A new strategy implementing mass spectrometry in the diagnosis of congenital disorders of N-glycosylation (CDG).

Objectives: Congenital disorders of N-glycosylation (CDG) are a large group of rare metabolic disorders caused by defects in the most common post-translational modification of proteins. CDGs are often difficult to diagnose as they are manifested with non-specific symptoms and signs. Analysis of serum transferrin (TRF) isoforms, as the classical procedure used to identify a CDG patient, enables to predict pathological steps in the N-linked glycosylation process.

Development of a fast LC-MS/MS protocol for combined measurement of six LSDs on dried blood spot in a newborn screening program.

New treatment options and improved strategies for Lysosomal Storage Disorders (LSDs) diagnosis on dried blood spot (DBS) have led to the development of several pilot newborn screening programs. Building on a previously published protocol, we devised a new 6-plex assay based on a single DBS punch incubated into a buffer containing a combination of substrates (GAA, GLA, ASM, GALC, ABG and IDUA). This new protocol incorporates a new trapping and clean-up procedure using perfusion chromatography connected on-line with an analytical column for analyte separation, after enzymatic reaction.

Practical fluorimetric assay for the detection of anticancer drug SN-38 in human plasma.

The implementation of therapeutic drug monitoring in the routine clinical practice in oncology is mainly limited by the lack of therapeutic indexes for the majority of the anticancer drugs, and by the absence of suitable analytical tools, which can accurately quantify in real time the concentration of the administered drugs and their relevant metabolites in biological fluids. In this work, a simple and efficient fluorimetric determination of SN-38, the active metabolite of the anticancer drug irinotecan, was developed and applied to human plasma samples. The intrinsic fluorescence of SN-38 allowed its quantification in the range 10-500 ng mL with a LOQ of 5.

Enzyme-Based Electrochemical Biosensor for Therapeutic Drug Monitoring of Anticancer Drug Irinotecan.

Therapeutic drug monitoring (TDM) is the clinical practice of measuring pharmaceutical drug concentrations in patients' biofluids at designated intervals, thus allowing a close and timely control of their dosage. To date, TDM in oncology can only be performed by trained personnel in centralized laboratories and core facilities employing conventional analytical techniques (e.g.

Analysis of organo-chlorine pesticides residue in raw coffee with a modified "quick easy cheap effective rugged and safe" extraction/clean up procedure for reducing the impact of caffeine on the gas chromatography-mass spectrometry measurement.

The control of pesticide residues on raw coffee is a task of great importance due to high consumption of this beverage in Italy and in many other countries. High caffeine content can hamper extraction and measurement of any pesticide residue. A tandem extraction protocol has been devised by exploiting the quick easy cheap effective rugged and safe (QuEChERS) scheme for extraction, coupled to a dispersive liquid-liquid micro-extraction (DLLME) in order to drastically reduce caffeine content in the final extract.

Screening of lysosomal storage disorders: application of the online trapping-and-cleanup liquid chromatography/mass spectrometry method for mucopolysaccharidosis I.

In recent years, new treatments have become available to treat some lysosomal storage disorders (LSDs) and many studies suggest that there is a benefit with starting therapy early. Newborn screening should detect diseases early enough for prompt treatment. Some countries include additional conditions, such as some LSDs, into their newborn screening panels.

A reliable and rapid tool for plasma quantification of 18 psychotropic drugs by ESI tandem mass spectrometry.

A simple liquid chromatographic tandem mass spectrometry (LC-MS/MS) method has been developed for simultaneous analysis of 17 basic and one acid psychotropic drugs in human plasma. The method relies on a protein precipitation step for sample preparation and offers high sensitivity, wide linearity without interferences from endogenous matrix components. Chromatography was run on a reversed-phase column with an acetonitrile-H₂O mixture.

Development of a highly sensitive method for the quantification of estrone and estradiol in serum by liquid chromatography tandem mass spectrometry without derivatization.

Measurement of estrone (E1) and estradiol (E2) values <1 pg/mL (3.7 pmol/L) is necessary for postmenopausal, pediatric and male serum samples. Until now this was rarely reached and only through derivatization which can present problems for estradiol.

Development of a fast and simple LC-MS/MS method for measuring the F2-isoprostanes in newborns.

Background: Quantification of F(2)-IsoPs isomer has been regarded as the "gold standard" to assess oxidative stress status in various adult and neonatal human diseases. These methods require high amounts of plasma.

Objective: To develop a fast and simple LC-MS/MS method for measuring F(2)-isoprostanes in newborns.

Serum steroid profiling by isotopic dilution-liquid chromatography-mass spectrometry: comparison with current immunoassays and reference intervals in healthy adults.

Background: The simultaneous, rapid and reliable measurement of a wide steroid panel is a powerful tool to unravel physiological and pathological hormone status. Clinical laboratories are currently dominated by high-throughput immunoassays, but these methods lack specificity due to cross-reactivity and matrix interferences. We developed and validated an isotopic dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS) method for the simultaneous measurement of cortisol, corticosterone, 11deoxycortisol, androstenedione, deoxycorticosterone (DOC), testosterone, 17OHprogesterone, dehydroepiandrosterone (DHEA) and progesterone in serum, and compared it to routine immunoassays employed in our laboratory.

High-throughput plasma docetaxel quantification by liquid chromatography-tandem mass spectrometry.

Background: The most valuable treatment option for breast, prostate and lung carcinomas is at present represented by a low dose of docetaxel, administered on a weekly basis. A better understanding of docetaxel pharmacokinetic and pharmacodynamic profiles could lead to an improvement in this dose regimen efficacy.

Methods: In this study a high-throughput method is described for the rapid quantification of docetaxel for large clinical pharmacology investigations.

Fast liquid chromatography-tandem mass spectrometry method for routine assessment of irinotecan metabolic phenotype.

Irinotecan (CPT-11) is an anticancer drug with a complex in vivo metabolism widely used in the treatment of colon cancer. The assessment of the CPT-11 metabolic phenotype is an important clinical component for personalizing the administered dose. In this study, we report the development of a rapid and sensitive liquid chromatography-tandem mass spectroscopy method for the simultaneous quantitation of CPT-11 and its major metabolites generated by hydrolysis (SN-38, active metabolite) or through oxidative (NPC and APC) and glucuronidation (SN-38G) pathways.

Liquid chromatography tandem mass spectrometry assay for fast and sensitive quantification of estrone-sulfate.

Background: The circulating pool of estrone-sulfate is considered as a "reservoir" of slowly-metabolized estrogen that can be exploited for assessing overall individual estrogenicity. The aim of this study was to develop a rapid and sensitive liquid chromatography-tandem mass spectrometry assay for the determination of estrone-sulfate, suitable for routine clinical investigations.

Methods: The proposed assay is based on a simple protein precipitation procedure and on a fast measurement with a triple-quadrupole mass spectrometer operating in negative ion mode and in multiple reaction monitoring.

Determination of total homocysteine in plasma using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS).

A detailed protocol using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS) is described for the determination of the total homocysteine (HCY) in plasma. Sample preparation is simple and relies on the complete reduction of any homocystine ((HCY)(2)) or protein-bound homocysteine, followed by the plasma protein precipitation. Any factor influencing the measurement is addressed.

Development of a method for the quantification of 1alpha,25(OH)2-vitamin D3 in serum by liquid chromatography tandem mass spectrometry without derivatization.

Quantification of 1alpha,25(OH)(2)-vitamin D(3) in serum is technically challenging because of its very low concentration. Even mass spectrometry faces a challenge due to the low sensitivity for this molecule, unless a specific derivatization is implemented. Therefore, there is still a need for a robust, simplified, sensitive and specific liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the quantification of 1alpha,25(OH)(2)-vitamin D(3).

New strategy for the screening of lysosomal storage disorders: the use of the online trapping-and-cleanup liquid chromatography/mass spectrometry.

The aim of this study was to set up a robust method suitable for large-scale studies (screening) with a minimized preparation process and with reduced running costs, for measuring five enzyme activities on dried blood spots by a new and simplified tandem mass spectrometry-based method. After incubation, all 5 reaction mixtures, carried out separately, were stopped, combined together, and centrifuged. The cleaning-up of the injected mixture was performed through a fast online trapping step preceding a liquid chromatography/tandem mass-spectrometry measurement.

A liquid chromatography-tandem mass spectrometry method for the simultaneous determination of exemestane and its metabolite 17-dihydroexemestane in human plasma.

A simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantitation of exemestane (Exe) and its main metabolite 17-dihydroexemestane (DhExe) in human plasma. The analytes were extracted by protein precipitation with acetonitrile, containing stable 13C-labelled Exe (13C3-Exe) as internal standard, and measured by LC-MS/MS. The best chromatographic separation of the analytes from the interferences was achieved by using a Phenyl column operating under isocratic regime conditions.

Setting up a 2D-LC/MS/MS method for the rapid quantitation of the prostanoid metabolites 6-oxo-PGF(1alpha) and TXB2 as markers for hemostasis assessment.

6-oxo-PGF(1alpha) and TXB(2) are the metabolites of the prostanglandin PGI(2) and of the thromboxane TXA(2), respectively. PGI(2) and TXA(2) are arachidonic acid-derived compounds which regulate the blood hemostasis. Their quick metabolism leads to the 6-oxo-PGF(1alpha) and TXB(2) metabolites in plasma.

Rapid and sensitive analysis of vincristine in human plasma using on-line extraction combined with liquid chromatography/tandem mass spectrometry.

A simple and rapid method has been developed and validated for the quantitation of vincristine in human plasma by liquid chromatography/tandem mass spectrometry (LC/MS/MS) with atmospheric pressure chemical ionization using on-line solid-phase extraction. The method uses vinblastine as internal standard and the sample preparation is limited just to a plasma protein precipitation step. Further sample clean-up is carried out on-line through a perfusion column preceding an analytical phenyl LC column, the latter directly connected to the mass spectrometer.

Second-tier test for quantification of alloisoleucine and branched-chain amino acids in dried blood spots to improve newborn screening for maple syrup urine disease (MSUD).

Background: Newborn screening for maple syrup urine disease (MSUD) relies on finding increased concentrations of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine by tandem mass spectrometry (MS/MS). d-Alloisoleucine (allo-Ile) is the only pathognomonic marker of MSUD, but it cannot be identified by existing screening methods because it is not differentiated from isobaric amino acids. Furthermore, newborns receiving total parenteral nutrition often have increased concentrations of BCAAs.

A rapid method for the quantification of the enantiomers of Warfarin, Phenprocoumon and Acenocoumarol by two-dimensional-enantioselective liquid chromatography/electrospray tandem mass spectrometry.

We describe a new fully validated enantioselective LC-MS/MS method for stereospecific quantification of both the racemic forms of Warfarin (WF), Phenprocoumon and Acenocoumarol in human plasma. Measurement specificity was assessed by using different blank donor plasma samples, where no interfering reagent peak appeared at the retention time (RT) of the targeted analytes. Response was linear for all analytes.

Implementing tandem mass spectrometry as a routine tool for characterizing the complete purine and pyrimidine metabolic profile in urine samples.

Purines and pyrimidines are the basic constituents of DNA and RNA and constitute the basis of at least 50 other important compounds that serve equally vital but separate roles as integral components of intracellular mononucleotide pools. They maintain the supply of these basic components to the different nucleotide pools through an extremely efficient mechanism involving the degradation and recycling of the daily waste products of normal cell turnover. We have developed an LC-MS/MS diagnostic and routine monitoring method for known defects due to both purine and pyrimidine metabolism in a single analysis.

A robust liquid chromatography tandem mass spectrometry method for total plasma homocysteine determination in clinical practice.

Background: Total plasma homocysteine has emerged as an independent risk factor for vascular disease. To meet increasing requests by clinicians for this homocysteine determination, a rapid assay for a routine use has been developed.

Methods: A robust, stable, isotope-dilution liquid chromatography tandem mass spectrometry (LC/MS/MS) method is described, including all the practical details and analytical performance results.

Inclusion of MPA and in a rapid multi-drug LC-tandem mass spectrometric method for simultaneous determination of immunosuppressants.

Background: [corrected] Mycophenolic Acid (MPA) is often co-prescribed as part of a multiple immunosuppressant drug regimen. In this study an established LC-MS/MS method for the measurement of immunosuppressants cyclosporine A, tacrolimus, sirolimus and everolimus was optimized to include MPA without changing the sample pre-treatment and the LC-MS/MS configuration.

Methods: The sample pretreatment for EDTA-plasma was used as for whole blood.