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Appendix D
5/20/2009
4
3.23
Holding time – The maximum time that samples may be held prior to
analysis and still be considered valid. (40 CFR Part 136) The time
elapsed from the time of sampling to the time of extraction or analysis,
as appropriate.
3.24
Instrument Detection Limit (IDL) – The minimum quantity of analyte of
the concentration equivalent which gives an analyte signal equal to three
times the standard deviation of the background signal at the selected
wavelength, mass, retention time absorbance line, etc.
3.25
Laboratory Duplicates (LD1 and LD2) – Two aliquots of the same
sample taken in the laboratory and analyzed separately with identical
procedures. Analyses of LD1 and LD2 indicate precision associated
with laboratory procedures, but not with sample collection, preservation,
or storage procedures.
3.26
Laboratory Reagent Blank (LRB) – A matrix blank (i.e., 90% acetone)
that is treated exactly as a sample including exposure to all glassware,
equipment, solvents, and reagents that are used with other samples. The
LRB is used to determine if method analytes or other interferences are
present in the laboratory environment, the reagents, or the instrument.
3.27
Laboratory Control Sample (LCS) – A sample matrix, free from the
analytes of interest, spiked with verified known amounts of analytes
from a source independent of the calibration standard or a material
containing known and verified amounts of analytes. The LCS is
generally used to establish intra-laboratory or analyst-specific precision
and bias or to assess the performance of all or a portion of the
measurement system. (NELAC)
3.28
Limit of Detection (LOD) – The lowest concentration level that can be
determined by a single analysis and with a defined level of confidence to
be statistically different from a blank. (ACS)
3.29
Limit of Quantitation (LOQ) – The minimum levels, concentrations, or
quantities of a target variable (target analyte) that can be reported with a
specified degree of confidence. The LOQ is set at 3 to 10 times the
LOD, depending on the degree of confidence desired.
3.30
Linear Dynamic Range (LDR) – The absolute quantity over which the
instrument response to an analyte is linear. This specification is also
referred to as the Linear Calibration Range (LCR).
3.31
Material Safety Data Sheets (MSDS) – Written information provided by
vendors concerning a chemical’s toxicity, health hazards, physical
properties, fire, and reactivity data including storage, spill, and handling
precautions.
3.32
May – Denotes permitted action, but not required action. (NELAC)
3.33
Method Detection Limit (MDL) – The minimum concentration of an
analyte that can be identified, measured, and reported with 98%
confidence that the analyte concentration is greater than zero.
3.34
Must – Denotes a requirement that must be met. (Random House
College Dictionary)