Mirex in seals

The Science of the Total Environment, 2 (1973) 196-198 © Elsevier Scientific Publishing Company, Amsterdam--Printed in Belgium

Short communication

M I R E X I N SEALS

M. C. TEN NOEVER DE BRAUW and C. VAN I N G E N

Central Institute for Nutrition and Food Research TNO, Zeist (The Netherlands) and J. H. K O E M A N

Department of Toxicology, Agricultural University, Wageningen (The Netherlands) (Received June 2nd, 1973)

During previous studies on chlorinated compounds in wild life in The Netherlands some obscure masses were observed in the gas chromatograms of tissue samples. Some of these appeared to be chlorinated styrenes, as described by Ten Noever de Brauw and K o e m a n 1. For the identification of another c o m p o u n d with the characteristic mass number 270, containing six chlorine atoms, a seal (Phoca vitulina) blubber extract was submitted to further qualitative analysis by high-resolution mass spectrometry. The identification is described in the present paper.

MATERIAL A N D METHODS

Extracts were injected into a computerised gas c h r o m a t o g r a p h y - m a s s spectrometry system (Ten Noever de Brauw and Koemanl). This system gives a total ion current c h r o m a t o g r a m from which the mass c h r o m a t o g r a m for the characteristic mass 270 (revealing the exact location of the compound under investigation) and the mass spectrum at this location are obtained. High-resolution measurements on the total extract were made with a double-focussing Varian-Mat 731 mass spectrometer (Varian-Mat, Bremen, G.F.R.). RESULTS A N D DISCUSSION

Fig. I shows the total ion current c h r o m a t o g r a m of the seal blubber extract starting with spectrum 50 and ending with spectrum 470. The main peaks in the chrom a t o g r a m are well known polychlorinated biphenyls (PCBs). When examining the mass spectrum at location 380 (Fig. 2), it can be seen that in this spectrum, which represents a PCB with molecular weight of 392 and containing seven chlorine atoms, two other fragment ions are present with masses 270 and 235, containing six and five chlorine atoms, respectively. These two latter masses do not correspond to PCBs. 196

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A selected mass plot of masses 270 and 235 (Fig. 3) reveals the exact location of the compound of interest. The retention time suggested that the compound has a higher molecular weight, and that the mass 270 was only a fragment ion. In order to identify this molecular ion, l 0 / d of the complete extract were introduced by means of a direct probe into a double-focussing mass spectrometer. The mass spectra recorded showed the presence of very small ion peaks at masses 540 and 505, with elemental composition calculated from exact mass measurements of CloC112 and C10C111, respectively. The elemental composition of the mass 270 was CsCI 6. F r o m this information it could be deduced that the component was 1,2,3,4,5,5,6,7,8,9,10,10-dodecachlorooctahydro-l,3,4-metheno-2H-cyclobuta[c,d]pentalene, also known as Mirex. The identification was further confirmed by comparison with a reference sample. Other molecular ions found in the spectra of the complete mixture were those of PCBs with molecular weights 426, 460 and 498, containing 8, 9, and I0 chlorine atoms, respectively. The compound Mirex is also available under the name of Dechlorane, used according to the Merck Index 2 as a flame retardent. Further studies are in progress to identify the sources and possible applications from which the compound Mirex originates. REFERENCES 1 M. C. ten Noever de Brauw and J. H. K o e m a n , Sci. Total Enciron., 1 (1972/1973) 427. 2 Merck Index, E. Merck & Co. Inc., Rahway, N.Y., 8th ed., 1968.

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