Measurment Of The Totaland Leaching Content Of Plasticizer In Plastic Water Pipes By Liquid-liquid Extraction-gas Chromatography

The organic pollution of water is more and more serious, thus people pay moreattentions to the safety of drinking water. Among all the pollution sources to drinkingwater, water-supply pipe caused pollution is one of the most important. Plastic pipehas become the most widely used water-supply pipe for its excellent featuresincluding light weight, resistant to corrosion, resistant to water osmosis, energy saving,convenient installation, long life, low cost, and et al. Beyond its advantages, plasticwater-supply pipes need additional plasticizers, like phthalic acid ester, during itsmanufacture. The additional plasticizers thus become a part of plastic water-supplypipes we used. From the perspective of environment and health concern, theseplasticizers are environmental endocrine which have a reproductive toxicity to allhuman being. In this research, we use liquid-liquid extraction along with gaschromatographic method to test the total content of plasticizers in ten different brandsof plastic water-supply pipe bought from the market. And the leaching content ofthese plasticizers to water within these purchased pipes are also tested. The effects ofleaching agents, leaching temperature, pH, and leaching time to the leaching contentof phthalic acid esters are further discussed, respectively. Leaching agent of2.0mg/Lavailable chlorine,100mg/L water hardness has largest leaching amount of theplasticizer. The leaching content increases significantly when the bath temperature isabove50℃. Among the pH of4.0to7.0, the amount of leaching phthalates decreasewith lower pH value. Leaching amount will be higher when the leaching time is longer. The content of dimethyl phthalate (DMP) and dibutyl phthalate (DBP) arehigher in most plastic service pipes while that of Di(2-ethylhexyl) phthalate(DEHP) ismuch lower. The results show that when we use the pipe at room temperature, pH ofwater is above6.0, and while the water is fresh and available chlorine and waterhardness are low enough, the damage from leaching phthalic acid ester of plasticwater pipes are low enough to human body. We can drink and use supply water safely.