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- LC-MS/MS (2) (entfernen)
HPLC-MS/MS quantification of hepcidin-25, a new promising iron biomarker, in human serum samples
(2017)
Hepcidin-25 has attracted much attention ever since its discovery in 2001. It is widely recognized that this liver produced peptide hormone plays a major role in the regulation of iron levels in mammals. Hepcidin levels could reveal important clinical information about several pathological states in patients suffering from iron-related disorders such as chronic kidney disease (CKD) or hereditary haemochromatosis (HH). Despite significant efforts though, the development of a reliable assay to quantify hepcidin proved to be problematic for the last 15 years.
With the aim to tackle the current difficulties in hepcidin quantification and improve the status of this promising biomarker in the clinical field, we developed a rapid and robust analytical strategy for the quantification of hepcidin-25 in human samples based on HPLC-MS/MS (QqQ) to be implemented in routine laboratories. The novelty of the method is the use of special HPLC vials to avoid adsorptive losses due to the basic character of the peptide that causes interaction with the silanol groups of the vial’s glass surface. Up to 90% decrease in the MS/MS signal was observed, when commercial HPLC vials were used, while vials treated with 3-(2-aminoethylamino)propylmethyl-dimethoxysilane or 1H,1H,2H,2H-perfluorooctyltriethoxysilane, leading to no significant losses in the dynamic range of physiological hepcidin-25 mean serum levels (10-20 µg/L).
Careful analytical validation was performed for determining the reproducibility, repeatability, limit of quantification (0.5 µg/L) and linearity (0.5-40 µg/L) of the method. Serum samples from 9 healthy volunteers were analyzed with a median hepcidin-25 level of 3.3 µg/L, comparable to results reported in the literature.
Chlorpyrifos (CPF), an anticholinesterase organophosphate insecticide, is commonly used to control pests in agricultural sectors. In recent years, it is one of the most frequently detected residues in fruits and vegetables. On the other hand, pesticides including chlorpyrifos undergo extensive abiotic (industrial processes, waste treatments and photodegradations) and/or biotic (metabolism and microbial activities) processes which lead to transformation products (TPs) with different toxicity. Furthermore, lack of representative standards and complexity of transformation mechanisms make monitoring of TPs in real samples difficult.
The aim of this work was to investigate CPF and its TPs in selected food matrices. Representative standards of TPs were synthesized by electrochemistry coupled online to liquid chromatography-mass spectrometry (EC/LC/MS) that equipped with a follow-through and/or synthesis cell with boron doped diamond working electrode. The TPs were characterized by LC-MS/MS and high resolution mass spectrometry (HRMS) and used for real sample investigations. Different fruit and spice samples (fortified by TPs standards and blank) were extracted by dispersive solid phase extraction (dSPE) and analyzed by LC-MS/MS.
Recoveries were obtained ranging between 94 – 101% (with matrix effect 85 – 97%). The method limit of detection (LOD) and quantification (LOQ) for CPF were 1.9 and 5.7 µg/kg, respectively. Among investigated samples CPF was detected in fresh lemon, black pepper and fenugreek seed with a content of 104, 31 and 4 µg/kg, respectively. Coriander and cinnamon samples also contained trace levels of CPF (<LOD). Transformation products of CPF mainly diethylthiophosphate (DETP), chlorpyrifos oxon (CPF oxon) and trichloropyridinol (TCP) were detected alongside of the parent compound in different samples. Hence, by synthesizing reference standards using EC/LC/MS we were able to detect the main TPs of CPF in real food samples. The results show that not only parent residues but also monitoring of TPs is vital to ensure future food safety.