From: "Susan Miller" <SMiller@bia.org> 

To: Jeff Telander/RTP/USEPA/US@EPA 

Cc: "Schimmel, Terry (Bricks - Phenix City)" <Terry.Schimmel@boral.com> 

Date: 10/21/2010 09:46 AM 

Subject: FW: EPA Request for Additional Lab Info for ERT Submittal Bessemer 

Attachments: Analytical Persoectives Determination of Detection Limits.pdf; Element 

One Determination of Detection Limits.pdf; Enthalpy Analytical 

Determination of Detection Limits.pdf

Jeff- 

 

Terry asked me to go ahead and send this to you. We are still trying to make sure we understand a few 

things on our end. I have included our issues here- your guys may actually be able to clear them up... 

 

susan 

 

 

From: Susan Miller 

Sent: Wednesday, October 20, 2010 12:37 PM 

To: 'Schimmel, Terry (Bricks - Phenix City)' 

Cc: Irene Kuo 

Subject: RE: EPA Request for Additional Lab Info for ERT Submittal Bessemer 

 

Still waiting to hear from Mike- but here are our questions... 

 

- Last paragraph on “Element 1 detection limit discussion” is a bit confusing 

- On that same page , it looks like they may be calling something a Method Detection that we 

believe sounds 

more like the Analytical Detection Limit- but we could be off... we see the hierarchy as instrument, 

analytical, 

method, reporting....we need to be sure that we are all using the same one. 

- In the equation for detection limit from Analytical Perspectives, we are not sure which of the 

above limits 

they are calling “detection limit” (instrument?) 

- Would like to hear from Mike as to whether the PM blanks and detection limit is how he thinks it 

should be 

done. I know he believes that Belden’s test was not correct. 
From: Keith Poole 

To: Schimmel, Terry (Bricks - Phenix City) 

Cc: Dan McCombs ; Troy Burrows ; Tasso Stratas 

Sent: Tue Oct 19 14:05:23 2010 

Subject: EPA Request for Additional Lab Info for ERT Submittal Bessemer 

Terry, 

 

I have finally compiled all of the responses from our sub-contract partners regarding detection limit 

determinations. 

 

Please let me know if anything additional is required. 

 

Regards, 

 

W. Keith Poole, QSTI 

Sr. Project Manager 

mail to: kpoole@entecservices.com 

704.938.8528 (Kannapolis, NC Office) 

704.796.8164 (Cell phone) 

 

 

* Baton Rouge, LA * Birmingham, AL * Mobile, AL * Raleigh (RTP), NC * 

 

www.entecservices.com 

2008, 2009 & 2010 Inc. 5000 Fastest Growing Small Business 
1

Keith Poole

From: Heather Steele [hsteele@ultratrace.com]

Sent: Tuesday, October 19, 2010 9:11 AM

To: Keith Poole

Subject: Detection Limits

Dear Keith: 

Our detection limits are determined using the equation: 

DL = ( 2.5 × HN × QIS) / ( HIS × W × RRF) 

In the equation: 

 DL is the estimated detection limit for homologous 2,3,7,8-substituted PCDD/PCDFs 

 HN is the height of the noise (using 20-30 data points to determine σ, with 4σ used as the value) 

 QIS is the amount (in pg) of extraction standard added to the sample before extraction 

 HIS is the peak height of the extraction standard

 W is the weight of the sample (for method 23 samples this value is always 1) 

 RRF is the calculated relative response factor for the analyte 

Please let me know if you have any questions or if you need any additional information. 

Heather 

Heather Steele PhD 

Project Manager 

Analytical Perspectives

2714 Exchange Dr. 

Wilmington, NC. 28405 

(910)-794-1613 Ext: 110 

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The Laboratory Certification Code requires a laboratory to statistically determine its detection 

limits. Element One, Inc. conforms to these guide lines as follows: 

Instrument Detection Limit (IDL) is the concentration equivalent to a signal, produced by the 

analyte of interest, which is the smallest signal that can be distinguished from background noise 

by a particular instrument. The IDL should always be below the method detection limit. It is not 

used for compliance data reporting, but may be used for statistical data analysis and comparing 

the attributes of different instruments. 

The IDL calculation is determined by analyzing 10 blanks on three nonconsecutive days, pooling 

the data from all days. From the IDL data an estimated detection level is chosen that is 1-10 

times the IDL. Since the MDL is an estimate for the lower level of the calibration curve, the best 

spiking level is 1 - 5 times the estimated detection level, as specified in the EPA procedure. 

Method Detection Limit (MDL) is the minimum concentration of a substance that can be 

measured and reported with 99% confidence that the analyte concentration is greater than zero. 

It is determined by analysis of a sample in a given matrix which contains the analyte. The MDL is 

based upon the variability, or precision, between seven or more replicates run at identical 

concentrations. 

Method detection limits change over time for a variety of reasons; therefore, it is necessary to 

periodically update the calculated MDL value. Many analytical methods require that the MDL be 

determined prior to using a new analytical system, and some even require annual updates. 

Element One verifies MDLs every six months, when new analysts are trained, and when new 

instruments are obtained. The frequency of the determination specified in the analytical method 

is followed. 

Reporting limits for Element One are set higher than the MDL using the lowest calibration 

standard. The MDL can be used as the reporting limit if reproducibility is proven by a valid study 

with seven replicates of the specific target concentration. No values are reported below the 

lowest calibration standard (reporting limit), unless a standard is prepared at that concentration 

and falls within a +/- 25% window. The Reporting Limit is an arbitrary number below which data 

is not reported. The reporting limits used by Element One are not statistically determined, but are 

based upon experience and judgment of the analyst. Analytical results below the reporting limit 

are expressed using the lowest calibration point for calculating the "less than" reported. Reporting 

limits are not substituted for the laboratory established detection limits. We do; however, 

occasionally reduce our reporting limit subsequent to having established lower values. 

Element One Determination of Detection Limits 10.08.09 Initial Version.doc 
1

Keith Poole

From: Jordan Laster [jordan.laster@enthalpy.com]

Sent: Tuesday, October 19, 2010 9:20 AM

To: Keith Poole

Subject: Minimum Detection Levels

Keith - 

For instrumental analysis (Such as EPA Method 26) the MDLs are determined by the analysis of at least seven replicate 

standards at a concentration near the expected MDL. To determine the MDL value, the standard deviation of the replicate 

analyses is calculated and that number is multiplied by the "Student t factor" that corresponds to the number of replicates 

analyzed. The MDL value should meet the criteria stated in the CFR Title 40, Part 136 B.

If the MDL determined does not meet these criteria, a default MDL value will be used which is 1/10 of the concentration of 

the standard used to produce the MDL value. 

For particulate analysis, there is no detection level determination. All samples are weighed on a 5 or 6 place balance (10 

microgram increments) which far exceeds the method requirements for variability between weights. The methods specify 

a constant weight as being no more than 0.5mg difference between measurements. Therefore, this is the most 

appropriate detection level if one must be reported.

Let me know if you have any questions or need any other information. 

-Jordan 

Jordan Laster - Sales / Engineer Enthalpy Analytical Inc. 2202 Ellis Rd, Durham, NC jordan.laster@enthalpy.com V: 919-850-4392 x300 M: 919-699-9991 F: 919-850-9012