A validated HPLC analytical method for the analysis of solasonine and solamargine in in vitro skin penetration studies

To assess topical delivery studies of glycoalkaloids, an analytical method by HPLC-UV was developed and validated for the determination of solasonine (SN) and solamargine (SM) in different skin layers, as well as in a topical formulation. The method was linear within the ranges 0.86 to 990.00 µg/mL for SN and 1.74 to 1000.00 µg/mL for SM (r = 0.9996). Moreover, the recoveries for both glycoalkaloids were higher than 88.94 and 93.23% from skin samples and topical formulation, respectively. The method developed is reliable and suitable for topical delivery skin studies and for determining the content of SN and SM in topical formulations.

Development of a simple analytical method for determining trihalomethanes in beer using a headspace solid-phase microextraction technique

We developed a simple, rapid, and solventless method for analyzing trihalomethanes in beer samples using headspace solid-phase microextraction. The effects of varying experimental parameters, such as extraction temperature and time, addition of sodium chloride, and agitation speed, on extraction yield were studied using a univariate experimental design. Limits of detection between 0.22 and 0.46 µg L- 1 and wide linear ranges were achieved for trihalomethanes. We measured the trihalomethane recoveries and precision (as the standard deviation of repeat measurements) and demonstrated the applicability of the proposed method by analyzing 32 beer samples.

Automatic evaluation and data generation for analytical chemistry instrumental analysis exercises

In general, laboratory activities are costly in terms of time, space, and money. As such, the ability to provide realistically simulated laboratory data that enables students to practice data analysis techniques as a complementary activity would be expected to reduce these costs while opening up very interesting possibilities. In the present work, a novel methodology is presented for design of analytical chemistry instrumental analysis exercises that can be automatically personalized for each student and the results evaluated immediately. The proposed system provides each student with a different set of experimental data generated randomly while satisfying a set of constraints, rather than using data obtained from actual laboratory work. This allows the instructor to provide students with a set of practical problems to complement their regular laboratory work along with the corresponding feedback provided by the system's automatic evaluation process. To this end, the Goodle Grading Management System (GMS), an innovative web-based educational tool for automating the collection and assessment of practical exercises for engineering and scientific courses, was developed. The proposed methodology takes full advantage of the Goodle GMS fusion code architecture. The design of a particular exercise is provided ad hoc by the instructor and requires basic Matlab knowledge. The system has been employed with satisfactory results in several university courses. To demonstrate the automatic evaluation process, three exercises are presented in detail. The first exercise involves a linear regression analysis of data and the calculation of the quality parameters of an instrumental analysis method. The second and third exercises address two different comparison tests, a comparison test of the mean and a t-paired test.

DEVELOPMENT AND VALIDATION OF ANALYTICAL METHOD FOR PALM OIL DETERMINATION IN MICROCAPSULES PRODUCED BY COMPLEX COACERVATION

The microencapsulation of palm oil may be a mechanism for protecting and promoting the controlled release of its bioactive compounds. To optimize the microencapsulation process, it is necessary to accurately quantify the palm oil present both external and internal to the microcapsules. In this study, we developed and validated a spectrophotometric method to determine the microencapsulation efficiency of palm oil by complex coacervation. We used gelatin and gum arabic (1:1) as wall material in a 5% concentration (w/v) and palm oil in the same concentration. The coacervates were obtained at pH 4.0 ± 0.01, decanted for 24 h, frozen (−40 ºC), and lyophilized for 72 h. Morphological analyzes were then performed. We standardized the extraction of the external palm oil through five successive washes with an organic solvent. We then explored the best method for rupturing the microcapsules. After successive extractions with hexane, we determined the amount of palm oil contained in the microcapsules using a spectrophotometer. The proposed method was shown to be of low cost, fast, and easy to implement. In addition, in the validation step, we confirmed the method to be safe and reliable, as it proved to be specific, accurate, precise, and robust.

Spectrophotometric study of iron oxidation in the iron(II)/thiocyanate/acetone system and some analytical applications

The possibility of using thiocyanate to determine iron(II) and/or iron(III) in water-acetone mixture has been re-examined as part of a systematic and comparative study involving metallic complexes of pseudohalide ligands. Some parameters that affect the complete oxidation of the ferrous cations, their subsequent complexation and the system stability have been studied to optimize the experimental conditions. Our results show the viability and potentiality of this simply methodology as an alternative analytical procedure to determine iron cations with high sensitivity, precision and accuracy. Studies on the calibration, stability, precision, and effect of various different ions have been carried out by using absorbance values measured at 480 nm. The analytical curve for the total iron determination obeys Beer's law (r = 0.9993), showing a higher sensitivity (molar absorptivity of 2.10x10(4) L cm-1 mol-1) when compared with other traditional systems (ligands) or even with the "similar" azide ion [1.53x10(4) L cm-1 mol-1, for iron-III/azide complexes, in 70% (v/v) tetrahydrofuran/water, at 396 nm]. Under such optimized experimental conditions, it is possible to determine iron in the concentration range from 0.5 to 2 ppm (15-65% T for older equipments, quartz cells of 1.00 cm). Analytical applications have been tested for some different materials (iron ores), also including pharmaceutical products for anemia, and results were compared with atomic absorption determinations. Very good agreement was obtained with these two different techniques, showing the potential of the present experimental conditions for the total iron spectrophotometric determinations (errors < 5%). The possibility of iron speciation was made evident by using another specific and auxiliary method for iron(II) or (III).

Spectrophotometric study of the chromium(III)/azide system in the ultraviolet region and its analytical application

A sensitive and alternative method for the spectrophotometric determination of chromium(III) based on the formation of chromium(III)/azide complexes was established by investigating a new band in the ultraviolet region. The best experimental conditions for the analytical determination of this metallic ion were: ligand and perchloric acid analytical concentration = 493 and 12.0 mmol L-1, respectively; aqueous medium; T = 25.0 ºC; contact time = 1 hour. The maximum molar absorptivity coefficient occurred at 287 nm (average 1.481 ± 0.008 ´ 10(4) L mol-1 cm-1), leading to the determination of metal ion concentrations one hundred times lower than the ones formerly determined in the visible region. The system obeys Beer's Law and is suitable for chromium determination in the 0.702-2.81 mg L-1 concentration range (15-65% T, 1.00 cm-width quartz cells). Analytical applications of the current method were tested with a nutritional supplement containing chromium. Results were compared with those obtained with atomic absorption spectrometry.

Potentiometric and conductimetric studies of chemical equilibria for pyridoxine hydrochloride in aqueous solutions: simple experimental determination of pKa values and analytical applications to pharmaceutical analysis

The combination of two low-cost classical procedures based on titrimetric techniques is presented for the determination of pyridoxine hydrochloride in pharmaceuticals samples. Initially some experiments were carried out aiming to determine both pKa1 and pKa2 values, being those compared to values of literature and theoretical procedures. Commercial samples containing pyridoxine hydrochloride were electrochemically analysed by exploiting their acid-base and precipitation reactions. Potentiometric titrations accomplished the reaction between the ionizable hydrogens present in pyridoxine hydrochloride, being NaOH used as titrant; while the conductimetric method was based on the chemical precipitation between the chloride of pyridoxine hydrochloride molecule and Ag+ ions from de silver nitrate, changing the conductivity of the solution. Both methods were applied to the same commercial samples leading to concordant results when compared by statistical tests (95 and 98% confidence levels). Recoveries ranging from 99.0 to 108.1% were observed, showing no significant interference on the results.

First dice your dill – new methods and techniques in sample handling

This book is dedicated to celebrate the 60th birthday of Professor Rainer Huopalahti. Professor Rainer “Repe” Huopalahti has had, and in fact is still enjoying a distinguished career in the analysis of food and food related flavor compounds. One will find it hard to make any progress in this particular field without a valid and innovative sample handling technique and this is a field in which Professor Huopalahti has made great contributions. The title and the front cover of this book honors Professor Huopahti’s early steps in science. His PhD thesis which was published on 1985 is entitled “Composition and content of aroma compounds in the dill herb, Anethum graveolens L., affected by different factors”. At that time, the thesis introduced new technology being applied to sample handling and analysis of flavoring compounds of dill. Sample handling is an essential task that in just about every analysis. If one is working with minor compounds in a sample or trying to detect trace levels of the analytes, one of the aims of sample handling may be to increase the sensitivity of the analytical method. On the other hand, if one is working with a challenging matrix such as the kind found in biological samples, one of the aims is to increase the selectivity. However, quite often the aim is to increase both the selectivity and the sensitivity. This book provides good and representative examples about the necessity of valid sample handling and the role of the sample handling in the analytical method. The contributors of the book are leading Finnish scientists on the field of organic instrumental analytical chemistry. Some of them are also Repe’ s personal friends and former students from the University of Turku, Department of Biochemistry and Food Chemistry. Importantly, the authors all know Repe in one way or another and are well aware of his achievements on the field of analytical chemistry. The editorial team had a great time during the planning phase and during the “hard work editorial phase” of the book. For example, we came up with many ideas on how to publish the book. After many long discussions, we decided to have a limited edition as an “old school hard cover book” – and to acknowledge more modern ways of disseminating knowledge by publishing an internet version of the book on the webpages of the University of Turku. Downloading the book from the webpage for personal use is free of charge. We believe and hope that the book will be read with great interest by scientists working in the fascinating field of organic instrumental analytical chemistry. We decided to publish our book in English for two main reasons. First, we believe that in the near future, more and more teaching in Finnish Universities will be delivered in English. To facilitate this process and encourage students to develop good language skills, it was decided to be published the book in English. Secondly, we believe that the book will also interest scientists outside Finland – particularly in the other member states of the European Union. The editorial team thanks all the authors for their willingness to contribute to this book – and to adhere to the very strict schedule. We also want to thank the various individuals and enterprises who financially supported the book project. Without that support, it would not have been possible to publish the hardcover book.

Qualitative Characteristics and Quantitative Measures of Solution's Reliability in Discrete Optimization: Traditional Analytical Approaches, Innovative Computational Methods and Applicability

The purpose of this thesis is twofold. The first and major part is devoted to sensitivity analysis of various discrete optimization problems while the second part addresses methods applied for calculating measures of solution stability and solving multicriteria discrete optimization problems. Despite numerous approaches to stability analysis of discrete optimization problems two major directions can be single out: quantitative and qualitative. Qualitative sensitivity analysis is conducted for multicriteria discrete optimization problems with minisum, minimax and minimin partial criteria. The main results obtained here are necessary and sufficient conditions for different stability types of optimal solutions (or a set of optimal solutions) of the considered problems. Within the framework of quantitative direction various measures of solution stability are investigated. A formula for a quantitative characteristic called stability radius is obtained for the generalized equilibrium situation invariant to changes of game parameters in the case of the H¨older metric. Quality of the problem solution can also be described in terms of robustness analysis. In this work the concepts of accuracy and robustness tolerances are presented for a strategic game with a finite number of players where initial coefficients (costs) of linear payoff functions are subject to perturbations. Investigation of stability radius also aims to devise methods for its calculation. A new metaheuristic approach is derived for calculation of stability radius of an optimal solution to the shortest path problem. The main advantage of the developed method is that it can be potentially applicable for calculating stability radii of NP-hard problems. The last chapter of the thesis focuses on deriving innovative methods based on interactive optimization approach for solving multicriteria combinatorial optimization problems. The key idea of the proposed approach is to utilize a parameterized achievement scalarizing function for solution calculation and to direct interactive procedure by changing weighting coefficients of this function. In order to illustrate the introduced ideas a decision making process is simulated for three objective median location problem. The concepts, models, and ideas collected and analyzed in this thesis create a good and relevant grounds for developing more complicated and integrated models of postoptimal analysis and solving the most computationally challenging problems related to it.

Serum biochemistry of 4-day-old ostriches (Struthio camelus)

An analysis was made of 30 four-day-old ostriches to evaluate their protein, metabolite, mineral, and serum enzyme profiles, to correlate them with the birds' sex. The values obtained were: Total proteins 3.59±0.72g/dL, albumin 1.04±0.14g/dL, globulins 2.51±0.56g/dL, A:G ratio 0.43± 0.07, total cholesterol 615.10±101.15mg/dL, high density lipoprotein cholesterol (HDL-C) 132.72±20.33mg/dL, low density lipoprotein cholesterol (LDL-C) 454.93±90.81mg/dL, very low density lipoprotein cholesterol (VLDL-C) 27.45±9.96mg/dL, triglycerides 137.23±49.78mg/dL, uric acid 6.24±2.15mg/dL, urea 18.27±12.33mg/dL, creatinine 0.30±0.04mg/dL, total calcium 9.38± 0.76mg/dL, ionized calcium 7.17±0.64mg/dL, phosphorus 6.96±0.91mg/dL, Ca:P ratio 1.37±0.21, iron 24.74±13.02µg/dL, sodium 142.03±6.17mEq/L, chlorides 109.59± 4.99mEq/L, aspartate aminotransferase (AST) 200.67±31.42 U/L, alanine aminotransferase (ALT) 3.90±1.92 U/L, γ-glutamyltransferase (GGT) 1.18±0.73 U/L, alkaline phosphatase (ALP) 597.30± 231.36 U/L, and creatine kinase (CK) 2348.30±755.60 U/L. Males and females showed significant differences in total proteins, globulins, alkaline phosphatase, A:G ratio, and uric acid.

Hematologic, serum biochemistry and urinary values for captive Crab-eating Fox (Cerdocyon thous) in São Paulo state, Brazil

The importance of studies with hematological, serum biochemistry and urinary values of Crab-eating Fox (Cerdocyon thous) is based on the need for health care and maintenance of those populations. This paper has the objective to investigate hematological, serum biochemistry and urinary physiological parameters of the Crab-eating fox, comparing gender and age differences. Blood samples were collected in 2003 from 52 animals of different Zoos in São Paulo state, Brazil; 7mL of blood was used to obtain a complete blood cell count (CBC) and the profile of the serum biochemistry. Moreover, 5mL of urine were collected for analysis. There was no difference in values for male and female animals, as for the CBC and serum biochemistry. Some hematological and serum biochemical parameters were influenced by age, showing significant differences. Urinalysis results were just demonstrated in a descriptive form. The studied values were, RBC 4.35±0.73 x 10(6) /µL, WBC 7.72±3.66 x 10³ /µL (predominance of segmented neutrophils), platelets 227.06±111.58 x 10³ /µL, urea 43.06±14.28mg/dL and creatinine 1.03±0.24mg/dL. Hematological, serum biochemistry and urinary values obtained in this study can be used as physiological values of the captive Crab-eating Fox. It is possible to conclude that wild species need their own reference values, differentiating animals in captivity from free-ranging animals.

Analytical methods for analyzing organic peroxides

Työn tarkoituksena oli kehittää analyyttinen erotusmenetelmä eräässä valmistusprosessissa käytettävän hapettavan aineen ja liuottimen välillä syntyvien reaktiotuotteiden tutkimiseen ja analysoimiseen. Lisäksi tarkoituksena oli tutkia prosessiolosuhteiden turvallisuutta. Kirjallisuusosassa käsitellään erilaisia orgaanisia peroksideja, niiden käyttötarkoituksia ja niiden käyttöön liittyviä huomioitavia asioita. Lisäksi tarkastellaan yleisimpiä analyysimenetelmiä, joita on käytetty erilaisten peroksidien analysoinnissa. Näitä analyysimenetelmiä on useimmiten käytetty nestemäisten näytteiden tutkimuksissa. Harvemmin on analysoitu kaasu- ja kiintoainenäytteitä. Kokeellisessa osassa kehitettiin kirjallisuuden perusteella peroksidiyhdisteille identifiointimenetelmä ja tutkittiin prosessin näytteet. Analyysimenetelmiksi valittiin iodometrinen titraus ja HPLC-UV-MS-menetelmä. Lisäksi käytettiin peroksidimittaukseen soveltuvia testiliuskoja. Tutkimus osoitti, että iodometrisen titrauksen ja testiliuskojen perusteella näytteissä oli vähäisiä määriä peroksideja viikon jälkeen peroksidilisäyksestä. HPLC-UV-MS-analyysien perusteella näytteiden analysointia häiritsi selluloosa, jota löytyi jokaisesta näytteestä.

Effects of condensation in microchannels with a porous boundary: analytical investigation on heat transfer and meniscus shape

In two-phase miniature and microchannel flows, the meniscus shape must be considered due to effects that are affected by condensation and/or evaporation and coupled with the transport phenomena in the thin film on the microchannel wall, when capillary forces drive the working fluid. This investigation presents an analytical model for microchannel condensers with a porous boundary, where capillary forces pump the fluid. Methanol was selected as the working fluid. Very low liquid Reynolds numbers were obtained (Re~6), but very high Nusselt numbers (Nu~150) could be found due to the channel size (1.5 mm) and the presence of the porous boundary. The meniscus calculation provided consistent results for the vapor interface temperature and pressure, as well as the meniscus curvature. The obtained results show that microchannel condensers with a porous boundary can be used for heat dissipation with reduced heat transfer area and very high heat dissipation capabilities.