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.

Designation: D2119 − 24

Standard Test Method for

Aldehydes in Styrene Monomer1
This standard is issued under the fixed designation D2119; 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* D6809 Guide for Quality Control and Quality Assurance

1.1 This test method covers the wet chemical determination Procedures for Aromatic Hydrocarbons and Related Ma-
of aldehydes in styrene monomer. Aldehydes are calculated terials
and reported as benzaldehyde. E29 Practice for Using Significant Digits in Test Data to
Determine Conformance with Specifications
1.2 This test method is applicable to samples with aldehyde 2.2 Other Documents:
concentrations to 0.030 mass%. The limit of detection (LOD) OSHA Regulations, 29 CFR paragraphs 1910.1000 and
is 0.0006 mass% and the limit of quantitation (LOQ) is 0.002 1910.12003
mass% based on the data in 13.1.
1.3 In determining conformance of the test results using this 3. Summary of Test Method
method to applicable specifications, results shall be rounded off 3.1 An alcoholic solution of hydroxylamine hydrochloride
in accordance with the rounding-off method of Practice E29. is added to a specimen of styrene monomer. Active aldehydes
1.4 The values stated in SI units are to be regarded as present react in accordance with the following equation:
standard. No other units of measurement are included in this RCHO1NH2 OH·HCl→RCHNOH1H 2 O1HCl (1)
standard.
The hydrochloric acid, which is equivalent to the aldehyde
1.5 This standard does not purport to address all of the present in the sample, is titrated with standard sodium hydrox-
safety concerns, if any, associated with its use. It is the ide solution.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 4. Significance and Use
mine the applicability of regulatory limitations prior to use. 4.1 This test method is suitable for determining the quantity
For specific hazard statements, see Section 8. of aldehydes, both for quality control and quality assurance of
1.6 This international standard was developed in accor- the product.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the 5. Interferences
Development of International Standards, Guides and Recom- 5.1 Ketones, if present, interfere by partially reacting with
mendations issued by the World Trade Organization Technical the reagent.
Barriers to Trade (TBT) Committee.
6. Apparatus
2. Referenced Documents
6.1 Erlenmeyer Flasks, glass-stoppered, 250 mL.
2.1 ASTM Standards:2
D1193 Specification for Reagent Water 6.2 Pipets, 25 mL.
D3437 Practice for Sampling and Handling Liquid Cyclic 6.3 Volumetric Flasks, 100 mL.
Products 6.4 Burets, 10 mL. (Microburets are preferred.)
6.5 Thermometers, capable of differentiating 1 °C at ambi-
1
This test method is under the jurisdiction of ASTM Committee D16 on ent.
Aromatic, Industrial, Specialty and Related Chemicals and is the direct responsi-
bility of Subcommittee D16.07 on Styrene, Ethylbenzene and C9 and C10 Aromatic 7. Reagents and Materials
Hydrocarbons.
Current edition approved Jan. 1, 2024. Published January 2024. Originally 7.1 Purity of Reagents—Reagent grade chemicals shall be
approved in 1962. Last previous edition approved in 2019 as D2119 – 19. DOI: used in all tests. Unless otherwise indicated, it is intended that
10.1520/D2119-24.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
Standards volume information, refer to the standard’s Document Summary page on Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http://
the ASTM website. www.dodssp.daps.mil.

*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

1
 D2119 − 24
all reagents conform to the specifications of the Committee on buret, and record the volume used. Let stand 1 h and again
Analytical Reagents of the American Chemical Society where titrate any acid that may have been liberated. Record the total
such specifications are available.4 Other grades may be used, volume of NaOH used.
provided it is first ascertained that the reagent is of sufficiently 10.2 Since methanol may contain aldehydes, run a blank
high purity to permit its use without lessening the accuracy of determination on 25 mL of methanol.
the determination.
7.2 Purity of Water—Unless otherwise indicated, references 11. Calculation
to water shall be understood to mean reagent water as defined 11.1 Calculate the percentage of aldehydes as benzaldehyde
by Type I or II of Specification D1193. as follows:
7.3 Hydrochloric Acid, Standard (0.05 N)—Prepare a 0.05 N Aldehydes, % 5 @ ~~ A 2 B ! N × 0.106! /25C # × 100 (2)
solution of hydrochloric acid (HCl CAS 7647-01-0) by diluting
4.15 mL of concentrated HCl (density 1.19 g/mL) to 1 L with where:
water. A = NaOH solution required for titration of the specimen,
7.4 Hydroxylamine Hydrochloride Solution—Dissolve 20 g mL,
of hydroxylamine hydrochloride (NH2OH·HCl, CAS 5470- B = NaOH solution required for titration of the methanol
11-1) in 1 L of methanol and neutralize to the red-yellow end blank, mL,
N = normality of NaOH solution used, and
point of thymol blue indicator.
C = density of styrene monomer.
7.5 Methanol (CAS 67-56-1).
7.6 Sodium Hydroxide, Standard Solution (0.05 N)— 12. Report
Dissolve 2.00 g of low-carbonate sodium hydroxide (NaOH, 12.1 Report the aldehydes content to the nearest
CAS 1310-73-2) in water and dilute to 1 L. Standardize against 0.001 mass%. Results less than 0.001 mass% should be re-
primary standard benzoic acid. ported as <0.001 mass%.
7.7 Thymol Blue Indicator Solution—Dissolve 0.1 g of
thymol sulfonphthalein, sodium salt (CAS 62625-21-2), in 13. Precision and Bias
water and dilute to 100 mL. 13.1 Intermediate Precision (formerly called
Repeatability)—On the basis of test error alone, the difference
8. Hazards
between two results obtained in the same laboratory on the
8.1 Consult the latest OSHA regulations, supplier’s Safety same material will be expected to exceed the value below only
Data Sheets, and local regulations regarding all materials used 5 % of the time:
in this test method. Aldehyde Content, mass% Repeatability, mass%
0.004 0.0006
8.2 Styrene monomer is flammable and polymerizes exo-
thermally on contact with peroxides, mineral acids, and AlCl3. 13.2 Reproducibility—On the basis of test error alone, the
Styrene also polymerizes exothermically in the absence of difference between two results obtained in different laborato-
inhibitor (Tert Butyl Catechol, TBC) and in the absence of ries on the same material will be expected to exceed the below
adequate oxygen in the liquid phase to support the inhibitor value only 5 % of the time:
(TBC). Aldehyde Content, mass% Reproducibility, mass%
0.004 0.0016
9. Sampling and Handling 13.3 Bias—Since there is no accepted reference material
9.1 Collect the sample as directed in Practice D3437. suitable for determining the bias in this test method for
measuring aldehydes in styrene, bias has not been determined.
10. Procedure
10.1 Pipet 25.0 mL of the sample (Warning—see 8.2) into 14. Quality Guidelines
a 250 mL glass-stoppered Erlenmeyer flask containing 25 mL 14.1 Laboratories shall have a quality control system in
of methanol. Record the temperature of the sample. Add 0.2 place.
mL of thymol blue indicator and, if necessary, neutralize with 14.1.1 Confirm the performance of the test instrument or
0.05 N NaOH solution or 0.05 N HCl to the red-yellow end test method by analyzing a quality control sample following
point (do not record). Add 25 mL of the neutralized hydrox- the guidelines of standard statistical quality control practices.
ylamine hydrochloride solution and allow to stand 1 h, shaking 14.1.2 A quality control sample is a stable material isolated
the flask occasionally. Titrate to the original red-yellow end from the production process and representative of the sample
point with 0.05 N NaOH solution, dispensed from a 10 mL being analyzed.
14.1.3 When QA/QC protocols are already established in
4
ACS Reagent Chemicals, Specifications and Procedures for Reagents and the testing facility, these protocols are acceptable when they
Standard-Grade Reference Materials, American Chemical Society, Washington, confirm the validity of test results.
DC. For suggestions on the testing of reagents not listed by the American Chemical
14.1.4 When there are no QA/QC protocols established in
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma- the testing facility, use the guidelines described in Guide
copeial Convention, Inc. (USPC), Rockville, MD. D6809 or similar statistical quality control practices.

2
 D2119 − 24
14.2 Interlaboratory Testing: for acceptance. Producers and customers need to have confi-
14.2.1 A program that includes multiple laboratories ana- dence that results from different producers are comparable.
lyzing the same samples is strongly encouraged. This program
should allow labs to compare their results with other labora- 15. Keywords
tories. This is particularly important when a plant is selling the
15.1 aldehyde content; aldehydes in styrene; styrene
product to customers or the laboratory is analyzing the product

SUMMARY OF CHANGES

Committee D16 has identified the location of selected changes to this standard since the last issue
(D2119 – 19) that may impact the use of this standard. (Approved January 1, 2024.)

(1) Updated Scope, 1.1, and 1.2 to be consistent with editorial (5) Revised Section 13 to be consistent with editorial guide-
guidelines. lines.
(2) Added CAS numbers to Section 7. (6) Revised Section 14 to be consistent with editorial guide-
(3) Changed to Type I or II water in 7.2. lines.
(4) Revised mass% information in 12.1.

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