QC term definitions and descriptions

Term

Abbreviation

ISM02.1 Definition/Description

200.7 (Rev 4.4 EMMC Version) Definition/Description

SW 486 (&/or 6010C Rev 3) Definition/Description

Accuracy

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The closeness of agreement between an observed value and an accepted reference value. When applied to a set of observed values, accuracy will be a combination of a random component and of a common

Aliquot

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A measured portion of a field sample, standard or solution taken for sample analysis and/or preparation.

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Analysis Date/Time

The date and military time (24-hour clock) of the introduction of the sample, standard, or blank into the analysis system.

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Analyte

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The element or ion an analysis seeks to determine; the element of interest.

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Analyte Addition Test

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See Post Digestion Spike (PDS).

An analyte(s) standard added to a portion of a prepared sample, or its dilution, should be recovered to within 85% to 115% of the known value.
The analyte(s) addition should produce a minimum level of 20 times and a maximum of 100 times the method detection limit.
If the analyte addition is <20% of the sample analyte concentration, the following dilution test should be used.
If recovery of the analyte(s) is not within the specified limits, a matrix effect should be suspected, and the associated data flagged accordingly.
The method of additions or the use of an appropriate internal standard element may provide more accurate data.

See Post Digestion Spike (PDS).

Analytical Method

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Specifies the procedures for sample preparation, instrument calibration, sample analysis and results calculations.

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Analytical Reference Standard

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Standards purchased from private chemical supply companies used to prepare calibration standards and CCV standards.

See Stock (Standard) Solution.

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Analytical Sample

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Any solution/media introduced to an instrument on which analysis is performed - excluding: ICV; ICB; CCV; CCB and tunes.
The following are all defined as analytical samples: undiluted and diluted samples; matrix spike samples; duplicate samples; serial dilution samples; post-digestion spike samples; Interference Check Samples (ICSs), Laboratory Control Samples (LCSs); Performance Evaluation (PE) samples, and Preparation Blanks.

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Background Correction

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A technique to compensate for variable background contribution to the instrument signal in the determination of trace elements.

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Batch

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A group of samples prepare at the same time in the same location using the same method.

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A group of samples which behave similarly with respect to the sampling or the testing procedures being employed and which are processed as a unit. For QC purposes, if the number of samples in a group is greater than 20, then each group of 20 samples or less will all be handled as a separate batch.

Bias

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The deviation due to matrix effects of the measured value from a known spiked amount.
Bias can be assessed by comparing a measured value to an accepted reference value in a sample of known concentration or by determining the recovery of a known amount of contaminant spiked into a sample (matrix spike).

Blank



 

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An analytical sample that has negligible or unmeasurable amounts of a substance of interest.
The blank is designed to assess specific sources of contamination.
Types of blanks include calibration blanks, preparation blanks and field blanks.
See the individual definitions for types of blanks.

See Calibration Blank, Field Reagent Blank (FRB), Laboratory Reagent Blank (LRB).

See Calibration Blank, Method Blank.

Calibration

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A set of operations that establish under specific conditions, the relationship between values indicated by a measuring instrument and the corresponding known values.
The calibration standards must be prepared using the same type of reagents or concentration of acids as used in the sample preparation.

See Calibration Standard(s).

See Calibration Curve, Calibration Standard(s), Standard Curve.
 

Calibration Blank

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A blank solution containing all of the reagents and in the same concentration as those used in the analytical sample preparation (not subjected to sample preparation for ICP-AES and ICP-MS).
Calibration blanks are used to verify that the instrument baseline is stable and the instrument is free from contamination.

A volume of reagent water acidified with the same acid matrix as in the calibration standards.
The calibration blank is a zero standard and is used to calibrate the ICP instrument.

A volume of reagent water prepared with the same amounts of acids or other reagents as were the standards and samples.

Calibration Curve

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See Calibration, Calibration Standard(s), Initial Calibration.

See Calibration Standard(s).

The functional relationship between analytical response and target analyte concentration determined for a series of calibration standards.
The calibration curve is obtained by plotting the analytical response versus concentration and performing a regression analysis of the data.

Calibration Standard(s)





 

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A series of known standard solutions used by the analyst for calibration of the instrument (ie., preparation of the analytical curve).
The solutions may or may not be subjected to the preparation method but contain the same matrix as the sample preparations to be analyzed.

(CAL) A solution prepared from the dilution of stock standard solutions.
The CAL solutions are used to calibrate the instrument response with respect to analyte concentration.

A series of solutions containing the target analyte at known and varying concentrations used by the analyst for instrument calibration (i.e., preparation of the calibration curve).

Continuing Calibration Verification

CCV

A single parameter or multi-parameter standard solution prepared by the analyst and used to verify the stability of the instrument calibration with time, and the instrument performance during the analysis of samples.
The CCV can be one of the calibration standards.
However, all parameters being measured by the particular system must be represented in this standard and the standard must have the same matrix (i.e., the same amount of reagents and/or preservatives) as the samples.
The CCV should have a concentration in the middle of the calibration range and shall be analyzed at the beginning of the day prior to the analysis of samples, and every 2 hours.

See Instrument Performance Check (IPC) Solution.

A solution containing a known concentration of analyte derived from the same source as the calibration standards.
The CCV is used to assure calibration accuracy during each analysis run.
It should be run for each analyte as described in the particular analytical method.
At a minimum, it should be analyzed at the beginning of the run and after the last analytical sample.
The CCV concentration should be at or near the mid-range levels of the calibration curve.

Contract Required Quantitation Limit

CRQL

Minimum level of quantitation acceptable under the contract Statement of Work (SOW).

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Control Limits

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A range within which specified measurement results must fall to be compliant.

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Control Sample

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A QC sample introduced into a process to monitor the performance of the system.

Data Quality Objectives

DQOs

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A statement of the overall level of uncertainty that a decision-maker is willing to accept in results obtained from environmental data.
This is qualitatively distinct from quality measurements such as precision, bias and detection limit.

Data Validation




 

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The process of evaluating the available data against the DQOs to make sure that the objectives are met.
Data validation may be very rigorous, or cursory, depending on DQOs.
The available data reviewed will include analytical results, field QC data and lab QC data, and may also include field records.

Date

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The date format for all reporting forms is MM/DD/YYYY.

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Day

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Unless otherwise specified, day shall mean calendar day.

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Dilution Test

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See Serial Dilution (SD).

If the analyte concentration is sufficiently high (minimally, a factor of 50 above the instrument detection limit in the original solution but <90% of the linear limit), an analysis of a 1+4 dilution should agree (after correction for the fivefold dilution) within ±10% of the original determination.
If not, a chemical or physical interference effect should be suspected and the associated data flagged accordingly.
The method of standard additions or the use of an internal-standard element may provide more accurate data for samples failing this test.

If the analyte concentration is sufficiently high (minimally, a factor of 10 above the lower limit of quantitation after dilution), an analysis of a 1:5 dilution should agree within ± 10% of the original determination.
If not, then a chemical or physical interference effect should be suspected.

Duplicate

DUP

A second aliquot of a sample that is treated the same as the original sample in order to evaluate the precision.

See Laboratory Duplicates (LD1 and LD2).

See Matrix Duplicate.

Estimated Quantitation Limit

EQL

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The lowest concentration that can be reliably achieved within specified limits of precision and accuracy during routine laboratory operating conditions.
The EQL is generally 5 to 10 times the MDL.
However, it may be nominally chosen within these guidelines to simplify data reporting.
For many analytes the EQL analyte concentration is selected as the lowest non-zero standard in the calibration curve.
Sample EQLs are highly matrix dependent.

Field Blank

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Any sample that is submitted from the field and is identified as a blank.
A field blank is used to check for cross-contamination during sample collection, sample shipment, and in the laboratory.
A field blank includes trip blanks, rinsate blanks, bottle blanks,  equipment blanks, preservative blanks, decontamination blanks, etc.

See Field Reagent Blank (FRB).

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Field Duplicate

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See Field QC.

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Independent samples which are collected as close as possible to the same point in space and time.
They are two separate samples taken from the same source, stored in separate containers, and analyzed independently.
These duplicates are useful in documenting the precision of the sampling process.

Field QC

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Any Quality Control (QC) sample submitted from the field to the laboratory.
Examples include, but are not limited to, field blanks, field duplicates, and field spikes.

See Field Reagent Blank (FRB).

See Field Duplicate.

Field Reagent Blank

FRB

See Field Blank.

An aliquot of reagent water or other blank matrix that is placed in a sample container in the laboratory and treated as a sample in all respects, including shipment to the sampling site, exposure to the sampling site conditions, storage, preservation, and all analytical procedures.
The purpose of the FRB is to determine if method analytes or other interferences are present in the field environment.

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Field Sample

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A portion of material received to be analyzed that is contained in single or multiple containers and identified by a unique EPA Sample Number.

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Independent Standard

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A Contractor-prepared standard solution that is composed of the analytes from a different source than those used in the standards for the calibration.

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Inductively Coupled Plasma-Atomic (Optical) Emission Spectroscopy

ICP-AES/
ICP-OES

A technique for the simultaneous or sequential multi-element determination of elements in solution.
The basis of the method is the measurement of atomic emission by an optical spectroscopic technique.
Characteristic atomic line emission spectra are produced by excitation of the sample in a radio frequency inductively coupled plasma.
 

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Initial Calibration

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Analysis of analytical standards for a series of different concentrations; used to define the quantitative response, linearity, and dynamic range of the instrument to target analytes.

See Calibration Standard(s).

See Calibration Curve, Calibration Standard(s), Standard Curve.

Initial Calibration Verification

ICV

Solution(s) prepared from stock standard solutions, metals, or salts obtained from a source separate from that utilized to prepare the calibration standards.
The ICV is used to verify the concentration of the calibration standards and the adequacy of the instrument calibration.
The ICV should be traceable to NIST or other certified standard sources when EPA ICV solutions are not available.

See Instrument Performance Check (IPC) Solution (and/or Quality Control Sample (QCS)).

A certified or independently-prepared solution from a source other than used for the calibration standards and used to verify the accuracy of the initial calibration.
For ICP analysis, it should be run at each wavelength used in the analysis at concentration near the mid point of the calibration curve.

Instrument Detection Limit

IDL

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The concentration equivalent to the analyte signal which is equal to three times the standard deviation of a series of 10 replicate measurements of the calibration blank signal at the same wavelength.

Typically used in metals analysis to evaluate the instrument noise level and response changes over time for analytes of interest.
IDLs can be estimated by calculating the average of the standard deviations of three analytical runs performed on three non-consecutive days from the analysis of a reagent blank solution with seven consecutive measurements per day.
Each measurement should be performed as though it were a separate analytical sample.
IDLs should be determined at least once every three months or at a project-specific designated frequency and the associated documentation kept with the instrument log book.

Instrument Performance Check Solution

IPC

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A solution of method analytes, used to evaluate the performance of the instrument system with respect to a defined set of method criteria.

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Interference Check Sample

ICS

A solution containing both interfering and analyte elements of known concentration that can be used to verify background and interelement correction factors.
The ICS consists of to solutions: ICS Solution A (ICSA) and ICS Solution AB (ICSAB).

See Spectral Interference Check (SIC) Solution.

A solution containing both interfering and analyte elements of known concentration that can be used in metals ICP and ICP-MS analysis to verify background and inter-element correction factors.

Interference Check Sample Solution A

ICSA

Consists of the interferents only at the levels specified.

See Spectral Interference Check (SIC) Solution.

See Interference Check Sample (ICS).

Interference Check Sample Solution AB

ICSAB

Consists of the analytes mixed with the interferents at the levels specified.

See Spectral Interference Check (SIC) Solution.

See Interference Check Sample (ICS).

Interferents

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Substances which affect the analysis for the analyte of interest.

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Internal Standard

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A non-target element added to a sample at a known concentration after preparation but prior to analysis.
Instrument responses to internal standards are monitored as a means of assessing overall instrument performance.
 

Pure analyte(s) added to a sample, extract, or standard solution in known amount(s) and used to measure the relative responses of other method analytes that are components of the same sample or solution.
The internal standard must be an analyte that is not a sample component.

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Laboratory Control Sample

LCS

A matrix spiked at a known concentration.
LCSs are analyzed using the same sample preparation, reagents, and analytical methods employed for the EPA samples received.

See Laboratory Fortified Blank (LFB).

A volume of reagent water spiked with known concentrations of analytes and carried through the same preparation and analysis procedure as a sample.
It is used to monitor analyte loss/recovery.
The LCS may either be prepared from the same source as the calibration standards or independently of the calibration standards.
An independently prepared LCS may either be obtained as or prepared from a certified reference solution or prepared from a certified reagent solid or from an alternate lot reagent solid relative to the calibration standards source.
For each analytical batch, at least one LCS should be prepared from the same source as the calibration standards.
In this way, if the recoveries of both the LCS and the matrix spike are outside the acceptance limits, the analyst will be able to determine whether the problem is due to a calibration error or a matrix interference.

Laboratory Duplicates

LD1 and LD2

See Duplicate (DUP).

Two aliquots of the same sample taken in the laboratory and analyzed separately with identical procedures.
Analyses of LD1 and LD2 indicates precision associated with laboratory procedures, but not with sample collection, preservation or storage procedures.

See Duplicate (DUP).

Laboratory Fortified Blank

LFB

See Laboratory Control Sample (LCS).

An aliquot of LRB to which known quantities of the method analytes are added in the laboratory.
The LFB is analyzed exactly like a sample, and its purpose is to determine whether the methodology is in control and whether the laboratory is capable of making accurate and precise measurements.

See Laboratory Control Sample (LCS).

Laboratory Fortified Sample Matrix

LFM

See Matrix Spike (MS).

An aliquot of an environmental sample to which known quantities of the method analytes are added in the laboratory.
The LFM is analyzed exactly like a sample, and its purpose is to determine whether the sample matrix contributes bias to the analytical results.
The background concentrations of the analytes in the sample matrix must be determined in a separate aliquot and the measured values in the LFM corrected for background concentrations.

See Matrix Spike (MS).

Laboratory Reagent Blank

LRB

See Preparation Blank (PB).

An aliquot of reagent water or other blank matrices that are treated exactly as a sample including exposure to all glassware, equipment, solvents, reagents, and internal standards that are used with other samples.
The LRB is used to determine if method analytes or other interferences are present in the laboratory environment, reagents, or apparatus.

See Method Blank.

Linear Dynamic Range

LDR

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The concentration range over which the instrument response to an analyte is linear.

In either ICP-AES and ICP-MS analysis based on a one-point calibration, the concentration range above the highest calibration point over which the functional relationship between analyte signal and analyte concentration remains linear.
A sample result that falls within the linear dynamic range is considered valid and may be reported, thus avoiding the need to dilute and reanalyze the sample.

Lower Limit of Quantitation

LLOQ

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The lowest point of quantitation, or in most cases, the lowest point in the calibration curve which is less than or equal to the desired regulatory action levels based on the stated project requirements.
Analysis of a standard prepared at the LLOQ concentration level or use of the LLOQ as the lowest point calibration standard provides confirmation of the established quantitation sensitivity of the method.
The LLOQ recovery should be within 50% of the true value, or some other mutually agreed upon recovery based upon the project-specific data quality objectives, in order to verify the data reporting limit.

Lower Limit of Quantitation Check Sample

LLQC

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The lower limit of quantitation check (LLQC) sample should be analyzed after establishing the lower laboratory reporting limits and on an as needed basis to demonstrate the desired detection capability.
Ideally, this check sample and the low-level calibration verification standard will be prepared at the same concentrations with the only difference being the LLQC sample is carried through the entire preparation and analytical procedure.
Lower limits of quantitation are verified when all analytes in the LLQC sample are detected within ± 30% of their true value.
This check should be used to both establish and confirm the lowest quantitation limit.

Low-Level Continuing Calibration Verification Standard

LLCCV

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The low-level continuing calibration verification (LLCCV) standard should also be analyzed at the end of each analysis batch.
A more frequent LLCCV analysis, i.e., every 10 samples, may be necessary if low-level sample concentrations are anticipated and the system stability at low end of the calibration is questionable.
In addition, the analysis of a LLCCV on a more frequent basis will minimize the number of samples for re-analysis should the LLCCV fail if only run at the end of the analysis batch.
The LLCCV standard should be made from the same source as the initial calibration standards at the established lower limit of quantitation as reported by the laboratory.
The acceptance criteria for the LLCCV standard should be ± 30% of its true value.
If the calibration cannot be verified within these specified limits, the analysis of samples containing the affected analytes at similar concentrations cannot continue until the cause is determined and the LLCCV standard successfully analyzed.
The instrument may need to be recalibrated or the lower limit of quantitation adjusted to a concentration that will ensure a compliant LLCCV analysis.
The analysis data for the LLCCV standard should be kept on file with the sample analysis data.

Low-Level Initial Calibration Verification Standard

LLICV

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A low-level initial calibration verification (LLICV) standard should be prepared, using the same source as the calibration standards, at a concentration expected to be the lower limit of quantitation.
The suggested acceptance criteria for the LLICV is ± 30% of its true value.
Once the calibration acceptance criteria is met, either the lowest calibration standard or the LLICV concentration can be used to demonstrate the lower limit of quantitation and sample results should not be quantitated below this lowest standard.

Matrix

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The predominant material of which the sample to be analyzed is composed.
For the purpose of this Statement of Work (SOW), a sample matrix is either aqueous/water, soil/sediment, or a wipe.
Matrix is not synonymous with phase (liquid or solid).

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The component or substrate which contains the analyte of interest.

Matrix Duplicate

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An intra-laboratory split sample which is used to document the precision of a method in a given sample matrix.

Matrix Effect

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The enhancement or suppression of minor element spectral lines due to a particular matrix constituent.

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Matrix Spike

MS

Aliquot of a sample fortified (spiked) with known quantities of specific compounds and subjected to the entire analytical procedure to indicate the appropriateness of the method for the matrix by measuring recovery.

See Laboratory Fortified Sample Matrix (LFM).

An aliquot of sample spiked with a known concentration of target analyte(s).
The spiking occurs prior to sample preparation and analysis.
They are used to document the bias of a method in a given sample matrix.

Matrix Spike Duplicates

MSD

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Intra-laboratory split samples spiked with identical concentrations of target analyte(s).
The spiking occurs prior to sample preparation and analysis.
They are used to document the precision and bias of a method in a given sample matrix.

Method Blank

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See Preparation Blank.

See Laboratory Reagent Blank (LRB).

An analyte free matrix to which all reagents are added in the same volumes or proportions as used in the processing of the samples.
The method blank must be carried through the complete sample preparation procedure and contain the same acid concentration in the final solution as the sample solution used for analysis.
The method blank is used to document contamination resulting from the analytical process.

Method Detection Limit

MDL

The concentration of a target parameter that, when a sample is processed through the complete method, produces a signal with 99% probability that it is different from the blank.
For 7 replicates of the sample, the mean value must be 3.14s above the blank, where "s" is the standard deviation of the 7 replicates.

The minimum concentration of an analyte that can be identified, measured, and reported with 99% confidence that the analyte concentration is greater than zero.

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Method of Standard Additions

MSA

See Standard Addition.

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An alternative calibration procedure employed when the signal response of the analyte of interest is different in a particular matrix than when it is in reagent water.
The procedure is generally reserved for analyzing complex matrices.
The standard addition technique involves the addition of known amounts of the target analyte to each of a series of replicate sample aliquots.
The final concentrations of the sample replicates should span the calibration range of the method.
The analytical responses versus the standard addition concentration for each of the replicates is plotted.
After performing a linear regression, the curve is extrapolated to the x-axis.
The analyte concentration in the original unspiked sample is equal to the inverse of the x-intercept.
See Method 7000, for more information.

Optimum Concentration Range

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In metals analysis, a concentration range, below which scale expansion should be used, and above which curve correction should be considered.
This range will vary with the sensitivity of the instrument and the operating conditions employed.

Percent Difference

%D

The Difference between the two values divided by one of the values multiplied by 100.

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Percent Recovery

%R

The percentage of an analyte or element added to a sample that is recovered.
It is the difference between the concentration detected in the spiked sample and that detected in the original (unspiked) sample, divided by the concentration added to the spiked sample multiplied by 100.

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Performance Evaluation Sample

PE

A sample of known composition to the EPA; however, unknown to the Contractor, that is provided to evaluate Contractor performance.

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Post-Digestion Spike

PDS

Samples prepared for metals analyses that have an analyte spike added to determine if matrix effects may be a factor in the results.
The spike addition should produce a method-specified minimum concentration above the method reporting limit.
A post digestion spike is analyzed with each batch of samples and recovery criteria are specified for each method.

See Analyte Addition Test.

If the MS/MSD recoveries are unacceptable, the same sample from which the MS/MSD aliquots were prepared should also be spiked with a post digestion spike.
Otherwise, another sample from the same preparation should be used as an alternative.
An analyte spike is added to a portion of a prepared sample, or its dilution, and should be recovered to within 80% to 120% of the known value.
The spike addition should produce a minimum level of 10 times and a maximum of 100 times the lower limit of quantitation.
If this spike fails, then the dilution test (Sec. 9.9.2) should be run on this sample.
If both the MS/MSD and the post digestion spike fail, then matrix effects are confirmed.

Precision

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The agreement among a set of replicate measurements without assumption of knowledge of the true value.
Precision is estimated by means of duplicate/replicate analyses.
The most commonly used estimates of precision are the relative standard deviation (RSD) or the coefficient of variation (CV).

Preparation Blank

PB

An analyte-free sample to which all reagents are added in the same volume or proportions as used in sample processing.
The preparation blank must be carried through the entire sample preparation and analytical procedures.
It is used to assess contamination resulting from the analytical process.

See Laboratory Reagent Blank (LRB).

See Method Blank.

Quality Control Sample

QCS

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A solution of method analytes of known concentrations which is used to fortify an aliquot of LRB or sample matrix.
The QCS is obtained from a source external to the laboratory and different from the source of calibration standards. It is used to check either laboratory or instrument performance.

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Raw Data

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The originally recorded and unprocessed measurements from any measuring device such as analytical instruments, balances, pipettes, thermometers, etc.

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Reagent Water

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The purity of this water must be equivalent to ASTM Type II reagent water of specification D1193-06, "Standard Specification for Reagent Water."

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Water that has been generated by any method which would achieve the performance specifications for ASTM Type II water.

Reference Material

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Standards used to verify method and instrument performance, eg., ICV, CCV, ICS, etc.

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A material containing known quantities of target analytes in solution or in a homogeneous matrix.
It is used to document the bias of the analytical process.

Relative Percent Difference

RPD

The relative percent difference is based on the mean of two values, and is reported as an absolute value (ie., always expressed as a positive number or zero).

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Reported Data

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Reported data are processed from the raw measurement values that may have been reformatted from the original measurement to meet specific reporting requirements, such as significant figures and decimal precision.

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Sample

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A portion of material to be analyzed that is contained in single or multiple containers and identified by a unique sample number.

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Sample Delivery Group

SDG

A unit within a sample Case that is used to identify a group of samples for delivery.  An SDG is defined by the following, whichever is most frequent: 

• Each 20 field samples (excluding Performance Evaluation (PE) samples) within a Case or

• Each 7 calendar day period (3 calendar day period for 7 day turnaround) during which field samples in a Case are received (said period beginning with the receipt of the first sample in the SDG).

• All samples scheduled with the same level of deliverables.

• In addition, all samples assigned to an SDG must have been scheduled under the same contractual turnaround time.  Preliminary Results have no impact on defining the SDG.
  Samples may be assigned to the SDGs by matrix at the discretion of the laboratory. Laboratories shall take all precautions to meet the 20 sample per SDG criteria.

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Sensitivity

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The ability of an analytical technique or instrument to discriminate between small differences in analyte concentration (Reference 1).
For metals analysis, the following methods are commonly employed to determine sensitivity.
(a) Atomic absorption (AA): The concentration of metal, in mg/L, that produces a transmission of 1%.
(b) Graphite furnace AA (GFAA): The mass of analyte required to give a response of 0.044 absorbance-seconds.
(c) Inductively coupled plasma (ICP): The average of the standard deviations of three runs of a reagent blank solution on three non-consecutive days with seven consecutive measurements per day.

Serial Dilution

SD

The dilution of a sample by a factor of five.
When corrected by the dilution factor, the diluted sample must agree with the original undiluted sample within specified limits.
Serial dilution may reflect the influence of interferents.

See Dilution Test.

See Dilution Test.

Spectral Interference Check Solution

SIC

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A solution of selected method analytes of higher concentrations which is used to evaluate the procedural routine for correcting known interelement spectral interferences with respect to a defined set of method criteria.

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Split Samples

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Aliquots of sample taken from the same container and analyzed independently.
In cases where aliquots of samples are impossible to obtain, field duplicate samples should be taken for the matrix duplicate analysis.
These are usually taken after mixing or composting and are used to document intra- or interlaboratory precision.

Standard Addition

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The addition of a known amount of analyte to the sample in order to determine the relative response of the detector to an analyte within the sample matrix.
The relative response is then used to assess either an operative matrix effect or the sample analyte concentration.

The practice of adding a known amount of an analyte to a sample immediately prior to analysis.
It is typically used to evaluate interferences.

Standard Curve

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See Calibration, Calibration Standard(s), Initial Calibration.

See Calibration Standard(s).

A plot of concentrations of known analyte standards versus the instrument response to the analyte. Calibration standards are prepared by successively diluting a standard solution to produce working standards which cover the working range of the instrument.  The calibration standards should be prepared using the same type of acid or solvent and at the same concentration as will result in the samples following sample preparation.

Stock (Standard) Solution

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A standard solution which can be diluted to derive other standards.

A concentrated solution containing one or more method analytes prepared in the laboratory using assayed reference materials or purchased from a reputable commercial source.

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Target Analyte List

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A list of Inorganic Analytes (metals and cyanide) as designated in Exhibit C – Inorganic Target Analyte List and Contract Required Quantitation Limits.

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Time

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HH:mm:ss - When required to record time on any deliverable item, time shall be expressed as Military Time (ie., a 24-hour clock (0000-2359)).

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