Abstract
Two analytical methods (HPLC-fluorimeter [HPLC-FLD] and tandem mass spectrometry LC/MS/MS) are available to assay phenyl-hydroxyethylmercapturic acids (PHEMAs), the mercapturic acids of styrene in humans. In the past, each method was used to check different populations of subjects, but until now no attempt has been made to compare the two methods. This study was designed to verify whether the two methods actually give comparable results. The influence of different conditions of sample storage in altering the concentration of PHEMAs was also investigated. Urine samples were collected at the beginning and at the end of the workshift from 10 workers exposed to different levels of styrene. Each sample was analysed both by LC/MS/MS after storage under different conditions (respectively, at -20 and +4°C, and after repeated freezing-thawing cycles), and by HPLC-FLD (in the same conditions of storage). Strong correlations were found between the two methods both for total PHEMAs and for each of the isomers measured, including the minor (S,R)-M1. Also an alternative approach, the Bland-Altman test, confirmed the agreement between the two methods. The different storage conditions tested did not decrease the concentration of PHEMAs but, surprisingly, a clear trend to increase was shown, particularly for (R,R)-M1, (S,R)-M2 and (R,R)-M2 in samples stored at +4°C for 1 week. In conclusion, the study demonstrates that the methods give comparable results. Indirectly, this confirms also the main characteristics of PHEMAs, showed in the previous experiments: low biotransformation rates of styrene into PHEMAs; large inter-individual variability; and the presence of a clear preference in the excretion of the isomers deriving from (S)-styrene oxide. PHEMAs appear stable under different storage conditions, but further studies are needed to explain the increase of levels that occurs when samples are not kept frozen. To avoid pre-analytical errors, samples collected for biomonitoring or research purposes should be frozen as soon as possible, and thawed only one time just before the analysis.
| Original language | English |
|---|---|
| Pages (from-to) | 225-233 |
| Number of pages | 9 |
| Journal | Toxicology Letters |
| Volume | 162 |
| Issue number | 2-3 SPEC. ISS. |
| DOIs | |
| Publication status | Published - Apr 10 2006 |
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Keywords
- HPLC
- Inter-lab control
- Mass spectrometry
- Mercapturic acids
- Styrene
ASJC Scopus subject areas
- Toxicology
Cite this
Mercapturic acids of styrene in man : Comparability of the results obtained by LC/MS/MS and by HPLC-fluorimeter, and stability of samples under different storage conditions. / Negri, Sara; Maestri, Luciano; Andreoli, Roberta; Manini, Paola; Mutti, Antonio; Imbriani, Marcello.
In: Toxicology Letters, Vol. 162, No. 2-3 SPEC. ISS., 10.04.2006, p. 225-233.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Mercapturic acids of styrene in man
T2 - Comparability of the results obtained by LC/MS/MS and by HPLC-fluorimeter, and stability of samples under different storage conditions
AU - Negri, Sara
AU - Maestri, Luciano
AU - Andreoli, Roberta
AU - Manini, Paola
AU - Mutti, Antonio
AU - Imbriani, Marcello
PY - 2006/4/10
Y1 - 2006/4/10
N2 - Two analytical methods (HPLC-fluorimeter [HPLC-FLD] and tandem mass spectrometry LC/MS/MS) are available to assay phenyl-hydroxyethylmercapturic acids (PHEMAs), the mercapturic acids of styrene in humans. In the past, each method was used to check different populations of subjects, but until now no attempt has been made to compare the two methods. This study was designed to verify whether the two methods actually give comparable results. The influence of different conditions of sample storage in altering the concentration of PHEMAs was also investigated. Urine samples were collected at the beginning and at the end of the workshift from 10 workers exposed to different levels of styrene. Each sample was analysed both by LC/MS/MS after storage under different conditions (respectively, at -20 and +4°C, and after repeated freezing-thawing cycles), and by HPLC-FLD (in the same conditions of storage). Strong correlations were found between the two methods both for total PHEMAs and for each of the isomers measured, including the minor (S,R)-M1. Also an alternative approach, the Bland-Altman test, confirmed the agreement between the two methods. The different storage conditions tested did not decrease the concentration of PHEMAs but, surprisingly, a clear trend to increase was shown, particularly for (R,R)-M1, (S,R)-M2 and (R,R)-M2 in samples stored at +4°C for 1 week. In conclusion, the study demonstrates that the methods give comparable results. Indirectly, this confirms also the main characteristics of PHEMAs, showed in the previous experiments: low biotransformation rates of styrene into PHEMAs; large inter-individual variability; and the presence of a clear preference in the excretion of the isomers deriving from (S)-styrene oxide. PHEMAs appear stable under different storage conditions, but further studies are needed to explain the increase of levels that occurs when samples are not kept frozen. To avoid pre-analytical errors, samples collected for biomonitoring or research purposes should be frozen as soon as possible, and thawed only one time just before the analysis.
AB - Two analytical methods (HPLC-fluorimeter [HPLC-FLD] and tandem mass spectrometry LC/MS/MS) are available to assay phenyl-hydroxyethylmercapturic acids (PHEMAs), the mercapturic acids of styrene in humans. In the past, each method was used to check different populations of subjects, but until now no attempt has been made to compare the two methods. This study was designed to verify whether the two methods actually give comparable results. The influence of different conditions of sample storage in altering the concentration of PHEMAs was also investigated. Urine samples were collected at the beginning and at the end of the workshift from 10 workers exposed to different levels of styrene. Each sample was analysed both by LC/MS/MS after storage under different conditions (respectively, at -20 and +4°C, and after repeated freezing-thawing cycles), and by HPLC-FLD (in the same conditions of storage). Strong correlations were found between the two methods both for total PHEMAs and for each of the isomers measured, including the minor (S,R)-M1. Also an alternative approach, the Bland-Altman test, confirmed the agreement between the two methods. The different storage conditions tested did not decrease the concentration of PHEMAs but, surprisingly, a clear trend to increase was shown, particularly for (R,R)-M1, (S,R)-M2 and (R,R)-M2 in samples stored at +4°C for 1 week. In conclusion, the study demonstrates that the methods give comparable results. Indirectly, this confirms also the main characteristics of PHEMAs, showed in the previous experiments: low biotransformation rates of styrene into PHEMAs; large inter-individual variability; and the presence of a clear preference in the excretion of the isomers deriving from (S)-styrene oxide. PHEMAs appear stable under different storage conditions, but further studies are needed to explain the increase of levels that occurs when samples are not kept frozen. To avoid pre-analytical errors, samples collected for biomonitoring or research purposes should be frozen as soon as possible, and thawed only one time just before the analysis.
KW - HPLC
KW - Inter-lab control
KW - Mass spectrometry
KW - Mercapturic acids
KW - Styrene
UR - http://www.scopus.com/inward/record.url?scp=32644438746&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=32644438746&partnerID=8YFLogxK
U2 - 10.1016/j.toxlet.2005.09.014
DO - 10.1016/j.toxlet.2005.09.014
M3 - Article
VL - 162
SP - 225
EP - 233
JO - Toxicology Letters
JF - Toxicology Letters
SN - 0378-4274
IS - 2-3 SPEC. ISS.
ER -