ASTM D7558-2019 pdf free download

ASTM D7558-2019 pdf free download.Standard Test Method for Colorimetric/Spectrophotometric Procedure to Quantify Extractable Chemical Dialkyldithiocarbamate, Thiuram, and Mercaptobenzothiazole Accelerators in Natural Rubber Latex and Nitrile Gloves
1. Scope
1.1 This test method is designed to quantify the amount of total extractable accelerators in natural rubber latex (NRL) and nitrile gloves. Three common classes of rubber accelerators, the mercaptobenzothiazole (MBT), thiuram, and thiocarbamate type compounds can be detected and quantified by this method. If the specific rubber accelerator(s) present in the glove material is not known, quantification is based on zinc dibutyl- dithiocarbamate (ZDBC) equivalents. This method will not detect all potential rubber accelerators, including mercaptoben- zothiazole disulfide, dimorpholine, thioureas and diphenyl diamine. 1.2 For the purpose of this test method, the range of chemical accelerator measurement is based on the limit of detection (LOD) established in the performing laboratory. 1.3 This test method should be performed by experienced analysts or under the supervision of those experienced in the use of spectroscopy and working with organic solvents. 1.4 This test method has not been validated for measure- ment oflong chain dithiocarbamates or accelerators from other rubber products, such as lubricated condoms (1). 2 Although this assay has been reported in the literature for the evaluation of accelerator levels in condoms, further validation for accel- erator measurement from other rubber products is required by the testing laboratory prior to use. 1.5 This test method is not designed to evaluate the potential of rubber materials to induce or elicit Type IV skin sensitiza- tion reactions (for Type IV skin sensitization reactions see Test Method D6355). Total extractable accelerator content does not reflect bioavailablity of individual accelerators that are de-tected and measured by this method. This test method should be used to test and measure the total residual chemical accelerator level in NRL and nitrile gloves under controlled laboratory conditions, and should not be used to describe, appraise, or assess the hazard or risk of these materials or products under actual in-use conditions. 1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.8 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Test Method
4.1 The rubber material is cut into small pieces and approximately 1 g is placed into the extraction vessel. Acetoni- trile is added to give a final volume/weight of 10 mL acetonitrile per gram of rubber. The extraction vessel is securely capped, placed onto a rotator and extracted at approxi- mately 200 rpm for a minimum of 2 h at room temperature (25 6 5°C). The acetonitrile extract is recovered and centrifuged in a sealed centrifuge tube at 500 × g for 20 min at room temperature to remove any residual particulate matter. The acetonitrile extract supernatant fluid is transferred to a clean container and capped. Zinc dibutyldithiocarbamate (ZDBC) standards at 500 to 31.25 µg/mL in acetonitrile and a blank are prepared. Cobalt chloride (10 µL, 420 mmol/L) aqueous solution is added to 1 mL aliquots of each sample extract and standard. Each individual solution is thoroughly mixed and then incubated for 120 min at 50 6 5°C. The extracts and standards are cooled to room temperature for approximately 15 min after the 50°C incubation. A 100 µL aliquot of each is diluted with 1.9 mL of acetonitrile. All are mixed thoroughly and absorbance of each sample, blank and standard is mea- sured at 320 nm on a UV spectrophotometer. Concentration of residual accelerator is obtained by extrapolation from the standard plot. Depending upon the number of samples tested, this test method takes about 5 h to complete.