Glossary

Accuracy

A data quality indicator, it is the extent of agreement between an observed value and the accepted, or true, value of the parameter being measured.  High accuracy can be defined as a combination of high precision and low bias.

Air Change Rate

Ratio of the volume of clean air brought hourly into the chamber or emission cell and the free volume of the chamber or emission cell measured in identical units.

Air Flow Rate

Air volume entering into the chamber or emission cell per time.

Air Sample

A VOC or aldehyde sample collected on specific sampling media.

Air Velocity

Air speed over the surface of a test specimen. 

Area Specific Air Flow Rate

Ratio between the supply air flow rate and the area of the test specimen.

BFB

4-Bromo-4-fluorobenzene, CAS 460-00-4; compound used as internal standard in GC/MS analysis of air samples.

Bias

Consistent deviation of the results of a measurement process from the true value.

Blind Sample

A type of sample used for quality control. The sample is submitted to an analytical lab without their knowledge of its identity or composition to test the lab’s expertise in performing the sample analysis.

Building Product

Product intended for incorporation in a permanent manner in construction work. 

Chain-of-custody

A process used to maintain and document the chronological history of an air or product sample.  It includes a description of the sample, the name of the individual collecting the sample and each person subsequently having custody of it, and the dates the sample was collected and transferred.

Chromatogram

Data obtained from a chromatography experiment. Typically plotted as intensity as a function of retention time.

Chromatography

A field of Analytical Science in which materials are separated for later identification or quantitation.

Clean Air

Air that does not contain any individual VOC at a concentration in excess of 2 µg/m³ and does not contain greater than 10 µg/m³ for the sum of VOCs measurable in a sample.  The air should be conditioned to remove particulates and ozone. 

DNPH

2,4-Dinitrophenylhydrazine, CAS 119-26-6

DNPH Cartridge

Pre-packed silica gel cartridge coated with an acid solution of DNPH and used as an active aldehyde sampler.

Duplicate Sample

Used for quality control, duplicate air samples are two samples taken at the same time from the same site, or the same environmental test equipment, that are carried through all assessment and analytical procedures in identical manner.

Equipment (Chamber) Blank

A type of air sample collected in the lab and used for quality control purposes.  The sample is used to check specifically for carryover contamination from re-use of the same sampling equipment (mostly environmental test chambers).

Field and Laboratory Emission Cell

FLEC; a transportable device used for the determination of VOC emissions from building products in which the product specimen forms one surface of the cell.

Field Blank

A type of air sample collected in the field and used for quality control purposes.  It is a clean sample that is otherwise treated the same as other samples taken from the field.  Field blanks are submitted to the lab along with all other samples and are used to detect any contaminants that may be introduced during field air sample collection.

Functional Group

The chemical characteristics of molecules - such as alcohol, acid, ester.

GC

Gas Chromatography - Technique for separating chemicals that are volatile. Chemicals can then be identified or quantitated.

GC/MS

Gas Chromatography/Mass Spectrometry - Technique for separating chemicals that are volatile and then obtaining a mass spectrum of that chemical. Mass spectrum can then be compared to reference materials for identification.

HAP

Hazardous Air Pollutant defined by U.S. EPA.

HPLC

High Performance Liquid Chromatography - Technique for separating chemicals that are non-volatile. Chemicals can then be identified or quantitated.

Hydrocarbon

A chemical containing only carbon and hydrogen. Petroleum based chemicals are typically hydrocarbons.

IAQ

Indoor air quality.

IEQ

Indoor environmental quality.

ISO 17025

International Organization for Standardization standard that sets the requirements for the competence of testing and calibration laboratories; it is acknowledged as he international benchmark for approving the competence of the testing and calibration laboratories.

LC

Liquid Chromatography - see HPLC.

Limit of Detection

Lowest level of a material that can be detected by technique - typically signal is three times baseline noise.

Limit of Quantitation

Lowest level of a material that can be quantitated by technique - typically signal is ten times baseline noise.

Mass Spectrometry

Technique for obtaining mass spectrum of material. Mass spectrum can be used to determine chemical structure and identify materials.

MDF

Medium density fiberboard.

Method Detection Limit (MDL)

The lowest concentration of a given substance or analyte that can be reliably detected by an analytical procedure (method).

Method Validation

A detailed investigation of an analytical method that confirms with a high degree of accuracy the effectiveness of the analytical method

MFC

Electronic mass flow controller used for regulation of gas flow rates. 

MSDS

Material Safety Data Sheet prepared by manufacturer of a product

PFTBA

Perfluorotributylamine; compound for electron impact tuning of mass spectrometer.

ppb

Parts per billion - a unit of measurement;100 ppb = 0.00001%.

ppm

Parts per million - a unit of measurement; 100 ppm = 0.01%.

Polymer

A material composed of repeating atoms, molecules, or functional groups that are linked together in sufficient amounts that removal or addition of a few units does not substantially vary the properties of the polymer.

Precision

A data quality indicator, it measures the level of agreement or variability among a set of repeated measurements, obtained under similar conditions.  Normally expressed as a standard deviation in absolute or relative terms.

Product Loading Factor

Ratio of exposed surface area of the test specimen and the free volume of the chamber or emission cell.

Product Sample

A sample that is typical of the whole product.

Product Test Specimen

A representative portion of the product sample that is prepared for testing in an environmental chamber.

Protocols

Detailed, written, standardized procedures for field or laboratory operations.

Relative Standard Deviation (RSD)

This is the standard deviation of a parameter expressed as a percentage of the mean and is used to evaluate the precision of repeated measurements. 

Relative Percent Difference (RPD)

This is an alternative to RSD, expressed as a percentage and is used to determine precision when only two measurement values are available.

RH

Relative humidity expressed in percent.

Specific Emission Rate (Emission Factor)

Product specific rate describing the mass of a VOC emitted from a product per time at a given time from the start of the test.  Typically expressed as mass emitted per product area per time, but may also be expressed as mass emitted per volume, length, mass, or whole product per time.

Spiked Sample

A sample to which a known concentration of a target compound has been added.  Used for quality control purposes.

Standard Deviation

Used to determine the precision of a set of repeated measurements and is expressed by the positive square root of the variance of the measurements.

TAC

Toxic Air Contaminant defined by California Air Resources Board.

TIC

Total Ion Chromatogram - Chromatogram acquired by GC/MS in which the responses of all scanned masses are summed.

Total Volatile Organic Compounds (TVOC)

The sum of those VOCs that elute between the retention time on n-pentane and n-hexadecane on a DB-1 (or equivalent) capillary GC column.  TVOC concentration is estimated based on a toluene response factor.

VCT

Vinyl composition tile.

Very Volatile Organic Compound (VVOC)

Low molecular weight organic compound that possess vapor pressure greater than 15 kPa at 25^oC and boiling point typically below 30^oC. 

Volatile Organic Compound (VOC)

All gas-phase organic compounds that are detectable by the specified sampling and analytical methods.