Analytical methods for the quantitative determination of selective serotonin reuptake inhibitors for therapeutic drug monitoring purposes in patients.

Five selective serotonin reuptake inhibitors (SSRIs) have been introduced recently: citalopram, fluoxetine, fluvoxamine, paroxetine and sertraline. Although no therapeutic window has been defined for SSRIs, in contrast to tricyclic antidepressants, analytical methods for therapeutic drug monitoring of SSRIs are useful in several instances. SSRIs differ widely in their chemical structure and in their metabolism. The fact that some of them have N-demethylated metabolites, which are also SSRIs, requires that methods be available which allow therapeutic drug monitoring of the parent compounds and of these active metabolites. most procedures are based on prepurification of the SSRIs by liquid-liquid extraction before they are submitted to separation by chromatographic procedures (high-performance liquid chromatography, gas chromatography, thin layer chromatography) and detection by various detectors (UV, fluorescence, electrochemical detector, nitrogen-phosphorus detector, mass spectrometry). This literature review shows that most methods allow quantitative determination of SSRIs in plasma, in the lower ng/ml range, and that they are, therefore, suitable for therapeutic drug monitoring purposes of this category of drugs.

Päällystetyn graafisen kartongin hajuominaisuudet

Diplomityön tavoitteena oli selvittää elintarvikepakkauksiin soveltuvan graafisen kartongin potentiaalinen hajun aiheuttaja. Lisäksi tavoitteena oli vähentää päällystetyn tasakoosteisen (SBS) kolmikerroskartongin hajutasoa keskittyen päällystyspastakomponentteihin sekä massaosaston jälkeen annosteltaviin kemikaaleihin. Kirjallisuusosassa tarkasteltiin eri kartonkilajeja, päällystyspastoja ja sen sisältämiä komponentteja, pääpainon ollessa kuitenkin kartongin hajuominaisuuksiin vaikuttavien tekijöiden selvittämisessä. Lisäksi luotiin katsaus kartonkien aistinvaraisiin ja instrumentaalisiin määritysmenetelmiin. Instrumentaalisista määritysmenetelmistä käsiteltiin headspace –kaasukromatografia (HSGC) sekä korkeanerotuskyvyn nestekromatografia yhdistettynä massaspektrometriin (HPLC/MS). Kokeellisen osan alussa kartoitettiin päällystyskemikaalien sekä liima- ja retentioaineiden haihtuvat yhdisteet HSGC- ja HPLC/MS –tekniikoiden avulla. Kaasukromatografisesti analysoidut kokonaishaihtuvien tasot eivät poikenneet normaaleista tasoista, joten jouduttiin siirtymään HPLC/MS –menetelmään. HPLC/MS –tekniikalla on päästy tutkimaan herkästi haihtuvien typpiyhdisteiden amiinipitoisuuksia. Kemikaalimittausten perusteella vaihdettiin potentiaaliset hajua aiheuttavat kemikaalit, kovete ja synteettinen paksuntaja, markkinoilla oleviin vaihtoehtoisiin kemikaaleihin ja suoritettiin pilot -koeajo sekä tehdasmittakaavaiset koeajot. Työssä perehdyttiin myös varastoinnin aiheuttamiin vaikutuksiin eri kartonkilaatujen aistinvaraisissa ominaisuuksissa. Päällystyspastan kemikaaleista suuren hajukuorman aiheuttavat kovete, dispergointiaine, päällystyspigmentit ja lateksit sekä synteettinen paksuntaja. Kovetteen annostelumäärä päällystyspastoihin on alhainen, mutta sen sisältämä ammoniakkipitoisuus on kuitenkin huomattavan suuri. Kovete ohjaakin lopputuotteen ammoniakkipitoisuutta. Merkittävän metyyliamiinikuorman sisältää dispergointiaine. Sen vaikutus lopputuotteeseen voidaan olettaa vähäiseksi johtuen kemikaalin pienestä määrästä pastassa. Päällystyspigmenttien ja lateksien korkea metyyliamiinikuorma voi puolestaan aiheuttaa lopputuotteeseen huomattavan hajukuorman johtuen niiden suurista annostelumääristä. Eri synteettisille paksuntajille tehtyjen tutkimusten mukaan niiden hajukuormat olivat hyvin samankaltaisia ja vaikutus lopputuotteen kokonaishajutasoon jäi pieneksi. Aistinvaraisesti tarkasteltuna eri kartonkilaaduille saadaan eri hajutasoja. Elintarvikepakkauksiin soveltuvan graafisen kartongin hajutasot olivat korkeita muihin kartonkilaatuihin nähden niin tuoreena kuin varastoinnin jälkeen. Erityisesti tuoreen kartonkinäytteen metyyliamiinipitoisuus ylitti hajukynnyksen. Käytetty lateksi, kovete ja synteettinen paksuntaja näyttävät muodostavan niin tiiviin hajua koteloivan päällystekerroksen kartongin pinnalle, että hajua vapautuu pitkällä aikavälillä. Myös varastointi tiiviinä pakkauksena estää amiinien haihtumisen. Tutkimusten mukaan ammoniakkivapaalla PZC –kovetteella saadaan alennettua graafisen kartongin ammoniakkikuormaa huomattavasti. Tämä on vaikuttamassa myös lopputuotteen hajutasoon, jota on mahdollisuus alentaa käyttämällä ammoniakkivapaata kovetetta.

Analytical Strategies for Doping Control Purposes: Needs, Challenges, and Perspectives.

The fight against doping in sports has been governed since 1999 by the World Anti-Doping Agency (WADA), an independent institution behind the implementation of the World Anti-Doping Code (Code). The intent of the Code is to protect clean athletes through the harmonization of anti-doping programs at the international level with special attention to detection, deterrence and prevention of doping.1 A new version of the Code came into force on January 1st 2015, introducing, among other improvements, longer periods of sanctioning for athletes (up to four years) and measures to strengthen the role of anti-doping investigations and intelligence. To ensure optimal harmonization, five International Standards covering different technical aspects of the Code are also currently in force: the List of Prohibited Substances and Methods (List), Testing and Investigations, Laboratories, Therapeutic Use Exemptions (TUE) and Protection of Privacy and Personal Information. Adherence to these standards is mandatory for all anti-doping stakeholders to be compliant with the Code. Among these documents, the eighth version of International Standard for Laboratories (ISL), which also came into effect on January 1st 2015, includes regulations for WADA and ISO/IEC 17025 accreditations and their application for urine and blood sample analysis by anti-doping laboratories.2 Specific requirements are also described in several Technical Documents or Guidelines in which various topics are highlighted such as the identification criteria for gas chromatography (GC) and liquid chromatography (LC) coupled to mass spectrometry (MS) techniques (IDCR), measurements and reporting of endogenous androgenic anabolic agents (EAAS) and analytical requirements for the Athlete Biological Passport (ABP).

Thermal Degradation of Small Molecules: A Global Metabolomic Investigation.

Thermal processes are widely used in small molecule chemical analysis and metabolomics for derivatization, vaporization, chromatography, and ionization, especially in gas chromatography mass spectrometry (GC/MS). In this study the effect of heating was examined on a set of 64 small molecule standards and, separately, on human plasma metabolite extracts. The samples, either derivatized or underivatized, were heated at three different temperatures (60, 100, and 250 °C) at different exposure times (30 s, 60 s, and 300 s). All the samples were analyzed by liquid chromatography coupled to electrospray ionization mass spectrometry (LC/MS) and the data processed by XCMS Online ( xcmsonline.scripps.edu ). The results showed that heating at an elevated temperature of 100 °C had an appreciable effect on both the underivatized and derivatized molecules, and heating at 250 °C created substantial changes in the profile. For example, over 40% of the molecular peaks were altered in the plasma metabolite analysis after heating (250 °C, 300s) with a significant formation of degradation and transformation products. The analysis of 64 small molecule standards validated the temperature-induced changes observed on the plasma metabolites, where most of the small molecules degraded at elevated temperatures even after minimal exposure times (30 s). For example, tri- and diorganophosphates (e.g., adenosine triphosphate and adenosine diphosphate) were readily degraded into a mono-organophosphate (e.g., adenosine monophosphate) during heating. Nucleosides and nucleotides (e.g., inosine and inosine monophosphate) were also found to be transformed into purine derivatives (e.g., hypoxanthine). A newly formed transformation product, oleoyl ethyl amide, was identified in both the underivatized and derivatized forms of the plasma extracts and small molecule standard mixture, and was likely generated from oleic acid. Overall these analyses show that small molecules and metabolites undergo significant time-sensitive alterations when exposed to elevated temperatures, especially those conditions that mimic sample preparation and analysis in GC/MS experiments.

Influência do material do alambique na composição química das aguardentes de cana-de-açúcar

This paper describes variations in the profile of the main volatile organic compounds present in Brazilian sugar cane spirits distilled in copper and stainless steel distillers. The main organic compounds: aldehydes, ketones, carboxylic acids, alcohols and esters, were determined through High Performance Liquid Chromatography (HPLC) and High Resolution Gas Cromatography (HRGC). The spirits produced in copper distillers exhibit higher contents of aldehydes with respect to the ones produced in stainless steel. The inverse is true with respect to the higher alcohol and ester contents. No significant variation has been observed for the carboxylic acids.

Análise de resíduos de pesticidas em tomates por cromatografia em camada delgada

Pesticide residues are determined by thin layer chromatography (TLC) using the Hill reaction as a detection method. Tomatoes samples without pesticide were fortified with atrazine, diuron, chloroxuron and metribuzin, and were applyed in silica gel plates with the help of a microsyringe. The pesticides were elued with ethyl acetate. There was no need of cleaning up because no interference was noticed. After the revelation of the plates, the diameters of the spots were measure by using a rule. The range of the determined concentration for all the pesticides was from 0.1 to1.0 ng/muL. The results obtained through TLC can be used for semi-quantitative analysis.The results obtained were compared to gas and liquid chromatography, showing good agreement between both techniques.

Influência do material do destilador na composição química das aguardentes de cana: parte II

The quantitative chemical analysis of the Brazilian sugar cane spirit distilled from glass column packaged with copper, stainless steel, aluminum sponge, or porcelain balls is described. The main chemical compounds determined by gas chromatography coupled with flame ionization (FID) and flame photometric (FPD) detectors and liquid chromatography coupled with diode array detector are aldehydes, ketones, carboxylic acids, alcohols, esters and dimethylsulfite (DMS). The spirits produced either in columns filled with copper or aluminum pot still exhibits the lowest DMS contents but the higher sulfate and methanol contents, whereas spirits produced in stainless steel or porcelain showed higher DMS concentration and lower teors of sulfate ion and methanol. These observations are coherent with DMS oxidation to sulfate, with methanol as by product, in the presence of either copper or aluminum.

Fluidos supercríticos em química analítica. II. Cromatografia com fluido supercrítico: instrumentação

The first paper in this series discussed the basic theory involved in supercritical fluid chromatography (SFC) and how the technique progressed from gas and liquid chromatography. The first SFC instruments were simple adaptations of the commercially available liquid chromatographs with packed columns followed by modifications in gas chromatographs using open tubular capillary columns. In this paper, the most important aspects regarding instrumentation are covered, including practical, simple, and the most important, inexpensive solutions to build a home-made SFC system.

Quantitative analysis of phenol and alkylphenols in Brazilian coal tar

The main purpose of this work is the identification and quantification of phenolic compounds in coal tar samples from a ceramics factory in Cocal (SC), Brazil. The samples were subjected to preparative scale liquid chromatography, using Amberlyst A-27TM ion-exchange resin as stationary phase. The fractions obtained were classified as "acids" and "BN" (bases and neutrals). The identification and quantification of phenols, in the acid fraction, was made by gas chromatography coupled to mass spectrometry (GC/MS). Nearly twenty-five phenols were identified in the samples and nine of them were also quantified. The results showed that coal tar has large quantities of phenolic compounds of industrial interest.

Métodos para análise de ácido clorogênico

This paper describes the analytical methods for determination of total chlorogenic acid (CGA) and their individual isomers. Spectrofotometric methods are adequate for total CGA analysis in green coffee but they can provide inflated results for coffee products. High pressure liquid chromatography (HPLC) with gel permeation column and ultraviolet (UV) monitoring is adequate for the simultaneous analysis of total CGA, alkaloids and sugars in coffee products. HPLC-UV-reversed phase is a simple, rapid and precise method for the determination of the individual isomers of CGA. Gas chromatography (GC) also is applied to the analysis of the individual isomers but phenolic acids need to be derivatized before analysis. Both HPLC- and GC-mass spectrometry provide an unequivocal identification of the individual isomers. The capillary electrophoresis method is simple, rapid and adequate to the simultaneous analysis of polyphenols and xanthines. Advantages and limitations of each method are discussed throughout the text.

Cromatografia unificada

The scope of this study encompasses an overview of the principles of unified chromatography as well as the principles of chromatographic techniques as applied to unified systems, which include gas chromatography, liquid chromatography, supercritical fluid chromatography, high temperature and high pressure liquid chromatography, micro-liquid chromatography, enhanced fluidity chromatography, and solvating gas chromatography. Theoretical considerations and individual instrumental parameters such as mobile phase, sample introduction system, columns, and detection system are also discussed. Future applications of this separation approach are discussed.

Fluidos supercríticos em química analítica. III.: aplicações

The first two papers in this series described the basic theory involved in supercritical fluid chromatography (SFC), how the technique evolved from gas and liquid chromatography and how the instrumentation was developed. Over the last two years, a commercial, dedicated packed-column SFC/MS instrument appeared on the market. The SFC continues to grow in use, with fundamental developments, coupled with a steady rise in the number of industrial users and applications.

Cafeína: revisão sobre métodos de análise

Gravimetric and Bailey-Andrew methods are tedious and provide inflated results. Spectrofotometry is adequate for caffeine analysis but is lengthy. Gas chromatography also is applied to the caffeine analysis but derivatization is needed. High performance liquid chromatography with ultraviolet detection (HPLC-UV) and reversed phase is simple and rapid for xanthine multianalysis. In HPLC-UV-gel permeation, organic solvents are not used. HPLC-mass spectrometry provides an unequivocal structural identification of xanthines. Capillary electrophoresis is fast and the solvent consumption is smaller than in HPLC. Chemometric methods offer an effective means for chemical data handling in multivariate analysis. Infrared spectroscopy alone or associated with chemometries could predict the caffeine content in a very accurate form. Electroanalytical methods are considered of low cost and easy application in caffeine analysis.

Comparison of GC and HPLC for quantification of organic acids in two jaboticaba (Myrciaria) fruit varieties

Gas chromatography (GC) with trimethylsilyl derivative formation was compared to high-performance liquid chromatography (HPLC) for quantification of organic acids (OAs) in two jaboticaba (Myrciaria) fruit (pulp and pericarp) varieties (Sabará and Açu Paulista). Succinic and citric acids were the major OAs found in all the samples analyzed. Besides being much more tedious, the results obtained with GC were significantly lower than HPLC (p<0.05) when the data (acids, variety, two parts and flowering days) were considered together. The presence of both acids was confirmed by gas chromatography-mass spectrometry (GC-MS).

Investigation of the occurrence of pesticide residues in rural wells and surface water following application to tobacco

In this work the exposure of wells and surface water to pesticides, commonly used for tobacco cropping, was assessed. Water consumption wells and surface water flows were sampled at different times. After a preconcentration step with solid phase extraction (SPE), the selected pesticides were determined by gas chromatography with electron capture detection (GC-ECD) or high performance liquid chromatography with diode array detection (HPLC-DAD). No pesticides were detected in the well water samples and surface water flow in the winter season. However, in the spring and summer higher concentrations of chlorpyrifos and imidacloprid were found in the water source samples. Atrazine, simazine and clomazone were also found. The occurrence of pesticides in collected water samples was related with the application to tobacco.