Background

Total Volatile Organic Compounds (TVOC) may be evaluated when building designers/managers are pursuing the Leadership in Energy and Environmental Design Green Building Rating System for New Construction (LEED-NC) EQ Credit 3.2. The latest LEED-NC guidance document specifies that the maximum allowed concentration of TVOC measured in a building (post construction, pre-occupancy) is 500 µg/m³; the guidance also mentions using the sampling/analytical methods in the US EPA Compendium of Methods for the Determination of Air Pollutants in Indoor Air. However, none of these sampling and analytical methods address TVOC in particular, and thus the existing methods must be modified. In addition, TVOC is not defined (in terms of boiling point range, etc.) in the latest LEED-NC guidance and therefore is left open for interpretation; historically, many definitions of “TVOC” exist in literature.

For TVOC measurement, the analytical technique used must always reference one compound for calibration purposes. All compounds detected are then assumed to have the same response factor as the calibration compound. For instance, handheld instruments are most often calibrated using isobutylene or methane, and laboratory-based methods may reference TVOC as hexane (C6), toluene, or some other chemical species.

In practice, indoor air quality practitioners may use several different techniques for evaluating TVOC in buildings. Each sampling & analytical method has its own benefits and drawbacks, cost implications, and applicability.

Handheld “Real-Time” Instruments

Handheld photoionization detectors (PIDs) and flame ionization detectors (FIDs) are common tools used for site investigation. PIDs contain a UV lamp of a particular energy (e.g. 10.6 eV or 11.7 eV); any chemical species with an ionization potential at or below this energy will be detected. FIDs require a fuel gas (hydrogen) to burn hydrocarbons in a small flame, ionizing the chemical species which are present; thus any chemical species with a C-H bond (hydrocarbons) will be detected (including lighter end C1-C3 hydrocarbons, which may not be considered part of a TVOC definition). This type of instrument is typically calibrated by running a “zero” (blank/clean air) and “span” (known concentration of calibration gas, isobutylene for PIDs and methane for FIDs) measurement—essentially a one point calibration forced through zero. While each of these instruments respond to a wide range of compounds and yield a “total” value, the detection limits of these instruments are typically in the range of 0.1-0.5 ppmV (as methane for FID, as isobutylene for PID), and therefore may not be suitable for the low-level TVOC assessment required for LEED. However, ultra-sensitive PIDs currently exist in the marketplace, with manufacturers claiming detection limits in the low ppbV range and accuracies within 20 percent. Costs to rent this type of equipment range from approximately $50-$100/day, plus any costs for associated equipment (calibration gases, dataloggers, etc.).

Charcoal Tubes

NIOSH/OSHA methods such as NIOSH 1500 or OSHA 07 use small coconut shell charcoal tubes and personal sampling pumps to sample for VOCs in air. Traditionally, these methods were written to address workplace exposure issues, and the reporting limits of these methods are typically in the ppmV (mg/m3) range. Air is drawn through the tubes with a pump at a known flow rate for a known amount of time, with the compounds of interest adsorbing on to the charcoal media. Back at the laboratory, the charcoal in the tubes is then chemically desorbed with a small volume (1-2 mL) of solvent such as carbon disulfide. A small microliter amount of that solvent extract is then injected into a gas chromatograph (GC), typically equipped with a flame ionization detector (FID). Since only a very small portion of the sample (approximately equivalent to 1/1000th of the volume of air sampled) is being analyzed, the sensitivity of the analysis is only moderate (although completely adequate for traditional workplace exposure monitoring). The laboratory analysis will determine the total mass of contaminants captured and report it as “TVOC as Toluene” (or other chemical species); concentration is calculated by dividing the mass by the total volume of air pulled through the tube. When using this technique to evaluate TVOC for LEED, it may be necessary to increase the sampling flow rate and/or sampling duration to lower the detection limit below 500 µg/m3. Costs for this type of analysis range from approximately $65-125 per sample.

Thermal Desorption Tubes

Methods such as EPA Method TO-17 (1999), EPA IP-1B (1990) and/or NIOSH 2549 (1996) use stainless steel thermal desorption tubes (packed with one or multiple sorbent materials) and a personal sampling pump to sample for VOCs in indoor/ambient air. In general, thermal desorption methods were written to detect low concentrations of VOCs in indoor/ambient air, with reporting limits typically in the low ppbV (µg/m3) range. Air is drawn through the tubes with a pump at a known flow rate for a known amount of time, with the compounds of interest adsorbing on to the sorbent media. The tube is then thermally desorbed and the entire amount of all compounds of interest is transferred to the GC column for analysis.

For this analysis, the GC is equipped with a mass spectrometer for the detector (GC/MS), allowing for qualitative and/or quantitative identification of all species present (based on retention time and matching of the sample spectrum against a NIST library). Since the entire sample may be consumed, the sensitivity of this analysis is 100-1000 times greater than the traditional (solvent desorption) charcoal tube approach. The laboratory analysis will determine the total mass of contaminants captured and report it as “TVOC as Toluene” (or other chemical species); concentration is calculated by dividing the mass by the total volume of air pulled through the tube. Costs for this type of analysis are in the range of $125-$250/sample.

Table 1 presents a summary of pros and cons for the solvent desorption (traditional charcoal tubes) and thermal desorption approaches.

Table 1. Solid Sorbent Sampling: Solvent Desorption vs. Thermal Desorption for TVOC

	Solvent Desorption	Thermal Desorption
Analytical Methods	NIOSH 1500,  OSHA 07	EPA TO-17, NIOSH 2549, EPA IP-1B
Typical Sorbent Used	Coconut shell charcoal	Tenax, Carbon Molecular Sieve, Carbopack, and/or various combinations thereof
Analytical Detector	Flame Ionization (FID)	Mass Spectrometry (MSD)
Concentration Range	high ppbV – ppmV	high pptV – low ppbV
Amount Analyzed	Only analyze a portion of total sample extract (~ 1/1000)	Entire sample may be analyzed for greater sensitivity
Advantages	Reanalysis possible Wide dynamic range	Lower reporting limits Qualitative ID of compounds comprising TVOC is possible
Disadvantages	Difficult to account for desorption efficiency when evaluating TVOC  Difficult to choose one appropriate desorption solvent when evaluating TVOC	Reanalysis may not be possible depending on analytical system Limited dynamic range

Passive Sorbent Samplers

Passive sampling technology has long been used to monitor workplace/indoor air exposures (both personal monitoring and area samples). A sorbent material is contained in some convenient form (e.g. clip on badge, tube with diffusive cap, etc.) and air passively enters the sampler without the use of a personal sampling pump. Compounds of interest are adsorbed onto the sorbent media, in the same manner as active sorbent sampling (either traditional charcoal tubes or thermal desorption tubes). Different types of passive samplers exist; some types utilize solvent desorption and some types utilize thermal desorption.

One main limiting factor for passive samplers is the uptake rates for various compounds of interest. Current technology such as the Radiello sampler allows for high diffusivity/effective flow rates, while also allowing for a sensitive GC/MS thermal desorption analysis.

Costs for passive sorbent samplers vary widely, depending on the analytical technique used (either solvent or thermal desorption).

Table 2 presents a summary of the pros and cons associated with passive sorbent sampling and active sorbent sampling (using a personal sampling pump).

Table 2. Solid Sorbent Sampling: Active Sampling vs. Passive Sampling

Canisters

EPA Method TO-15 (and IP-1A) utilizes evacuated stainless steel canisters to collect whole air samples for VOC analysis. Canisters will be fully evacuated by the analytical laboratory so that when the canister valve is opened, air enters the canister without the use of a pump. A flow controller may be put inline to restrict the flow entering the canister so that the canister fills over a longer time period (i.e. four hours for LEED sampling). Since only an aliquot of the total volume collected is analyzed, re-analysis and/or dilutions are possible from the same sample canister. Similar to the thermal desorption techniques, the analysis is via GC/MS, allowing for qualitative and/or quantitative identification of target compounds. Costs for this type of analysis are in the range of $125-$250/sample.

Figure 1 summarizes the types of compounds that will be detected by whole air sampling (i.e. canisters) and solid sorbent sampling, and which compounds may be detected via either technique.

Figure 1. Compounds Detected via Whole Air Sampling (Canisters) vs. Solid Sorbent Sampling

Summary

Many analytical choices exist for measurement of TVOC for LEED projects. Practitioners must make an educated choice, consulting with their laboratory personnel where applicable, to decide which TVOC method may be most appropriate for their project. When deciding which sampling/analytical method to use, consideration must be given to the sample analysis/equipment rental costs, time frame/turnaround time needed, the building owner’s interest in having detailed chemical indoor air quality information, as well as which building materials (e.g. paints, carpet glues, finishes, cabinetry, etc.) are used. Also, if qualitative information is desired about which specific compounds comprise the TVOC value (e.g. for troubleshooting purposes if a building continues to fail to meet the 500 µg/m3 criteria), a GC/MS technique (thermal desorption or canisters) must be used. Until TVOC is defined more specifically, and/or until specific analytical methods are given in the LEED documentation, practitioners will have a wide range of options available to meet this credit requirement.

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Read about LEED Testing services…

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For years, dietary supplements have been scrutinized by the media for being marketed as “snake-oil” cure-alls, potentially containing components considered harmful to consumers. Under-regulation by the Food and Drug Administration (FDA) lead to concerns that these products did not fall under the same regulatory requirements as pharmaceuticals. Until now.

New FDA regulations for the dietary supplement industry aim to eradicate consumer concern and health risks associated with these products. Dietary supplement manufacturers and distributors are now required to follow Good Manufacturing Practices (GMPs) similar to those of the pharmaceutical industry. The FDA 21 Code of Federal Regulations (CFR) Part 111 was established to insure the identity, purity, quality, strength, and composition of dietary supplements and applies to those involved in the manufacture, packaging, labeling or holding of a dietary supplement, with the exception of retail establishments selling directly to consumers.

The federal government is taking a tiered approach to enforcement: companies with more than 500 employees were required to become compliant by June 2008; companies with 21-499 employees must become compliant before June 2009; and companies with fewer than 20 employees will need to be compliant by 2010.

To become compliant with the GMP guidelines, passed in 2007, dietary supplement companies need to perform analytical testing of their products. Analytical laboratory analysis falls under the category of “manufacture” as defined by FDA CFR.  Therefore, if testing is not performed the dietary supplement company will be considered non-compliant regardless of the reason for not testing. Reasons for not testing range from it being cost prohibitive to it’s impossible as an option for raw materials, in-process or final products. Those non-compliant and unable to meet GMP guidelines will run the risk of not being able to sell their products due to regulatory agency action. This may result in some companies going out of business or, at the least, an increased need for analytical testing.

In some ways, GMPs for dietary supplements have been considered to be more strict than those for pharmaceuticals. For example, many pharmaceutical compounds can be considered “pure” if they meet 90-98 percent of the requirement. Purity constraints for dietary supplements can be as much or more than 100 percent as a requirement. The GMPs for dietary supplements are a combination of GMPs for both food and drugs. The abundance of new regulations may be a response to the public scrutiny the dietary supplement industries have received in recent years.

GMP compliant analytical testing for GMP guidelines may include residual solvent and heavy metals analysis, water determination by Karl Fischer, and microbial limit testing. These tests are designed to ensure product quality and consumer safety, but there is a need for identity testing and potency as well. Identity and potency will confirm for manufacturers that the product label accurately reflects the actual ingredients as well as potency of each batch or lot of product.  In other words, “it is what it is” and the manufacturer has the compliant analytical quality control laboratory documentation to prove it.

This new challenge for production will require substantial new testing in order to maintain compliance. Some dietary supplement companies have already found that outsourcing the testing, though thousands of dollars per year, is a more sensible business strategy than investing millions developing and maintaining their own compliant laboratories. When outsourcing analytical testing to laboratories, the FDA requires the outside lab to be cGMP compliant and FDA inspected. The Quality Unit of compliant laboratories will be able to readily supply information including documentation of quality systems and FDA inspection reports.

Manufacturers may want to assess the most cost effective and efficient means to deal with these new FDA regulations.

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References:

FDA Issues Dietary Supplements Final Rule

http://www.fda.gov/bbs/topics/NEWS/2007/NEW01657.html

FDA 21 CFR part 111

http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=111&showFR=1FDA

The most significant updates to the APH method include:

• Analyte List Revisions - 2-Methylnaphthalene was removed from the target analyte list and is no longer considered an air-phase petroleum hydrocarbon. In addition, laboratories will no longer report the “unadjusted” hydrocarbon ranges.
• Calibration Standards Revisions - Indene, hexylcyclohexane and 1-methynaphthalene were removed as hydrocarbon range calibration standards/retention time markers, due to poor performance and stability in the whole air matrix.
• Standard Preparation – The newly revised method will only allow vapor phase standards to be used for calibration. (Previously, in the draft method, methanol based standards were allowed.)
• Calibration & Quality Control Requirements, Holding Time and Performance Standards – Many small changes were made in order to make the APH method consistent with EPA Method TO-15.

The MassDEP APH method is currently the only existing method to look at vapor phase hydrocarbons in a risk based corrective action approach (i.e. with fractionated aliphatic and aromatic ranges). Going beyond EPA Method TO-15 or a traditional total petroleum hydrocarbons (TPH) approach, this method provides more specific information about the type of hydrocarbon contamination at a site.

As an example of the utility of the APH method, Figure 1 shows the total ion chromatogram for a soil gas sample collected at a site impacted by historical subsurface petroleum product contamination. For this example, all the APH target compounds (1,3-butadiene, benzene, toluene, ethylbenzene, xylenes, MTBE, and naphthalene) as well as several other petroleum indicator species (1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, n-nonane, n-decane, n-dodecane, n-undecane) were not present above the laboratory reporting limit. However, as is visually evident, there was still a strong weathered petroleum pattern present in the sample. The hydrocarbon ranges reported in the APH method were able to capture this information which otherwise might have been overlooked in a basic review of the numerical results.

Figure 1. - Total Ion Chromatogram of Real-World APH Sample

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References (Current as of December 2008)

1. MassDEP Method for the Determination of Air-Phase Petroleum Hydrocarbons (APH), December 2008. Available at: http://www.mass.gov/dep/cleanup/laws/qaqcdocs.htm#IV

2. MassDEP Standard Operating Procedure for Indoor Air Contamination, SOP-BWSC-07-01, August 2007 (made available April 2008). Available at: http://www.mass.gov/dep/cleanup/laws/policies.htm#iasop

3. MassDEP Indoor Air Sampling & Evaluation Guide, WSC Policy #02-430, April 2002. Available at: http://www.mass.gov/dep/cleanup/laws/policies.htm#indair

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View the APH method flyer (PDF file)

Read about testing for petroleum hydrocarbon contaminations

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Organochlorine pesticides (OCPs) have a long history of use in the United States and around the world. Although the production and use of many OCPs has been banned since the 1970s, the compounds are extremely persistent in the environment and are known for accumulating in sediments, plants and animals. OCPs have a wide range of both acute and chronic health effects, including cancer, neurological damage, and birth defects. Many OCPs are also suspected as endocrine disruptors.¹

Due to the need to monitor levels of OCPs, significant research and development has taken place over the last 40 years. This has culminated in two primary methods used by the Environmental Protection Agency (EPA) to regulate the transport and fate of OCPs; EPA Method 1699 and EPA Method 8081.

EPA Method 1699, isotope dilution and high-resolution mass spectrometry, is considered the ultimate in pesticide analysis relative to sensitivity and selectivity, but can be cost prohibitive.

EPA Method 8081 is a gas chromatography method that employs electron capture as a means of detection. To achieve some level of selectivity, the method is run in dual column mode with two dissimilar analytical columns. It has been well documented that the use of ECD can lead to false positives or high biases in the results generated by this method.²

This lack of selectivity is especially apparent when polychlorinated biphenyls (PCB) are present in the sample.

Table 1 lists the apparent concentration of pesticides when a 100 ng/mL PCB standard in analyzed using EPA Method 8081. While quantifying the interferences can help in data interpretation, a more selective and robust alternative is needed.

Goals for the for the determination of OCPs by GC/MS/MS

• Provide a lower cost alternative to GC/HRMS
• Achieve lower reporting limits than GC-ECD
• Maximize selectivity using two transitions per analyte
• Use isotope dilution quantitation

GC/MS/MS Instrumentation

The key to achieving the selectivity needed to eliminate PCB and other co-extractable interferences is to operate the tandem mass spectrometer in the Multiple Reaction Monitoring (MRM) mode.

MRM Mode

• Precursor ion selected with the first quad (MS1)
• Ion enters the collision cell where fragmentation occurs
• Compound-specific fragment ions are selected with the second quad (MS2) and then detected

The MRM operating mode is depicted in Figure 1.

This ionization of a precursor to a product mass is called a transition.Two unique transitions are acquired for each analyte of interest. The ratio of the two transitions is then used to set criteria to increase confidence in analyte identification of unknown samples. The MRM mode is also inherently more sensitive because the signal to noise ratio is increased.

Materials & Methods

Sample Preparation

• All samples are spiked with labeled isotopes prior to extraction
• Solid samples are prepared using EPA Method 3541- Automated Soxhlet Extraction
• 10 grams for soils, sediments and tissues
• 1 mL final extract volume
• Liquid samples prepared using EPA Method 3535 – Solid Phase Extraction
• One liter sample size
• 1 mL final extract volume
• Prior to sample analysis tissue extracts are subject to lipid removal using Supleco lipid removal agent. Soil/sediments samples are subject to carbon cleanup. Alternate cleanups include GPC and Florisil®
• Method Detection Limit studies were prepared for water, soil and tissue matrices

Standards

• Individual pesticide standards, Accustandard, Inc.
• Labeled isotope standards, Cambridge Isotope Laboratories, Inc. and CDN Isotopes.
• Internal standard of PCB52 (¹³C₁₂99%), Cambridge Isotope Laboratories, Inc.
• Each standard and sample is spiked with 100 ng/mL of internal standard prior to analysis.
• A calibration curve was then prepared at a nominal concentration of 0.5 ng/mL to 100 ng/mL.

Injector Parameters

• Agilent PTV
• Mode Solvent Vent, Ramped pressure
• Injector Liner: Baffled, Restek Siltek Deactivated; #21704-214-10
• Injection Volume: 5 μl
• Injection speed: Slow
• Post injection dwell: 1.0 min
• Carrier gas: Helium @ 0.7 mL/min
• Injector temperature: 40-320°C, temperature programmed

GC/MS Run Conditions

• GC: Agilent 6890N
• Mass Spec: Waters Micromass Quattro Tandem MS
• Column: Phenomenex ZB-1, 30m x 0.25mm x 0.25μm
• Oven: 65°C initial temp for 2.0min
     • 20°C/min to 240°C for 0.0min
     • 6.1°C/min to 280°C for 0.0min
     • 15°C/min to 310°C for 0.7min
     • Run Time – 20 minutes
• Source temp: 225°C
• Detector interface temp: 250°C
• Collision gas: Argon @ 2-3 x 10-3 torr

Results & Discussion

The chromatography conditions yielded good resolution of OCPs by GC/MS/MS as the reconstructed ion chromatograph of the MS/MS acquisition shows in Figure 2. While peak resolution isn’t as critical as in GC/ECD analysis, it is still required to separate isobaric interferences and to maximize dwell time for optimal sensitivity.

The response of the low calibration point of 0.5 ng/mL produced excellent signal to noise ratios as shown in Figure 3. The calibration of each pesticide showed good linearity with most under 10% RSD, and all within EPA criteria. Table 2 summarizes calibration results of each analyte.

Acceptable method detection limits studies were analyzed for water, soil and tissue matrices and are summarized in Table 3. All method detection and reporting limits exceed the sensitivity of GC-ECD and are about an order of magnitude above high-resolution MS limits.

To assess selectivity a 5000 ng/mL standard of Aroclor 1254 was acquired under the MS/MS method. Note this level is 50X higher than the standard that gives false positives by GC-ECD. The results are summarized in Table 4. 

To further assess selectivity, SRM 1945 (Whale Blubber) was analyzed and compared against GCECD. The results are summarized in Figure 4. Overall the GC/MS/MS analysis of SRM 1945 produced solid recoveries against the true values. It again shows superior selectivity when comparing results for cis-Nonachlor, 2,4’-DDD, 2,4’-DDT, 4,4’-DDT and Dieldrin, all of which had a high bias using GC-ECD for the tissue matrix due to the presence PCB congeners.

Conclusions

• GC/MS/MS provides superior performance of GC-ECD and a solid alternative to GC/HRMS

• Up 20X decrease in reporting limits over GC-ECD

• Significant increase in selectivity operating in MRM mode using two transitions per analyte

• Cost of analysis is less than half of GC/HRMS

References

1. D. Muir, E. Sverko, Analytical Methods for PCBs and Organochlorine Pesticides in Environmental Monitoring and Surveillance: a Critical Appraisal, Anal Bioanal Chem, (2006) 386:769-789.

2. L. Jones, M. Tritt, A Unique Approach for Evaluating Aroclor Interferences of Chlorinated Pesticides in Tissue for Portland Harbor Superfund Site, Poster Presentation SETAC, 2005.

3. Waters Quattro Micro™ GC Applications Training Documentation, Chapter 1, March, 2008.

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Learn more about GC/MS/MS and Pesticide Testing…

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Several potential pathways of media contamination will be examined, including: canisters, flow controllers/critical orifice assemblies, vacuum gauges, and canister pressurization/fill stations in the laboratory.

Several contamination situations will be explored and quantified. The resulting data will be used to support laboratory and field sampling best practice recommendations.

Read the complete air sampling media cleanliness case study… (Acrobat PDF)

Two commonly applied methods of measuring vapor phase naphthalene include EPA Method TO-15, which utilizes whole air sampling in passivated stainless steel canisters; and EPA Method TO-13A, which utilizes high volume sorbent based sampling with polyurethane foam/XAD resin cartridges. Analytical differences between these two methods will be discussed, keeping reference to naphthalene’s unique chemical & physical properties.

This case study will present weekly data spanning a twelve month period (December 2006 – December 2007) from co-located EPA Method TO-15 and TO-13A ambient air samples at the perimeter of two MGP cleanup remediation sites. Distinct trends are noted and discussed in this paper when comparing the concentration results from the two methods.

Read the complete naphthalene air sampling case study… (Acrobat PDF)

Some of the most successful TRIAD case histories involve the use of X-ray Fluorescence (XRF) screening for metals. Prior to the advent of field-worthy XRF systems, site investigation and remediation for metal contaminants proceeded in a more classical manner of waiting for fixed laboratory results  or paying a premium for rush results.

In some cases, fixed laboratory methods were performed in a mobile laboratory setting with good results. This practice involved the use of concentrated acids and time consuming digestion steps and was useful for only a limited number of elements. This is no longer a problem with the availability of field portable and transportable Energy Dispersive X-ray Fluorescence Spectrometers (EDXRF).

Reporting limits are element, instrument, and sample matrix dependent. Each dependent variable contributes to the final achievable reporting limit. Once the suite of elements and instrument conditions are modeled, the only variable left is the sample matrix which can vary from site to site, or even within a particular site.

XRF techniques are not very useful for light elements (elements between atomic numbers 11-18). The remaining elements, those between atomic numbers 19 and 92, are candidates for this technique.

Reporting limits are also instrument dependent and can vary between manufacturers for a variety of reasons.

For radioisotope sources, the following factors impact the reporting limit: isotope used (Fe-55, Cd-109, Am-241, Cm-244); half life of the isotope; and the amount of isotope in millicuries. For X-ray tube sources, the energy level of tube and the current level of tube both impact the reporting limit. Both radioisotope and X-ray tube sources are affected by count time during analysis; detector type (gas filled, or Si(Li); grain size of sample; and moisture of sample.

Applications for EDXRF are varied and include lead investigations at battery recycling businesses, remedial investigations of military and public shooting ranges, munitions demolition areas, weapons manufacturing facilities, copper ore assay from mine tailing piles, and many industrial and household remedial actions for leaded paint removal.

As always, the benefit of a field analytical method is in providing near real time data so that time-critical decisions can be made in the field. This concept works best when the target analytes are limited to the main chemicals of concern for a particular site. The following application examples are from sites that had a limited list of target analytes so that the XRF method could be customized to maximize sample throughput and sensitivity.

Example 1. Lead Remediation at a Landfill Burn Site

This project had several time critical aspects: the rainy season was approaching, and there was a narrow window of time to complete all of the site work before a protected species of bird returned to the area. The project involved removal of 20,000 tons of lead-contaminated soil and ash from a burn pit operation at an abandoned land fill. The lead had contaminated the entire area surrounding the landfill, which bordered on an elementary school and a public lake. The required reporting limit for lead was 15 mg/kg, and the sample throughput was to be 40 samples per day. Confirmation samples were taken initially at a 10 percent frequency, and dropped to a five percent frequency once the correlation was determined.

A transportable XRF unit was set up on location in a mobile laboratory, complete with fume hood, generator power, and water. All samples were prepared by sieving, drying, and grinding prior to analysis. The calibration model used was Fundamental Parameters and results were provided at a rate of four samples per hour. The data correlated at R=0.988 (see North Chollas for data spanning nearly three orders of magnitude). The project was completed within the allotted time frame and budget.

The XRF approach was approved by city and state agencies, with the stipulation that a correlation be determined at the start of the project and confirmation samples be split throughout the project, initially at a 10 percent frequency, then decreasing to no less than five percent.

Example 2. Lead Remediation at an Active Battery Recycling Shop

This project was a State Superfund cleanup of lead-contaminated  soil from a battery recycling shop located in a residential area. The initial site study called for removal of 1,315 cubic yards of soil for transport and disposal at a Class I landfill at an approximate cost of $620,000. By using the EDXRF system, the volume of soil actually sent was reduced to 666 cubic yards, which saved $306,000. Other critical aspects of the project involved minimization of exposure risks to nearby residents and site workers. By using the rapid turnaround results from the EDXRF system, the site was cleaned up to an action level of 220 mg/kg with correlation to EPA method 6010 of R=0.989.

The State of California, under the State Superfund program, sanctioned this project. The XRF approach was initially approved with the stipulation that site-specific calibration be performed. The samples were quantified by using Fundamental Parameters software, and since the correlation was >0.900, the site-specific calibration was not needed.

Example 3.  Multiple Elements at Navy Dump Site

This project was a technology demonstration of both the EDXRF and a soil washing technique at a known contaminated site, Hunter’s Point. This site was adjacent to a densely populated area. It had been used by the Navy and private industry for a variety of activities, including transformer and battery storage and vehicle maintenance activities. The site was moderately contaminated with lead concentrations above non-residential clean up levels. Other elements of concern were mercury, antimony, copper, zinc, and chromium. During the two-week project, the EDXRF system was used to help optimize the soil washing system prior to the actual demonstration. The demonstration yielded 80 washed samples of which 23 were sent for confirmation.

The correlation for antimony was rather poor and was a function of the solubility of antimony in the acid digestion used in EPA Method 6010. Aside from antimony, all correlation coefficients were >0.990. Mercury was not detected in any of the samples, nor by the confirmation laboratory at a level >10 mg/kg. This demonstration helped confirm the findings from an earlier study published by the California Military Environmental Coordination Committee that a correlation coefficient of 0.9 or greater indicates that the field XRF data may be considered definitive (i.e. equivalent in data quality to CLP methods).

XRF techniques are rapidly gaining acceptance as a viable field solution to rapid metal analysis in a field setting. XRF is no longer considered an emerging technique and is in widespread use by state and federal agencies, as well as by environmental professionals throughout the country. Whether portable or transportable, the EDXRF technique is proving its worth as a rapid, accurate, and cost-effective tool for site investigation and remedial activities.

References

1. USEPA Field Analytic Technologies Encyclopedia (FATE), Online resource: http://fate.clu-in.org. Last updated, January, 2003.
2. USEPA TRIAD Report, Online resource: http://www.epa.gov/tio/triad. Last updated November, 2005.
3. TN Spectrace, Spectrace Instruments EDXRF Users School Manual, Spectrace Instruments, Fort Collins, Colorado.
4. Merck & Co., Inc., The Merck Index, Eleventh Edition, Table of Radioactive Isotopes, Merck & Co., Inc., Rahway, New Jersey, 1989.
5. Bertin, E.P., Introduction to X-Ray Spectrometric Analysis, Plenum Publishing, New York, 1978.
6. Panuscka, Barber, Smith, Mobile EDXRF Screening at Lead Contaminated Soil Removal Project, Conference Proceedings, Hazwaste World Superfund XVII, October, 1996, Washington D.C.
7. CMECC, Field Analytical Measurement Technologies, Applications, and Selection, April 1996.
8. Barber, M, Application Analysis Report, Onsite Environmental Laboratories, Bay Area Conversion Action Team (BADCAT).

Odor is a parameter which may be measured unto itself, following established ASTM and/or European Standards. This approach will quantify how odorous a sample is, ranking it on a relative scale with units of dilution to threshold (D/T).

Knowing the magnitude of an odor problem is useful, but often more detailed chemical information is necessary when odor control engineering solutions are being evaluated.  When a detailed chemical analysis of odorous compounds is needed, there are several analytical options:

1. Produced during the acidogenesis stage of anaerobic digestion, reduced sulfur compounds have a very characteristic odor of rotten eggs, rotten garlic/cabbage, skunk or natural gas. In fact, the human nose is sometimes more sensitive than the most current analytical instrumentation used to detect these compounds. An example of these compounds is methyl mercaptan, which has an extremely low odor threshold (this is why mercaptans are used as natural gas odorants). The most popular analytical option for reduced sulfur compounds is ASTM Method D5504. This method quantifies a list of 20 speciated reduced sulfur compounds (such as hydrogen sulfide, mercaptans, thiophenes) using gas chromatography with a sulfur chemiluminescence detector (GC/SCD).

2. With a characteristic fishy/fertilizer or putrid/sour/pungent odor, amines are the result of the biological breakdown of amino acids and are produced at various stages of anaerobic digestion. Columbia Analytical has developed a comprehensive amine sampling and analytical method that reports a list of 13 amine compounds with reporting limits at or below published odor threshold concentrations. A sample is collected on an in-house designed sorbent tube using a personal sampling pump. Due to their unique chemical characteristics, amines will not always be detected in any of the other tests described here (e.g. VOC test). Analysis of the samples is via a specially modified gas chromatography with nitrogen phosphorous detection (GC/NPD).

3. Ammonia, which is produced by microbial decomposition of animal waste, has a characteristic odor most people will recognize due to the compound’s use in window cleaners. At higher concentrations, ammonia can cause serious health damage, irritating and/or burning nasal passages and lungs. Collection of airborne ammonia may follow the OSHA ID-188 method, which uses sulfuric acid-coated Anasorb-747 (carbon bead) tubes and a personal sampling pump for collection. This means of sample collection is much easier and safer than the traditional collection technique of sulfuric acid solution impingers. Analysis may follow the OSHA-ID 164 analysis, which utilizes an ion-specific electrode (ISE) to detect ammonia.

4. Carboxylic (volatile fatty) acids are produced as a result of the biological anaerobic breakdown of proteins, with typical odor characteristics including a rancid, fecal, vomitous, or sweaty gym sock smell. Columbia Analytical has developed a comprehensive sampling and analytical method that reports a list of 15 carboxylic acid compounds with reporting limits at or below published odor threshold concentrations. The sample is collected on a sodium hydroxide-treated silica gel tube using a personal sampling pump; the subsequent sample is then analyzed via gas chromatography/mass spectrometry (GC/MS).

5. Several other analytical methods may be used to quantify levels of aldehydes and other miscellaneous volatile organic compounds (VOCs). EPA Method TO-11A (silica gel tubes coated with acidified 2,4-dinitrophenylhydrazine (DNPH) ) is an appropriate method for sampling of aldehydes (carbonyl compounds).  EPA Methods TO-15 (stainless steel canisters) and TO-17 (thermal desorption tubes) are appropriate methods for sampling of volatile organic compounds.  Polar volatile compounds such as alcohols, aldehydes, esters, ketones, ethers, phenols and cresols are often contributors to nuisance odors.

Due to their complex nature, there is no “one size fits all” approach for evaluating the chemical composition of odors. Odorous compounds may have additive, synergistic or antagonistic effects, all contributing to odor perception. Multiple analytical methods or evaluation approaches may be required to address a single source.

Learn more about Odor Testing…

Depending on the disinfection procedure used (chlorination, chloramines, bromine, ozone etc.) and the chemical composition of the water prior to disinfection, many different organic chemical disinfection byproducts can form in drinking water. Trihalomethanes (THMs) are a byproduct of chlorine disinfection and to a lesser degree, disinfection using chloroamines. The THMs (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) are formed when free chlorine combines with organic matter, like decaying vegetation commonly found in lakes and reservoirs. Total Trihalomethanes (TTHM) are regulated by the EPA at a maximum allowable annual average of 80 parts per billion. Some of the THMs are very volatile and will vaporize into air easily, so they may be inhaled while showering, however, the EPA has determined that this exposure is minimal compared to that from consumption. The Levels of THMs formed can vary widely on a number of factors including temperature, amount of chlorine used, season, and amount of plant material in the water, among others.

Some drinking water systems use chloroamines as a residual disinfection agent in place of chlorine. Chloroamine is not as reactive as chlorine and less THMs are formed. However, there are also drawbacks to chloroamine use. Chloroamine may cause nitrification and corrosion and may also increase exposure to other disinfection byproducts, such as N-nitrosodimethylamine (NDMA).

EPA Method 524.2 is used to analyze samples for TTHMs. This method involves concentrating the THMs from a water sample using a technique known as purge and trap. This technique isolates the volatile organic compounds (VOCs) from the water. The VOCs are then desorbed into a gas chromatograph/mass spectrometer (GC/MS) where they are separated, their identity is confirmed, and their concentrations are determined. Standard reporting limits for individual TTH with this method are 0.5 µ/L

There is still controversy over PFOA’s toxicity, though the compound is persistent (doesn’t biodegrade, hydrolyse or photolyse), bioaccumulates in human and animal tissue (binds to proteins in the blood and liver), and biomagnifies up the food chain. In 2007, the Center for Disease Control and Prevention published the results of two studies on the levels of 11 different polyfluorochemicals in humans. In those studies PFOS, PFOA and Perfluorohexane Sulfonic Acid (PFHS) were found in 98% of those tested, confirming widespread exposure to these compounds. Exposure may occur through consumption of contaminated food or water or through the use of products containing these compounds, but not all sources are known or understood.

PFOA is a polymerization aid used in the manufacturing of fluoropolymers. The carbon fluorine part of the molecule is water resistant, which makes them valuable in producing fluoropolymer products that can repel water, grease and oil. These compounds are used in making non-stick surfaces for cookware, stain resistant clothing, carpets and other fabrics and in fire fighting foams. It is because of its unique polar anionic chemical properties that traditional models used to predict chemical behavior of non-polar organic chemicals, like PCBs or dioxins, in wildlife and humans, cannot be extrapolated from standard experimental data on mice and rats. In rodents PFOA has been shown to be carcinogen and immunotoxic, but whether this can be translated into information about its effect on humans is not clear. Studies continue. It should be noted, in February 2006, the EPA’s Science Advisory Board voted to approve a recommendation that PFOA should be considered a likely carcinogen.

The principal fluoropolymer producers committed to a minimum 50-percent reduction in total global emissions by 2006 (using 2000 as the baseline year), 95% reduction in emissions and product content by 2010 and elimination of its use altogether by 2015. However, because of the persistence of these compounds in the environment and the bioaccumulation and biomagnification in the food chain these compounds will continue to be in the environment long after manufacturing ceases.

Perfluorinated compounds are large molecules and are not amenable to common analytical techniques such as Gas Chromatography/Mass Spectroscopy (GC/MS).

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