MATERIALS AND METHODS

In order to find the determining factors in the migration process 4 assays were carried out.

Assay design table:

Static: Water remains still in pipe.Open Dynamic: Fresh treated water runs through pipe.

All pipes were brand new, set in dark isothermic room.

Pipes used in STATIC Flow Mode:-HDPE: Internal diameter: 90 mm

Length: 2,1m Internal Volume: 13,35 l Contact

area: 5,9 m2

-LDPE: Internal diameter: 45,8 mm Length: 8,1m

Internal Volume: 13,35 l Contact area: 11,6 m2

Pipes used in open DYNAMIC Flow mode:-HDPE: Internal diameter: 90 mm

Length: 2 m Water flow: 0,8 m/s Contact

area: 5,6 m2

-LDPE: Internal diameter: 45,8 mm Length: 2 m

Water flow: 0,9 m/s Contact area: 2,9 m2

POTENTIAL WATER MIGRATION OF ORGANIC COMPOUNDS FROM

POLYETHYLENE (PE) PIPES. ANALYSIS BY CLSA AND GC/MS M. Om, M. Cortina, J. Caixach* and J.

RiveraLaboratori d’Espectrometria de Masses, Dept. d’Ecotecnologies, IIQAB-CSIC, Jordi Girona 18-26, 08034 Barcelona.

C. de Ciurana, X. BallellLaboratori d’Aigües de Girona, Salt i Sarria de Ter S.A.ETAP Montfullà, 17162 Bescanó Girona.

INTRODUCTION

Polyethylene pipes (PE) are widely used in treated water distribution services. Migration of low molecular weight compounds from PE into the treated water can change its final quality. This study was done to identify and quantify the migration compounds from two types of PE pipes; high density HDPE and low density LDPE polyethylene, under different conditions of temperature, time of contact and water flow.

RESULTS AND DISCUSSION

Low density polyethylene (LDPE) shows the highest migration potential at 40ºC; 8 times higher than the HDPE at 40ºC, and around 22 times over the LDPE at 14ºC. (Static Assays).

Compounds detected:

1. Among BHT degradation by-products (8 metabolites were detected); dm-BHT, ox-BHT and Quinona-BHT are found to be the major.

Mass Spectra related:

BHT CAS nº 128-37-0

dm-BHT CAS nº 128-39-2

Quinona-BHT CAS nº 719-22-2

2. Plastic manufacturing by-products such as aldehides, cetones and short-chain hidrocarbons and alkylbenzenes were also detected.These chemicals are susceptible to change water organoleptic quality giving taste and odor.

ACKNOWLEDGMENTS

The Authors wish to thank both Laboratories staff for their collaboration in this study.

REFERENCES 1.Productos Químicos Industriales, H.A,Wittcoff, B.G. Reuben: Vol 2.; Editorial Limusa, 1985.2. Plastics Additives Handbook, 3 rd Edition, R. Gächter and H. Müller Editors. Hanser Publishers, Munich, Viena New, York.3. A. Bruchet, C. Hochereau, Analysis, 25, M32-M34, 1997.4. J. Rivera et al., J.Chromatography, 562, 481-492, 1991.5. Standard Methods, 20 th Edition, 1998. Part 6000, 8-18 6040B.6. D.W Shorten, Food Chem., 8, 109-119, 1982.7. A. Hoff et al., Scand. J. Work Environ. Health, 8 (sup. 2) 3-27 1982.8. J. P. H. Linsen et al., Food Chemistry, 46, 367-371, 1993.9. S. Monarca et al., Food Chemistry Toxic., 32, 783-788,1994.10. B. Rindone et al., Water Research, 28, 1595-1600, 1994.11. S. rigal, J. Dasnjou, Water Sci. & Tech., 406, 203-208, 1999.12. M. van Leeuwen et al., Polym. Laminations Coat Conference, Vol 1, 229-237, 1998.

Assay Flow mode Temperature Contact time1 Static 40 ºC 72 h2 Static 14 ºC 8 h3 Open Dynamic 14 ºC 24 h4 Open Dynamic 14 ºC 11h, 5 h, 30 min

ANALYSIS

Identification and quantification were carried out using CLSA (Closed Loop Striping Analysis) extraction technique and Gas Chromatography coupled to Mass Spectrometry (MD-800 Thermo-Finnigan) using a 60 m J&W column (0,25 m film thickness) with “on Column” sample injection in electron impact ionisation mode (70 eV). Data was processed using Masslab software, Wiley 6th and NIST 98 libraries were used.

Acquired 22-Apr-1999 at 09:04:28Sample ID: LDPE1604

50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300m/z0

100

%

191

57

551639173

6560 6774 88

7911510710595

147128117 133 135 161175

164 176

206

192

193 207

9A22_1 4164 (55.529) Scan EI+ 4.18e6

Acquired 22-Apr-1999 at 09:04:28Sample ID: LDPE1604

50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300m/z0

100

%

177

67

5753

65

63

9177

6975

79

81 85

135

95121105

103107 133

149

136144

163159

151164

220

205178

192187 193206 221

9A22_1 4029 (53.729) Scan EI+ 8.50e4

Acquired 05-Jul-2001 at 09:38:21

50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300m/z0

100

%

205

57

5553 145918177676558 69 10595 115 119128

133 177161149

163 189178

220206

207 221

1JL5_2 390 (13.203) Scan EI+ 1.47e6