Dimensional Liquid Research Articles

Quantification of the Plasma Concentration of Apatinib by 2-Dimensional Liquid Chromatography.

Apatinib is a new oral micromolecular tyrosine kinase inhibitor, which is mainly used as a third-line treatment for chemotherapy-refractory advanced metastatic gastric cancer patients. However, apatinib has shown dose titration and severe adverse reactions in clinical practice. Quantification of plasma concentrations of apatinib may be an effective method to balance the clinical efficacy and adverse reactions. The purpose of this study was to develop and validate a 2-dimensional liquid chromatography method for the measurement of apatinib in plasma. The analysis of apatinib was performed using a 2-dimensional high-performance liquid chromatography system. We precipitated the proteins with acetonitrile. The mobile phases consisted of a first-dimensional mobile phase (acetonitrile:methanol:25 mmol·L ammonium phosphate = 25:25:50, V/V/V, pH adjusted to 7.2 using phosphoric acid) and a second-dimensional mobile phase (acetonitrile:10 mmol·L ammonium phosphate = 28:72, vol/vol, pH adjusted to 3.7 using phosphoric acid). The ultraviolet detection wavelength was set at 340 nm. The temperature of the detector cell was 40°C, and the injection volume was 500 μL. The range of calibration curve was 15.27-1491.48 ng/mL. The accuracy and imprecision were within ±2.23% and less than 10.22%, respectively (intraday and interday). The range of recovery was 97.45%-108.92%. The intraday and interday relative SDs (reproducibility) of high-performance liquid chromatography retention times were less than 0.18% and 0.46%, respectively. In the clinical assessment, the dose range of apatinib mesylate for patients with gastric cancer was 250-500 mg every day (2-60 days), resulting in trough plasma concentrations between 272.7 and 727.8 ng/mL. A simple, convenient, accurate, and robust 2-dimensional liquid chromatography method was developed and verified, which successfully determined the plasma concentrations of apatinib in patients with gastric cancer.

Variation in the Protein Composition and Biological Activity of King Cobra (Ophiophagus hannah) Venoms.

The biochemical properties and biological activities of the venom from three individual Ophiophagus hannah (King cobra) specimens was compared. The toxicity against mice, the cytotoxicity against five cell lines, and the antioxidant activity were measured. The KV2 venom showed a higher cytotoxicity than the KV6 and the non-cytotoxic KV9 venoms. Comparative analysis of the O. hannah venom proteins was performed after 2-dimensional (2-D) denaturing gel electrophoresis and reverse phase high performance liquid chromatography (RP-HPLC). 2-D analysis by isoelectric focusing (IEF) Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) resolution of the venoms revealed significant differences between all three venoms, with most spots being unique to that venom. Only 2 out of the 13-16 distinct spots were common to all three venoms, and four spots were common to KV6 and KV9. KV2 had the highest proportion of low molecular mass spots, and KV6 and KV9 appeared more related to each other than to KV9. From peptide mass mapping by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and MASCOT-based amino acid sequence database searching, the two venom proteins that were common to all three specimens are likely to be ophanin and acidic phospholipase A2 (PLA2), whilst the proteins unique to the cytotoxic KV2 venom, included three other PLA2 proteins. The RP-HPLC pattern of KV2 was different from the other two venoms with a higher protein concentration eluting in the 31-41% (v/v) acetonitrile (ACN) fraction than for the other two venoms.

Blow-up criteria for the 3D liquid crystal flows involving two velocity components

This note is devoted to investigating blow-up criteria for the three dimensional nematic liquid crystal flows. More precisely, we mainly proved that the strong solution (u,d) can be extended beyond T, provided that the horizontal velocity components uh=(u1,u2) satisfy uh∈Ls(0,T;Lq(R3)),2s+3q≤12,6≤q≤∞.

The identification and isolation of anti-inflammatory ingredients of ethno medicine Breynia fruticosa

Ethnopharmacological relevanceBreynia fruticosa is a folk medicine in China, traditionally used to treat gastroenteritis, sore throat, eczema and arthritis. However, the bioactive ingredients are unknown. Aim of the studyTo identify and isolate the anti-inflammatory ingredients of B. fruticosa. Materials and methodsB. fruticosa extracts were fractioned by Amberchrom CG161M and Toyopearl HW40C resins. Acetic acid-induced capillary permeability mice model was used to evaluate the anti-inflammation activities of fractions. The anti-inflammatory ingredients were identified by high performance liquid chromatography/mass spectroscopy (HPLC-MS). On-line two dimensional liquid chromatography system was constructed to remove the tannins and enrich the breynins. The breynins were purified by preparative HPLC and evaluated for their anti-arthritis activities using complete Freund's adjuvant (CFA) induced arthritis rats model. ResultsThe anti-inflammatory ingredients of B. fruticosa are sulfur containing sesquiterpenoids (breynins). The on-line two dimensional preparative liquid chromatography system can effectively remove the tannins and enrich the bioactive ingredients in large scale within 1 h. Four major breynins were purified, and their structures were elucidated by analysis of MS and NMR data. Breynins can significantly prevent the rats' arthritis deterioration, with inhibition ratio 50% at dose 0.2 mg kg−1, comparable with that of indomethacin at dose 2 mg kg−1. ConclusionThe breynins have strong anti-arthritis activities, which is responsible to the anti-inflammatory effects of B. fruticosa. However, breynins are also toxic components of B. fruticosa.

Quantitative analysis of cembranoids in tobacco leaf by using heart‐cutting two‐dimensional liquid chromatography

AbstractA novel heart‐cutting two dimensional liquid chromatography method had been developed to analyze two cembranoids tobacco leaf. The reversed phase liquid chromatography column was employed for separation. Then target elution was cut to the trap column by on‐line dilution from the compensate pump. After switching the six‐port valve, the analytes were eluted to the second dimension. The two cembranoids were determined qualitatively and quantitatively by UV detection. The new method was fairly simplified sample pretreatment. When the approach was engaged to real samples, it showed high sensitivity without matrix interference. Limits of detection for two cembranoids were 0.0083 and 0.0060 mg/g, and limits of quantification were 0.027 and 0.020 mg/g, respectively. The intra‐day and inter‐day relative standard deviation of the cembranoids were within 1.8%. Spiked recoveries were ranged from 98.4 to 109.5%. Therefore, the two dimensional liquid chromatography method was successfully utilized to cembranoids detection in a wide range of the tobacco samples.

Nanofluid thin film flow of Sisko fluid and variable heat transfer over an unsteady stretching surface with external magnetic field

This research paper investigates two dimensional liquid film flow of Sisko nanofluid with variable heat transmission over an unsteady stretching sheet in the existence of uniform magnetic field. The basic governing time-dependent equations of the nanofluid flow phenomena with Sisko fluid are modeled and reduced to a system of differential equations with use of similarity transformation. The significant influence of Brownian motion and thermophoresis has been taken in the nanofluids model. An optimal approach is used to obtain the solution of the modeled problems. The convergence of the Homotopy Analysis Method (HAM) method has been shown numerically. The variation of the skin friction, Nusselt number and Sherwood number, their influence on liquid film flow with heat and mass transfer have been examined. The influence of the unsteadiness parameter [Formula: see text] over thin film is explored analytically for different values. Moreover for comprehension, the physical presentation of the embedded parameters, like [Formula: see text], magnetic parameter [Formula: see text], stretching parameter [Formula: see text] and Sisko fluid parameters [Formula: see text], Prandtl number Pr, thermophoretic parameter [Formula: see text], Brownian motion parameter [Formula: see text], Schmidt number [Formula: see text] have been represented by graph and discussed.

Darcy-Forchheimer flow of MHD nanofluid thin film flow with Joule dissipation and Navier’s partial slip

In this paper investigation is carried out on two dimensional liquid film with heat generation/absorption and variable heat transmission of nanofluid MHD flow on an unsteady stretching sheet. Flow of nanofluid phenomenon is model from the basic governing time-dependent equations. By the use of suitable similarity transformation, these basic equations are transformed to differential equations system. The nanofluid is supposed to slip along the boundary of the sheet. To find the solution of the transformed modeled equations Homotopy Analysis technique is used. A numerical survey is presented for the convergence of the implemented technique. Effects of variations of different influential parameters like Nu number and Cfx for fluid flow of liquid film with mass and heat transfer is observed. The effect of unsteadiness parameter S over thin film is explored analytically for different values. It is investigated that for large values of M that the nanofluid films velocity distribution decreases,where increase in the value of K1, a reduction in the porous medium permeability. Thickness of thermal boundary layer decreases with increasing values of S, while increase of radiation parameter, the Nusselt number also increases. Furthermore, the embedded parameters used for comprehension of the physical presentation, like inertial parameter F1, magnetic parameter M, permeability parameter K1, Eckert number Ec, Prandtl number Pr, and parameters ε1, ε2 and γ has been presented by graphs and discussed in detail.

A novel two-dimensional liquid chromatography - Mass spectrometry method for direct drug impurity identification from HPLC eluent containing ion-pairing reagent in mobile phases

In this study, a novel two dimensional liquid chromatography – mass spectrometry (2D-LC-MS) method with use of a weak anion exchange column between the 1st DLC RP column and the 2nd DLC RP column (RP1-WAX-RP2) was developed and applied to identify drug impurities from MS incompatible mobile phases containing sodium 1-octanesulfonate and non-volatile buffer. The 1st DLC conditions follow exactly the original standard HPLC method recorded in Chinese Pharmacopeia (ChP), European Pharmacopeia (EP) or US Pharmacopeia (USP). An impurity fraction was collected with a built-in sample loop (100 μL) and transferred to the WAX column where 1-octanesulfonate and phosphate were trapped and removed. While, the impurity and other cations were eluted to the 2nd D column (RP2) for separation and identification by connected IT-TOF MS. Methods were programmed and applied to identify impurities in two generic drugs, sulpiride (hydrophilic drug with logP 0.57) and dobutamine (hydrophobic drug with logP 3.6). The results indicate that the methods based on RP1-WAX-RP2 column configuration offer a feasible solution for direct impurity identification in generic drug product or API without needs of off-line desalting from the MS incompatible mobile phases containing ion-pairing reagent and non-volatile buffer.

Discovery of β2- adrenoceptor agonists in Curcuma zedoaria Rosc using label-free cell phenotypic assay combined with two-dimensional liquid chromatography

Traditional Chinese Medicines (TCMs) have been widely used in clinical practice, and provided a rich source for discovering new drug leads. However, efficient identification of active molecules responsible for the therapeutic effects of complex TCMs is still highly challenging. Here, we combined label-free cell phenotypic assay with two dimensional liquid chromatography (2DLC) to identify potential β2-adrenoceptor (β2-AR) agonists related to anti-asthmatic effect of Curcuma zedoaria Rosc (C.zedoaria), a commonly used TCM. The ethyl acetate extract of C.zedoaria was first fractionated into 26 fractions. Label-free cell phenotypic profiling was then used to locate the active sites. Orthogonal second-dimensional (D2) separation was performed on two fractions displaying agonistic effect at the β2-AR, combined with screening of the D2 fractions to track the activity. Finally, this approach led to the isolation of three known diarylheptanoids, among which diarylheptanoid b exhibited the most potent agonistic activity with an EC50 value of 5.93 μM. This result was further demonstrated through the chemical synthesis of diarylheptanoid b. It is the first time to discover that diarylheptanoids could activate the β2-AR, which may be responsible for the anti-asthmatic effect of C.zedoaria observed traditionally and in clinical application. This study also demonstrates the potential of this integrated strategy for identifying active ingredients and determining the basis of therapeutic materials in complex TCMs.

Brief Report: Anti-Calponin 3 Autoantibodies: A Newly Identified Specificity in Patients With Sjögren's Syndrome.

Autoantibodies are clinically useful for phenotyping patients across the spectrum of autoimmune rheumatic diseases. Using serum from a patient with Sjögren's syndrome (SS), we detected a new specificity by immunoblotting. This study was undertaken to identify this autoantibody and to evaluate its disease specificity. A prominent 40-kd band was detected when immunoblotting was performed using SS patient serum and lysate from rat dorsal root ganglia (DRGs). Using 2-dimensional gel electrophoresis and liquid chromatography tandem mass spectrometry peptide sequencing, the autoantigen was identified as calponin 3. Anti-calponin 3 antibodies were evaluated in sera from patients with primary SS (n = 209), patients with systemic lupus erythematosus (SLE; n = 138), patients with myositis (n = 138), patients with multiple sclerosis (MS; n = 44), and healthy controls (n = 46) by enzyme-linked immunosorbent assay. Expression of calponin 3 was assessed by immunohistochemistry. Calponin 3 was identified as a new autoantigen. Anti-calponin 3 antibodies were detected in 23 (11.0%) of the 209 SS patients, 12 (8.7%) of the 138 SLE patients, 7 (5.1%) of the 138 myositis patients, 3 (6.8%) of the 44 MS patients, and 1 (2.2%) of the 46 healthy controls. Among SS patients, the frequency of anti-calponin 3 antibodies was highest in those with neuropathies (7 [17.9%] of 39). In this subset, the frequency of anti-calponin 3 antibodies differed significantly from that in the control group (P = 0.02). Calponin 3 was expressed primarily in rat DRG perineuronal satellite cells but not neurons. Calponin 3 is a novel autoantigen. Antibodies against this protein are found in SS and associate with the subset of patients experiencing neuropathies. Intriguingly, we found that calponin 3 is expressed in DRG perineuronal satellite cells, suggesting that these may be a target in SS.

3D flow of Carreau polymer fluid over variable thickness sheet in a suspension of microorganisms with Cattaneo-Christov heat flux

Numerical study of three dimensional Carreau liquid flow with heat and mass transport features over a variable thickness sheet filled with microorganisms is analyzed. We considered the non-uniform heat sink or source and multiple slip effects. The governing non-linear partially differential expressions are developed into ordinary differential systems by using variable transformations. These expressions are solved numerically by using Runge-Kutta fourth order method connected with shooting methodology. A Parametric study is implemented to demonstrate the effects of Hartmann number, Prandtl number, Weissenberg number, Peclet number, chemical reaction and heat sink/source parameters on liquid velocity, temperature and concentration profiles. The quantities of physical interest are described within the boundary layer. From this analysis, we found that the magnetic parameter decrease the local Sherwood and local Nusselt numbers for both and cases. The constraint of chemical reaction enhances the mass transfer rate and decelerates the density of motile mass transfer rate. The space dependent and temperature dependent heat source/sink suppress the local Nusselt number.

Proteomic analysis on recurrence-associated proteins for large hepatocellular carcinoma following radical resection

Objective Using comparative proteomic approach to analyze proteins relevant to the recurrence of large hepatocellular carcinoma (HCC). Methods The HCC samples of group R≤6 m (n=9), R6-12 m (n=9), R>24 m (n=6) were analyzed using the technique of isobaric tags for relative and absolute quantification (iTRAQ)-two dimensional liquid chromatography tandem mass spectrometry (2DLC-MS/MS). The differentially expressed proteins were confirmed by real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) and Western blotting using frozen tissues (n=30). To further analyzed the differentially expressed proteins, immunohistochemical experiment was performed using paraffin-embedded tissue (n=201), and the results were analyzed using clinical-pathological characteristics. Results We screened 10 differentially expressed proteins with the different time of recurrence. Five proteins were up-regulated [calcium binding protein A9 (S100A9), myeloperoxidase (MPO), apolipoprotein A4 (APOA4), transmembrane protein 97 (TMEM97), human nuclear receptor hblf (NR5A2)] and five proteins were down-regulated [dehydrogenase / reductase 2 (DHRS2), three or four amino acid repeat domain 4 (TTC4), chromatin remodeling factor (CHD2), 4-hydroxybenzoate dioxygenase (HPD), methylamine transferase-cyclase deaminase (FTCD)]. The FQ-PCR and Western blot assays showed that the expression level of TMEM97 was consistent with the that of proteomic. The immunohistochemical experiment showed that the high expression level of TMEM97, the high level of serum alpha fetal protein (AFP), multiple tumor, larger tumor diameter, portal vein tumor thrombus (PVTT), microvascular tumor thrombus (MVI), incomplete tumor capsule, transfusions were the independent risk factors of tumor recurrence. Conclusion There are many proteins associated with the recurrence of large HCC. TMEM97 might be used as a potential alternative marker for recurrence. Key words: Hepatocellular carcinoma; Recurrence; Proteomic; Transmembrane protein 97

Analysis of hydrophobically modified ethylene oxide urethane rheology modifiers by comprehensive two dimensional liquid chromatography

Hydrophobically modified ethylene oxide urethane (HEUR) rheology modifiers are polymers used widely in waterborne coatings and other consumer products. The incorporation of hydrophobic end-groups significantly affects the thickening performance of HEURs. Therefore, understanding the degree of incorporation of hydrophobic end-groups on the polymer chain can help gain important insights on the structure/property relationship for HEUR rheology modifiers.A comprehensive two-dimensional liquid chromatography (2D-LC) method was developed for separating polymeric HEUR rheology modifiers based on the number of hydrophobic end-groups incorporated on the polymer chain. Our 2D-LC method uses a size exclusion chromatography (SEC) separation in the first dimension (1D) using an ultra-high performance Advance Polymer Chromatography (APC) column and a gradient reversed-phase liquid chromatography (RPLC) separation in the second dimension (2D). A low flow rate was used in the first dimension SEC separation to minimize the strong organic eluent transferred to the second dimension LC column. A small inner diameter (ID) LC column was used for the second dimension to reduce the total solvent consumption for routine analysis of process samples. The 1D flow rate, 2D transfer volume and gradient profile were all optimized to avoid polymer breakthrough and to achieve optimal separation of the polymer chains based on end-groups. Three types of polymer chains with 0, 1, and 2 terminal hydrophobes were successfully separated using this method. The total run time was further reduced by implementing flow programing in the first dimension separation. The 2D-LC method was applied to study how the polymerization process recipes affected hydrophobe incorporation and how the hydrophobe incorporation correlated with thickening efficiency. The method was also used to separate HEUR rheology modifier with branched polymer architecture.

Expression of HSP90AA1/HSPA8 in hepatocellular carcinoma patients with depression.

BackgroundDepression may influence susceptibility to cancer, and the genes and signaling pathways that may mediate this association are unclear.MethodsHere, we used isobaric tagging for relative and absolute quantitation, 2-dimensional liquid chromatography, and mass spectrometry to compare proteins expressed in hepatocellular carcinoma in patients with or without depression.ResultsA total of 89 proteins were up-regulated and 44 were down-regulated in patients with depression. HSP90AA1 and HSPA8 were up-regulated, which correlated with elevated levels of VEGF, VEGFR2, PI3K, and AKT1 and reduced levels of caspase 9 and BAD. Disease-free survival rate was significantly lower and risk of tumor recurrence was significantly higher in patients with depression, which may reflect high HSP90AA1/HSPA8 expression.ConclusionThese results suggest that the VEGF/VEGFR2 pathway may be associated with HCC recurrence in patients expressing high levels of HSP90AA1/HSPA8.

Electronic sound modes and plasmons in hydrodynamic two-dimensional metals

Using an analytically tractable kinetic model of a two dimensional Fermi liquid of electrons, we characterize the crossovers between zero sound, first sound and plasmons. For experimentally realized Fermi liquids in a hydrodynamic limit, both zero and first sound waves are essentially replaced by plasmons. The plasmon dispersion relation is robust against hydrodynamic effects, up to acquiring the viscous-limited decay rate of a first sound wave in the hydrodynamic limit. We discuss implications for experiments in clean two dimensional electron gases.

Exploration of differentially expressed plasma proteins in patients with lung adenocarcinoma using iTRAQ-coupled 2D LC-MS/MS.

Lung adenocarcinoma is characterized by early asymptomatic progression and metastasis. Appearance of respiratory symptoms usually means the disease is aggravated. The aim of this study was to identify the protein profile in plasma of lung adenocarcinoma of stages I-IV, and look for novel diagnostic biomarkers. Isobaric tags for relative and absolute quantification (iTRAQ) coupled with two dimensional liquid chromatography - tandem mass spectrometry technology (2D LC-MS/MS) was applied to separate and identify differential expression of proteins in plasma specimens from 10 healthy individuals, 10 patients with pneumonia, 7 patients with lung adenocarcinoma of stages I-II, respectively, and 10 patients with lung adenocarcinoma of stages III-IV, then analyze the functions of the differential expression of proteins by bioinformatics. ADAMTS-like protein 4, Fibrinogen-like protein 1 precursor, secretoglobin family 3A member 2 and haptoglobin were up-regulated in patients with lung adenocarcinoma by proteomics analysis, and the expression levels of SCGB3A2 and Hp by ELISA were consistent. Pathway analysis of identified differential expression of proteins showed they were mainly involved in chemokine/p53/TGF-beta signaling pathway. Plasma SCGB3A2 is a potential maker for diagnosis of primary pulmonary adenocarcinoma. Abnormal post-translational protein modification may be associated with the progression of lung cancer.

The PBII gene of the human salivary proline-rich protein P-B produces another protein, Q504X8, with an opiorphin homolog, QRGPR

ObjectivesThe NCBI gene database and human-transcriptome database for alternative splicing were used to determine the expression of mRNAs for P-B (SMR3B) and variant form of P-B. The translational product from the former mRNA was identified as the protein named P-B, whereas that from the latter has not yet been elucidated. In the present study, we investigated the expression of P-B and its variant form at the protein level. DesignTo identify the variant protein of P-B, (1) cationic proteins with a higher isoelectric point in human pooled whole saliva were purified by a two dimensional liquid chromatography; (2) the peptide fragments generated from the in-solution of all proteins digested with trypsin separated and analyzed by MALDI-TOF-MS; and (3) the presence or absence of P-B in individual saliva was examined by 15% SDS-PAGE. ResultsThe peptide sequences (I37PPPYSCTPNMNNCSR52, C53HHHHKRHHYPCNYCFCYPK72, R59HHYPCNYCFCYPK72 and H60HYPCNYCFCYPK72) present in the variant protein of P-B were identified. The peptide sequence (G6PYPPGPLAPPQPFGPGFVPPPPPPPYGPGR36) in P-B (or the variant) and sequence (I37PPPPPAPYGPGIFPPPPPQP57) in P-B were identified. The sum of the sequences identified indicated a 91.23% sequence identity for P-B and 79.76% for the variant. There were cases in which P-B existed in individual saliva, but there were cases in which it did not exist in individual saliva. ConclusionsThe variant protein is produced by excising a non-canonical intron (CC-AC pair) from the 3′-noncoding sequence of the PBII gene. Both P-B and the variant are subject to proteolysis in the oral cavity.

Separation of chemical compositions in root of Rumex patientia L. with off-line two-dimensional liquid chromatography

An innovative analytical method based on the off-line two-dimensional reversed-phase/reversed-phase liquid chromatography (2D-RPLC/RPLC) was established to separate the components of root of Rumex patientia L. The chromatograms of ethyl acetate extract of root of Rumex patientia L. on a phenyl/tetrazolium column (250 mm×4.6 mm, 7 μm) and a Unitary C18 column (250 mm×4.6 mm, 7 μm) were compared, and they showed different separation abilities. A phenyl/tetrazolium column was used for the first dimensional separation with 0.1% (v/v) formic acid aqueous solution and methanol as mobile phases, and 18 fractions was collected. The second dimensional liquid chromatography analysis was carried out on a Unitary C18 column with 0.1% (v/v) formic acid aqueous solution and methanol as mobile phases. Based on the experiment setup and results, it was concluded that off-line 2D-LC can be an effective method for the separation of the trace components and the screening of active compounds of root of Rumex patientia L.

Coarsening and pattern formation during true morphological phase separation in unstable thin films under gravity.

We address in detail the problem of true morphological phase separation (MPS) in three-dimensional or (2+1)-dimensional unstable thin liquid films (>100nm) under the influence of gravity. The free-energy functionals of these films are asymmetric and show two points of common tangency, which facilitates the formation of two equilibrium phases. Three distinct patterns formed by relative preponderance of these phases are clearly identified in "true MPS". Asymmetricity induces two different pathways of pattern formation, viz., defect and direct pathway for true MPS. The pattern formation and phase-ordering dynamics have been studied using statistical measures such as structure factor, correlation function, and growth laws. In the late stage of coarsening, the system reaches into a scaling regime for both pathways, and the characteristic domain size follows the Lifshitz-Slyozov growth law [L(t)∼t^{1/3}]. However, for the defect pathway, there is a crossover of domain growth behavior from L(t)∼t^{1/4}→t^{1/3} in the dynamical scaling regime. We also underline the analogies and differences behind the mechanisms of MPS and true MPS in thin liquid films and generic spinodal phase separation in binary mixtures.

Simultaneous quantification of fluoxetine and norfluoxetine in colostrum and mature human milk using a 2-dimensional liquid chromatography–tandem mass spectrometry system

A two-dimensional liquid chromatography system coupled to triple quadrupole tandem mass spectrometer (2D LC–MS/MS) was employed for the determination of fluoxetine (FLU) and norfluoxetine (N-FLU) in colostrum and mature milk by direct sample injection. With a run time of 12 min representing a gain in throughput analysis, the validated methods furnished selectivity, extraction efficiency, accuracy, and precision in accordance with the criteria preconized by the European Medicines Agency guidelines. With a linear range of 3.00–150 ng/mL for FLU and 4.00–200 ng/mL for N-FLU they were applied to the analysis of colostrum and mature milk samples from nursing mothers. The paper discusses the differences and similarity of sample preparation for this two sample matrices. The herein reported methods are an advance in sample preparation procedures providing waste reduction and a sustainable approach.