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6.4 Leng
1. DETERMINATION OF BIS(2-PROPYLHEPTYL)PHTHALATE (DPHP)
EXPOSURE IN THE GENERAL POPULATION
Gabriele Leng and Wolfgang Gries
Institute of Biomonitoring, Leverkusen, Germany
Holger Koch
Institute for Prevention and Occupational Medicine, Bochum, Germany
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A company of
Bayer and LANXESS
2. DPHP - APPLICATIONS
• plasticizer for technical applications
• substitution product for Di-(2-ethylhexyl)phthalate (DEHP)
• alternative to Diisononylphthalate (DiNP) or Diisodecylphthalate (DIDP)
• Aim:
Development of an analytical method for the sensitive and selective
determination of DPHP body burden (metabolites in urine)
Examine which analytical way meets the tasks:
LC-MS/MS (in general standard method for phthalate metabolites)
OR
GC-HRMS, GC-MS/MS
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4. DPHP – METHOD OVERVIEW
GC-MS
HPLC-MS/MS
1 ml Urine-enzymatic hydrolysis: + d4-internal standard;
pH 6.5, glucuronidase-incubation
like GC-MS
Acidification at pH 2 with hydrochloric acid
like GC-MS
Extraction with tert-butylmethylether
like GC-MS
Evaporation in nitrogen to dryness
like GC-MS
Disolution in acetonitrile
Disolution in methanol
Selective derivatization on carboxylic group with
1,1,1,3,3,3- hexafluoro-2-isopropanol (HFIP) + N,N‘diisopropylcarbodiimide
./.
1 M sodium hydrogen carbonate
./.
Extraction in iso-octan
./.
1 µL split-splitless; GC-MS-NCI detection
10 µL
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7. POOL URINE SPIKED WITH 1 µg/L OF EACH METABOLITE
LC-MS/MS
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GC-HRMS after HFIP-derivatization
8. HUMAN ELIMINATION KINETIC STUDY
Aim:
To examine if Cx-MPHxP, OH-MPHP and Oxo-MPHP
are main DPHP-metabolites in humans
To get information about the elimination kinetics of DPHP in humans
Performed by Holger Koch at IPA
approved by Ethical commission University of Bochum (registration number
4022-11, 24.5.2011)
5 male volunteers
Oral intake of about 50 mg D4-DPHP
Urine collected during the first 48 hours after intake in intervals
Analysis of DPHP metabolites
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9. HUMAN ELIMINATION KINETIC STUDY
0++
0++ 48 h
0–
Elimination % of dose
Elimination % of dose
0 – 24 h
volunteer
volunteer
• 24 % of applied dose was found during the first 48 h
• main metabolite: oxo-MPHP > OH-MPHP >> cx-MPHxP
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11. LESSONS LEARNT SO FAR
Human elimination kinetic study:
DPHP-specific metabolites in urine:
Major: Mono-2-(propyl-6-oxoheptyl)-phthalate (oxo-MPHP)
Major: Mono-2-(propyl-6-hydroxy-heptyl)-phthalate (OH-MPHP)
Very minor: Mono-2-(propyl-6-carboxy-hexyl)-phthalate (cx-MPHxP)
DPHP-metabolites are eliminated within 48 h
24 % of applied oral dose is found
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12. FACTORS CONTRIBUTING TO FALSE POSITIVE
DPHP VALUES
DiNP – Diisononylphthalate
DiDP – Diisodecylphthalate
DiNPs (DINP1 and DINP2) and DiDP consist of different isomers
DiNP-metabolites:
7OH-Mono-methyloctylphthalate (OH-MiNP)
7oxo-Mono-methyloctylphthalate (oxo-MiNP)
7carboxy-Mono-methylheptylphthalate (cx-MiNP)
DiDP and DPHP – metabolites:
OH-Mono-isodecylphthalate (OH-MiDP)
oxo-Mono-isodecylphthalate (oxo-MiDP)
Carboxy-Mono-isodecylphthalate (cx-MiDP)
DPHP and DIDP are both C10 phthalates that are not separated by HPLC
DiNP1 contains branched C10 - side chains (up to 10 %)
DINP1, CAS No. 68515-48-0, 1,2-benzenedicarboxylic acid, di-C8-10-branched alkyl esters, C9-rich
DINP2, CAS No. 28553-12-0, Diisononylphthalate
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13. DIDP/DPHP METABOLITES IN 12 WORKERS WITH
PLASTISOL (DINP AND DIDP) EXPOSURE
HPLC-MS/MS
GC-HRMS
Sum of cx
Sum of OH
Sum of oxo
cx-MPHxP
OH-MPHP
oxo-MPHP
Median (µg/L)
15.7
44.9
6.1
<LOQ
<LOQ
0.26
Mean (µg/L
28.3
127.7
16.9
<LOQ
<LOQ
0.31
Range (µg/L)
2.1-99.7
7.7-337
1.1-49.2
<LOQ
<LOQ
<LOQ-0.72
Detection rate
(%)
100
100
100
0
0
58
Samples provided by Holger Koch, IPA
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14. DPHP ANALYSIS BY LC-MS/MS
Chromatograms of urine sample
of DiDP/DiNP exposed person,
overlaid with a 1 µg/L standard of
DPHP metabolites
Result:
sum of metabolites from
DiDP + DiNP + DPHP
is found, i.e. no selective
determination of DPHP-body
burden possible
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15. DPHP ANALYSIS BY GC-HRMS
Chromatograms of urine sample
of DiDP/DiNP exposed person,
overlaid with a 1 µg/L standard of
DPHP metabolites
Result:
DPHP-metabolites can be
separated from DiDP + DiNP
metabolites, i.e. selective
determination of DPHP-body
burden is possible
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16. DPHP IN GENERAL POPULATION
40 urine samples of general population
Analysis done by GC/HRMS
Results:
in 35 urine samples DPHP metabolites < LOQ
In 15 urine samples DPHP metabolites > LOQ – see next table
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18. CONCLUSIONS DPHP-ANALYSIS
HPLC-MS/MS only adequate for prescreening
GC-HRMS (or GC-MS/MS) necessary for selective DPHP analysis
Oxo-MPHP found in 15 out of 40 urine samples of general population,
Low range
More information:
Gries, Ellrich, Küpper, Ladermann, Leng: Analytical method for the sensitive
determination of major di-(2-propylheptyl)-phthalate metabolites in human
urine, Journal of Chromatography B, 908, 128-136, 2012
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19. ACKNOWLEDGEMENT
Human kinetic study: Holger Koch, Institute for Prevention and
Occupational Medicine of the German Social Accident Insurance –
Institute for the Ruhr-Universität Bochum (IPA)
Method development:
part of project on human biomonitoring as a cooperation between
BMU (Federal Ministry for the Environment, Nature, Conservation and Nuclear Safety)
and
VCI (German Chemical Industry Association)
Toxicological advise & project lead: Rainer Otter, BASF SE
My biomonitoring team
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