This paper describes the validation of an analytical method to determine the minimum amount of residual corn starch powder that can reliably be detected on “powderless” gloves. Our procedures are similar to the ASTM D 11.40 method currently under development titled “ASTM D 11.40, Section I Working Draft for Powder-free Glove Method.” The various steps in the procedure were analyzed to determine their limitations and effects on the final results. The ability of the washing steps to remove residual powder from “powderless” gloves was ascertained by conducting recovery studies. An average powder recovery of 81.52% with a relative standard deviation (rsd) value of 8.12% (n = 15) was obtained by the draft ASTM D 11.40 procedure. The efficiency of the filtration and transfer steps was measured. A new device designed in this laboratory received an average yield of 1.51 ± 0.13 mg/glove (n = 15) as compared to the updated draft ASTM D 11.40 method with 0.84 ± 0.11 mg/glove (n = 15). Our new procedure gave an increase of 79% in yield with a rsd value of 8.5%. To enhance yield and powder recovery, it is crucial to rinse the glove surface effectively and reduce the washwater transfer steps.
The use of β-cyclodextrin (β-CD) as an aqueous phase modifier was investigated. The results obtained with (β-CD) increased the powder recovery per glove to 102% with a pooled standard deviation (psd) of 8% (n = 30, 10 level), corresponding to a rsd value of 8% when powder recovery was in the range of 0.5–10 mg. With water alone, the average recovery was 89% with a psd value of 16% in the same range. However, when the range was limited to 1–10 mg, the powder recovery per glove when using water alone was 95% with a psd value of 14%. The 2.7 μm glass microfiber filter collects 96% of the powder applied to it.
The degree of dependency to which the amount of powder on the glove affects powder recovery was studied using the relative error coefficient (rec). The rec values are less than 0.5%/mg/glove throughout the range of 0.5–10 mg using β-CD. With water alone in the same study range, a rec value of less than 3%/mg/glove was obtained. The correlation coefficients for percent powder recovery versus amount of powder on the glove show much less correlation over these study ranges. β-CD increased the recovery 15% and decreased the dependency of recovery on the amount of powder on the glove by 7.3-fold. The slopes and intercepts of recovered powder versus added powder were 1.01 ± 0.02 and 1.0 × 10−2 ± 1.3 × 10−1 mg for β-CD wash, and 0.95 ± 0.04 and −6.0 × 10−2 ± 2.5 × 10−1 mg for water wash in the range of 0.5–10 mg, respectively.