The effect of PVC packaging on the acidity of 0.9% saline

Intravenous fluids in polyvinyl chloride (PVC) packaging are known to be ac idic. We proposed to determine the effect of PVC packaging on the pH of 0.9 % saline solutions by comparing the predicted and measured pH of 0.9% salin e equilibrated with atmospheric carbon dioxide and the measured pH of comme rcial solutions of 0.9% saline in PVC and polypropylene packaging. Calculat ion of pH was made fr om available physical chemistry constants find data. Measurement was made of the pH of 12 samples of prepared 0.9% saline equili brated with atmospheric carbon dioxide. Comparison with the pH of seven com mercial samples of saline in PVC packaging for intravenous use was undertak en. Further comparison was made between commercial samples of 0.9% saline i n PVC or polypropylene packaging. The calculated pH of 0.9% saline was 5.61 at 20 degrees C. The median pH of the prepared samples was statistically s ignificantly less acidic than the median pH of the PVC packaged samples for intravenous use: 5.47 vs 4.60, P<0.05. The median pH of the PVC packaged s aline was also statistically significantly more acidic than the pH of the p olypropylene packaged saline: 4.62 vs 5.71, P<0.05. The acidity of the intr avenous solutions of 0.9% saline packaged in PVC was much greater than expe cted and is only partially explained by dissolved carbon dioxide. This acid ity could be a result of packaging in PVC.