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042-EN, General section

Substitution of 2-mercaptoethanol with 1,4-dithiothreitol for use as reducing agent in sample preparation for electrophoresis.


This example concerns the substitution of 2-mercaptoethanol with 1,4-dithiothreitol for use as a reducing agent in sample preparations of proteins or DNA/RNA before electrophoresis.

Substituted substance(s)

  1. 2-Mercaptoethanol

    CAS No. 60-24-2 EC No. 200-464-6 Index No. 

Alternative substance(s)

  1. 1,4-Dithiothreitol

    CAS No. 3483-12-3 EC No. 222-468-7 Index No. 

Other type of alternative

Reliability of information

Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication

Hazard assessment

The alternative is not included in in the database of hazardous substances according to SUBSPORT screening criteria (SDSC), however it holds the R-phrases R22 and R36/37/38.

» Check the Substance Database according to SUBSPORT Screening Criteria (SDSC)

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Substitution description

2-Mercaptoethanol has been used as a reducing agent in sample preparation before electrophoresis. The function of the reducing agent is to remove the last remnants of tertiary and quaternary structure of the protein by breaking disulfide bonds which in the absence of a reducing agent would be formed spontaneously. The disulfide bonds are covalent and can therefore not be broken without a reducing agent.

Dithiothreitol can be used as a substitute for 2-mercaptoethanol in nearly all cases.

Dithiothreitol is not as volatile and toxic as mercaptoethanol which means it is easier to work with as well as safer for the analyst.

It is also significantly more clean than 2-mercaptoethanol resulting in a higher accuracy in detecting and measuring bands in electrophoresis.

Dithiothreitol is slightly less stable in solution than 2-mercaptoethanol. This means that it might be a good idea to use 2-mercaptoethanol when handling larger buffers to keep reduction capacity during a long time.

Dithiothreitol is a good substitute for 2-mercaptoethanol in almost every case. When using especially large buffers 2-mercaptoethanol might be better to use because of its higher stability in solution.

Dithiothreitol is also slightly more expensive than 2-mercaptoethanol.

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Case/substitution evaluation

The alternative is harmful if swallowed and irritating to eyes, respiratory system and skin. The substituted substance holds the same properties and is also toxic in contact with skin and is more volatile than the alternative.  Since 2-mercaptoethanol is more volatile the alternative is both safer and easier to work with. It should however be handled with care.

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Other solutions

Further information

Further languages available

Who provided the information

Type of information supplier


Thomas Åkerlund, Microbiologist
Swedish Institute for Communicable Disease Control,

Publication source

Type of publication and availability 

Comments from SUBSPORT users

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