Although the benefits of ICP-MS are well documented, the determination of analytes at low levels in high concentrations of matrix elements has proved difficult. As ICP-MS is a 'flow into' instrument the deposition of salts throughout the system is a common cause of significant loss of signal. The application of desolvation of aluminosilicate samples, to aid in the production of more robust plasma conditions, was investigated to increase the efficiency of the ICP in processing the sample. The performance of the ICP-MS was monitored with different cone arrangements and by running the skimmer cones at elevated temperatures. An alternative to modification of the instrument is to employ chemical modification of the sample and hence the separation of Au and Pt from an aluminosilicate matrix via the use of solid phase extraction (SPE) columns were investigated as a means of dealing with high levels of dissolved solids. OVB based SPE columns were found to give high retentions of Au and Pt when chelated with ammonium pyrrolidinediethylcarbamate (APOC). A second alternative that avoided digestion of the aluminosilicate matrices, was to carry out the analysis using laser ablation (LA). LA-ICP-MS is becoming increasingly used for trace elemental analysis but as yet no universal calibration method is available. The general problems associated with matrix matched standards are inherent as the ablation mechanism and plasma conditions can differ dramatically with very small changes in matrix composition. Hence the addition of chromophores was employed to increase the absorption of the laser energy. The use of vanillic, nicotinic and pyrazinoic acid were used to improve the ablation of pressed powder discs at the laser wavelength of 213 nm. Synthetic aluminosilicate discs and standard additions were both employed for the calibration and determination of Ti.

ABSTRACT PRECONCENTRATION OF SOME PRECIOUS METALS USING DEBT IMPREGNATED RESIN Refiker, H&uuml / rm&uuml / s M. Sc., Department of Chemistry Supervisor: Prof. Dr. R. Sezer Ayg&uuml / n Co-supervisor: Assoc. Prof. Dr. Melek Merdivan August 2005, 107 pages In this thesis, trace amounts of gold and silver have been determined by flame absorption spectrometry (FAAS) after preconcentration by N,N-diethyl-N&#039 / -benzoylthiourea (DEBT) impregnated resin (Amberlite XAD-16). In the first part of the thesis, sorption behaviours of gold and silver with DEBT impregnated resin under optimized conditions / stirring time, pH, desorption of metals and metal ion capacities of the resin have been studied in batch process. Metal ion capacity of resin is calculated as 0.17 mmol/g resin and 0.104 mmol/g resin for silver and for gold, respectively. In the second part of the thesis, preconcentration of gold and silver was tried by DEBT impregnated resin using column process under optimized conditions / pH, flow rate and volume of sample solution, nature of eluent, flow rate and volume of eluent However, due to partial leaching of DEBT by time, no satisfactory and reproducible results could be obtained. In the final part of the study, metal chelates prepared in aqueous solutions were passed through the column under optimized conditions and satisfactory sorption-desorption and selective preconcentration could be achieved. Under optimized conditions, silver and gold ions at the concentrations of 0.05 &amp / #61549 / g/mL and 0.015 &amp / #61549 / g/mL with preconcentration factors of 7.7 and 6.7, respectively could be determined by FAAS. The proposed method is highly selective without the need for any interference elimination process. Keywords: Precious metals, Solid-phase extraction, DEBT, Amberlite XAD-16

104f. / Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2013-04-10T12:46:40Z No. of bitstreams: 1 Dissertação.pdf: 828536 bytes, checksum: 3694e4a12f58240a1aaa95041bf6ed2f (MD5) / Approved for entry into archive by Ana Hilda Fonseca(anahilda@ufba.br) on 2013-05-09T17:35:10Z (GMT) No. of bitstreams: 1 Dissertação.pdf: 828536 bytes, checksum: 3694e4a12f58240a1aaa95041bf6ed2f (MD5) / Made available in DSpace on 2013-05-09T17:35:10Z (GMT). No. of bitstreams: 1 Dissertação.pdf: 828536 bytes, checksum: 3694e4a12f58240a1aaa95041bf6ed2f (MD5) Previous issue date: 2009 / CAPES / O vinho é um produto da fermentação de açúcares naturais presente em suco de uva. É uma bebida amplamente consumida em muitas partes do mundo por milhares de anos, com elevado valor comercial e importância social. Esta dissertação apresenta o desenvolvimento de dois métodos para determinação de metais em vinho. O primeiro descreve a otimização e validação de um método para determinação direta de cádmio em amostras de vinho por espectrometria de absorção atômica com atomização eletrotérmica (ET AAS). A otimização foi realizada empregando um planejamento fatorial completo de dois níveis, incluindo os fatores: tempo (10 s) e temperatura de pirólise (600 oC), temperatura de atomização (1300 oC) e massa de modificador (15 mg). Sob as condições otimizadas, foi encontrada uma massa característica de 0,7 pg, limite de detecção e quantificação de 0,030 e 0,100 mg L-1, respectivamente, para um volume de amostra de 20 mL. A precisão foi de 0,30, 0,37 e 0,49% (RSD) para amostras de vinho com concentrações de cádmio 1,286, 0,266 e 0,356 mg L-1, respectivamente. A exatidão do método de determinação direta empregando ET AAS foi avaliada por comparação usando um método de digestão ácida e determinação também por ET AAS para cinco amostras de vinho. O método foi aplicado para determinação de cádmio em 30 amostras de vinhos Brasileiros. A concentração de cádmio variou de 0,146 a 1,563 mg L-1, cujos valores estão abaixo do nível máximo permitido pela Organização Internacional de vinha e vinho (OIV) e pela legislação Brasileira, 10 mg L-1. No segundo método foram avaliados processos de extração em fase sólida de Cu, Fe, Zn, e Mn em amostras de vinhos, utilizando carvão ativo e resina de troca iônica como adsorventes. As quantificações foram realizadas por FAAS. Com base nos resultados pode-se observar que o carvão ativo demonstrou ser bastante eficiente na extração de Cu, Fe, Zn e Mn em vinho, e que o Cu, Fe e Zn estão na forma de organocomplexos. Já, o Mn presente nas soluções residuais da extração apresentou-se predominantemente na forma iônica. A resina de troca catiônica apresentou uma alta capacidade de sorção para todos os metais avaliados. Entretanto, a resina aniônica apresentou certa afinidade de sorção pelos metais Cu, Fe e Zn. Os limites de detecção para Cu, Fe, Zn e Mn foram 0,02, 0,04, 0,02 e 0,02 mg L-1, respectivamente. Os limites de quantificação para Cu, Fe, Zn e Mn foram 0,08, 0,13, 0,06 e 0,06 mg L-1, respectivamente. A precisão foi expressa como desvio padrão relativo (%RSD), variando de 1,78 a 6,78%, para amostra de vinho com concentrações de 0,13, 3,33, 0,36 e 1,52 para Cu, Fe, Zn e Mn, respectivamente. Esta avaliação foi feita para seis amostras de vinhos brasileiros. / Salvador

Os contaminantes emergentes são considerados compostos onipresentes em águas, portanto investigar a degradação e comportamento dessas substâncias torna-se necessária, pois é reportado que estes compostos causam efeitos adversos em seres vivos. O composto 2-(tiocianometiltio) benzotiazol (TCMTB), considerado um contaminante emergente, é amplamente empregado na indústria do couro como biocida com a finalidade de inibir o desenvolvimento de microrganismos na pele. Sendo assim, o objetivo do presente trabalho foi estudar a degradação do contaminante emergente TCMTB, por meio das técnicas de fotólise direta com radiação UV, radiação solar e oxidação com ozônio. Experimentos de fotólise direta do TCMTB, em soluções aquosas com diferentes concentrações, em efluente do processo de remolho e efluente simulado do remolho, foram conduzidos em reator com lâmpada de vapor de mercúrio (250 W). O teste de hidrólise foi realizado protegido da luz, a temperatura ambiente com diferentes concentrações do TCMTB para observar o comportamento do contaminante na ausência de luz. O maior coeficiente de absorção molar foi medido e identificado em 220 e 280 nm como 20489 e 11317 M-1 cm-1, respectivamente, para pH 5,0. Os resultados experimentais da fotodegradação mostraram que TCMTB foi rapidamente degradado por fotólise direta em soluções aquosas em 30 min de tratamento fotolítico. Os resultados do estudo do pH, demonstraram que pH interfere no processo fotoquímico, uma vez que em condições alcalinas o composto é mais estável e a taxa de fotodegradação diminui. Os ensaios com o efluente do processo de remolho mostraram que a degradação do TCMTB tem comportamento semelhante às soluções aquosas. O efluente simulado do remolho mostrou que uma alta concentração do contaminante leva a um maior tempo de irradiação de luz para a degradação. A aplicação de luz natural evidenciou degradação mais lenta, mas ainda assim, foi possível observar degradação de até 96% para a concentração de 6 mg L-1 em 420 min. A utilização do oxidante ozônio como tratamento, alcançou 40% de remoção do contaminante em 30 min, assinalando a alta estabilidade do composto. Portanto, este trabalho aponta o potencial do uso de fotólise direta (luz v artificial), ou radiação solar (luz natural) para a degradação de contaminantes emergentes como o 2 (tiocianometiltio) benzotiazol (TCMTB). / Emerging contaminants are considered omnipresent compounds in water, thus investigate the degradation and behavior of these substances becomes necessary as it is reported that these compounds cause adverse effects on living beings. The 2- (thiocyanomethylthio) benzothiazole compound (TCMTB), considered an emerging contaminant, is widely used in the leather industry as a microbicide for the purpose of inhibiting the development of microorganisms in the skin and leather. In this context, the purpose of the present work was to study the degradation of the emerging contaminant TCMTB by direct photolysis with UV radiation, solar radiation and ozone. Experiments of direct photolysis of the TCMTB in aqueous solutions with different concentrations, in the effluent from the soaking process were conducted in a reactor with mercury vapor lamp (250 W). The hydrolysis test was performed protected from light at room temperature with different concentrations of TCMTB to observe the behavior of the contaminant in the absence of light. The highest molar absorption coefficient was measured and identified at 220 and 280 nm as 20489 and 11317 M-1 cm -1, respectively, at pH 5.0. The experimental results of photodegradation showed that TCMTB was rapidly degraded by direct photolysis in aqueous solutions in 30 min of photolytic treatment. The results of the pH study showed that pH interfered in the photochemical process, since under alkaline conditions the compound is more stable and the photodegradation rate decreases. Assays of the direct photolysis in effluent from the soaking process have shown that TCMTB degradation behaves similarly to aqueous solutions. The direct photolysis of the the simulated effluent from the soaking showed that a high concentration of the contaminant leads to a longer time of light irradiation for degradation. The application of natural light evidenced slower degradation, however, it was possible to observe degradation of up to 96% for the 6 mg L-1 concentration with 420 min. The use of the ozone oxidant as a treatment, achieved 40% removal of the contaminant for 30 min of treatment, indicating the high stability of the compound. Therefore, this work highlights the potential of the use of direct photolysis (artificial light), or solar radiation (natural light) for the vii degradation of emerging contaminants such as 2 (thiocyanomethylthio) benzothiazole (TCMTB).

Os contaminantes emergentes são considerados compostos onipresentes em águas, portanto investigar a degradação e comportamento dessas substâncias torna-se necessária, pois é reportado que estes compostos causam efeitos adversos em seres vivos. O composto 2-(tiocianometiltio) benzotiazol (TCMTB), considerado um contaminante emergente, é amplamente empregado na indústria do couro como biocida com a finalidade de inibir o desenvolvimento de microrganismos na pele. Sendo assim, o objetivo do presente trabalho foi estudar a degradação do contaminante emergente TCMTB, por meio das técnicas de fotólise direta com radiação UV, radiação solar e oxidação com ozônio. Experimentos de fotólise direta do TCMTB, em soluções aquosas com diferentes concentrações, em efluente do processo de remolho e efluente simulado do remolho, foram conduzidos em reator com lâmpada de vapor de mercúrio (250 W). O teste de hidrólise foi realizado protegido da luz, a temperatura ambiente com diferentes concentrações do TCMTB para observar o comportamento do contaminante na ausência de luz. O maior coeficiente de absorção molar foi medido e identificado em 220 e 280 nm como 20489 e 11317 M-1 cm-1, respectivamente, para pH 5,0. Os resultados experimentais da fotodegradação mostraram que TCMTB foi rapidamente degradado por fotólise direta em soluções aquosas em 30 min de tratamento fotolítico. Os resultados do estudo do pH, demonstraram que pH interfere no processo fotoquímico, uma vez que em condições alcalinas o composto é mais estável e a taxa de fotodegradação diminui. Os ensaios com o efluente do processo de remolho mostraram que a degradação do TCMTB tem comportamento semelhante às soluções aquosas. O efluente simulado do remolho mostrou que uma alta concentração do contaminante leva a um maior tempo de irradiação de luz para a degradação. A aplicação de luz natural evidenciou degradação mais lenta, mas ainda assim, foi possível observar degradação de até 96% para a concentração de 6 mg L-1 em 420 min. A utilização do oxidante ozônio como tratamento, alcançou 40% de remoção do contaminante em 30 min, assinalando a alta estabilidade do composto. Portanto, este trabalho aponta o potencial do uso de fotólise direta (luz v artificial), ou radiação solar (luz natural) para a degradação de contaminantes emergentes como o 2 (tiocianometiltio) benzotiazol (TCMTB). / Emerging contaminants are considered omnipresent compounds in water, thus investigate the degradation and behavior of these substances becomes necessary as it is reported that these compounds cause adverse effects on living beings. The 2- (thiocyanomethylthio) benzothiazole compound (TCMTB), considered an emerging contaminant, is widely used in the leather industry as a microbicide for the purpose of inhibiting the development of microorganisms in the skin and leather. In this context, the purpose of the present work was to study the degradation of the emerging contaminant TCMTB by direct photolysis with UV radiation, solar radiation and ozone. Experiments of direct photolysis of the TCMTB in aqueous solutions with different concentrations, in the effluent from the soaking process were conducted in a reactor with mercury vapor lamp (250 W). The hydrolysis test was performed protected from light at room temperature with different concentrations of TCMTB to observe the behavior of the contaminant in the absence of light. The highest molar absorption coefficient was measured and identified at 220 and 280 nm as 20489 and 11317 M-1 cm -1, respectively, at pH 5.0. The experimental results of photodegradation showed that TCMTB was rapidly degraded by direct photolysis in aqueous solutions in 30 min of photolytic treatment. The results of the pH study showed that pH interfered in the photochemical process, since under alkaline conditions the compound is more stable and the photodegradation rate decreases. Assays of the direct photolysis in effluent from the soaking process have shown that TCMTB degradation behaves similarly to aqueous solutions. The direct photolysis of the the simulated effluent from the soaking showed that a high concentration of the contaminant leads to a longer time of light irradiation for degradation. The application of natural light evidenced slower degradation, however, it was possible to observe degradation of up to 96% for the 6 mg L-1 concentration with 420 min. The use of the ozone oxidant as a treatment, achieved 40% removal of the contaminant for 30 min of treatment, indicating the high stability of the compound. Therefore, this work highlights the potential of the use of direct photolysis (artificial light), or solar radiation (natural light) for the vii degradation of emerging contaminants such as 2 (thiocyanomethylthio) benzothiazole (TCMTB).

Orientadores: Felix Guillermo Reyes Reyes, Susanne Rath / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-26T09:04:09Z (GMT). No. of bitstreams: 1 Ribeiro_CyntiaCabral_D.pdf: 2553496 bytes, checksum: c2200295b5cb6899de7fa33b75518899 (MD5) Previous issue date: 2014 / Resumo: Sulfonamidas e fluoroquinolonas são fármacos veterinários amplamente utilizados na produção aviária para prevenção e tratamento de doenças e, quando não respeitadas as boas práticas veterinárias, resíduos desses fármacos podem ser encontrados acima dos limites máximos de resíduos podendo representar risco à saúde dos consumidores. Sendo o ovo uma matriz biológica complexa, quantidades significativas de interferentes podem prejudicar a determinação dos analitos de interesse por cromatografia líquida, especialmente resíduos de fármacos veterinários, que se encontram em níveis na ordem de ng g-1. Entre as diversas técnicas de preparo de amostras capazes de eliminar interferentes e concentrar o analito de interesse, a extração em fase sólida (SPE) se destaca pela sua eficiência, robustez, seletividade e baixo consumo de solventes. Ainda assim, devido à complexidade da matriz e a baixa concentração dos analitos, o estabelecimento de métodos de preparo de amostras com seletividade na remoção de interferentes e eficiência de extração adequados ainda é um desafio na análise de resíduos. Desta forma, afim de se contornar as limitações da SPE convencional, esta tese teve como objetivo avaliar a aplicação de potencial elétrico em SPE (E-SPE) para a determinação de resíduos de sulfonamidas e fluoroquinolonas em ovos por cromatografia líquida de alta (HPLC) e ultra eficiência (UHPLC) associada à detectores por arranjo de fotodiodos (DAD), fluorescência (FLD) ou espectrômetro de massas sequencial (MS/MS). Os parâmetros de E-SPE foram avaliados de forma a obter a melhor condição no preparo de amostras e o método para a determinação de resíduos de sulfonamidas e fluoroquinolonas em ovos por E-SPE UHPLC-MS/MS foi avaliado em relação a linearidade, precisão, exatidão, além dos efeitos de supressão ou incremento de sinal analítico (efeito matriz) / Abstract: Sulfonamides and fluoroquinolones are veterinary drugs widely used in the poultry production for the prevention and treatment of diseases and, when good veterinary practices are not observed, residues of these drugs can be found above the maximum residue limit and may represent a risk to the consumers health. Since egg is a complex biological matrix, significant amounts of interferents can hinder the determination of analytes by liquid chromatography, particularly residues of veterinary drugs, which are at levels in the order of ng g-1. Among the various sample preparation techniques capable to eliminate interferences and concentrate the analyte of interest, the solid phase extraction (SPE) stands out for its efficiency, robustness, selectivity and low solvent consumption. Nevertheless, due to the complexity of the matrix and the low concentration of the analytes, the establishment of sample preparation methods with selectivity in removing interferents and appropriate extraction efficiency is still a challenge in residue analysis. Thus, in order to overcome the limitations of conventional SPE, this thesis aimed to evaluate the application of electrical potential in SPE (E-SPE) for the determination of sulfonamides and fluoroquinolones residues in eggs by high efficient (HPLC) and ultra efficient (UHPLC) performance liquid chromatography associated with a photodiode array (DAD), fluorescence (FLD) or sequential mass spectrometer (MS/MS) detectors. The E-SPE parameters were evaluated to obtain the best condition for sample preparation and the method for the determination of sulfonamides and fluoroquinolones residues in eggs by E-SPE UHPLC-MS/MS was evaluated for linearity, precision, accuracy, in addition to the effects of suppression or increase of the analytical signal (matrix effect) / Doutorado / Ciência de Alimentos / Doutora em Ciência de Alimentos

Orientador: Isabel Cristina Sales Fontes Jardim / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T21:45:28Z (GMT). No. of bitstreams: 1 Magueta_RenatadaCosta_M.pdf: 9269521 bytes, checksum: ce3c0368312fe2614e36d33195d8da7b (MD5) Previous issue date: 2013 / Resumo: Um novo sorvente para extração em fase sólida foi preparado utilizando a imobilização térmica do polímero poli(metiloctilsiloxano) sobre sílica zirconizada. Foram estudadas as etapas de preparo do sorvente, avaliando-se a quantidade de polímero, a temperatura e o tempo de imobilização e a extração do excesso de polímero não imobilizado. Também se determinou o volume de breakthrough e a eficiência de extração dos cartuchos preparados. Para avaliação da eficiência de extração dos sorventes, foram utilizadas amostras de água fortificadas com uma mistura dos agrotóxicos carbendazim, imidacloprido, acetamiprido, cimoxanil, carbofuram, carbaril, metiocarbe, tebuconazol, difenoconazol, pirimifós-metílico e piriproxifem. Os resultados de cada estudo realizado foram comparados com os obtidos para o sorvente preparado sobre sílica não modificada e foram consideradas adequadas as eficiências de extração entre 70 e 120%, com coeficiente de variação de até 20%. Com a sílica zirconizada, os melhores resultados foram obtidos com 50% de polímero sobre o suporte, imobilização a 120 °C por 4 horas e extração do excesso de polímero utilizando n-hexano, numa proporção de 36 mL de solvente para cada 1 g de material, a temperatura de 50 °C e vazão de 0,6 mL/min. A caracterização físico-química dos materiais mostrou que houve incorporação satisfatória do zircônio ao suporte de sílica no processo de metalização e o polímero encontra-se fisicamente sorvido e quimicamente ligado ao suporte. O estudo do volume de breakthrough dos cartuchos e a avaliação do desempenho do sorvente frente a variações de pH mostraram que a presença de átomos de zircônio na superfície do suporte aumenta a acidez dos grupos silanóis residuais, de modo que estes sítios interagem fortemente com os analitos básicos em pH elevado. Pôde-se observar que as eficiências de extração dos agrotóxicos também variam com a polaridade dos compostos, sendo que, o mecanismo de retenção é complexo, alternando entre interações hidrofóbicas e eletrostáticas. A aplicação do sorvente zirconizado na extração de agrotóxicos em amostras de suco de tomate mostrou que o mesmo apresenta potencial para ser empregado na extração em fase sólida de multirresíduos com características diversas de matrizes complexas / Abstract: A new sorbent for solid-phase extraction was prepared using thermal immobilization of the polymer poly(methyloctylsiloxane) onto a zirconized silica support. The steps of the preparation were studied evaluating the polymer loading, the temperature and time of immobilization and the extraction of the excess non-immobilized polymer as well as the cartridge¿s breakthrough volume and extraction efficiency. To evaluate the cartridge¿s extraction efficiency water samples fortified with a mixture of the pesticides carbendazin, imidacloprid, acetamiprid, cymoxanil, carbofuran, carbaryl, methiocarb, tebuconazole, difenoconazole, pirimiphos-methyl and pyriproxyfen were used. The results of each step were compared with those from the sorbent prepared with unmodified silica and adequate extraction efficiencies were considered as being between 70 and 120% with variation coefficients under 20%. With zirconized silica the best results were achieved with 50% polymer loading onto the support, immobilization at 120 °C for 4 hours and extraction of the excess non-immobilized polymer using n-hexane, in the proportion of 36 mL of solvent for 1 g of material, at 50 °C and at a 0.6 mL/min flow rate. The physical-chemical characterization of the materials showed that the incorporation of zirconium onto the silica support in the metalization process was satisfactory and the polymer is physically sorbed and chemically attached to the support. The studies concerning the breakthrough volume and the evaluation of the cartridge¿s performance over pH variations showed that the presence of the zirconium on the support¿s surface increases the acidity of the residual silanol so that these sites interact strongly with basic analytes at high pH. It was also possible to observe that the extraction efficiencies vary with the polarity of the compounds. The retention mechanism is complex, mixing hydrophobic and electrostatic interactions. The application of the zirconized sorbent in the extraction of pesticides from tomato juice samples showed that the sorbent has the potential to be used for multiresidue solid-phase extraction of complex matrices having a wide range of characteristics / Mestrado / Quimica Analitica / Mestra em Química

The diploma thesis is focused on the determination of tetracyclines, sulfonamides and fluoroquinolones from soil. Antibiotics such as tetracycline, chlortetracycline, oxytetracycline. ciprofloxacin, trimethoprim, sulfamethaxazole and sulfadiazin were selected due to frequent use in veterinary medicine. Due to the fact that the soil is a complex matrix and contains many components that can interfere with the detection signal of analytes, it was necessary to use the MAX column in the SPE method, which removes fulvic aned humic acid from analytes and the HLB column Final analysis of the analytes was performed by liquid chromatography with mass detesction (LC-MS). The method was also used for real soil samples, which were delivered from ÚKZUS.

This research study successfully completed three objectives: 1) validate liquid-liquid, supported-liquid, and solid-phase extractions for the quantitation of three barbiturates (amobarbital, butalbital, and phenobarbital) in blood and urine using liquid chromatography-tandem mass spectrometry; 2) to compare the efficiency and effectiveness among methods in accomplishing extraction of barbiturates under the laboratory setting at Boston University School of Medicine; and 3) to report all the analytical data to RTI International for interlaboratory comparison. For the validation study, a six-point linear calibration model (20-2000 ng/mL) with inversely weighted concentration (1/x) was reproducible in all three sample preparation methods for both blood and urine with r2 greater than or equal to 0.994. Bias and precision evaluated from three controls throughout the range of the curve were within ±20% and ±20%CV, respectively. Neither carryover nor interference was observed. Detection limits were evaluated down to 5 ng/mL depending on the extraction procedure. Samples were able to be diluted up to 50 times prior to instrumental analysis. Samples were stable on autosampler at room temperature up to 72 hours after their initial analysis. Recovery of barbiturates from blood and urine all ranged from 45% to 86%. The effect of ionization suppression or enhancement was found to have minimal impact on the validation. For choosing the most suitable method quantifying barbiturates, efficiency and effectiveness were studied. Efficiency evaluates the time and ease of sample preparation required to prepare a sample for analysis. Supported-liquid extraction was found to be the most efficient method for extracting barbiturates as it required the least amount of time to perform and could be easily automated with minimal training. Effectiveness is an assessment of one’s ability to selectively recover target analyte at a reasonably low concentration. By considering a method’s recovery, extract cleanliness, detection limits, and reproducibility, liquid-liquid extraction was the best at quantifying barbiturates in blood and supported-liquid extraction was the most suitable method for extracting barbiturates from urine. For interlaboratory comparison, all the data collected has been reported to RTI International. These findings can be used for examining the overall reliability and reproducibility of the validated methods. Results obtained can also be used to explore the possibility for streamlining sample preparation in the forensic laboratory, and hence reducing the case backlog.

The issue with maintaining stability of compounds during storage and transportation has been universal across many fields such as clinical, pharmaceutical, food industry and especially in forensic laboratories where case backlogs hinder immediate analysis of samples upon collection. This study compares various storage conditions and analyzes changes in compound stability over 28 days. The various storage conditions compared in this study are temperature (+4 °C and -20 °C); water sample and urine sample and solid state (loading onto Solid Phase Extraction cartridges) and storing in its liquid state (present in the urine or water sample). 51 compounds were analyzed in this study belonging to pharmaceutical and hormone classes. Two Dimensional Liquid Chromatography was used for separation allowing the analysis of varied compounds in terms of chemistry. Mass Spectrometry was used for detection of these compounds. This study conclusively helped determine that there is no significant difference in stability of 42 out of 51 of these compounds on comparing them in solid versus liquid state over a period of 28 days. This helps determine that Solid Phase Extraction (SPE) cartridges can be used as an alternative for storage and transportation of these compounds. 46 compounds showed no significant difference in +4 and -20 °C temperature storage conditions as well. Despite not including a wash step during sample preparation between loading and elution, 11 out of 51 compounds did not show suppression or enhancement due to matrix effect. This study not only highlights the importance of sample preparation prior to analysis but also shows how SPE technique could help maintain stability of compounds during storage. In future studies, stability changes using SPE for long term storage could provide beneficial results to conclude if SPE techniques can provide an advantage over liquid state for a period longer than a month.