Abstract
A growing body of research indicates that the most biologically active PCB congeners and organochlorines are not the most abundant components in human and wildlife samples. As researchers attempt measurement on a wider pool of less abundant compounds, they inevitably face quantification problems. To address this problem and enhance comparability across studies, we propose a standardized approach to report organochlorines that is based on a reproducible method to determine the limit of quantification (L Q). Two statistical methods are incorporated into our approach, one by Gibbons termed the Alternative Minimum Level (AML), and one based on determining a region of stable relativestandard deviation in instrument response (RSD). We illustrate our approach using historical samples collected during the 1960s from a cohort of pregnant women enrolled in the Child Health and Development Study. The results are applicable to determining the L Q of any method, and are of utmost importance to environmental scientists conducting trace organic analyses of complex mixtures. Our results demonstrate that: (1) precision as measured by RSD is the most important criterion in determining L Q; (2) the AML routinely isolates a region of constant RSD; and (3) the precision of the instrument detector response as measured with pure standards locates the L Q applicable for real samples - that is, the true limits of quantification reside in the detector, not the matrix effects or analyte recoveries associated with real samples. A corollary of these findings is that bias due to matrix effects and analyte recoveries can be assessed separately from precision and L Q determination. Previous approaches involved spiking matrix blanks to determine L Q, a problematic strategy for real world, complex matrices. We have now validated the use of pure standards in L Q determination, an approach that is practical and accessible to most analysts.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1395-1402 |
| Number of pages | 8 |
| Journal | Chemosphere |
| Volume | 44 |
| Issue number | 6 |
| DOIs | |
| State | Published - 2001 |
| Externally published | Yes |
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Keywords
- DDE
- DDT
- Heptachlor epoxide
- Limit of quantification
- Limit of quantitation
- Organochlorines
- PCBs
- Polychlorinated biphenyls
ASJC Scopus subject areas
- Environmental Chemistry
- Environmental Science(all)
Cite this
A reproducible approach to the reporting of organochlorine compounds in epidemiologic studies. / Willman, Eric J.; Hertz-Picciotto, Irva; Keller, Jean A.; Martinez, Eugenio; Judith Charles, M.
In: Chemosphere, Vol. 44, No. 6, 2001, p. 1395-1402.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A reproducible approach to the reporting of organochlorine compounds in epidemiologic studies
AU - Willman, Eric J.
AU - Hertz-Picciotto, Irva
AU - Keller, Jean A.
AU - Martinez, Eugenio
AU - Judith Charles, M.
PY - 2001
Y1 - 2001
N2 - A growing body of research indicates that the most biologically active PCB congeners and organochlorines are not the most abundant components in human and wildlife samples. As researchers attempt measurement on a wider pool of less abundant compounds, they inevitably face quantification problems. To address this problem and enhance comparability across studies, we propose a standardized approach to report organochlorines that is based on a reproducible method to determine the limit of quantification (L Q). Two statistical methods are incorporated into our approach, one by Gibbons termed the Alternative Minimum Level (AML), and one based on determining a region of stable relativestandard deviation in instrument response (RSD). We illustrate our approach using historical samples collected during the 1960s from a cohort of pregnant women enrolled in the Child Health and Development Study. The results are applicable to determining the L Q of any method, and are of utmost importance to environmental scientists conducting trace organic analyses of complex mixtures. Our results demonstrate that: (1) precision as measured by RSD is the most important criterion in determining L Q; (2) the AML routinely isolates a region of constant RSD; and (3) the precision of the instrument detector response as measured with pure standards locates the L Q applicable for real samples - that is, the true limits of quantification reside in the detector, not the matrix effects or analyte recoveries associated with real samples. A corollary of these findings is that bias due to matrix effects and analyte recoveries can be assessed separately from precision and L Q determination. Previous approaches involved spiking matrix blanks to determine L Q, a problematic strategy for real world, complex matrices. We have now validated the use of pure standards in L Q determination, an approach that is practical and accessible to most analysts.
AB - A growing body of research indicates that the most biologically active PCB congeners and organochlorines are not the most abundant components in human and wildlife samples. As researchers attempt measurement on a wider pool of less abundant compounds, they inevitably face quantification problems. To address this problem and enhance comparability across studies, we propose a standardized approach to report organochlorines that is based on a reproducible method to determine the limit of quantification (L Q). Two statistical methods are incorporated into our approach, one by Gibbons termed the Alternative Minimum Level (AML), and one based on determining a region of stable relativestandard deviation in instrument response (RSD). We illustrate our approach using historical samples collected during the 1960s from a cohort of pregnant women enrolled in the Child Health and Development Study. The results are applicable to determining the L Q of any method, and are of utmost importance to environmental scientists conducting trace organic analyses of complex mixtures. Our results demonstrate that: (1) precision as measured by RSD is the most important criterion in determining L Q; (2) the AML routinely isolates a region of constant RSD; and (3) the precision of the instrument detector response as measured with pure standards locates the L Q applicable for real samples - that is, the true limits of quantification reside in the detector, not the matrix effects or analyte recoveries associated with real samples. A corollary of these findings is that bias due to matrix effects and analyte recoveries can be assessed separately from precision and L Q determination. Previous approaches involved spiking matrix blanks to determine L Q, a problematic strategy for real world, complex matrices. We have now validated the use of pure standards in L Q determination, an approach that is practical and accessible to most analysts.
KW - DDE
KW - DDT
KW - Heptachlor epoxide
KW - Limit of quantification
KW - Limit of quantitation
KW - Organochlorines
KW - PCBs
KW - Polychlorinated biphenyls
UR - http://www.scopus.com/inward/record.url?scp=0034884449&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034884449&partnerID=8YFLogxK
U2 - 10.1016/S0045-6535(00)00465-3
DO - 10.1016/S0045-6535(00)00465-3
M3 - Article
C2 - 11513118
AN - SCOPUS:0034884449
VL - 44
SP - 1395
EP - 1402
JO - Chemosphere
JF - Chemosphere
SN - 0045-6535
IS - 6
ER -