Hi Ron 

We're recommending for your consideration as part of the response to comments for this CFR proposal the 

following method change: 

 

6.3.9 Sonication device. The device must have a nominal sonication frequency of 25 to 40 kHz 

and be approximately 4 to 6 inches deep to accommodate the sample extractor tube.

 

This may help respond to questions about sonicator specifications. Most modern sonicators operate at 40 kHz 

although you can still order one at 25 kHz. 

 

Ray 

>>> <Myers.Ron@epamail.epa.gov> 1/7/2010 2:26 PM >>> 

Paul: 

I have re-read OTM-28 and there is no requirement to measure the pH of the samples until the aqueous portion 

is rehydrated and then neutralized with 0.1 N NaOH (para 11.2.2.4). 

Paragraph 11.2.1 and subsequent subparagraphs cover the sonication of the filters. We can not recommend 

any specific sonicator. But any sonicator that the vesel you have placed the filter would be completely imersed 

to the water line would be acceptable. The goal is to dislodge all the particulate from the filter and get it into 

solution. 

_________________________________ 

Ron Myers 

U.S. Environmental Protection Agency 

Office of Air Quality Planning and Standards 

Sector Policy and Programs Division 

Monitoring Policy Group, D243-05 

RTP NC 27711 

Tel. 919.541.5407 

Fax 919.541.1039 

E-mail myers.ron@epa.gov 

-----"Taverna, Paul" <paul.taverna@aecom.com> wrote: ----- 

To: Ron Myers/RTP/USEPA/US@EPA 

From: "Taverna, Paul" <paul.taverna@aecom.com> 

Date: 01/07/2010 11:12AM 

cc: "Moll, David" <David.Moll@aecom.com>, "Tringale, Frank" <frank.tringale@aecom.com> 

Subject: OTM-28 Analysis 

From: Ray Merrill

To: Myers.Ron@epamail.epa.gov

Date: 1/7/2010 3:00 PM

Subject: Re: OTM-28 Analysis

CC: Greene, Danny; Merrill, Ray

file://C:\Documents and Settings\KFaught\Local Settings\Temp\XPgrpwise\4CF4D21AD... 11/30/2010
Ron, 

I manage in the AECOM gravimetric laboratory in Harvard MA and we are in the process of equipping our 

laboratory to perform the OTM-28 test method. I work with Dave Moll at AECOM and he suggested asking you 

some questions I have about the analysis. I would greatly appreciate any help or advice you could give me for 

the following questions; 

1. Do we need to test the PH level of the samples in the lab if the PH levels are measured in the field during 

recovery? I did not see in the method where this step was required to be done in the lab. 

2. Do we need to use the sonicator bath on each sample? The sonic bath is listed in the equipment, but I am 

unclear as to where in the process to use the sonic bath. Also, can you recommend what type of sonicator (i.e. 

brand and size) would be appropriate for this test method? 

Thanks for any help you can provide. 

Paul 

Paul Taverna 

Project Specialist 

AECOM Environment 

D: (978)589-3200 x3523 C: (978)758-2542 

paul.taverna@aecom.com 

AECOM 

2 Technology Park Drive 

Westford, MA 01886 

T: (978)589-3000 F: (978)589-3312 

www.aecom.com 

Please note: My e-mail has changed to [paul.taverna@aecom.com]. Please update your address books 

accordingly. 

. 

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