Liquid Chromatography With Diode Array Detection Research Articles

Effects of Natural Extract Rosmarinic Acid on Sleep Quality and Daily Care in Patients with Depression

The mechanism of action of rosmarinic acid (RA), a natural extract from rosemary, on sleep quality (SQ) and daily care (DC) in depressed patients was investigated. Firstly, RA was extracted from rosemary and prepared into RA essential oil (RAEO). High-performance liquid chromatography with diode array detector (HPLC-DAD) was utilized to analyze the chromatography of RA. Subsequently, a retrospective analysis was conducted on 60 depressed patients admitted to the hospital, who were randomly rolled into an observation (Obs) group (treated with escitalopram (SE) and RA) (n = 30) and a control (Ctrl) group (treated with SE) (n = 30). The efficacy of patients was analyzed before and after they were treated differently at 2, 4, 6, and 8 weeks. The levels of nitric oxide (NO) and NO synthase (NOS) of patients in different groups were compared, and the depression status, sleep quality (evaluated using the Pittsburgh Sleep Quality Index, PSQI), and overall quality of life (QOL, evaluated using the General Quality of Life Inventory-74, GQOLI-74) were assessed. The HPLC-DAD-MS analysis indicated that the aqueous solution of RA had multiple biological activities. The PSQI score in the Obs group was lower and the GQOLI-74 score was higher, showing great differences with P <0.05 to those in the Ctrl group. Furthermore, the Obs group had much higher Hamilton Depression Scale (HAMD) scores after 2, 4, 6, and 8 weeks of treatment (P <0.05). The Hamilton Anxiety Scale (HAMA) scores of both groups gradually decreased with the increase of treatment duration, showing great differences before treatment, at the 2nd week, and the 4th week of treatment (P >0.05). However, marked differences were observed at the 6th and 8th weeks in contrast to those before treatment (P <0.05). In the 8th week, patients in the Obs and Ctrl groups exhibited obvious differences to the anxiety levels before treatment (P <0.05). It suggested that the anxiety levels of all patients improved, but that in the Obs group was improved more. In conclusion, the RAEO had a positive impact on sleep quality and daily care in depressed patients, and can serve as a feasible adjunctive treatment method worthy of clinical promotion.

Dispersive liquid-liquid microextraction (DLLME) for determination of tricyclic antidepressants in whole blood and plasma samples and analysis by liquid chromatography with diode array detector (LC-DAD)

Microextractions have been developed for the tricyclic antidepressants (TCAs) analysis in biological matrices, including dispersive liquid-liquid microextraction (DLLME). The proposed DLLME employed 490 µL of biological sample (whole blood or plasma), which were added 15 mg of NaCl, 10 µL of medazepam as internal standard (10 µg/mL) and 100 µL of 2 M NaOH. This mixture was homogenized by vortex (2800 rpm/10 s) and 400 µL of hexane (extractor solvent) with 600 µL of methanol (dispersing solvent) were added to the sample. After the vortex step (2800 rpm/5 s), an ultrasonic bath for 300 s was employed. Then, this content was centrifuged (10 min/10000 rpm), organic phase was collected and dried under air flow. After, 30 µL of the mobile phase was used for resuspension and 20 µL is injected into LC-DAD. This method was optimized and fully validated according to UNODC and SWGTOX guidelines, reaching limits of detection equivalent to analytical methodologies that employ mass spectrometry (MS). Also, it was applied in real cases involving suspected exposure to TCAs. So, the developed DLLME for the determination of TCAs in whole blood and plasma samples proved to be a simple, reliable, robust and reproducible method that can be used in toxicology and clinical laboratories.

Challenges in Drug Surveillance: Strengthening the Analysis of New Psychoactive Substances by Harmonizing Drug Checking Services in Proficiency Testing.

Drug checking is a proven harm reduction strategy and provides real-time information on the market of new psychoactive substances (NPS). It combines chemical analysis of samples with direct engagement with people who use drugs (PWUD), giving the ability to increase preparedness and responsiveness towards NPS. Next to that, it supports rapid identification of potential unwitting consumption. However, NPS cause a toxicological battle for the researchers, as factors such as the unpredictability and quick shift of the market complicate the detection. To evaluate challenges posed towards drug checking services, proficiency testing was set up to evaluate existing analytical techniques and investigate the capability to correctly identify circulating NPS. Twenty blind substances, covering the most common categories of substances, were analyzed according to the existing protocols of the existing drug checking services, including several analytical methods such as gas chromatography-mass spectrometry (GC-MS) and liquid chromatography with diode array detector (LC-DAD). The proficiency test scores range from 80 to 97.5% accuracy. The most common issues and errors are mainly unidentified compounds, presumably due to no up-to-date libraries, and/ or confusion between structural isomers, such as 3- and 4-chloroethcathinone, or structural analogs, such as MIPLA (N-methyl-N-isopropyl lysergamide) and LSD (D-lysergic acid diethylamide). The participating drug checking services have access to adequate analytical tools to provide feedback to drug users and provide up-to-date information on NPS.

A green evaluation of ecstasy determination methods by using different greenness criteria

The determination of 3,4-methylenedioxymethamphetamine (MDMA) in seized samples, by employing five different analytical procedures, has been used to illustrate the differences in their greenness classification depending on the selected evaluation criteria. A set of seventeen MDMA seized samples were analysed by: a) liquid chromatography with diode array detection (LC-DAD), b) gas chromatography with flame ionization detection (GC-FID), c) ion mobility spectrometry (IMS), d) total attenuated reflectance mid-infrared spectroscopy (ATR-FTIR) and e) diffuse reflectance near infrared spectroscopy (DR-NIR). The studied analytical procedures provided statistically comparable MDMA concentration values. However, the greenness scores of analytical procedures using the three criteria of Green Analytical Eco-Scale, the Green Analytical Procedure Index (GAPI) and the Analytical GREEnness metric approach (AGREE) provided significant differences but in all cases ATR-FTIR and DR-NIR were the greenest methods followed by IMS, GC and LC. The aforementioned greenness aspects are discussed in this study.

Effect of Ripening on the Phenolic and Sugar Contents in the Meso- and Epicarp of Olive Fruits (Olea europaea L.) Cultivar ‘Leccino’

The study was conducted during the harvest season in the year 2020 to identify and quantify primary and secondary metabolites in olive fruit of the ‘Leccino’ cultivar during ripening. Sugars, individual phenolic compounds, total phenolic content and total tannin content were measured separately for the first time in the skin and pulp. Most of the studied metabolites were higher in the skin. Five sugars were identified, the most important being glucose in both tissues, although its content decreased during ripening. The highest total phenolic content was observed in the skin at the last stage of ripening, because of the accumulation of anthocyanins. Individual phenolic compounds were measured by high performance liquid chromatography with-diode array detector (HPLC-DAD) and confirmed by mass spectrometry. Thirty phenolic compounds were characterized and quantified. The main individual phenolic compound in the skin and pulp was oleuropein, which decreased during ripening. Two previously unreported anthocyanins, cyanidin-3-O-diglucoside and cyanidin-3,5-O-sophoroside, were identified for the first time in olive skin. These results will allow us to better understand the synthesis, distribution and storage of some primary and secondary metabolites in different tissues of olive fruits during ripening.

Chemical composition and photoprotective potential of aqueous extract from Casearia sylvestris var. lingua (Cambess.) Eichler leaves

Casearia sylvestris var. lingua (Cambess.) Eichler is widely used in traditional medicine to treat diseases. Simultaneously, the growing search for phytocosmetics has culminated in the exploration of plant extracts. In this context, the aim of this study was to obtain the chemical composition and antioxidant and photoprotective potential of the infusion of C. sylvestris var. lingua leaves. The techniques of UV/Vis spectroscopy, gas chromatography with mass spectrometry detector (GC-MS) and liquid chromatography with diode array detector (LC-DAD) were used to get the results. The total phenolic content in the infusion of leaves from C. sylvestris var. lingua was 101.57 mg GAE g-1, flavonoids 50.37 mg RE g-1 and tannins 1.12 mg TAE g-1. Quercetin, ferulic acid, gallic acid, ellagic acid, caffeic acid, β-sitosterol, lupeol, lupeol acetate, stigmasterol and campesterol were identified and quantified in the samples. The infusion of C. sylvestris var. lingua leaves has potential for application in phytocosmetics and sunscreens, with a sun protection factor of 8.65 ± 0.45, a UVA/UVB ratio of 1.16 and a critical wavelength of 373.

Enantioselective Monitoring of Biodegradation of Ketamine and Its Metabolite Norketamine by Liquid Chromatography

Ketamine (K) and its main metabolite, norketamine (NK), are chiral compounds that have been found in effluents from wastewater treatment plants (WWTPs) and aquatic environments. Little is known about their enantioselective biodegradation during sewage treatment; however, this information is pivotal for risk assessment, the evaluation of WWTP performance and wastewater epidemiological studies. The aim of this study was to investigate the biodegradation pattern of the enantiomers of K by activated sludge (AS) from a WWTP. For that, an enantioselective liquid chromatography with diode array detection (LC-DAD) method was developed and validated to quantify the enantiomers of K and NK. Both K and NK enantiomers were separated, in the same chromatographic run, using a Lux® 3 µm cellulose-4 analytical column under isocratic elution mode. The method was demonstrated to be linear (r2 > 0.99) and precise (<11.3%). Accuracy ranged between 85.9 and 113.6% and recovery ranged between 50.1 and 86.9%. The limit of quantification was 1.25 µg/mL for the enantiomers of NK and 2.5 µg/mL for K. The method was applied to monitor the biodegradation assay of the enantiomers of K by AS for 14 days. K was poorly biodegraded, less than 15% for both enantiomers, and enantioselectivity in the biodegradation was not observed. The metabolite NK and other possible degradation products were not detected. This work reports, for the first time, the behavior of both enantiomers of K in biodegradation studies.

Globoidnan A, rabdosiin and globoidnan B as new phenolic markers in European-sourced comfrey (Symphytum officinale L.) root samples.

Symphytum officinale L. (comfrey, Boraginaceae) is a cultivated or spontaneously growing medicinal plant that is traditionally used for the treatment of bone fractures, hematomas, muscle pains and joint pains. A wide range of topical preparations and dried roots for ex tempore applications are marketed in European drug stores or pharmacies. The aim of this study was to perform the qualitative and quantitative analysis of pyrrolizidine alkaloids (PAs) and phenolic compounds in the hydroethanolic extracts of 16 commercial comfrey root batches purchased from 12 different European countries. Liquid chromatography hyphenated with high-resolution tandem mass spectrometry (LC-HRMS/MS) was used for the profiling of PAs and phenolic compounds, whereas LC-MS/MS and liquid chromatography with diode array detection (LC-DAD) were used for their quantification. 20 PAs (i.e. intermedine, lycopsamine, acetylintermedine, acetyllycopsamine, symphytine, symphytine-N-oxide), 17 phenolic compounds (i.e. caffeic and rosmarinic acids, rabdosiin, globoidnan A, globoidnan B) and 9 nonphenolic compounds (sugars, organic and fatty acids) were fully or partly annotated in the analysed samples. In addition, the quantitative analyses revealed that globoidnan B, rabdosiin and globoidnan A are new phenolic markers that can be used together with rosmarinic acid and PAs for the quality control of commercial comfrey root batches. This study brings new insights into the phytochemical complexity of S. officinale, revealing not only numerous toxic PAs, but also a significant number of valuable phenolic compounds that could contribute to the bioactivities of comfrey-based preparations.

Simultaneous Determination of Medicinal Drugs with Overlapping Profiles Contained in Low Chromatographic Resolution Data using HPLC-DAD and Multivariate Curve Resolution

Background: The increasing demand of effective pharmaceutical products directed to fight against malaria lead to the combination of at least two antimalarial drugs. This combination aims to minimize the Plasmodium falciparum resistance which is found when the most frequently used drugs are taken individually. Within this context, proguanil hydrochloride and chloroquine phosphate which have independent modes of action are taken together to prevent malaria. This paper aims to develop a fast and powerful analytical method for the simultaneous determination of proguanil hydrochloride and chloroquine phosphate in the commercial Paludrine/Avloclor dosage forms using a multi-way chromatographic calibration based on high-performance liquid chromatography with diode array detection (HPLC-DAD) and multivariate curve resolution – alternating leastsquares (MCR-ALS). Methods: A rapid and powerful analytical method based on HPLC-DAD and MCR-ALS was developed for the simultaneous quantification of proguanil hydrochloride and chloroquine phosphate in the commercial Paludrine/Avloclor antimalarial drugs. An isocratic mobile phase composed by 0.2 M ammonium acetate, acetonitrile, and methanol (40:25:35) and a flow rate of 1.2 mL min-1 were employed in the chromatographic runs with an elution time about 5 min. Results: This approach demonstrates that chromatographic analysis may become considerably simpler and economical in terms of time, cost, and organic solvent consumption when coupled to multiway calibration models such as MCR-ALS. In fact, this multi-way chromatographic calibration based on second-order HPLC-DAD data matrices (with extremely low chromatographic resolution) and MCR-ALS allows the development of greener analytical methods for complex samples. The proposed analytical method allowed the simultaneous quantification of two antimalarial APIs present in the commercial Paludrine/Avloclor drugs with low REP values below 8% for the simultaneous determination of proguanil hydrochloride and chloroquine phosphate. Conclusion: The proposed multi-way chromatographic strategy can be used for routine control of pharmaceutical dosage forms. It should be highlighted that MCR-ALS allowed to: (a) achieve the second- order advantage and the quantification of analytes in the presence of uncalibrated compounds such as coeluted profile measured in different magnitude of the signal in each successive chromatographic run and significant overlapping profiles and (b) separate the contribution of several components from chromatographic runs with extremely low separation of peaks through the deconvolution of the signal obtained, performing the so-called mathematical chromatography.

Impairment of adenosinergic system in Rett syndrome: Novel therapeutic target to boost BDNF signalling

Rett syndrome (RTT; OMIM#312750) is mainly caused by mutations in the X-linked MECP2 gene (methyl-CpG-binding protein 2 gene; OMIM*300005), which leads to impairments in the brain-derived neurotrophic factor (BDNF) signalling. The boost of BDNF mediated effects would be a significant breakthrough but it has been hampered by the difficulty to administer BDNF to the central nervous system. Adenosine, an endogenous neuromodulator, may accomplish that role since through A2AR it potentiates BDNF synaptic actions in healthy animals. We thus characterized several hallmarks of the adenosinergic and BDNF signalling in RTT and explored whether A2AR activation could boost BDNF actions.For this study, the RTT animal model, the Mecp2 knockout (Mecp2−/y) (B6.129P2 (C)-Mecp2tm1.1Bird/J) mouse was used. Whenever possible, parallel data was also obtained from post-mortem brain samples from one RTT patient. Ex vivo extracellular recordings of field excitatory post-synaptic potentials in CA1 hippocampal area were performed to evaluate synaptic transmission and long-term potentiation (LTP). RT-PCR was used to assess mRNA levels and Western Blot or radioligand binding assays were performed to evaluate protein levels. Changes in cortical and hippocampal adenosine content were assessed by liquid chromatography with diode array detection (LC/DAD).Hippocampal ex vivo experiments revealed that the facilitatory actions of BDNF upon LTP is absent in Mecp2−/y mice and that TrkB full-length (TrkB-FL) receptor levels are significantly decreased. Extracts of the hippocampus and cortex of Mecp2−/y mice revealed less adenosine amount as well as less A2AR protein levels when compared to WT littermates, which may partially explain the deficits in adenosinergic tonus in these animals. Remarkably, the lack of BDNF effect on hippocampal LTP in Mecp2−/y mice was overcome by selective activation of A2AR with CGS21680.Overall, in Mecp2−/y mice there is an impairment on adenosinergic system and BDNF signalling. These findings set the stage for adenosine-based pharmacological therapeutic strategies for RTT, highlighting A2AR as a therapeutic target in this devastating pathology.

Chromatographic quantification of seven pesticide residues in vegetable: Univariate and multiway calibration comparison

Second order algorithms have been used in many chromatographic data analyses to overcome the interference drawback of an unexpected coeluted constituent, however the majority of the works partially coelute the analytes to reduces the elution time, this require the multiway calibration even if an unexpected constituent is not present at the sample. It is always preferable to perform a univariate quantification than perform a multiway calibration. For this purpose, it is necessary to use a detection system whose selectivity reduces the probability of interferences, for instance a liquid chromatography with mass spectrometry (LC–MS), unfortunately the operating costs can be considerably high. In this work, a comprehensive study of univariate and multiway calibration was performed for the quantification of seven pesticide residues in vegetables using a liquid chromatography with diode array detector (LC-DAD). The univariate and multiway calibration comparison study was performed along the data acquired for a full validation of the univariate methodology, where the analytes were separated in the column previously to detection. At the vegetable samples analysis, it was shown that the results are the same when the interference is not present and only the multiway approach lead to accuracy results when it is present. Performing the multiway calibration only when it is necessary, leading to faster data analyzes, and eliminate the need of another injection, revalidation or resampling when an interferent is present and reduce the analysis cost by the use of a LC-DAD system. In addition, in this work it is possible to evaluate the multiway calibration efficiency comparing the results with the well stablished univariate calibration, which was done for the first time, using the same data, as long as the authors knowledge.

Flavonoid determination in onion, chili and leek by hard cap espresso extraction and liquid chromatography with diode array detection

A low cost extraction procedure, based on the use of a hard cap espresso machine, has been developed for the extraction of myricetin, quercetin, luteolin and kaempferol from vegetables by using 50 mL of ethanol in water (80% v/v) in <30 s. Direct determination of extracts were carried out by liquid chromatography with diode array detection (LC-DAD), offering limit of detection values from 3 to 8 μg g−1. Intra and inter-day precision ranged from 8 to 16%, and from 10 to 23%, respectively. Quantitative recoveries were assessed from leek and Habanero, Thai, and red chili samples spiked at different flavonoid concentrations with values ranging from 100 to 110%, from 80 to 108%, from 74 to 88%, and from 70 to 115%, respectively. Efficiency of the proposed extraction procedure was compared with ultrasound-assisted extraction and free quercetin was determined directly in onion samples and after a hydrolysis of extracts and/or fungal fermentation.

Evaluation of a Hollow-Fiber Liquid-Phase Microextraction Technique for the Simultaneous Determination of PPI Drugs in Human Plasma by LC-DAD.

This study involved the development, validation and application of a three-phase hollow-fiber liquid-phase microextraction (HF-LPME) and liquid chromatography with diode array detection (LC-DAD) method for the simultaneous determination of the proton pump inhibitor (PPI) drugs omeprazole, pantoprazole and lansoprazole in human plasma. The evaluation of the HF-LPME parameters was crucial for the determination of the drugs and the conditions selected were: 1-octanol as solvent; phosphate buffer at pH 5 as donor phase; borate buffer at pH 10 as acceptor phase; extraction time of 15 min; stirring at 750 rpm and NaCl was added at 5% (w/v). Validation of the method according to US-FDA recommendations showed a good linear range (0.2-2.0 μg/mL) for all analytes, with a determination coefficient >0.9910. Precision was evaluated using intra- and inter-day assays, which showed relative standard deviations (RSD), <15% for all concentrations, with a limit of quantification (LOQ) of 0.2 μg/mL. Accuracy was also assessed at these concentration levels and was in the range from 80 to 130%. Finally, the sensitive, selective and reproducible HF-LPME/LC-DAD developed method was successfully applied to human plasma samples from patients undergoing therapy with the PPI drugs.

Determination of Parabens in Surface Water from Mogi Guaçu River (São Paulo, Brazil) Using Dispersive Liquid-Liquid Microextraction Based on Low Density Solvent and LC-DAD

A method using dispersive liquid-liquid microextraction (DLLME) based on low density solvent (LDS) combined with liquid chromatography with diode array detection (LC-DAD) has been developed for determination of parabens. Some DLLME parameters such as kind and volumes of extraction and disperser solvents, pH of the aqueous samples, ionic strength, extraction, centrifugation and speed time, were investigated. The method exhibits good linearity (0.9990 to 0.9993), limits of detection (0.5-0.8 µg L-1), and limits of quantification (1.3-2.4 µg L-1). In optimum conditions, enrichment factors and recoveries of studied parabens obtained were 38.9 to 88.4% and 30.3 to 68.0%, respectively. Surface water samples collected from Mogi Guacu River (Sao Paulo state, Brazil) were analyzed, showing average contents of methyl-, ethyl-, propyl-, and n-butylparaben of 8.0, 5.8, 13.1 and 15.1 µg L-1, respectively. This is the first study on parabens in a Brazilian River, in a long stretch of river (ca. 300 km of extension).

Dissipation and persistence of thiacloprid in pepper fruits

This study gives insight into the behavior of the neonicotinoid insecticide thiacloprid in greenhouse production of pepper. Thiacloprid was applied at a concentration of 96 g a.i./ ha, as recommended by the manufacturer for aphid control. Degradation of thiacloprid in pepper fruits was evaluated over a ten-day period, starting from the moment of insecticide application. Sample preparation was performed using the QuEChERS method for liquid chromatography with diode array detection for identification and quantification of thiacloprid residues in extracts of pepper samples. The method was validated in accordance with the SANCO/12571/2013 document. The obtained mean recovery value was 83.69%, with RSD 5.05%. Intraday precision was 3.21%. Within a concentration range from 0.01-2.0 ?g/ml, thiacloprid showed linear calibration with R2 0.997%, while the quantification limit of the method was 0.01 mg/kg. The results of a field trial showed that thiacloprid dissipated rapidly from 1.136 mg/kg to 0.321 mg/kg with a loss of 72% in the first two days after application. Throughout the experimental period, thiacloprid residues in pepper fruits basically remained at a stable low level, and no residue exceeding 0.198 mg/kg was detected in the terminal residue experiment, which was below the MRL of 1.0 mg/kg. The half-life (DT50) of thiacloprid in pepper fruits obtained in this study was 4.95 days. Finally, the pre-harvest interval (PHI) for thiacloprid prescribed by Serbian authorities was proved to be safe enough in greenhouse production of pepper.

Determination of Phenolic Acids and Hydrolyzable Tannins in Pomegranate Fruit and Beverages by Liquid Chromatography with Diode Array Detection and Time-of-Flight Mass Spectrometry

Three phenolic acids (gallic, 3,4-dihydroxybenzoic, and ellagic acids) and four hydrolyzable tannins (punicalin, punicalagins A and B, and corilagin) have been determined in pomegranate beverages and different parts of the fresh fruit and tree by liquid chromatography with diode array detection coupled to electrospray ionization and time-of-flight mass spectrometry (LC-DAD-ESI-ToFMS). For the fruit and tree analysis, the lyophilized sample was submitted to extraction in methanol for 2 h. Centrifuged and filtered beverages were diluted 1:10 with water for the quantification of corilagin and 3,4-dihydroxybenzoic acid and 1:100 for the rest of polyphenols. Calibration against external aqueous standards was used for quantification by liquid chromatography with diode array detection (LC-DAD), achieving detection limits in the 1.8–9.2 ng ml−1 range (0.2–1.1 μg g−1), depending on the compound. Matrix-matched calibration was applied for liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry (LC-ESI-ToFMS), with detection limits ranging between 0.16 and 1.4 ng ml−1 (0.02–0.17 μg g−1). Satisfactory recovery values between 88 and 110 % were obtained for beverages and solid samples spiked in the 5–100 μg ml−1 and 10–100 μg g−1 concentration ranges, respectively, with the two detection modes used. The polyphenols were quantified in the beverages between 0.3 and 325 mg l−1, for corilagin and punicalagin A, respectively, and between 0.04 and 22.82 mg g−1 (as dry matter) for 3,4-dihydroxybenzoic acid and punicalagin A, respectively, in the different parts of the fruit and tree.

Effects of the strawberry (Fragaria ananassa) purée elaboration process on non-anthocyanin phenolic composition and antioxidant activity

Strawberries are harvested in a short period of time frequently involving fruit surplus. This paper studies the impact of the strawberry purée elaboration process on the chemical composition of the final products. Thirty-two phenolic compounds were studied by Liquid Chromatography with Diode Array Detector (LC-DAD) and Mass Spectrometry (LC-MS). An LC-DAD method was set up and validated and the non-anthocyanin phenolic profile was quantified at the different steps of production, for three elaboration processes and two harvests (2011 and 2012). We have tentatively identified apigenin-7-O-glucoside, luteolin-3-O-glucuronide, malonyl caffeoylquinic acid, trans-resveratrol glucoside and caffeoylglucaric isomer. (+)-Catechin and HHDP-galloylglucose were the most abundant phenolic compounds. The most abundant flavonol was kaempferol-3-glucoside.The purée maintains the fruit’s non-anthocyanin phenolic composition and in vitro antioxidant activity as determined by ORAC and DPPH methods. This fact suggests that strawberry purée could be considered a valuable ingredient for producing food derivatives.

A SIMPLE AND EFFECTIVE METHOD FOR THE DETERMINATION OF CHLORANTRANILIPROLE AND SPIRODICLOFEN IN TOBACCO BY LIQUID CHROMATOGRAPHY AFTER ACCELERATED SOLVENT EXTRACTION AND SILICA GEL CLEAN-UP

A new method for the determination of chlorantraniliprole (CAP) and spirodiclofen (SDF) residues in tobacco was developed by using liquid chromatography with diode-array detection (LC-DAD) after accelerated solvent extraction (ASE) and silica gel cleanup. The conditions of ASE, silica gel cleanup, and LC were investigated and optimized. A Waters C18 column (250 × 4.6 mm ID, 5 µm) was used for the LC using a mobile phase composed of methanol and water (90:10, v/v). Under optimal conditions, the linearity was satisfactory in the range of 0.03–1.5 µg/mL with a correlation coefficient of 0.9994 for CAP and 0.13–2.5 µg/mL with a correlation coefficient of 0.9991 for SDF. The method limit of quantification (LOQ) was 16.5 µg/kg for CAP and 64.3 µg/kg for SDF, which is lower than their maximum residue limits (MRLs). The recoveries were 88.5–102% with relative standard deviations (RSDs) of 2.7–6.9% for CAP, and 87.7–98.5% with RSDs of 1.8–5.9% for SDF. The proposed method is simple, rapid, effective, and provides the sensitivity and linearity necessary for analysis of the pesticides in tobacco.

Dispersive liquid–liquid microextraction for the determination of macrocyclic lactones in milk by liquid chromatography with diode array detection and atmospheric pressure chemical ionization ion-trap tandem mass spectrometry

Eprinomectin (EPRI), abamectin (ABA), doramectin (DOR), moxidectin (MOX) and ivermectin (IVM) were determined in milk samples using dispersive liquid–liquid microextraction (DLLME) and liquid chromatography with diode array detection (LC-DAD) coupled to atmospheric pressure chemical ionization in negative ion mode ion-trap tandem mass spectrometry (APCI-IT-MS/MS). Milk proteins were removed by precipitation with trichloroacetic acid and the analytes were preconcentrated using 2mL of acetonitrile containing 200μL of chloroform as extraction mixture. The effect of several parameters for the liquid–liquid microextraction efficiency was evaluated. Standard additions method was used for quantification purposes, the correlation coefficients were better than 0.9970 in all cases and the quantification limits ranged from 1.0 to 4.7ngg−1 and from 0.1 to 2.4ngg−1 when using DAD and MS, respectively. The DLLME-LC-APCI-IT-MS/MS optimized method was successfully applied to different milk samples and none of the studied analytes was detected in the samples studied. The recoveries for milk samples spiked at concentration levels ranging between 0.5 and 50ngg−1, depending on the compound, were between 89.5 and 105%, with relative standard deviations lower than 9% (n=135). Simplicity, rapidity and reliability are important advantages of the proposed method, while the sample preparation step can be regarded as environmentally friendly.

Differences and Similarities in the Metabolism of Glyburide for Various Species: An Analysis by LC-DAD-Q-TRAP-MS/MS

Studies were conducted on the Metabolism of sulfonylurea drug glyburide (5-chloro-N-(4-[N-(cyclohexylcarbamoyl) sulfamoyl] phenethyl)-2-methoxybenzamide) in human, mouse, rat, dog and monkey hepatic microsomes. Liquid chromatography with Diode array detector (LC-DAD) hyphenated with Q-Trap-Mass Spectrometer (Q-TRAP-MS/ MS) was employed to study the metabolism of glyburide in different species. The primary objective of the present study is to identify the similarities and differences in the metabolism of glyburide and to confirm the recent newly identified metabolites across the species. Results obtained from LC-UV and LC-MS/MS confirm the similarities and differences in the biotransformation of glyburide across the species. LC-UV-MS/MS data clearly suggests that the quantities of metabolites formed in all the species are dissimilar. Drug metabolite ratio is also different in all the species considered for tests. Mono-oxygenated metabolites and a metabolite due to the ring loss were identified in all the species. Similarities and differences in the metabolism of glyburide confirm the role of cytochrome P450 (CYP 45) enzymes and its distinct activity across the species.