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1.
Molecules ; 27(15)2022 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-35956972

RESUMO

Bladder cancer is one of most common types of cancer diagnosed in the genitourinary tract. Typical tests are costly and characterized by low sensitivity, which contributes to a growing interest in volatile biomarkers. Head space solid phase microextraction (SPME) was applied for the extraction of volatile organic compounds from urine samples, and gas chromatography time of flight mass spectrometry (GC×GC TOF MS) was used for the separation and detection of urinary volatiles. A cohort of 40 adult patients with bladder cancer and 57 healthy persons was recruited. Different VOC profiles were obtained for urine samples taken from each group. Twelvecompounds were found only in the samples from theBC group.The proposed candidate biomarkers are butyrolactone; 2-methoxyphenol; 3-methoxy-5-methylphenol; 1-(2,6,6-trimethylcyclohexa-1,3-dien-1-yl)-2-buten-1-one; nootkatone and 1-(2,6,6-trimethyl-1-cyclohexenyl)-2-buten-1-one.Since most of the studies published in the field are proving the potential of VOCs detected in urine samples for the screening and discrimination of patients with bladder cancer from healthy, but rarely presenting the identity of proposed biomarkers, our study represents a novel approach.


Assuntos
Neoplasias da Bexiga Urinária , Compostos Orgânicos Voláteis , Adulto , Biomarcadores , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos , Doenças Raras , Microextração em Fase Sólida/métodos , Neoplasias da Bexiga Urinária/diagnóstico , Compostos Orgânicos Voláteis/análise
2.
Sensors (Basel) ; 21(15)2021 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-34372282

RESUMO

Sensitive real-time detection of vapors produced by toxic industrial chemicals (TICs) always represents a stringent priority. Hydrogen cyanide (HCN) is definitely a TIC, being widely used in various industries and as an insecticide; it is a reactive, very flammable, and highly toxic compound that affects the central nervous system, cardiovascular system, eyes, nose, throat, and also has systemic effects. Moreover, HCN is considered a blood chemical warfare agent. This study was focused toward quick detection and quantification of HCN in air using time-of-flight ion mobility spectrometry (ToF IMS). Results obtained clearly indicate that IMS can rapidly detect HCN at sub-ppmv levels in air. Ion mobility spectrometric response was obtained in the negative ion mode and presented one single distinct product ion, at reduced ion mobility K0 of 2.38 cm2 V-1 s-1. Our study demonstrated that by using a miniaturized commercial IMS system with nonradioactive ionization source model LCD-3.2E (Smiths Detection Ltd., London, UK), one can easily measure HCN at concentrations of 0.1 ppmv (0.11 mg m-3) in negative ion mode, which is far below the OSHA PEL-TWA value of 10 ppmv. Measurement range was from 0.1 to 10 ppmv and the estimated limit of detection LoD was ca. 20 ppbv (0.02 mg m-3).


Assuntos
Substâncias para a Guerra Química , Cianeto de Hidrogênio , Substâncias para a Guerra Química/análise , Gases , Cianeto de Hidrogênio/análise , Espectrometria de Mobilidade Iônica , Londres
3.
Molecules ; 26(24)2021 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-34946786

RESUMO

Saponins are an important group of secondary metabolites naturally occurring in plants with important properties like: antibacterial, antiviral and antifungal. Moreover, they are widely used in the cosmetic industry and household chemistry. The sapogenins are saponin hydrolyses products, frequently used to facilitate saponin detection. In the present study, an improved methodology for isolation and separation of five sapogenins extracted from nettle (Urtica dioica L.), white dead-nettle (Lamium album L.), common soapwort (Saponaria officinalis L.) and washnut (Sapindus mukorossi Gaertn.) was developed using ultra-high-performance liquid chromatography with an evaporative light-scattering detector (UHPLC-ELSD). Based on quantitative analysis, the highest content of hederagenin (999.1 ± 6.3 µg/g) and oleanolic acid (386.5 ± 27.7 µg/g) was found in washnut extracts. Good recoveries (71% ± 6 up to 99% ± 8) were achieved for four investigated targets, while just 22.2% ± 0.5 was obtained for the fifth one. Moreover, hederagenin and oleanolic acid of whose highest amount was detected in washnut (999.1 ± 6.3 µg/g and 386.5 ± 27.7 µg/g, respectively) were subject to another approach. Consequently, liquid chromatography coupled mass spectrometry (LC/MS) with multiple reaction monitoring mode (MRM) was used as an additional technique for fast and simultaneous identification of the mentioned targets.


Assuntos
Sapindus/química , Sapogeninas/análise , Sapogeninas/isolamento & purificação , Saponaria/química , Urtica dioica/química
4.
Molecules ; 26(6)2021 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-33810121

RESUMO

Volatile organic compounds (VOCs) have been assessed in breath samples as possible indicators of diseases. The present study aimed to quantify 29 VOCs (previously reported as potential biomarkers of lung diseases) in breath samples collected from controls and individuals with lung cancer, chronic obstructive pulmonary disease and asthma. Besides that, global VOC profiles were investigated. A needle trap device (NTD) was used as pre-concentration technique, associated to gas chromatography-mass spectrometry (GC-MS) analysis. Univariate and multivariate approaches were applied to assess VOC distributions according to the studied diseases. Limits of quantitation ranged from 0.003 to 6.21 ppbv and calculated relative standard deviations did not exceed 10%. At least 15 of the quantified targets presented themselves as discriminating features. A random forest (RF) method was performed in order to classify enrolled conditions according to VOCs' latent patterns, considering VOCs responses in global profiles. The developed model was based on 12 discriminating features and provided overall balanced accuracy of 85.7%. Ultimately, multinomial logistic regression (MLR) analysis was conducted using the concentration of the nine most discriminative targets (2-propanol, 3-methylpentane, (E)-ocimene, limonene, m-cymene, benzonitrile, undecane, terpineol, phenol) as input and provided an average overall accuracy of 95.5% for multiclass prediction.


Assuntos
Adenocarcinoma de Pulmão/metabolismo , Asma/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Neoplasias Pulmonares/metabolismo , Doença Pulmonar Obstrutiva Crônica/metabolismo , Compostos Orgânicos Voláteis/metabolismo , Adulto , Testes Respiratórios , Feminino , Humanos , Masculino
5.
Molecules ; 26(7)2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33804943

RESUMO

Volatile organic compounds (VOCs) exiting in urine are potential biomarkers of chronic kidney diseases. Headspace solid phase microextraction (HS-SPME) was applied for extraction VOCs over the urine samples. Volatile metabolites were separated and identified by means of two-dimensional gas chromatography and time of flight mass spectrometry (GC × GC TOF MS). Patients with glomerular diseases (n = 27) and healthy controls (n = 20) were recruited in the study. Different VOCs profiles were obtained from patients and control. Developed methodology offers the opportunity to examine the metabolic profile associated with glomerulopathy. Four compounds found in elevated amounts in the patients group, i.e., methyl hexadecanoate; 9-hexadecen-1-ol; 6,10-dimethyl-5,9-undecadien-2-one and 2-pentanone were proposed as markers of glomerular diseases.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Insuficiência Renal Crônica/urina , Compostos Orgânicos Voláteis/urina , Biomarcadores/urina , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
6.
Molecules ; 25(24)2020 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-33317195

RESUMO

A method development for determination of neonicotinoid residues in honey samples was developed. The proposed methodology consisted in QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe). That was used for sample preparation and UHPLC/UV (ultra-performance liquid chromatography with ultraviolet detection) utilized for chromatographic analysis. The developed method proved to be sensitive, with LOD (Limit of detection) value in the range of 60.80 to 80.98 ng/g hence LOQ (Limit of quantification) value was in the range of 184.26 to 245.40 ng/g. The method has tested on Polish honey and applied to honey from various countries (Bulgaria, Czech Republic, France, Greece, Italy, Portugal, Romania, Australia, Brazil, Cameroon, Russia, USA and Turkey). Several honey types were tested, while physicochemical properties of all honeys and were investigated. The methodology for general characterization of pollen grains originated from selected plants, to confirm the type of honey was also presented. There was a total lack of the mentioned neonicotinoids in sunflower honey. Except of this, only two samples of rapeseed and two samples of acacia honey (from Poland and Romania) were neonicotinoids free. In 19 samples the targeted pesticides were detected above LOQ. In all other investigated samples, the neonicotinoids were found at least at the LOD or LOQ level.


Assuntos
Mel/análise , Neonicotinoides/análise , Animais , Austrália , Abelhas , Brasil , Fenômenos Químicos , Cromatografia Líquida de Alta Pressão , Europa (Continente) , Flores/química , Inseticidas/análise , Inseticidas/química , Limite de Detecção , Neonicotinoides/química , Polônia , Pólen/química , Pólen/ultraestrutura , Polinização , Estados Unidos
7.
Molecules ; 25(8)2020 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-32316669

RESUMO

Sensitive real-time detection of vapors produced by the precursors, reagents and solvents used in the illegal drugs manufacture represents a priority nowadays. Acetic anhydride (AA) is the key chemical used as acetylation agent in producing the illegal drugs heroin and methaqualone. This study was directed towards quick detection and quantification of AA in air, using two fast and very sensitive analytical techniques: photoionization detection (PID) and ion mobility spectrometry (IMS). Results obtained indicated that both PID and IMS can sense AA at ultra-trace levels in air, but while PID produces a non-selective response, IMS offers richer information. Ion mobility spectrometric response in the positive ion mode presented one product ion, at reduced ion mobility K0 of 1.89 cm2 V-1 s-1 (almost overlapped with positive reactant ion peak), while in the negative ion mode two well separated product ions, with K0 of 1.90 and 1.71 cm2 V-1 s-1, were noticed. Our study showed that by using a portable, commercial IMS system (model Mini IMS, I.U.T. GmbH Berlin) AA can be easily measured at concentrations of 0.05 ppmv (0.2 mg m-3) in negative ion mode. Best selectivity and sensitivity of the IMS response were therefore achieved in the negative operation mode.


Assuntos
Anidridos Acéticos/análise , Técnicas Biossensoriais , Drogas Ilícitas/análise , Drogas Ilícitas/química , Espectrometria de Mobilidade Iônica , Oligoelementos/análise , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Técnicas Biossensoriais/normas , Espectrometria de Mobilidade Iônica/instrumentação , Espectrometria de Mobilidade Iônica/métodos , Espectrometria de Mobilidade Iônica/normas , Reprodutibilidade dos Testes
8.
Anal Biochem ; 578: 36-44, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31085164

RESUMO

Considering the shortcomings related to antibiotics usage, the introduction of other bacteriostatic and bactericidal agents that present synergetic effects or standalone properties is urgently needed. AgNO3 is an important bactericidal agent, which imparts various functions on bacteria dependent on its concentration. Therefore, an understanding of its mechanisms of action in infinitesimal concentrations plays an important role which can ultimately lead to AgNO3 involvement in the pharmaceutical industry. The monitoring of VOC (volatile organic compound) profiles emitted by bacteria is a simple method to assess changes occurring in bacterial metabolism. In this study, VOCs of Hafnia alvei, Pseudomonas luteola and Staphylococcus warneri cultures were analyzed both in the absence and in the presence of three concentrations of AgNO3. Headspace solid-phase microextraction gas chromatography/mass spectrometry (HS-SPME-GC/MS) was employed for extraction and analysis. After supplementation with AgNO3, changes in the emitted fingerprints were investigated. Odorants associated with mouth-related and systemic diseases, like dimethyl trisulfide, indole (halitosis) and 2-hexanone (celiac disease), were also affected by addition of AgNO3. Statistical tests proved discrimination between obtained profiles with more that 90% variability. Moreover, physiological states of bacteria after dosage with various concentration of stressing agent were investigated and explained by the mechanisms of action.


Assuntos
Hafnia alvei/efeitos dos fármacos , Pseudomonas/efeitos dos fármacos , Saliva/microbiologia , Nitrato de Prata/farmacologia , Staphylococcus/efeitos dos fármacos , Compostos Orgânicos Voláteis/metabolismo , Humanos
9.
Anal Biochem ; 585: 113407, 2019 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-31449777

RESUMO

Escherichia coli (E. coli) is a Gram-negative bacterium commonly found in the lower intestine of warm-blooded organisms, including humans. Although the majority of the strains are considerably harmless, some serotypes are pathogenic, frequently causing diarrhea and other illnesses outside the intestinal tract. The standard antidote against bacteria is the use of antibiotics. Depending on their type, the antibiotics have various mechanisms of action on bacteria. Moreover, in case of in-vitro cultivation of bacteria, the used growth media plays a crucial role, since it influences bacterial inhibition as well. In the present study, we emphasize the importance of cultivability in bacterial inhibition under the treatment with five different antibiotics belonging to different classes. Consequently, E. coli was cultivated in three different growth media: trypcase soy broth (TSB), Mueller Hinton (MH), and minimal salts (M9) enriched with glucose, respectively. MALDI-TOF MS (matrix-assisted laser desorption ionization time-of-flight mass spectrometry) analyses, that were used for fast characterization of changes that occur in ribosomal protein profiles, revealed differentiation and similarities between investigated cases, while flow cytometry (FCM) tests better explained the given changes that occurred in the analyzed samples after 3, 24 and 48 h of experimental campaign.


Assuntos
Antibacterianos/metabolismo , Meios de Cultura/química , Meios de Cultura/metabolismo , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Proteínas de Bactérias/análise , Citometria de Fluxo , Glucose/química , Proteínas Ribossômicas/análise , Proteínas Ribossômicas/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Fatores de Tempo
10.
J Sep Sci ; 42(6): 1265-1272, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30653834

RESUMO

Cyclitols and sugars were obtained as a mixture from Medicago sativa L., in a comparative study by using maceration, and pressurized liquid extraction, as a modern and green extraction techniques. The influence of extraction parameters including: extraction temperature, time and number of cycles on the content of sugars and cyclitols was investigated based on response surface methodology. The highest total amount of sugars and cyclitols (62.27 ± 2.30 and 50.35 ± 0.77 mg/g of dry material, respectively) was obtained when extraction was performed at 88°C, for 22 min, in two cycles. The methodology used involved extraction, purification, selective separation (using yeast and anion exchange resin) and derivatization, followed by gas chromatography -mass spectrometry analysis. The use of yeast treatment realized an effective fractionation of cyclitols and sugars, which allowed the removal of most sugars. The involvement of anion exchange resin after yeast allowed the removal of sugar alcohols and lactose, together with other sugar traces remained and to obtain a solution containing six cyclitols. The recrystallization of dry residue after solvent evaporation, from ethanol, allowed us to obtain 14.65 mg of white pure crystals identified with NMR spectroscopy, liquid chromatography with mass spectrometry, gas chromatography with mass spectrometry, optical rotation and melting point as analysis D-pinitol.


Assuntos
Ciclitóis/isolamento & purificação , Extração Líquido-Líquido , Medicago sativa/química , Açúcares/isolamento & purificação , Temperatura , Configuração de Carboidratos , Ciclitóis/química , Pressão , Açúcares/química , Propriedades de Superfície , Fatores de Tempo
11.
J Sep Sci ; 42(20): 3243-3252, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31444853

RESUMO

The aim of the present study was to develop an optimization procedure for supercritical fluid extraction parameters, in order to obtain the highest possible yield of sugars and cyclitols from plant material. Response surface methodology based on Box-Behnken design was applied to evaluate the effect of: temperature (40, 60, 80°C), pressure (100, 200, 300 bar), and co-solvent (methanol) percentage (20, 25, 30%). As a result of the optimization process, we found that the highest amount of sugars (15.02 mg/gof dried material) and cyclitols (0.86 mg/g of dried material) was obtained when the following parameters were applied: 80°C, 228 bar, and 30% of methanol. Moreover, co-solvent concentration and temperature had a higher influence onto the obtained amounts compared with the pressure.

12.
Molecules ; 25(1)2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31861887

RESUMO

Honey is a natural sweetener, with an osmotic effect on microorganisms due to the increased sugar content and low amount of water. Cyclitols are minor constituents of honey. They play a defensive role in plants against unfavorable environmental conditions. Honey's physicochemical properties can vary, resulting in a wide range of colors, flavors, scents, antioxidant activity, dissimilar values of pH, acidity, electrical conductivity, etc. Some literature regarding correlation between honey types is already available, but a comprehensive study displaying an ample evaluation of multifarious aspects is still needed. This study focuses on the correlation between 18 honey types, originating from 10 countries, collected during four years, summarizing a total of 38 samples. A total of 6 physicochemical properties and 18 target components (sugars and cyclitols) were considered as variables. A correlation analysis is presented between the investigated parameters and between honey types, together with the statistical analysis which allowed for observation of the clusters' distribution according with the investigated variables.


Assuntos
Ciclitóis/análise , Mel/análise , Açúcares/análise
13.
Molecules ; 24(16)2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31426356

RESUMO

Halitosis and submandibular abscesses are examples of mouth-related diseases with the possible bacterial origin. Salivary volatile organic compounds (VOCs) are potential biomarkers of them, once they can be addressed as metabolites of bacterial activity. Healthy patients (n = 15), subjects with submandibular abscesses located in fascial deep space (n = 10), and subjects with halitosis (n = 5) were enrolled in the study. Saliva samples were subjected to headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to mass spectrometry (GC/MS) analysis. A total number of 164 VOCs was detected by the developed methodology, 23 specific for halitosis and 41 for abscess. Halitosis' profiles were characterized by a larger number of sulfur compounds, while for abscess they had a higher variety of alcohols, aldehydes, and hydrocarbons-biomarkers of inflammatory processes. Principal components analysis allowed visualization of clusters formed according to the evaluated conditions. Kruskal-Wallis test indicated that 39 VOCs presented differentiated responses between the studied groups, with statistical relevance (p < 0.05). Random forest was applied, and a prediction model based on eight VOCs (2-butanone, methyl thioacetate, 2-methylbutanoic acid, S-methyl pentanethioate, dimethyl tetrasulfide, indolizine, pentadecane, and octadecanal) provided 100% of sensitivity, 82% of specificity, and 91% of balanced accuracy, indicating the specific presence of submandibular abscess.


Assuntos
Abscesso/diagnóstico , Álcoois/isolamento & purificação , Aldeídos/isolamento & purificação , Halitose/diagnóstico , Hidrocarbonetos/isolamento & purificação , Compostos de Enxofre/isolamento & purificação , Abscesso/metabolismo , Abscesso/patologia , Adulto , Idoso , Álcoois/classificação , Aldeídos/classificação , Biomarcadores/análise , Estudos de Casos e Controles , Giro Denteado/metabolismo , Giro Denteado/patologia , Diagnóstico Diferencial , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Halitose/metabolismo , Halitose/patologia , Humanos , Hidrocarbonetos/classificação , Masculino , Mandíbula/metabolismo , Mandíbula/patologia , Pessoa de Meia-Idade , Análise de Componente Principal , Saliva/química , Sensibilidade e Especificidade , Microextração em Fase Sólida/métodos , Compostos de Enxofre/classificação , Compostos Orgânicos Voláteis
14.
Electrophoresis ; 2018 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-29603754

RESUMO

Based on the bioactive properties of certain compounds, such as antioxidant and anti-inflammatory activities, an interesting subject of research are natural substances present in various parts of plants. The choice of the most appropriate method for separation and quantification of biologically active compounds from plants and natural products is a crucial step of any analytical procedure. The aim of this review article is to present an overview of a comprehensive literature study from the last 10 years (2007-2017), where relevant articles exposed the latest trends and the most appropriate methods applicable for separation and quantification of biologically active compounds from plant material and natural products. Consequently, various extraction methods have been discussed, together with the available procedures for purification and pre-concentration and dedicated methods used for analysis.

15.
Electrophoresis ; 2018 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-29543989

RESUMO

Cyclitols are phytochemicals naturally occurring in plant material, which attracted an increasing interest due to multiple medicinal attributes, among which the most important are the antidiabetic, antioxidant, and anticancer properties. Due to their valuable properties, sugars are used in the food industry as sweeteners, preservatives, texture modifiers, fermentation substrates, and flavoring and coloring agents. In this study, we report for the first time the quantitative analysis of sugars and cyclitols isolated from Solidago virgaurea L., which was used for the selection of the optimal solvent and extraction technique that can provide the best possible yield. Moreover, the quantities of sugars and cyclitols extracted from two other species, Solidago canadensis and Solidago gigantea, were investigated using the best extraction method and the most appropriate solvent. Comparative analysis of natural plant extracts obtained using five different techniques-maceration, Soxhlet extraction, pressurized liquid extraction, ultrasound-assisted extraction, and supercritical fluid extraction-was performed in order to decide the most suitable, efficient, and economically convenient extraction method. Three different solvents were used. Analysis of samples has been performed by solid-phase extraction for purification and pre-concentration, followed by derivation and GC-MS analysis. Highest efficiency for the total amount of obtained compounds has been reached by PLE, when water was used as a solvent. d-pinitol amount was almost similar for every solvent and for all the extraction techniques involved.

16.
J Sep Sci ; 41(5): 1118-1128, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29250921

RESUMO

Plant research interest has increased all over the world, and a large body of evidence has been collected to show the huge potential of medicinal plants in various disease treatments. Medicago sativa L., known as alfalfa, is a rich source of biologically active components and secondary metabolites and was frequently used from the ancient times both as fodder crop and as a traditional medicine in the treatment of various diseases. Cyclitols, naturally occurring in this plant, have a particular interest for us due to their significant anti-diabetic, antioxidant, anti-inflammatory, and anti-cancer properties. In the present study we revealed the isolation, the identification, and the quantification of some cyclitols and sugars extracted from different morphological parts of alfalfa plant. Soxhlet extraction and solid phase extraction were used as extraction and purification methods, while for the analyses derivatization followed by gas chromatography with mass spectrometry was involved. The obtained results showed significant differences in the quantities of cyclitols and sugars found in the investigated morphological parts, ranging between 0.02 and 13.86 mg/g of plant in case of cyclitols, and in the range of 0.09 and 40.09 mg/g of plant for sugars. However, roots have the richest part of cyclitols and sugars in contrast to the leaves.


Assuntos
Ciclitóis/análise , Medicago sativa/química , Componentes Aéreos da Planta/química , Açúcares/análise , Cromatografia Gasosa-Espectrometria de Massas , Extração em Fase Sólida
17.
Nat Prod Res ; 37(1): 107-112, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34180317

RESUMO

Through this study, we aimed to develop a new analytical method for identification and quantification of sugars and cyclitols isolated from different morphological parts of Raphanus sativus L (R. sativus). Accelerated solvent extraction with water was involved for targets extraction. Solid phase extraction was used for purification and preconcentration, while high performance liquid chromatography with evaporative light scattering detector (HPLC-ELSD) was used for chromatographic analyses. A short method of only 30 min for a single analysis was developed finally. The obtained results, allowed for quantification of eight targets, i.e., three cyclitols (D-pinitol, allo-inositol and scyllo-inositol) and five sugars (xylose, D-mannose, D-fructose, D-glucose and sucrose) that were determined simultaneously using a single analysis. The developed method can be applied in industry as a routine method for analysis of sugars and cyclitols from different sources.


Assuntos
Ciclitóis , Raphanus , Açúcares , Ciclitóis/análise , Glucose/análise , Frutose , Cromatografia Líquida de Alta Pressão/métodos
18.
Analyst ; 137(6): 1458-65, 2012 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-22318171

RESUMO

A piezoelectric injector has been interfaced to a differential mobility spectrometer to enable fast and reversible control of dopant/transport-gas modifier levels within the reaction region of the instrument. Operating at 1 Hz with optimised bipolar waveforms for the piezoelectric injector and gas flows within the injector, steady-state 2-butanol mass fluxes of 21 to 1230 ng min(-1) and 1-bromohexane mass fluxes of 149 to 2644 ng min(-1) were delivered to the differential mobility cell. Control of split-flow and transport-gas flow rates enabled rapid and flexible control of the dopant concentrations. The system was consistently reproducible with a relative standard deviation (RSD) of 7.9% at every mass- flux level studied. Stable responses were achieved between 3 to 5 s following a change in the control levels and no significant hysteresis effects were observed. In the positive mode it was possible to control the extent of formation protonated monomer and proton bound cluster ions, tentatively assigned to{C(4)H(9)OH(H(2)O)(n)H}(+) and {(C(4)H(9)OH)(2)(H(2)O)(n)H}(+) and similar control was possible in the negative mode where the concentration relationship for the formation of bromide clusters indicated the presence of multiple ionisation mechanisms. A dopant formulation for the simultaneous control of ions in both the positive and negative modes was demonstrated by the injection of a 50%/50% v/v solution of 2-butanol/1-bromohexane with mass fluxes of 2-butanol in the mixture of between 11 and 1161 ng min(-1) and between 13 and 1325 ng min(-1) for 1-bromohexane.

19.
Sci Rep ; 11(1): 18780, 2021 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-34548581

RESUMO

VOCs (volatile organic compounds) are increasingly wished to be used in diagnosis of diseases. They present strategic advantages, when compared to classical methods used, such as simplicity and current availability of performant non-invasive sample collection methods/systems. However, standardized sampling methods are required in order to achieve reproducible results. In the current study we developed a method to be used for feces sampling using a Micro-Chamber/Thermal Extractor (µ-CTE). Design Expert software (with Box-Behnken design) was used to predict the solutions. Therefore, by using the simulation experimental plan that was further experimentally verified, extraction time of 19.6 min, at extraction temperature of 30.6 °C by using a flow rate of 48.7 mL/min provided the higher response. The developed method was validated by using correlation tests and Network analysis, which both proved the validity of the developed model.


Assuntos
Fezes/química , Compostos Orgânicos Voláteis/análise , Biomarcadores/metabolismo , Cromatografia Gasosa-Espectrometria de Massas/métodos , Humanos
20.
Crit Rev Anal Chem ; 51(2): 150-173, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-31820658

RESUMO

A chromatographic column is the fundamental element required for gas-chromatographic analysis. The separation of components coming from complex mixtures, prior to their detection was leading to a prominent revolution in different areas of science. Moreover, current advances in gas chromatographic (GC) columns technology and development have been providing almost unlimited possibilities for analysis employing diverse matrices. We aim through this review article to describe the evolution of chromatographic columns, by pointing the most important stages, as well as the new trends and future perspectives predicted for the new generation of GC columns. Furthermore, it was in our scope to present the main fundamentals regarding the theoretical relationships that describe the chromatographic separation, to introduce concepts related to columns selection in accordance with the required application as well as to discuss the available evaluation parameters for columns efficiency. Consequently, the early stages of first columns preparation up to the development of GC capillary columns used nowadays, together with examples of their applications are also reported and described in detail.


Assuntos
Cromatografia Gasosa/métodos , Biomarcadores Tumorais/análise , Biomarcadores Tumorais/metabolismo , Humanos , Neoplasias/diagnóstico , Polímeros/química , Porosidade , Siloxanas/química , Compostos Orgânicos Voláteis/análise
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