Quadrupole Mass Detector Research Articles

Oxidative degradation and mineralization of bentazone from water

Bentazone degradation efficiency and mineralization in water solutions using chlorine dioxide treatment were evaluated. Double distilled water and a river water sample spiked with bentazone were studied and compared after chlorine dioxide treatment. Degradation efficiency was determined using high-performance liquid chromatography (HPLC). Daphnia magna toxicity testing and total organic carbon (TOC) analysis were used to ascertain the toxicity of the degraded solutions and mineralization degree. Bentazone degradation products were identified using gas chromatography with a triple quadrupole mass detector (GC-MS-MS). A simple mechanistic scheme for oxidative degradation of bentazone was proposed based on the degradation products that were identified. Decrease in D. magna mortality, high degradation efficiency and partial bentazone mineralization were achieved by waters containing bentazone degradation products, which indicate the formation of less toxic compounds than the parent bentazone and effective removal of bentazone from the waters. Bentazone degraded into four main degradation products. Humic acid from Sava River water influenced bentazone degradation, resulting in a lower degradation efficiency in this matrix (about 10% lower than in distilled water). Chlorine dioxide treatment of water to degrade bentazone is efficient and offers a novel approach in the development of new technology for removal of this herbicide from contaminated water.

Degradation Products, Mineralization, and Toxicity Assessment of Pesticides Malathion and Fenitrothion

The aim of this study was to investigate, analyze, and compare applied techniques suitable for achieving efficient removal of organophosphorus pesticides (OPPs) (malathion and fenitrothion) from aqueous solutions and analyze the degradation products and processes. Pesticide degradation efficiency (%) was monitored by high-performance liquid chromatography (HPLC) equipped with a photodiode array detector (DAD), while mineralization degree was determined by total organic carbon analysis (TOC). Daphnia magna was used for screening the environmental safety aspects of the degradation methods, i.e., for assessing the toxicity of solutions obtained after degradation. Additionally, a surface river water was utilized to examine the likely influence of organic matter on the pesticides’ degradation. Pesticide degradation products were identified using gas chromatography with a triple quadrupole mass detector (GC-MS/MS) as well as ultrahigh-performance liquid chromatography coupled with a linear ion trap, Orbitrap mass spectrometer (UHPLC-LTQ Orbitrap MS), and a simple pesticide degradation mechanism is proposed. Removal of pesticides from water using chlorine dioxide was successful, resulting in high degradation efficiency (98% for malathion and 81% for fenitrothion). Partial mineralization was achieved, and Daphnia magna mortality decreased in the waters containing degradation products (compared with the parent pesticides), indicating that the solutions formed were less toxic than the parent pesticides. Lower degradation rates (80% for malathion and 72% for fenitrothion) in Sava River water were measured, indicating the influence of the organic matter contained in this naturally occurring surface water. The results prove that chlorine dioxide could be used as an agent for successful removal of these OPPs from water.

Development and validation of a selective marker-based quantification of polysorbate 20 in biopharmaceutical formulations using UPLC QDa detection

Polysorbates are widely used as non-ionic surfactant in biopharmaceutical formulations. Recently, the degradation of polysorbate moved into the focus of attention, because in several published studies it was described, that stability issues in polysorbate containing formulations were observed leading to the formation and appearance of sub-visible and visible particles. For this reason, monitoring of polysorbate and its degradation products is of importance throughout the development of parenterals. The aim of the study was to develop a method for the selective marker-based quantification of adequate polysorbate 20 components of interest without the need to apply derivatization or complex detection techniques. A single quadrupole mass (QDa) detector was used coupled to an ultra-high performance liquid chromatography (UPLC) system.Method development was based on a reversed phase-high performance liquid chromatography assay coupled to a charged aerosol detector (RP-HPLC CAD). Instead of a charged aerosol detector (CAD) a QDa detector was used in order to significantly improve the selectivity. The focus of this study is the development of the QDa based method for the analysis of polysorbate 20. Modifications of the mobile phase and the type of chromatography column allowed the separation of several components of polysorbate 20 from polar non-esterified to apolar higher order species. In addition, a multitude of components could be quantified by their individual m/z values. The peak assignment identified 676 compounds which originated from polysorbate 20. Some of these were selected and defined as marker components. It was shown that the developed method is capable to determine polysorbate 20 in different biopharmaceutical formulations. The proposed assay is based on a smart sample preparation as well as a unique calibration procedure that make the determination of several selected components achievable. Furthermore, it was successfully demonstrated that the analytical procedure is valid to reliably quantify several polysorbate 20 components at its 100% level (corresponds to 0.4 mg/mL intact polysorbate 20) and even at lower concentrations that occur e.g. in case of polysorbate 20 degradation. In conclusion, the method is beneficial to determine selected polysorbate 20 species during formulation development of biopharmaceuticals as well as during stability testing and trouble shooting.

LC-MS Profile, Gastrointestinal and Gut Microbiota Stability and Antioxidant Activity of Rhodiola rosea Herb Metabolites: A Comparative Study with Subterranean Organs.

Golden root (Rhodiola rosea L., Crassulaceae) is a famous medical plant with a one-sided history of scientific interest in the roots and rhizomes as sources of bioactive compounds, unlike the herb, which has not been studied extensively. To address this deficiency, we used high-performance liquid chromatography with diode array and electrospray triple quadrupole mass detection for comparative qualitative and quantitative analysis of the metabolic profiles of Rhodiola rosea organs before and after gastrointestinal digestion in simulated conditions together with various biochemical assays to determine antioxidant properties of the extracts and selected compounds. R. rosea organs showed 146 compounds, including galloyl O-glucosides, catechins, procyanidins, simple phenolics, phenethyl alcohol derivatives, (hydroxy)cinnamates, hydroxynitrile glucosides, monoterpene O-glucosides, and flavonol O-glycosides, most of them for the first time in the species. The organ-specific distribution of compounds found for catechins, procyanidins, and cinnamyl alcohols and glucosides was typical for underground organs and flavonoids and galloylated glucoses concentrated in the herb. Extracts from rhizomes, leaves and flowers showed high phenolic content and were effective scavengers of free radicals (2,2-diphenyl-1-picrylhydrazyl (DPPH•), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), O2•−, •OH) and protected β-carotene in a bleaching assay. Digestion in the gastric and intestine phase influenced the composition of R. rosea extracts negatively, affecting the content of catechins, procyanidins, and galloyl glucoses, and therefore, the antioxidativity level. After gut microbiota treatment, the antioxidant capacity of rhizome extract was lower than leaves and flowers due to the aglycone composition found in the colonic phase of digestion. Our study demonstrated that the herb of R. rosea is a rich source of metabolites with high antioxidant properties and could be a valuable plant for new bioactive products.

Examination of degradation and ecotoxicology of pethoxamid and metazachlor after chlorine dioxide treatment.

Chlorine dioxide has been reported as very efficiently removing pesticides and other organic compounds from water matrixes. Due to pesticide toxicity and potential toxicity of their degradation products, it is important to monitor these compounds as environmental pollutants in ground and surface waters. Evaluating the effects of chlorine dioxide treatment is necessary, and toxicity studies are used to ascertain the severity of effects of intermediates due to incomplete degradation of the parent compounds. In this paper, for the first time, chlorine dioxide is applied and evaluated for the removal of chloroacetamide herbicides (pethoxamid and metazachlor) from waters (deionized water and Sava River water). The degradation degree of herbicides was measured by high-performance liquid chromatography, the main degradation products were identified using gas chromatography with a triple quadrupole mass detector, and the degree of mineralization was monitored by total organic carbon analysis. Four and two degradation products were identified after pethoxamid and metazachlor degradation, respectively. Total organic carbon analysis showed mineralization occurred, but it was incomplete. The mineralization and the characteristics of the degradation products obtained were tested using Daphnia magna and showed lower toxicity than the parent herbicides. The advantage of the applied treatment was a very high degradation percentage for pethoxamid removal from deionized water and Sava River water (100% and 97%, respectively), with higher mineralization efficiency (65%) than metazachlor. Slightly lower degradation efficiency in the Sava River water was due to chlorine dioxide oxidizing the herbicides and dissolved organic matter simultaneously.

Evaluation of azamethiphos and dimethoate degradation using chlorine dioxide during water treatment.

Chlorine dioxide (ClO2) degradation of the organophosphorus pesticides azamethiphos (AZA) and dimethoate (DM) (10 mg/L) in deionized water and in Sava River water was investigated for the first time. Pesticide degradation was studied in terms of ClO2 level (5 and 10 mg/L), degradation duration (0.5, 1, 2, 3, 6, and 24 h), pH (3.00, 7.00, and 9.00), and under light/dark conditions in deionized water. Degradation was monitored using high-performance liquid chromatography. Gas chromatography coupled with triple quadrupole mass detector was used to identify degradation products of pesticides. Total organic carbon was measured to determine the extent of mineralization after pesticide degradation. Real river water was used under recommended conditions to study the influence of organic matter on pesticide degradation. High degradation efficiency (88-100% for AZA and 85-98% for DM) was achieved in deionized water under various conditions, proving the flexibility of ClO2 degradation for the examined organophosphorus pesticides. In Sava River water, however, extended treatment duration achieved lower degradation efficiency, so ClO2 oxidized both the pesticides and dissolved organic matter in parallel. After degradation, AZA produced four identified products (6-chlorooxazolo[4,5-b]pyridin-2(3H)-one; O,O,S-trimethyl phosphorothioate; 6-chloro-3-(hydroxymethyl)oxazolo[4,5-b]pyridin-2(3H)-one; O,O-dimethyl S-hydrogen phosphorothioate) and DM produced three (O,O-dimethyl S-(2-(methylamino)-2-oxoethyl) phosphorothioate; e.g., omethoate; S-(2-(methylamino)-2-oxoethyl) O,O-dihydrogen phosphorothioate; O,O,S-trimethyl phosphorodithioate). Simple pesticide degradation mechanisms were deduced. Daphnia magna toxicity tests showed degradation products were less toxic than parent compounds. These results contribute to our understanding of the multiple influences that organophosphorus pesticides and their degradation products have on environmental ecosystems and to improving pesticide removal processes from water.

Dispersed organic matter characteristics as an indicator of rock alteration degree of the Safyanovskoe copper-sulphide deposit (Middle Urals)

Relevance of the study is due to the importance of composition and maturity of the dispersed organic matter (DOM) as indicators of rock forming conditions, which may contribute to the paleoecological reconstruction of sedimentation conditions for rocks in the ore-bearing stratum of the Safyanovskoe deposit. Objective: to analyze the composition and characteristics of DOM in carbon-siliceous rocks of the ore-bearing stratum of the Safyanovsky copper-pyrite deposit. The obtained characteristics of the DOM make it possible to reveal the source of original accumulation and the level of its transformation under the influence of various geological processes. Methods. A detailed study of DOM was carried out by the EPR method (electron paramagnetic resonance) for powder preparations. EPR spectra were recorded at room temperature on X-band spectrometers DX-70, ESR 70-03 DX/2, and SE/X-2547 RadioPAN. The analytical procedure for studying organic matter (OM) included: determination of insoluble residue and C org content in the rock, extraction of the chloroform bitumoids (CB) and the alcohol-benzol bitumoids (ABB), humic acids (HA), determining the group composition of CB and hydrocarbons (HC), chromatographic fractionation with determination of the sum of methane-naphthenic and aromatic fractions of hydrocarbons, GC-MS analysis of n-alkanes, cyclic and polyaromatic hydrocarbons (PAHs). GC-MS analysis was performed on the complex Hewlett Packard 6850/5973 with a quadrupole mass detector and analytical information processing software. Results. Analysis of the EPR spectra of carbon-siliceous rocks of the Safyanovskoe deposit showed the presence of the two types of carbon signal (C-org), characteristic of the plant and the animal residues. It was also found that the DOM has never been exposed to temperatures greater than 300 °C. Geochemical analysis of OM indicates that DOM is at a high maturation stage (residual organic matter (ROM) > 99%). But the type of distribution of polyaromatic hydrocarbons (PAHs) suggests that the primary OM was specifically altered at elevated temperatures. Conclusions. DOM of carbon-siliceous rocks of the Safyanovsky deposit is genetically the same, its type is mainly sapropelic and accumulation is associated with marine conditions. A characteristic feature is, on the one hand, its high polymerization, which is typical for DOM of the stage of late mesocatagenesis, and, on the other hand, its molecular composition does not allow us to talk about the maturation of DOM in the process of natural regional metamorphism.

Development and Validation of Atazanavir and Ritonavir Determination in Human Plasma by HPLC-MS Method

Introduction . HIV infection is one of the most relevant diseases from a medical, epidemiological and social point of view. Timely diagnosis, detection and control of the disease, adequate prescription of antiretroviral therapy can sufficiently reduce the viral load on the patient's body, reduce the risk of transmission of infection. Currently, combinations of various antiretroviral drugs are increasingly being prescribed as therapy. One of the most important is combination of atazanavir and ritonavir. The most important stage for the study of pharmacokinetics, studies of comparative pharmacokinetics and bioequivalence is the development of an analytical method that allows you to determine the investigated substances in human plasma. There are currently no published methods for the determination of atazanavir and ritonavir in human plasma using high performance liquid chromatography with mass selective detection using a single quadrupole mass detector. In this article presents the development and validation of a method for the determination of atazanavir and ritonavir in blood plasma after sample preparation by the method of protein precipitation. Aim . The aim of the study is to develop a method for the quantitative determination of atazanavir and ritonavir in human plasma by HPLC with mass spectrometric detection for performing the analytical part of pharmacokinetic studies. Materials and methods . Determination of atazanavir and ritonavir in human plasma by HPLC with mass spectrometric detection. A sample was prepared using protein deposition. Results and discussion . The method was validated of selectivity, matrix effect, calibration curve, accuracy, precision, limit of quantification, carry-over effect and sample stability. Conclusion . The method of the determination of atazanavir and ritonavir in human plasma was developed and validated by HPLC-MS. The analytical range of the was 50.0–10000.0 ng/mL in plasma for atazanavir and 10.0–2500.0 ng/mL in plasma for ritonavir. Method could be applied to determination of atazanavir and ritonavir in plasma for PK and BE studies.

Simultaneous LC/MS Analysis of Carotenoids and Fat-Soluble Vitamins in Costa Rican Avocados (Persea americana Mill.).

Avocado (a fruit that represents a billion-dollar industry) has become a relevant crop in global trade. The benefits of eating avocados have also been thoroughly described as they contain important nutrients needed to ensure biological functions. For example, avocados contain considerable amounts of vitamins and other phytonutrients, such as carotenoids (e.g., β-carotene), which are fat-soluble. Hence, there is a need to assess accurately these types of compounds. Herein we describe a method that chromatographically separates commercial standard solutions containing both fat-soluble vitamins (vitamin A acetate and palmitate, Vitamin D2 and D3, vitamin K1, α-, δ-, and γ-vitamin E isomers) and carotenoids (β-cryptoxanthin, zeaxanthin, lutein, β-carotene, and lycopene) effectively (i.e., analytical recoveries ranging from 80.43% to 117.02%, for vitamins, and from 43.80% to 108.63%). We optimized saponification conditions and settled at 80 °C using 1 mmol KOH L−1 ethanol during 1 h. We used a non-aqueous gradient that included methanol and methyl tert-butyl ether (starting at an 80:20 ratio) and a C30 chromatographic column to achieve analyte separation (in less than 40 min) and applied this method to avocado, a fruit that characteristically contains both types of compounds. We obtained a method with good linearity at the mid to low range of the mg L−1 (determination coefficients 0.9006–0.9964). To determine both types of compounds in avocado, we developed and validated for the simultaneous analysis of carotenoids and fat-soluble vitamins based on liquid chromatography and single quadrupole mass detection (LC/MS). From actual avocado samples, we found relevant concentrations for cholecalciferol (ranging from 103.5 to 119.5), δ-tocopherol (ranging from 6.16 to 42.48), and lutein (ranging from 6.41 to 15.13 mg/100 g dry weight basis). Simmonds cultivar demonstrated the higher values for all analytes (ranging from 0.03 (zeaxanthin) to 119.5 (cholecalciferol) mg/100 g dry weight basis).

Caucasian Gentiana Species: Untargeted LC-MS Metabolic Profiling, Antioxidant and Digestive Enzyme Inhibiting Activity of Six Plants.

The members of Gentiana genus are widely distributed in the Caucasus region where they are used as phytoremedies, but they still have not been studied for their chemical composition and bioactivity. High-performance liquid chromatography with diode array and electrospray triple quadrupole mass detection (HPLC-DAD-ESI-QQQ-MS) was used to investigate metabolites of herb and roots of six gentians (Gentiana asclepiadea, G. cruciata, G. gelida, G. paradoxa, G. pneumonanthe, G. septemfida) grown in the Caucasus. In total, 137 compounds were found including three carbohydrates, 71 iridoid glycosides (mostly loganic acid), loganin, swertiamarin, gentiopicroside and sweroside derivatives, 40 flavones C-, O-, C,O-glycosides (such as luteolin, apigenin, chrysoeriol, and acacetin derivatives), two phenolic O-glycosides, five hydroxycinnamates, eight xanthones, and seven triterpene glycosides. Most of these compounds were identified in gentian samples for the first time. Quantitative differences were found in levels of seven iridoid glycosides, nine glycosylflavones, and two xanthones obtained by HPLC-DAD assay. The gentian extracts were evaluated for their radical-scavenging properties against DPPH and superoxide anion radicals, lipid peroxidation inhibition, and α-amylase/α-glycosidase inhibition. The herb extracts showed higher activity than root extracts. Positive correlations were found between the content of quantified phenolics and antioxidant and digestive enzymes inhibiting activity. The findings presented in our work suggest that the Caucasian gentians are a good source of bioactive phytocompounds with antioxidant and antidiabetic potential.

Caffeoylquinic Acids and Flavonoids of Fringed Sagewort (Artemisia frigida Willd.): HPLC-DAD-ESI-QQQ-MS Profile, HPLC-DAD Quantification, in Vitro Digestion Stability, and Antioxidant Capacity.

Fringed sagewort (Artemisia frigida Willd., Compositae family) is a well-known medicinal plant in Asian medical systems. Fifty-nine hydroxycinnamates and flavonoids have been found in A. frigida herbs of Siberian origin by high-performance liquid chromatography with diode array and electrospray triple quadrupole mass detection (HPLC-DAD-ESI-QQQ-MS). Their structures were determined after mass fragmentation analysis as caffeoylquinic acids, flavone O-/C-glycosides, flavones, and flavonol aglycones. Most of the discovered components were described in A. frigida for the first time. It was shown that flavonoids with different types of substitution have chemotaxonomic significance for species of Artemisia subsection Frigidae (section Absinthium). After HPLC-DAD quantification of 16 major phenolics in 21 Siberian populations of A. frigida and subsequent principal component analysis, we found substantial variation in the selected compounds, suggesting the existence of two geographical groups of A. frigida. The antioxidant activity of A. frigida herbal tea was determined using 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH•) and hydrophilic/lipophilic oxygen radical absorbance capacity (ORAC) assays and DPPH•-HPLC profiling, revealing it to be high. The effect of digestive media on the phenolic profile and antioxidant capacity of A. frigida herbal tea was assessed under simulated gastrointestinal digestion. We found a minor reduction in caffeoylquinic acid content and ORAC values, but remaining levels were satisfactory for antioxidant protection. These results suggest that A. frigida and its food derivate herbal tea could be recommended as new plant antioxidants rich in phenolics.

An Automated and Qualified Platform Method for Site-Specific Succinimide and Deamidation Quantitation Using Low-pH Peptide Mapping

mAbs undergo several post-translational modifications, including the formation of succinimide from the deamidation of asparagine or the isomerization of aspartic acid. Because of the potential impact of succinimide formation on the biological activity of mAbs, detection and quantification of this species is a key area of interest for the pharmaceutical industry. However, studies assessing succinimide stability have been limited, and methods developed to monitor succinimide are either product specific or not robust. Here, we report the development of a platform low-pH peptide-mapping method using a combination of low-pH-resistant Lys-C and modified trypsin to maintain succinimide stability, eliminate deamidation assay artifact, and achieve efficient mAb digestion equivalent to conventional tryptic peptide-mapping method under alkaline condition. Using this method, succinimide stability in serum was accurately assessed in vitro study and the half-life was determined to be 1.5 days. With potential patient exposure to succinimide intermediate, a reliable method was developed to measure site-specific deamidation and succinimide intermediate. Coupled with a single quadrupole mass detector, our method was automated from digestion to data processing and applicable in a good manufacturing practice environment. The method was fully qualified to demonstrate accuracy, precision, linearity, and robustness.

Development of new and robust LC-MS method for simultaneous quantification of polyphenols from Sambucus ebulus fruits

A new and simple LC-MS method for analysis of flavonoids from Sambucus ebulus berry extracts was developed and validated. Successfully were quantitated seven polyphenols: epicatechin, epigallocatechin gallate, rutin, resveratrol, myricetin, quercetin, and kaempferol.Two detectors, working in parallel, were used: photodiode-array and single quadrupole mass-detector. The mass detection was used for identification and quantification of the analytes, while the diode-array detector was as confirmation tool. The following m/z were tracked: 457.15 (epigallocatechin gallate); 289.06 (epicatechin); 609.13 (rutin); 227.05 (resveratrol); 317.0 (myricetin); 301.02 (quercetin); 285.02 (kaempferol). For optimization the chromatographic separation three wavelengths 205 nm, 305 nm, 272 nm were monitored. The method was capable to detect in one run compounds with no UV or fluorescence chromophore and with very similar structures, such as plant polyphenols. The linearity was from 0.05 mg/L to 50 mg/L (R2 0.9962–0.9987). The recoveries for all tested analytes were between 81.6% and 104.7%.The method was applied for analysis of crude extract of Sambucus ebulus ripe fruits. Three major polyphenols – epicatechin (0.84 mg/100gFW), quercetin (0.15 mg/100gFW) and kaempferol (0.05 mg/100gFW) were identified and quantified.The proposed method could be successfully used for routine analysis of epigallocatechin gallate, epicatechin, rutin, resveratrol, myricetin, quercetin, and kaempferol in Sambucus ebulus extracts.

A high-performance liquid chromatography-tandem mass spectrometry method for the quantitative determination of four genotoxic impurities in gefitinib

In this work, a method for the determination of the amounts of the four genotoxic impurities in gefitinib has been developed. A simple and sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) approach has been developed, optimized, and validated. The genotoxic impurities were 3-chloro-4-fluoroaniline, 3,4-difluoroaniline, 3-fluoro-4-chloroaniline, and 3,4-dichloroaniline. Separation was achieved on an Inertsil ODS-3 column (100 mm×3.0 mm, 3 μm). The column temperature was 40 ℃, and the running time was 12 min. A triple quadrupole mass detector with positive electrospray ionization in the multiple reaction monitoring (MRM) mode was applied. The method was validated in terms of its specifi-city, linearity, precision, accuracy, stability, and robustness. The correlation coefficient of each impurity was higher than 0.999 in the range of 0.6-96.0 μg/L. The limits of detection (LODs) and limits of quantity (LOQs) were in the ranges of 0.2-2.0 μg/L and 0.6-6.0 μg/L, respectively. The recoveries of all impurities at 6, 30, and 60 μg/L were within 91.0%-98.5%. All impurities were stable within 2 h. After detection, only 3-chloro-4-fluoroaniline was detected in the batch number 16052301 and R16052501-1 gefitinib samples, but its concentration was below the impurity limit (6 mg/L). This method is simple, reliable, and suitable for the determination of four genotoxic impurities in gefitinib. It can be further applied as a reference for quality control.

A Sensitive Liquid Chromatography-tandem Mass Spectrometry Method for the Estimation of Cilostazol in Bulk and in a Pharmaceutical Formulation

The present study reports on a liquid chromatography-tandem mass spectroscopy method for the analysis of Cilostazol drug substance in its formulation. The materials utilize a Zorbax SB C18 analytical column with electrospray ionization and a triple quadrupole mass detector in multiple reaction monitoring (MRM) mode, resulting in a short analysis of 1.5 min runtime and the analyte elute at 0.76 min. Change from SIM to MRM mode resulted in increased sensitivity and low quantitation limit which in turn produces a detection limit of 1 ng/ml. The obtained method was validated in a range of 5-100 ng/ml with a correlation coefficient of 0.9991. The percentage recovery of the present method was found to be in the range of 94% to 100%. The developed method was validated as per the ICH guidelines.

A simple, sensitive, and straightforward LC–MS approach for rapid analysis of three potential genotoxic impurities in rabeprazole formulations

In the present study, a sensitive and fully validated liquid chromatography with mass spectrometry method was developed for the quantification of three potential genotoxic impurities in rabeprazole drug substance. The separation was achieved on Symmetry C18 column (100×4.6mm, 3.5μm) using 0.1% formic acid in water as mobile phase A and acetonitrile as mobile phase B in gradient elution mode at 0.5mL/min flow rate. Triple quadrupole mass detection with electrospray ionization was operated in selected ion recording mode for the quantification of impurities. The calibration curves were demonstrated good linearity over the concentration range of 1.0-4.5ppm for O-phenylenediamine, 1.8-4.5ppm for 4-nitrolutidine-N-oxide and 1.0-4.5ppm for benzyltriethylammonium chloride with respect to 10mg/mL of rabeprazole. The correlation coefficient obtained in each case was >0.998. The recoveries were found satisfactory over the range between 94.22 and 106.84% for all selected impurities. The method validation was carried out following International Conference on Harmonization guidelines, from which the developed method was able to quantitate the impurities at 1.0ppm for O-phenylenediamine, 1.8ppm for 4-nitrolutidine-N-oxide and 1.0ppm for benzyltriethylammonium chloride. Furthermore, the proposed method was successfully evaluated for the determination of selected impurities from bulk drug and formulation samples of rabeprazole within the acceptable limits.

Assessment of Degradation of Sulfonylurea Herbicides in Water by Chlorine Dioxide

The degradation of two sulfonylurea herbicides, nicosulfuron and thifensulfuron methyl in water by chlorine dioxide, was studied for the first time in this paper. In order to examine the optimal parameters for degradation of both herbicides, degradation was investigated under light or dark conditions with different amount of chlorine dioxide, different degradation periods, and at different pH values. Degradation efficiency of herbicides was monitored using high-performance liquid chromatography with photodiode array detection (HPLC-DAD). The degradation products were analyzed by gas chromatography with triple quadrupole mass detector (GC–QQQ). Three products were identified after degradation of nicosulfuron and two products after degradation of thifensulfuron methyl. Total organic analysis (TOC) gave insight into some differences in degradation mechanisms and degrees of mineralization after degradation of the herbicides using chlorine dioxide. A simple mechanism of herbicide degradation was proposed. Acute toxicity tests were performed on the products produced after degradation with chlorine dioxide, and the results showed that the degradation products were less toxic than the parent compounds. The findings of the present study are very useful for the treatment of wastewaters contaminated with herbicides.

Analytical Method for Pesticides in Avocado and Papaya by Means of Ultra-High Performance Liquid Chromatography Coupled to a Triple Quadrupole Mass Detector: Validation and Uncertainty Assessment.

The present analytical method could be used for pesticides determination in different kind of fruits as papaya and avocado and as a practical guide for uncertainty and matrix effect determination.

An untargeted lipidomic strategy combining comprehensive two-dimensional liquid chromatography and chemometric analysis

Untargeted lipidomic samples are extremely complex and often exceed the limits of peak capacity achievable by one-dimensional liquid chromatography (LC). Comprehensive two-dimensional liquid chromatography (LC × LC) appears as a promising alternative to overcome this drawback. Unfortunately, this approach generates highly complex datasets which untargeted analysis is challenging. In this work, a global methodological strategy combining LC × LC–MS/MS with chemometric data analysis is proposed for untargeted lipidomic studies. The feasibility of the proposed methodology is demonstrated by its application to assess the effects of arsenic exposure on the lipidome of growing rice samples. A two-dimensional chromatographic setup coupling reversed phase (RP) and hydrophilic interaction liquid chromatography (HILIC) modes together with a triple quadrupole mass detector (TQD) is proposed to analyze lipid extracts from rice samples at different experimental conditions. Chemometric tools were used for data compression, spectral and elution profiles resolution, feature detection and statistical analysis of the multidimensional LC × LC–MS/MS data. The obtained results revealed that the proposed methodology was useful to gather relevant information from untargeted lipidomic studies and detect potential biomarkers.

A comparison of single quadrupole mass detection and diode array ultraviolet detection interfaced to ultra-high performance supercritical chromatography for the quantitative analysis of synthetic cathinones

A comparison of single quadruple mass spectrometry and diode array-ultraviolet (PDA-UV) detection interfaced to ultra-high performance supercritical fluid chromatography was performed for the quantitative analysis of synthetic cathinones. Synthetic cathinones, also known as “bath salts”, are derived from cathinone, a component of the khat plant. For 15 controlled solutes linearity, repeatability, and limits of detection were determined using both UV and MS detection. Quantitation studies were performed using the above detectors for 19 mixtures of up to 4 of the above compounds with an adulterant to simulate seized samples. MS detection provided approximately an order of magnitude greater linearity range and allowed for two to three orders of magnitude lower limits of detection than UV detection. Both detection techniques exhibited similar results of analysis and comparable repeatability. The latter detection mode which provided significantly high linearity correlation coefficients (0.9994 ≤ R2 ≤ 1.0000) would be preferred for quantitative analysis.