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HomeSoil, Solid Waste & Groundwater TestingAnalytical Method: Sulfate in Building Materials

Photometric Determination of Sulfate in Building Materials with Turbidimetric Method After Water Extraction

This protocol outlines the photometric determination of sulfate levels in building materials using Spectroquant® test kits. Following a sample preparation by water extraction, the procedure utilizes a spectrophotometer to measure the sulfate content, ensuring precise results.

Section Overview

three models of Spectroquant® spectrophotometers: Prove 100 plus, Prove 300 plus, and Prove 600 plus. Each device has a sleek, modern design with a rectangular body. The largest model in the foreground, Prove 600 plus, is green with a black top and features a touchscreen interface displaying measurement data, as well as a slot for sample insertion. The top right corner of the device has a yellow "M" logo and "600+" printed in bold yellow on the front corner. Two smaller models, Prove 100 plus and Prove 300 plus, are placed in the background. Prove 100 plus is light green with a black top, while Prove 300 plus is yellow with a black top. Both also feature touchscreens and the "M" logo.


Spectroquant® spectrophotometers - Prove 100 plus, Prove 300 plus, & Prove 600 plus

 

Introduction

Sulfate can have a significant impact on the durability and stability of construction materials. Excess sulfate may lead to a chemical reaction with certain building materials, such as concrete, resulting in a phenomenon known as a sulfate attack. This can compromise structural integrity over time, leading to cracking, expansion, and deterioration. Hence, measuring and monitoring sulfate content in building materials is essential for ensuring the longevity and performance of structures. This is particularly important in environments where sulfate exposure is a concern, such as near coastal areas or in soil with high sulfate levels.1

Common determination methods for analyzing sulfate in building material after appropriate sample preparation include photometric analysis, gravimetric analysis2, titration methods2, and ion chromatography3. The photometric method offers distinct benefits, including high sensitivity, rapid analysis, cost-effectiveness, and a user-friendly process with minimal sample preparation. This makes it the preferred choice for accurate and efficient determination of sulfate content in building materials.

Experimental

This Application Note describes the sample preparation for Sulfate in building materials before the photometric determination of Sulfate using Spectroquant® Sulfate Cell Tests (1.01812, 1.02532, 1.14548, 1.02537, 1.00617, 1.14564).

With the Spectroquant® Sulfate Tests the sulfate content can be determined quickly and easily. The methods are preprogrammed on the corresponding Spectroquant® photometers. Calibration is not necessary. All reagents required for the measurement are included in the test kits.

Method

After the sample preparation using hot water extraction the sulfate ions react with barium ions to form slightly soluble barium sulfate. The resulting turbidity is measured with a photometer (turbidimetric method).

The method is analogous to EPA 375.4, APHA 4500-SO42- E, and ASTM D516-16.

Measuring Ranges, Test Kits and Method Numbers

Expected content in original sample

(measuring range of related test kit)

Cell

Instruments

Method No.

Test kit

Sulfate content, water - soluble (0.002 – 4% SO42-)

0.002 – 0.04% SO42-

(0.5 – 10.0 mg/L SO42-)

50 mm rectangular cell

Prove1) 100/300/600 plus,

Nova 60A

224

1.01812

0.0052 – 0.1% SO42-

(1.3 – 25.0 mg/L SO42-)

20 mm rectangular cell

0.01 – 0.2% SO42-

(2.5 – 50.0 mg/L SO42-)

10 mm rectangular cell

0.004 – 0.2% SO42-

(1.0 – 50.0 mg/L SO42-)

16 mm round cell

Prove1) 100/300/600 plus,

Nova 60A

229

1.02532

0.008 – 0.2% SO42-

(2.0 – 50.0 mg/L SO42-)

Move 100

444

0.02 – 1% SO42-

(5 – 250 mg/L SO42-)

16 mm round cell

Prove1) 100/300/600 plus,

Nova 60A

64

1.14548

Move 100

440

0.02 – 1.2% SO42-

(5 – 300 mg/L SO42-)

16 mm round cell

Prove1) 100/300/600 plus,

Nova 60A

230

1.02537

0.04 – 1.2% SO42-

(10 – 300 mg/L SO42-)

Move 100

446

0.2 – 2% SO42-

(50 - 500 mg/L SO42-)

16 mm round cell

Prove1) 100/300/600 plus,

Nova 60A

154

1.00617

0.04 – 4% SO42-

(10 – 1000 mg/L SO42-)

16 mm round cell

Prove1) 100/300/600 plus,

Nova 60A

82

1.14564

1) Also, legacy system Spectroquant® Prove 600/300/100 and the Nova series are compatible and preprogrammed with these methods.

Applicable Sample

  • Building materials

Influence of Foreign Substances

Foreign substances in the sample solution can

  • increase the measurement value because of an amplification of the reaction
  • lower the measurement value because of a prevention of the reaction

A quantification of these effects is stated in tabular form in the respective package inserts for the most important foreign ions and substances. The tolerance limits have been determined for the individual ions and substances; they may not be evaluated cumulatively.

In the case of samples with a complex, in many cases inexactly known composition (matrix) it is particularly difficult to estimate the potential influence of the foreign substances on the analysis (matrix effect). The following instructions describe a method by means of which the user can test whether a matrix effect is present or not.

Reagents, Instruments and Materials

Test/Reagents/Kit(s)

For the sample preparation, depending on the chosen procedure (see below), some or all of the following is necessary:

  • Analytical balance
  • 200-mL volumetric flask
  • Water for analysis EMSURE® (1.16754)
  • Heating plate
  • 100-mL volumetric cylinder
  • 200-mL volumetric flask
  • Paper filter

If necessary, required for pH adjustment:

  • Sodium hydroxide solution 1 mol/L Titripur® (1.09137)
  • Hydrochloric acid 1 mol/L Titripur® (1.09057)
  • Universal Indicator strips pH 0 – 14 (1.09535)

For the measurement, one of the following Spectroquant® test kits is necessary:

For the measurement, one of the following Spectroquant® photometers is necessary:

  • Spectroquant® UV/VIS Spectrophotometer Prove 600 plus (1.73028)
  • Spectroquant® UV/VIS Spectrophotometer Prove 300 plus (1.73027)
  • Spectroquant® VIS Spectrophotometer Prove 100 plus (1.73026)
  • Spectroquant® Colorimeter Move 100 (1.73632)  – see suitability in the table “Measuring ranges, test kits and method numbers”

Also, legacy systems are suitable:

  • Spectroquant® Spectrophotometer Prove 600/300/100
  • Spectroquant® Photometer NOVA 60A

Instrument Accessories

Rectangular cells are necessary for Spectroquant® Sulfate Test (1.01812)

  • Rectangular cells 10 mm (1.14946) and/or
  • Rectangular cells 20 mm (1.14947) and/or
  • Rectangular cells 50 mm (1.14944

Software for Data transfer (optional)

The Spectroquant® Prove Connect to LIMS software package provides an easy way to transfer your data into a preexisting LIMS system.

Analytical Procedure

Sample preparation - hot water extraction:

  • Prepare a fine powder of the sample and dry at 105 °C.
  • Mix 5 g with water for analysis and boil for 30 minutes on a hot plate.
  • Allow to cool, transfer the suspension to a 200-mL volumetric flask, and make up to the mark with water for analysis.
  • Mix well, filter through a paper filter, and then use as a sample for the determination of water – soluble sulfate.

Photometric Analysis

This prepared sample can be analyzed with the following test kits:

  • Spectroquant® Sulfate Tests (1.01812)
  • Spectroquant® Sulfate Cell Test (1.02532)
  • Spectroquant® Sulfate Cell Test (1.14548)
  • Spectroquant® Sulfate Cell Test (1.02537)
  • Spectroquant® Sulfate Cell Test (1.00617)
  • Spectroquant® Sulfate Cell Test (1.14564)

Follow the instructions given in the package inserts or instrument manual.

Notes on measurement

If the prepared sample is colored, perform a sample blank before the measurement of the sample itself. This step is necessary to compensate for the intrinsic color.

Follow the instructions given in the instrument manual and package inserts.

Calculation

The obtained result read off in mg/L SO42- must be converted as follows:

                      Sulfate (water-soluble) content in % = analysis value in mg/L SO42- x 0.004

Analytical quality assurance

Analytical quality assurance (AQA) is recommended before each measurement series.

To check the photometric measurement system (test reagent, measurement device, handling) and the mode of working, sulfate standard solutions or Spectroquant® CombiCheck kits can be used. Besides standard solutions, CombiCheck also contains an additional solution for determining sample-dependent interferences (matrix effects).

A certificate of analysis is provided for each batch and can be downloaded online on the product page of the test as well as a certificate of quality, where all batches are considered. In the certificates, the performance characteristics determined in accordance with ISO 8466-2 and DIN 38402 A51 are given.

Nevertheless, it is recommended to determine the performance characteristic yourself so that all specific factors that may impact the performance (test reagents, measurement device, handling) are considered in the characteristic data.

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References

1.
Marchand J, Odler I, Skalny JP. Sulfate Attack on Concrete, CRC Press. https://doi.org/10.4324/9780203301623
3.
Weiss J. 2016. Handbook of Ion Chromatography: 3 Volume Set. 4th Edition. Weinheim: Wiley-VCH.
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