NCD980602163_19960501_Warren County PCB Landfill_SERB C_Quality Control Samples-OCR

Oualitv Control Samples
Quality control samples are collected during field studies for various purposes :wliicli include the isolation
of site effects ( control samples), define background conditions (background sample), evaluate field/laboratory
variability (spikes and blanks, trip blanks, duplicate, split samples).
The definitions for specific quality control samples are listed below:
Control Samp e --typically a discrete grab sample collected to isolate a source of contamination.
Isolation of a source could require the collection of both an upstream sample at a location where the
medium being studied is unaffected by the site being studied, as well as a downstream control which
could be affected by contaminants contributed from the site under study.
Background Sample --a sample (usually a grab sample) collected from an area, water body, or site
similar to the one being studied, but located in an area known or thought to be free from pollutants of
concern.
Split Sample --a sample which has been portioned into two or more containers from a single sample
container or sample mixing container. The primary purpose of a split sample is to measure sample
handling variability.
Duplicate Samp!e' --two or more samples collected from a common source. The purpose of a duplicate
sample is to estimate the variability of a given characteristic or contaminant associated with a population.
Trip Blanks --a sample which is prepared prior to the sampling event in the actual container and is
stored with the investigative samples throughout the sampling event. They are then packaged for
shipment with the other samples and submitted for analysis. At no time after their preparation are trip
blanks to be opened before they reach the laboratory. Trip blanks are used to determine if samples were
contaminated during storage and/or transportation back to the laboratory (a measure of sample handling
variability resulting in positive bias in contaminant concentration). If samples are to be shipped, trip
blanks are to be provided with each shipment but not for each cooler.
Spikes --a sample with known concentrations of contaminants. Spike samples are often packaged for
shipment with other samples and sent for analysis. At no time after their preparation are the sample
containers to be opened before they reach the laboratory. Spiked samples are normally sent with each
shipment to contract laboratories only. Spiked samples are used to measure negative bias due to sample
handling or analytical procedures, or to assess the performance of a laboratory.
Equipment Field Blanks --a sample collected using organic-free water which has been run over/through
sample collection equipment. These samples are used to determine if contaminants have been introduced
by contact of the sample medium with sampling equipment. Equipment field blanks are often associated
with collecting rinse blanks of equipment that has been field cleaned
EISOPQAM 5-3 May 1996
,.
Pre-and Post-Preservative Blanks --a sample that is prepared in the field and used to determine if the
preservative used during field operations was contaminated, thereby causing a positive bias in the
contaminant concentration. On small studies, usually only a post-preservative blank is prepared at the
end of all sampling activities. On studies extending beyond one week, a pre-preservative blank should
also be prepared prior to beginning sampling activities. At the discretion of the project leader, additional
preservative blanks can be prepared at intervals throughout the field investigation. These blanks are
prepared by putting organic/analyte-free water in the container and then preserving the sample with the
appropriate preservative.
Field Blanks --a sample that is prepared in the field to evaluate the potential for contamination of a
sample by site contaminants from a source not associated with the sample collected (for example air-
borne dust or organic vapors which could contaminate a soil sample). Organic-free water is taken to
the field in sealed containers or generated on-site. The water is poured into the appropriate sample
containers at pre-designated locations at the site. Field blanks should be collected in dusty environments
and/or from areas where volatile organic contamination is present in the atmosphere and originating from
a source other than the source being sampled.
Material Blanks --samples of sampling materials (e.g., material used to collect wipe samples, etc.),
construction materials (e.g., well construction materials), or reagents (e.g., organic/analyte free water
generated in the field, water from local water supplies used to mix well grout, etc.) collected to measure
any positive bias from sample handling variability. Commonly collected material blanks are listed
below:
EISOPQAM
Wipe Sample Blanks --a sample of the material used for collecting wipe samples. The material is
handled, packaged, and transported in the same manner as all other wipe samples with the exception
that it is not exposed to actual contact with the sample medium.
Grout Blanks --a sample of the material used to make seals around the annular space in monitoring
wells.
Filter Pack Blanks --a sample of the material used to create an interface around the screened interval
of a monitoring \Yell.
Construction Water Blanks --a sample of the water used to mix or hydrate construction materials
such as monitoring well grout.
Organic/Analvte Free Water Blanks --a sample collected from a field organic/analyte free water
generating system. The sample is normally collected at the end of sampling activities since the
organic/analyte free water system is recharged prior to use on a study. On large studies, samples can
be collected at intervals at the discretion of the project leader. The purpose of the organic/analyte
free water blank is to measure positive bias from sample handling variability due ·to possible
localized contamination of the organic/analyte free water generating system or contamination
introduced to the sample containers during storage at the site. Organic/analyte free water blanks
differ from field blanks in that the sample should be collected in as clean an area as possible (a usual
location for the organic/analyte free water system) so that only the water generating
system/containers are measured.
5-4 May 1996