm, wavelength repeatability 0.3 nm or less at 220 nm, and a photometric accuracy of 60.5 % T or less, in the transmittance
region above 50 % T. Stray light shall be less than 0.1 % at 220 nm. The instrument shall be provided with matched quartz (fused
silica) cells with pathlengths of 50 6 0.1 mm or pathlength of 10 mm 6 0.01 mm. Use of 50-mm cell should provide better
precision.
5.1.1 Optional Single Beam Spectrophotometer—Use the same cell for measurement of the blank and the sample.
5.1.2 Terminology E131, Practice E169, and Practice E275 have additional information on the operation of spectrophotometers.
5.2 Nitrogen Stripping Apparatus (Option A, 3.2.1), consisting of an oil-free pressure reducing valve to fit the nitrogen cylinder,
a control valve, vinyl tubing, and a disposable glass pipette to be inserted in a 25-mL25 mL volumetric flask or bottle. Components
should be clean and free of ultravioletUV contaminants. Avoid contacting the sample with any plastic material containing
plasticizers. Plasticizers can leach out of the material and cause erroneous results. Replace the disposable pipette by a clean, new
one after each sample handling. (See Section 10.)
5.3 Bottles, capacity at least 0.5 L, with lined, well-fitting cap. Use a fresh bottle for each determination.
5.4 Glassware:
5.4.1 Volumetric Flask or Bottle, 25 mL.
6. Reagents and Materials
6.1 Purity of Reagents—Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the
E2193 − 23
Committee on Analytical Reagents of the American Chemical Society where such specifications are available. Other grades may
be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy
of the determination.
6.2 Holmium Oxide Wavelength Calibration Filter,Filter. calibrated (if required; see 9.1.1).
NOTE 1—The standard reference material SRM 2034, available from the National Institute of Standards and Technology (NIST),Commercial reference
standards traceable to NIST SRM’s are available. is suitable.
6.3 Standard Absorbance Filter, with certified absorbance values (if required; see values.9.1.2).
NOTE 2—The standard reference material SRM 2031, available from NIST, is suitable. In addition, SRM 935a may be used (see 6.4).
6.4 Stray Light Filter, for measuring stray light at 220 nm (if required; see nm.9.1.3).
NOTE 3—The (potassium iodide) standard reference material SRM 2032, available from NIST, is suitable (see also 6.8).
6.5 Naphthalene Solution—(1 mg/L isooctane) (Warning—Isooctane is highly flammable and irritating to the respiratory system.
Avoid contact with skin. Naphthalene is irritating to the skin, eyes, and respiratory system. It may cause sensitization by skin
contact. Avoid contact with eyes. Wear suitable protective clothing.)
6.6 Nitrogen, minimum purity 99.99 % (V/V), oil-free.
6.7 Potassium Dichromate or Potassium Chromate, for checking photometric accuracy (if required; see accuracy.9.1.2).
NOTE 4—The standard reference material, no. SRM 935a, available from NIST, is suitable.
(Warning—Potassium dichromate is harmful in contact with skin, toxic if swallowed, and very toxic by inhalation. It is irritating
to the respiratory system and skin. Risk of serious damage to eyes. It may cause sensitization by skin contact. It may cause heritable
genetic damage. It may cause cancer by inhalation. In case of accident or if you feel unwell, seek medical advice immediately
(show the label where possible). immediately. Avoid exposure—obtain special instructions before use. This material or its
container, or both, must be disposed of as hazardous waste. Avoid release to the environment. Refer to special instructions/safety
data sheets.) (Warning—Potassium chromate is irritating to eyes, respiratory system, and skin. It may cause sensitization by skin
contact. It may cause heritable genetic damage. It may cause cancer by inhalation. In case of accident or if you feel unwell, seek
medical advice immediately (show the label where possible). immediately. Avoid exposure—obtain special instructions before use.
This material or its container, or both, must be disposed of as hazardous waste. Avoid release to the environment. Refer to special
instructions/safety data sheets.)
6.8 Potassium or Sodium Iodide Solution, for measuring stray light at 220 nm (if required; see nm.9.1.3).
NOTE 5—The “UV-VIS Standard” sodium iodide solution, is suitable. Potassium iodide solutions can be prepared from NIST standard reference material
SRM 2032 (see 6.4 and Note 3).
6.9 Water, Low UV Absorbance—Water—HPLC grade or reagent water type I Type I grade of reagent water (Specification D1193).
6.10 Monoethylene Glycol MEG Quality Control Sample—It is recommended to select a Monoethylene GlycolMEG sample
similar to the product being analyzed and to use it as a quality control sample (Warning—see 7.2). To this end, ensure to obtain
a sufficient amount and store it in such a way that it is stable for a known period of time and use it as such during this period of
time only. For more details, see Section 11.514.
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USP),(USPC),
Rockville, MD.
E2193 − 23
7. Hazards
7.1 Consult current OSHA regulations and supplier’s Safety Data Sheets and local regulations for all materials used in this test
method.
7.2 Monoethylene Glycol—MEG—Although monoethylene glycol, MEG, in general, is not classified as dangerous or flammable
and is not expected to impose a health hazard when used under normal conditions, it is recommended to avoid inhalation and
contact with skin and eyes. Wear suitable protective clothing and gloves. Do not breathe gas, fumes, vapor, or spray. Use only in
well-ventilated areas. In cases of contact with eyes, rinse with plenty of water and seek medical advice.
8. Sampling
8.1 The following precautions must be observed carefully since the ultravioletUV transmittance is very sensitive to small amounts
of extraneous material contaminating the sample and to oxygen dissolved in the sample through air contact. The sample connection
must be protected against accidental contamination and designed so that it will permit convenient positioning of the sample bottle
to the sample outlet in order to minimize air contact, that is, the descending stream of sample should be as short as possible. Purge
the sampling line thoroughly with sample. Fill the bottle partly with sample (Warning—see 7.2), shake and discard. Repeat the
rinsing procedure. Then take the sample in a “gentle stream,” thus filling the bottle to within 10 mm 10 mm of the top. A “gentle
stream” is a rate of flow that avoids spattering, splashing, or other aggressive manifestations on the part of the sample flow. Cap
and avoid excessive shaking during transport (see also Section 10).
9. Preparation of Apparatus
9.1 Spectrophotometer—Check the performance of the spectrophotometer as described below. General information on the
measurement of performance of spectrophotometers is given in Practice E275.
9.1.1 Wavelength Accuracy—Check the wavelength accuracy of the spectrophotometer at 220 nm, in accordance with the
manufacturer’s instructions, for example, by means of a naphthalene solution ((seeWarning—see 6.5 6.5) in a 10-mm10 mm cell.
If the scale reading at the observed band maximum differs by more than 0.3 nm from 220.6 nm (wavelength of naphthalene band
maximum), measure the absorbance in the actual procedure (Section 11) at a wavelength setting of 0.6 nm below the value found
for the naphthalene band maximum.
9.1.1.1 Alternatively, wavelength accuracy may be checked using the calibrated holmium oxide filter ((see 6.2). Naphthalene is
the preferred material for this purpose but holmium oxide is a sufficient alternative.
NOTE 2—Since the absorbance of monoethylene glycol MEG rises considerably at wavelengths shorter than 220 nm, it is essential that the wavelength
position in this region is accurately set.
9.1.2 Photometric Accuracy—Check that the photometric accuracy of the spectrophotometer is in accordance with the
instrumental specification (see 5.1), for example, by means of standard absorbance filters (see 6.3) or solutions of suitable materials
((seeWarnin
...