Assurance / Quality Control
Enviroscience Laboratories Inc. is proud to have a team of
well trained and highly experienced analytical chemists. A comprehensive
Quality Assurance / Quality Control (QA/QC) program has been developed
and followed for all sampled analyzed at our laboratory. We are committed
to providing the highest quality data possible.
The basis of our QA/QC plan is the batch method. Each batch of samples
(with accompanying QC samples) goes from sample work up through instrumentation
and on to data interpretation and final reports as a unit. The QA/QC
data are evaluated to assess the quality of each sample batch. Certain
criteria must be satisfied before sample data are reviewed.
- Sample batch
– Each batch consists of a maximum of nine samples, plus three
QA/QC samples: reference material or spiked sample, a duplicate sample,
and a procedural blank.
Material – Standard or certified reference material are
routinely analyzed where they are available. For analyses where no
certified materials are available, spiked samples are used to assess
the accuracy of the data. For data acceptance, results must be within
– Results for duplicates are presented along with the analysis
results. One sample in each batch is analyzed in duplicate at no extra
cost to the client. Duplicate results must agree to within limits
specified for each analysis.
– One procedural blank is analyzed with each batch of samples
to ensure the absence of interferences.
– Chemically labeled analogues of the target compound are added
to each sample prior to sample work up for evaluation and correction
of the recoveries of the target analytes.
Standards – Additional labeled analogues are added to each
extract after sample work up and prior to instrumental analysis for
determination of surrogate standard recoveries.
Instrumental QA/QC procedures are implemented prior to analysis and
on an ongoing basis.
– Instrumental linearity is routinely determined by a multi-point
calibration. The Relative Response Factors (RRFs) for the linearity
set must agree to within 15-20%, depending on protocol.
- Daily Calibration
– Mass Spectrometers are tuned and mass calibrated on an ongoing
basis. RRFs are determined by a single point calibration prior to
analysis of each batch of samples, bracketing if necessary sets of
samples. RRFs at the beginning and end of each sample bracket (12
runs) must agree to within 10% and to within 15% of the linearity
- Sample Carryover
– The absence of sample carryover from previous injections is
assured by running a solvent after every calibration standard. In
addition, sample data is scrupulously monitored to ensure that carryover
of a proceeding sample has not occurred.
- Window Standard
– A standard check is run before analysis of each batch of samples
to define the retention time window during which a group of compounds
- When sample batch
and instrumental QA/QC criteria are satisfied, sample data are evaluated
for chromatographic quality, ion ratios, retention times and linear
- Recoveries of
the labeled surrogate compounds (added as internal standards) are
required to be in an acceptable range, which is defined for each analysis,
but is generally 40-120%.
- Detection limits
are reported for each sample and are calculated as the concentration
equivalent to the minimum detectable instrument response. This is
determined from the mass chromatogram of the compound and is defined
as a peak of height three times the maximum height of the noise.
Laboratories Inc. stands by its high quality data. The company’s
reputation is a pure result of a combination our chemist’s expertise,
meticulous methodologies, state-of-the-art instrumentation and uncompromising
sophisticated QA/QC program.