Application Note: Rapid, Quantitative Analysis Of Phthalates In PVC Plastics

By F. G. Haibach and S. K. Schreyer

PVC is one of the most common plastics in use, in part because of the versatility provided by additives. Children's toys are now required to contain less than 0.1% phthalate esters because of concerns about reproductive toxicity. Phthalate-containing PVC remains one of the most common forms of plastic in children's toys. In one study, 60 of 72 toys (>80%) contained phthalate-plasticized PVC components. A more recent study confirms that PVC toy components contain 10-40% phthalates.

Phthalates can be detected in plastics down to the part per billion level using HPLC and GC methods. Accurate determination of plasticizer content requires grinding and extraction of the plasticizer and the plastic. The extraction process can take from 30 minutes to several hours. Midinfrared methods are available that do not require extraction, but only the surface of the prepared plastic piece is measured.

Near infrared (NIR) offers a rapid, non-preparative method for phthalate determination. NIR can provide results within seconds, without grinding the sample. NIR is sensitive to the quantity and environment of CH, NH, OH and other functional groups. Phthalates have a distinct structure from PVC. The unique absorbance band of aromatic ring of the phthalate is easily distinguished from the polymer.