December 2006
Volume V, Issue 3

"PATI Achieves AIHA IHLAP Accreditation"

Dear All,

I am proud to announce that Prism Analytical Technologies, Inc. received AIHA IHLAP Laboratory Accreditation as documented by the AIHA Scope of Accreditation Certificate in October.  This is a big achievement of which our dedicated staff is very proud of. PATI is committed to the ISO 17025 Quality standards and to providing you, our client, with the finest in air testing, science based technology coupled with extraordinary service.  Now you can be assured that you are working with one of the finest air testing labs in the world.

Our focus in this issue of Trapped Air will be the "hows" of reading and understanding the air analytical reports known as TDT Air Scan®.  As you will see there is much more to the report than just the analytical results.  Randall Fike, Ph.D., writes in this issue "How do I Read a PATI TDT Air Scan® Report."  This article reviews all the components of a TDT Air Scan® Report. You can also follow along by clicking on the TDT Air Scan Report link as you go through the article.

Be sure to read Laura Riera's interesting case study where she has used good science and good detective work to uncover an old refrigerant tank hidden in the walls of an old apartment complex.  Speaking of refrigerant, learn more about the refrigerant R-410A in "The Technical Forum."

As always, we welcome your feedback and ideas.  Please feel free to forward Trapped Air to others as well as to send any suggestions for future issues our way at trappedair@pati-air.com.

Best Regards, Lester H. Keepper III President

"How do I Read a PATI TDT Air Scan® Report?"
or
"PATI-Speak"

By Randall S. Fike, Ph.D.

To understand what a PATI TDT Air Scan® report means (Click Here), you must be able to read it in the first place.   This article is a compilation of headings and their meanings along with frequently asked questions to help understand the PATI-Speak we use in our reports.

Analysis name

This defines the scope of the analysis and applicable sections of Technical Bulletin 503, "Air Survey Analyses - List of Compounds," that may apply.

Units

The unit used most often is ng/L (ng/L = ug/m3); however, other units may be used.

Paragraph under banner

This statement tells the submitter what compounds were investigated. Target Scans investigate only the specific compounds listed in the report.  Air Scans involve investigations of compounds listed in Technical Bulletin 503, "Air Survey Analyses - List of Compounds".   Only those compounds that were detected are listed in the report.  A copy of TB-503 accompanies each report.

Laboratory ID

This is the number under which all laboratory records are stored.   If you call to discuss your results, it would be helpful to give this number to the person who answers the phone before you ask for the technical department.

Detection limits

The detection limit is determined by the volume of air sampled and by the total quantity of VOCs present.   For samples that have massive quantities of analytes, many lower level compounds will be masked.  It is usually best to address the source for the high level compounds and then resample to uncover other potential problems.

Compound

This column lists the most common name for the compound. While it may be a trivial name (such as "Toluene") it is usually an IUPAC name.  IUPAC stands for International Union of Pure and Applied Chemistry.  This organization has established a system of nomenclature for chemicals that is universally accepted.  Other names for the compound may also be included under the "Comments" section.  Where a compound is listed that is not specifically identified (such as C4-C6 Hydrocarbon) an indication of functionality (i.e. aldehyde, alcohol, ketone, etc.) is often included under the "Comments" section.

What does Cx mean?

Where Cx is listed separately, such as C6, C7, C8, etc., it indicates the specific, straight chain hydrocarbon (n-hexane, n-heptane, n-octane, etc.).  This nomenclature is used for brevity and clarity (C14 is shorter to write and is easier to understand than n-tetradecane). Where Cx is used in a range, such as C6-C8 Hydrocarbon, it indicates all of the C6, C7, and C8 hydrocarbons within that range.

Calculated Result

If a compound is determined quantitatively, that is to say, there is an established calibration curve for the compound (this is true for all Quantitative List A compounds in Technical Bulletin 503), no number will be listed in this column.   A number appears in this column only if the compound listed is determined semiquantitatively.   An estimate of the concentration of semiquantitative compounds is made by taking a ratio of its chromatographic peak area to the area of the internal standards.  Calculated values can be used quantitatively to determine the ratios between samples. For example, if Sample A has a calculated value for a specific compound of 400 and Sample B has a calculated value for the same compound of 800, it can be said quantitatively that Sample B has twice as much of that compound as Sample A.  However, the number cannot be used definitively as a stand-alone value.   Since the objective for taking a TDT Air Scan® sample is usually to discover what compounds are present and their approximate concentrations in an effort to determine potential problems and sources, the accuracy of the values listed under "Calculated Result" is sufficient.   Should more accurate values be required, a calibration curve can be established and additional samples analyzed.

Actual Result

If a compound is determined quantitatively, a single number is listed in this column.   The value can be substantiated through the calibration curve and applicable quality control procedures. If a compound is determined semiquantitatively, a single number is listed under "Calculated Result" and a range is listed under "Actual Result".  This range is typically 50% to 200% of the calculated value. Within one standard deviation, the actual concentration will fall within these limits.

Comments

If the entry under Compound is not a specific chemical (such as "substituted benzene" or C4-C6 Hydrocarbon), the first line in Comments column will include the retention time together with as much supporting information about the compound as possible. The retention time is listed to facilitate correlation between samples.   For example, if the chemical listed under Compound is "C4-C6 Hydrocarbon", using the retention time, it is possible to match the compound to a "C4-C6 Hydrocarbon" listed for another sample.   This is especially useful in cases where multiple hydrocarbons are listed.

If the entry under Compound is a specific chemical, the first line in this column lists other names for the compound.  Where the name listed under Compound is a trivial name, like "toluene", the Column will indicate the IUPAC name "methylbenzene".  Where the name listed under Compound is an IUPAC name like "isopropylbenzene", the Comments column will indicate the trivial name "cumene". Additional comments may also be included.   In the case of some odorants, the nature of the odorant is listed, for example, "sweet pine", "rose", or "tangerine".

If the entry under Compound is not a specific chemical, no information is listed in the bottom line.  If the entry under Compound is a specific chemical, the bottom line lists the following:

ppb:	This is parts per billion on a volume basis.  This is a number calculated from the ng/L value listed under Actual Result (for quantitative compounds) or Calculated Result (for semiquantitative compounds) using the formula:

ppb = ng/L X (24.04 / MW)

where:

MW = the molecular weight of the compound and 24.04 = 22.4 X (293 / 273)

where:

22.4 is the volume of one mole of ideal gas at 273 ºK (0 ºC) and 293 is the assumed sampling temperature in ºK.

This formula assumes a sampling temperature of 20 ºC (68 ºF).  Some organizations prefer to use 25 ºC (77 ºF) as the assumed sampling temperature which will change the 24.04 factor to 24.45.

MW

This is the mass spectral molecular weight of the compound. The mass spectral molecular weight is a whole number based on the sum of the weights of the most abundant isotopes of the atoms present. For example, benzene has a mass spectral molecular weight of 78 rather than the actual molecular weight of 78.11.

CAS	The Chemical Abstract Service assigns a unique number to all chemicals.  This number is particularly useful in eliminating confusion in communicating the identity of the compound and in performing web searches.

Validity of Compound Identification

To determine the identity of each compound, the analyst will use various computerized search algorithms, his knowledge and skill in mass spectral interpretation, his supportive data from the Fourier Transform Infrared, and his experience in the details and quirks of GC-MS analysis.  The operator must be at least 95% confident in the validity of an identification before it will be listed specifically by name under "Compound" in a TDT Air Scan® analysis.  Where there is uncertainty in the validity of the identity of a compound, that level of uncertainty is written in standardized format and is provided to the submitter as part of the analytical report.

This is shown in the following table:

PATI is a consultative Air Testing Laboratory.  We always welcome your questions and comments to help us learn new ways to serve you better.

In October, 2006, PATI received a call from Laura Riera.   She was very concerned about the source of an odor in an apartment building in San Francisco.  She described the odor as being a heavy, sweet smell that left a sweet taste in the back of the throat.  To read more on this case study Click Here

Q.   Have you been asked about R-410A yet?

A.   You probably will be.  R-410A is an ASHRAE-assigned number given to an azeotropic mixture of HFC-32/HFC-125. HFC-32 is difluoromethane and HFC-125 is pentafluoroethane.  This refrigerant is being used to replace the commonly used R-22, chlorodifluoromethane.   Currently, the U.S. uses over 160 million pounds of R-22 each year. By 2015, the cap on R-22 will be reduced to a maximum of about 60 million pounds of virgin R-22 produced in or imported into the U.S.  This new refrigerant is fairly innocuous, having an LC50 (rat) dose of over 50%.  The determination of HFC-32 and HFC-125 in the air is accomplished by collecting a sample in a Tedlar bag and performing the analysis using Fourier Transform Infrared.   Remember that if you do this analysis, the samples must be analyzed within 72 hours of being taken.

To peruse the MSDS on R-410A Click Here.

Prism Analytical Technologies, Inc., (PATI) is the leading specialty analytical laboratory in the United States that is devoted to the chemical identification and analysis of contaminants in the air.  PATI's expertise includes:

PATI News:
Randall S. Fike, Ph.D. has been selected to present at the Maine Indoor Air Quality Council's 2007 Conference, March 28, 2007 a paper entitled "Applications of Thermal Desorption Sampling Tubes (NIOSH 2549) for the Evaluation of Indoor Air Quality." The conference will be held in Augusta, Maine.

PATI will exhibit their IAQ AIR ANALYSIS services at the AIHce 2007 Conference in Philadelphia, June 2 - 7.

Do you have your PATI Air Analytical Tool Box?

To receive a copy of PATI Air Analytical Tool Box click here Tool Box

PATI is a consultative air testing lab which means we encourage you to ask questions whether you are in the planning stage of an air study or have questions regarding your analytical report.  When planning your next air project be sure to consult your PATI Tool Box. Quick easy to look up charts are provided for each analysis. Put our experience to work for you.

Have a Case Study to Share?

We encourage you to alert us to successes you've had using PATI products so that we may feature you as a case study in an upcoming issue of Trapped Air.

Typical Guideline for Trapped Air Case Study