Formaldehyde Testing, Aldehydes and Ketones, HPLC and GCMS Analysis

Introduction

Formaldehyde (and other aldehydes and ketones) can be determined by several chromatographic methods. The old chromatropic acid method for 

Formaldehyde by HPLC 

EPA has published methods using dinitrophenylhydrazine (DNPH) derivatization followed by liquid chromatography (LC). Both the GC and LC methods can be applied to other aldehydes, while the DNPH-LC method is also applicable to ketones as well. The EPA methods have been published for water and wastes (Formaldehyde, EPA 8315A) and air (EPA TO-5 and TO-11). The California Air Resources Board Method 430 and EPA TO-5 use impingers for sampling air, while TO-11 uses silica gel tubes coated with DNPH.

An example LC chromatogram below demonstrates the analysis of 14 common aldehydes and ketones using DNPH derivatives. This method is not without problems.  While it generally works well in fairly clean waters, we have noted that recoveries are often low in highly contaminated or alkaline samples.

We can supply you with sampling media and analysis for all the methods listed above.  

For a quotation...

Formaldehyde by GCMS and LC-MS/MS

Many methods have been developed over the years to measure formaldehyde. Currently, we typically use HPLC to determine formaldehyde after derivatization with 2,4-dinitrophenylhydrazine (DNPH), which forms derivatives with aldehydes and ketones. This method is sensitive (detection limit in water is approximately 6 ppb) and relatively specific, since the derivative has an absorbance maximum at 360 nm.

Although interferences are greatly reduced at this wavelength, they are not eliminated entirely. Other colored

LC-MS/MS can also be done.  The detection limit is ~20 ug/L, and because of the MS/MS interferences are eliminated.

If you have any questions about formaldehyde, and whether GCMS may be able to solve your specific problem, give Mike Shelton a call at extension 702.

EPA Method 556

EPA Method 556 offers yet another alternative to measuring formaldehyde and other aldehydes.  This method uses pentafluorobenzyl hydroxylamine (PFBHA) to form oxime derivatives of the aldehydes in an aqueous solution at pH 4.  The derivatives are extracted into hexane and analyzed by GC-ECD or GCMS.  Of course the ECD offers the best detection limits (<1 ug/L for most

compounds).  GCMS has better specificity but only has detection limits in the range of ~10 ug/L.  

The chromatogram below is taken from EPA Method 556.  Note that most aldehydes which are assymetrical around the  carbonyl group produce both E and Z isomers, i.e. two peaks per compound.

For a quotation...

Formaldehyde in Hair Products and Cosmetics

In 2010, suppliers of hair products argued that their products contained methylene glycol, the hydrated form of formaldehyde, rather than formadehyde itself.  Regulators took the position that methylene glycol is simply the water solution form of formaldehyde and that the regulations apply. 

Formerly West Coast Analytical Service (WCAS) and Bodycote Testing Group