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# Inline HEPA Filter on CNT Glove Weighing Process Exhaust Duct Airborne Testing Report

Executive Summary:

On December 2, 2010 “NIOSH Current Intelligence Bulletin: Occupational Exposure to Carbon Nanotube and Nanofibers” was published by the National Institute for Occupational Safety and Health.

Based upon the data from animal studies, a recommended exposure limit (REL) of 1.0ug/m3 has been established to protect workers’ health. NIOSH came up with this REL and calculation based on the animal dose-response date of early-stage fibrotic and inflammatory lung response to CNT exposure. This data gives us an estimation of the exposure that employees could possibly be exposed to through out their life time. Working lifetime exposure concentrations have been calculated based on estimates ofeither the deposited or retained alveolar lung dose of CNT. It goes by an 8-hour timeweighted average (TWA) work shift exposure during a 40-hour work week, 50 weeks per year, for 45 years.

, conducted two samples by using NIOSH Method 7402. This method utilizes a Transmission Electron Microscopy (TEM) follow up to a Phase Contrast Microscopy (PCM) analysis via NIOSH 7400. Taking advantage of the TEM's ability to positively identify each fiber(or carbon nanotube), the method determines the percentage of asbestos fibers (or carbon nanotubes) versus non-asbestos fibers in the sample. This method helps determine the potential exposure for all workers who could be exposed to CNTs. This test was done by using a SKC Leland Legacy air pump. It is connected 1⁄4’’ of tygon r-3603 tubing Preloaded Quartz Fiber Cassette, MCE backing, 0.8um, 37mm connected to another 1⁄4’’ tygon r-3603 tubing. Then we will send this sample to

Scientist) for analysis via NIOSH Method 7402 for asbestos fibers testing.



## Process Description :

Our Hypothesis: The purpose of this experiment to determine the effectiveness of the inline 0.5um HEPA filter and its ability to remove CNTs. Our expectations prior to performing testing was to have CNTs being detected on the “Pre-HEPA Filter” sample and not on the “Post-HEPA Filter” sample 

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On May 29, 2013 we began our process by calibrating our SKC Leland Legacy Pump.

Calibration Flow Average Date of Calibration Process Descriptions

At -40 L/min (this is the amount of flow that we adjusted so we can get the volume of 5L/min At -40 L/min 4.9782 4.9782 5/29/2013 SKC Leland Legacy Pump was connected to Bios Defender 510 calibration machine 4.8657 4.9219 5.0654 5.0654 4.964 5.0147 4.9059 4.9059 5.0152 4.9605

Then we adjusted back up to 5L/min so we can compare the flow volume with the Bios Defender Calibration MachinAt 5L/min 5.0256 4.9782 5/29/2013 SKC Leland Legacy Pump was connected to Bios Defender 510 calibration machine 5.0019 5.0019 4.8823 4.8823 4.9827 4.9209 4.9478 4.9388 5.0311 4.9426



### On the same day at the facility at 10:54 AM we performed an airborne sampling test on the exhaust duct (Pre-Hepa Filter). We drilled a 1⁄4” hole into the Glove Box exhaust duct pre the inline HEPA filter and then we inserted the1/4’’ piece of Tygon r-3603 tubing approximately one inch into the hole. Then we connected this to the SKC Leland Legacy pump. The Leland Legacy pump was run at 5.00 L/Min for 420min for a total volume of air of 5.00L/Min x 420min 2100L. During the run time, we had someone in the lab weighing our 3 separate 50grams aliquots of CNTs. This was done from 11:30AM to Noon (30 minutes). Samples were sent to for analysis via NIOSH Method 7402 for TEM asbestos fibers test. 

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### [ ] Page 3 7/30/2013 Firgure 1-1 Glove Box Exhaust Duct (Pre-Hepa Filter) 

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On May 31, 2013 we began our process by calibrating our SKC Leland Legacy Pump

.

Calibration Flow Average Date of Calibration Process Descriptions

At -40 L/min (this is the amount of flow that we adjusted so we can get the volume of 5L/min 5.0088 5.0088 5/31/2013 SKC Leland Legacy Pump was connected to Bios Defender 510 calibration machine 4.9274 4.9274 4.9051 4.9051 4.9071 4.9071 4.9059 4.9059 5.0226 5.0226

Then we adjusted back up to 5L/min so we can compare the flow volume with the Bios Defender Calibration Machine 5/31/2013 SKC Leland Legacy Pump was connected to Bios Defender 510 calibration machine 5.0019 5.0019 4.8823 4.8823 4.9827 4.9209 4.9478 4.9388 5.0311 4.9426 5.0983 5.0983



### On the same day at the facility at 8:54 AM we performed an airborne sampling test on the exhaust duct (Post-Hepa Filter). We drilled a 1⁄4” hole into the Glove Box exhaust duct post the inline HEPA f ilter and then we inserted the1/4’’ piece of Tygon r-3603 tubing approximately one inch into the hole. Then we connected this to the SKC Leland Legacy pump. The Leland Legacy pump was run at 5.00 L/Min for 420min for a total volume of air of 5.00L/Min x 420min 2100L. During the run time, we had someone in the lab weighing our 3 separate 50grams aliquots of CNTs. This was done from 11:30AM to Noon (30 minutes). Samples were sent to for analysis via NIOSH Method 7402 for TEM asbestos fibers test. 

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### [ ] Page 5 7/30/2013 Firgure 1-2 Glove Box Exhaust Duct (Post Hepa Filter) 

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## Results: Two samples were analyzed using NIOSH Method 7402 for TEM asbestos fibers at the Analysis for both samples came back on 6/12/2013 with the results being (ND) Non-Detectable (See Table 1)

Table 1: NIOSH Method 7402 Airborne Results



## Conclusions:

Based on the results, we concluded that our Glove Box weighing process is not introducing enough CNT material into the exhaust duct for it to be detectable. This is probably due to our purge and wipe down method while using the Glove Box, which significantly reduces or eliminates airborne CNTs from escaping the Glove Box. Furthermore, this does not determine what the efficiency of the 0.5um inline HEPA filter is for removing CNTs from the exhaust air stream. One could conclude based upon these results that the need for this inline HEPA filter could be eliminated as no CNTs were found in either sample (pre and post HEPA filter). Sample # Sample Description Date Sample Taken Type of Filter Total Air Flow (L/min) Date of Results EC (ug/sq

cm)

17 Glove Box Pre Hepa Filter 5/29/2013 Preloaded Cassette,

MCE, 0.8um, 37mm, 3Piece, PreBanded 2100 6/12/2013 N/D

18 Glove Box Post Hepa Filter 5/31/2013 Preloaded Cassette,

MCE, 0.8um, 37mm, 3Piece, PreBanded 2100 6/12/2013 N/D 

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