Sensitive biomonitoring of phthalate metabolites in human urine using packed capillary column switching liquid chromatography coupled to electrospray ionization ion-trap mass spectrometry

Abstract

A rapid and sensitive method for the determination of the phthalate monoesters monoethyl phthalate (MEP), monobutyl phthalate (MBP), monobenzyl phthalate (MBzP) and monoethylhexyl phthalate (MEHP), in human urine, using packed capillary column liquid chromatography coupled to electrospray quadrupole-ion trap mass spectrometry (ESI-QITMS(n)) has been developed. Sample volumes of 200 microL of deconjugated and diluted urine were loaded onto a precolumn of 30 mmx0.32 mm I.D. packed with Hypercarb 5 microm particles, using a sample carrier consisting of acetonitrile/water (15/85, v/v, adjusted to pH 2 using HCl) with a flow rate of 20 microL/min. Backflushed elution onto a 100 mmx0.32 mm I.D. analytical column packed with 5 microm Hypercarb particles was conducted using a tetrahydrofuran/water gradient where both solvents contained 10 mM ammonium acetate, at a flow rate of 4 microL/min. Determination of the monophthalates was achieved within 8 min. Ionization was performed in the negative mode and the analytes were observed as [M-H](-) at m/ z=193.1, 221.1, 255.1 and 277.0 for MEP, MBP, MBzP and MEHP, respectively. Quantification was performed in the multiple reaction monitoring (MRM) mode monitoring the fragments at m/ z=121.1, 177.0, 183.0 and 233.0 for MEP, MBP, MBzP and MEHP, respectively. The method was validated over the concentration range 2.5-125 ng/mL in pretreated urine samples, corresponding to 25-1250 ng/mL untreated urine, yielding correlation coefficients in the range 0.996-0.999. The within-assay ( n=6) and between-assay ( n=6) repeatabilities were in the range 4.0-18% and 4.8-15% RSD, respectively. The mass limits of detection were in the range 32-70 pg, corresponding to concentration limits of detection of 1.6-3.5 ng/mL of untreated urine.

Determination of bradykinin and arg‐bradykinin in rat muscle tissue by microdialysis and capillary column‐switching liquid chromatography with mass spectrometric detection

“…C 18 Zorbax columns (0.5 mm ID6150 mm and 0.3 mm ID650 mm) were purchased from Agilent (Palo Alto, CA, USA). For preconcentration of the analytes, HotSepm Tracy trace enrichment columns (G&T Septech, Kolbotn, Norway) were employed.…”

“…For preconcentration of the analytes, HotSepm Tracy trace enrichment columns (G&T Septech, Kolbotn, Norway) were employed. The dimensions were 1.0 mm ID65 mm, and the columns were packed with 5 lm Kromasil C 18 particles with a pore size of 100 . Columns packed in-house contained 3.5 lm Kromasil C 18 particles (Eka Nobel, Bohus, Sweden).…”

“…When reducing the ID of the system's column and connections, the radial dilution of the chromatographic band is reduced, resulting in a higher sensitivity when using concentration-sensitive detection principles such as ESI-MS. The overall sensitivity of an LC-ESI-MS method with regard to the concentration of an analyte in a sample can be improved by using preconcentration techniques, such as online column-switching techniques [12][13][14][15][16][17][18]. Switching techniques with capillary columns have also been used for analysis of peptides in dialysate samples, but with electrochemical detection [19].…”

The Production of Testosterone and Gene Expression in Neonatal Testes of Rats Exposed to Diisoheptyl Phthalate During Pregnancy is Inhibited

“…DIHP can be leached from plastics containing DIHP into environments such as food and water. Although there are no data on the absorption, distribution, metabolism, and excretion of DIHP in animal models and humans (ECHA, 2011), like other phthalates in the human body, DIHP may be rapidly converted to monoortho phthalate metabolites by lipase (Holm et al, 2004).…”

Determination of benzo[a]pyrene tetrols by column-switching capillary liquid chromatography with fluorescence and micro-electrospray ionization mass spectrometric detection

“…Compared to the use of conventional columns, packed capillary LC with column inner diameters ranging from 500 to 50 mm has offered enhanced mass sensitivity due to reduced dilution of the chromatographic band. 15,16 Further improvements in concentration sensitivity are accessible with focusing techniques and column switching systems, [16][17][18][19][20][21] making time-efficient large volume injections and potentially total sample exploitation available, in addition to on-line sample clean up. Furthermore, the low flow rates used with miniaturized LC columns are especially attractive with regard to electrospray ionization (ESI) mass spectrometry (MS) coupling.…”