75 - Urine extraction from disposable gel diaper

Analyzing urine is a crucial part of diagnosis, monitoring clinical progression, and research in neonates. The current methods of collecting urine from infants are either uncomfortable or result in a limited amount of urine being recovered and may necessitate parental informed consent. Disposable diapers are widely used; therefore, they are ideal media for urine collection. Disposable gel diapers typically contain several parts: a polyacrylate absorbent pad mixed with cellulose fibers, lateral tapes, and an elastic band around the legs. Disposable diapers are considered discarded waste and therefore may not require informed consent to collect.

Objective:

This study aims to investigate a urine extraction methodology from disposable diapers using different salt solutions and various storage conditions for neonatal urine collection.

Design/Methods:

In this study we used Pampers Preemie Swaddlers size P2 diaper. Artificial preterm urine was prepared as previously published. Diapers were spiked with 10 ml of artificial urine and, to mimic normal conditions, put in an incubator at 36°C for 30 mins. Absorbent pad of the diaper was removed and stored overnight. Storage conditions tested included 4°C, -20°C and -80°C. To separate the polyacrylate gel from the cellulose of the absorbent pad, the front and back sheet of the pad was peeled, and the mixture was placed into a stainless-steel mesh basket and sifted for 2 min at 300 rpm in a shaker. Sifted sodium polyacrylate gel was weighed in 50 ml tube and mixed with the salt solution. (10 ml of salt solution for 10 gram of polyacrylate gel). Free liquid was decanted, and volume was measured. Salt solutions tested included calcium chloride (CaCl₂), magnesium chloride (MgCl2), magnesium sulfate, ammonium acetate, potassium chloride, and sodium chloride. Each salt solution tested at 0.5 mol/l, 1 mol/l and 2 mol/l in triplicate.

Results:

Only CaCl₂ and MgCl2 salts caused observable shrinkage of polyacrylate gel, with urine recovery ranging from 74% to 86% under each storage condition. At -80°C storage, 2 mol/l CaCl2 solution provided the best urine extraction condition. The extraction rate of urine with magnesium sulfate salt varied from 27% to 42% under various storage conditions. The recovery rates with other salt solutions (ammonium sulfate, potassium chloride, sodium chloride) were only up to 23%. 

Conclusion(s): We concluded that calcium chloride can effectively release urine from polyacrylate gel diapers, and the method is promising for urine collection from infants. Further investigation of salt effect on urinalysis and urinary biomarker analysis is required.