Suspended Solids Quality Test for Bleach Using Vacuum Filtration

Developed by:
Dr. Bernard Bubnis of Novachem
Phone: 513.523.3605
Fax 513.523.4025


The suspended solids quality test for bleach using vacuum filtration is a general procedure for assessing bleach clarity. In the manufacture of bleach, off-color and turbidity are frequent problems in unfiltered bleach due to the presence of transition metal ion complexes in solution and as precipitates.

This procedure is based on the time it takes to filter 1 liter of bleach at constant vacuum. A laboratory water aspirator will typically pull a vacuum equal to 20 inches of Hg on a filtration flask. When 1 liter of bleach is filtered under vacuum (20 inches Hg), high clarity bleach will take <3 minutes to filter. In contrast, low clarity bleach will take at least twice this amount of time and frequently filtration times beyond 20 minutes are observed. This large difference between low clarity and high clarity bleach can be used as a quality assessment of bleach.

Utilities that specify the use of the Suspended Solids Quality Test for Bleach Using Vacuum Filtration as an acceptance criterion for delivered bleach have found that high clarity bleach results in increased customer satisfaction by preventing floccing problems, oxygen gassing, as well as pipe and instrumentation coating and clogging.

Analytical Method

Because it is difficult to standardize water aspirator vacuum, the Alltech Benchtop Vacuum Station (Deerfield, IL) was used to establish the vacuum guidelines for the bleach suspended solids test. Subsequent testing has also shown that the Millipore glass filtration apparatus (sintered glass filter with a wide edge butt joint) helps prevent membrane tears.

  • Apparatus Catalog Number
  • *Alltech Vacuum Station, 115 V 6417
  • **Millipore 1 liter ground glass flask, 47mm XX1504705
  • Millipore base and tube cap, 47 mm XX15047O2
  • Millipore 300 mL funnel, 47 mm XX1004704
  • Millipore spring clamp, 47 mm XX1004703
  • Millipore Filter Paper, Type AA, 0.8 micron AAWP 047 00
  • *Alltech Assoc. **Millipore (Corporate Headquarters) 2051 Waukegan Road 80 Ashby Road Deerfield IL 60015 Bedford MA 01730 Phone: 800.255.8324 or 847.948.8600 Phone: 800.MILLIPORE; Fax: 847.948.1078 Fax: 781.533.3110

Assembling the Filtering Apparatus

The filtering apparatus is comprised of the vacuum station, ground glass flask, base and tube, funnel, clamp, tygon tubing and filter paper.

More Information:

This article is available as a PDF. Click here to download it. For more information about sodium hypochlorite, visit the Technical Information section.