Batch lot variability in permeation through nitrile gloves

Many factors should be considered in the selection of chemical protective clothing, but the majority of selections are based on manufacturers' permeation data composed of average results for three replicates; usually no information about variability is provided. It was hypothesized that variability across batch lots might be considerable, and that variability may be due to cure factors that may vary from one site to another within the same company. Glass transition temperature (Tg) has been demonstrated to be an indicator of cure, and so its relationship to permeation parameters was examined. Steady state permeation rate, breakthrough detection time (BDT), cumulative permeation at 125 minutes (ASTM F1407), and Tg (ASTM E1356) were measured for two makes of nitrile gloves presumably in four batches. Tg was not related to any of the permeation parameters even though batch-to-batch variability was statistically significant for all parameters except BDT. A comparison with recent ASTM round-robin results indicates that some of the variability may be due to the method; however, manufacturer quality control must be suspected as the major source of variability based on the results of this study.