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Alternative method for determining formaldehyde in commercial samples


A spectrophotometric method using magnesium sulphate instead of concentrated sulphuric acid is proposed for the analysis of formaldehyde in disinfectants and hair products.

Substituted substance(s)

  1. Sulphuric acid

    CAS No. 7664-93-9 EC No. 231-639-5 Index No. 016-020-00-8

Alternative substance(s)

  1. Magnesium sulfate heptahydrate

    CAS No. 10034-99-8 EC No. 231-298-2 Index No. 

Other type of alternative

Reliability of information

Internet information: data are from an internet document and only a basic and partial evaluation could be performed

Hazard assessment

Magnesium sulphate heptahydrate is not included in the database for substances known to be of concern, according to SUBSPORT criteria. It is not classified according to EU harmonized legislation and is not self-classified in ECHA C&L Inventory database. The MSDS of one of the distributors identified possible irritation to skin, eye and respiratory tract due to exposure to magnesium sulphate heptahydrate (see Further information).

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

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Substitution description

An alternative method for the analysis of formaldehyde in commercial products replaces concentrated sulphuric acid by magnesium sulphate.The method was applied in a laboratory study for the analysis of commercial disinfectants and deffrizzing hair products containing illicit formaldehyde.
Both the original and the alternative spectrophotometric methods are based on the reaction of formaldehyde with chromotropic acid. The original method (published by NIOSH 1994, method 3500(2) ) uses concentrated sulphuric acid heated on a steam bath (1000C) for about one hour. The alternative  also includes the  heating stage on the steam bath  but  uses a 60% magnesium sulphate (heptahydrate)  aqueous solution instead of the corrosive sulphuric acid.
The alternative method proved to have good selectivity for formaldehyde and high accuracy.

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Case/substitution evaluation

The alternative is easy to implement. It reduces the chemical risks  associated with the use of sulphuric acid, classified as corrosive. Magnesium sulphate is not classified corrosive ( it is however an irritant) and  being a coarse powder it is easier to transport, store and manipulate  compared  liquid, concentrated sulphuric acid.

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Other solutions

Further information

– Magnesium sulphate heptahydrate MSDS for Sigma Aldrich

– National Institute for Occupational Safety and Health, NIOSH Manual of Analytical Methods (NMAN), 4th ed., US Department of Health, Education and Welfare: US, 1994, method 3500(2) – formaldehyde.

Further languages available

Who provided the information

Type of information supplier


Fabrícia Gasparini, Patrícia L. Weinert, Liliane S. Lima, Leonardo Pezza and Helena R. Pezza
Instituto de Química, Universidade Estadual Paulista, CP 355, 14801-970 Araraquara-SP, Brazil

J. Braz. Chem. Soc., Vol. 19, No. 8, 1531-1537, 2008.,

Publication source

The information is based on the article  ’ A Simple and Green Analytical Method for the Determination of Formaldehyde’ writen by  Fabrícia Gasparini, Patrícia L. Weinert, Liliane S. Lima, Leonardo Pezza and Helena R. Pezza and published in J. Braz. Chem. Soc., Vol. 19, No. 8, 1531-1537, 2008.

Type of publication and availability 

Article published in scientific journal, freely available

Original document: click here

Comments from SUBSPORT users

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Publication or last update: September 2011