A validated method using RP-HPLC for quantification of reserpine in the Brazilian tree Rauvolfia sellowii Müll. Arg. (Apocynaceae)

This study describes a simple, fast and reproducible method using RP-HPLC-UV, in a gradient system, for quantification of reserpine in Rauvolfia sellowii stem bark. The analysis were carried out on a C18 column; mobile phase was water and acetonitrile, and separations were carried out in 10 min, flow rate of 1.0 mL min-1, 25 ºC and 268 nm. The validation data showed that the method was specific, accurate, precise and robust. Results were linear over a range of 0.625-40.0 μg mL-1, and the mean recovery was 95.1%. The amount of reserpine found in the dried stem bark was 0.01% (m/m).

Development and validation of a novel stability indicating RP-UPLC method for simultaneous determination of nizatidine, methylparaben and propylparaben in oral liquid pharmaceutical formulation

A selective and accurate stability-indicating gradient reverse phase ultra performance liquid chromatographic method has been developed and validated for the simultaneous determination of nizatidine, methylparaben and propylparaben in pharmaceutical oral liquid formulation. The separation was achieved on Acquity UPLC TM HSS T3 1.8 µm column by using mobile phase containing a gradient mixture of solvent A (0.02 Mol L-1 KH2PO4, pH 7.5) and B (60:40 v/v mixture of methanol and acetonitrile) at flow rate of 0.4 mL min-1. Drug product was exposed to the stress conditions of oxidative, acid, base, hydrolytic, thermal and photolytic degradation. The developed method was validated as per international ICH guidelines with respect to specificity, linearity, accuracy, precision and robustness.

Simultaneous determination of non-steroidal anti-inflammatory drugs in pharmaceutical formulations and human serum by reversed phase high performance liquid chromatography

A rapid and sensitive method using high performance liquid chromatography has been developed and validated for the simultaneous determination of non-steroidal anti-inflammatory drugs (NSAIDs) in pharmaceutical formulations and human serum. Six NSAIDs including: naproxen sodium, diclofenac sodium, meloxicam, flurbiprofen, tiaprofenic and mefenamic acid were analyzed simultaneously in presence of ibuprofen as internal standard on Mediterranea C18 (5 µm, 250 x 0.46 mm) column. Mobile phase comprised of methanol: acetonitrile: H2O (60:20:20, v/v; pH 3.35) and pumped at a flow rate of 1 mL min-1 using 265 nm UV detection. The method was linear over a concentration range of 0.25-50 µg mL-1 (r² = 0.9999).

Development and validation of a High Performance Liquid Chromatographic method for determination of etoposide in biodegradable polymeric implants

A method using HPLC-UV was developed and validated for the determination of etoposide incorporated into polycaprolactone implants. The method was carried out in isocratic mode using a C18 column (250 x 4.6 mm; 5 µm), at 25 ºC, with acetonitrile and acetic acid 4% (70:30) as mobile phase, a flow rate of 2 mL/min, and UV detection at 285 nm. The method was linear (r² > 0.99) over the range of 5 to 65 µg/mL, precise (RSD < 5%), accurate (recovery of 98.7%), robust, selective regarding excipient of the sample, and had a quantitation limit equal to 1.76 µg/mL. The validated method can be successfully employed for routine quality control analyses.

Multi-component quantitation of loratadine, pseudoephedrine and paracetamol in plasma and pharmaceutical formulations with liquid chromatography-tandem mass spectrometry utilizing a monolithic column

The purpose of this study was to develop a rapid, simple and sensitive quantitation method for pseudoephedrine (PSE), paracetamol (PAR) and loratadine (LOR) in plasma and pharmaceuticals using liquid chromatography-tandem mass spectrometry with a monolithic column. Separation was achieved using a gradient composition of methanol-0.1% formic acid at a flow rate of 1.0 mL min-1. Mass spectral transitions were recorded in SRM mode. System validation was evaluated for precision, specificity and linearity. Limit of detection for pseudoephedrine, paracetamol, and loratadine were determined to be 3.14, 1.86 and 1.44 ng mL-1, respectively, allowing easy determination in plasma with % recovery of 93.12 to 101.56%.

Determination of fipronil in bovine plasma by solid-phase extraction and liquid chromatography with ultraviolet detection

A fast and efficient method has been developed and validated for the determination of fipronil in bovine plasma. Samples were subjected to solid-phase extraction (SPE) followed by reversed phase liquid chromatography (LC) separation, using acetonitrile/water (60:40 v/v) as the mobile phase with a flow rate of 1.0 mL/min and ultraviolet (UV) detection at 210 nm. Ethiprole was used as the internal standard (IS). The method was found to be linear over the range 5-500 ng/mL (r = 0.999). The limit of quantitation (LOQ) was validated at 5 ng/mL. The method was successfully applied to monitor plasma concentrations following subcutaneous administration of fipronil in cattle.

Synthesis, characterization and application of ion imprinted poly(vinylimidazole) for zinc ion extraction/preconcentration with faas determination

In this paper, we describe the synthesis of an ion imprinted polymer (IIP) by homogeneous polymerization and its use in solid-phase to extract and preconcentrate zinc ions. Under optimal conditions (pH 5.0, preconcentration flow rate of 12.0 mL min-1, and eluted with 1.0 mol L-1 HNO3) this procedure allows the determination of zinc with an enrichment factor of 10.2, and with limits of detection and quantification of 1.5 and 5.0 µg L-1, respectively. The accuracy of our results was confirmed by analysis of tap water and certified reference materials: NIST 1570a (Spinach leaves) and NIST 1515 (Apple leaves).

Determination of Copper, Iron, Nickel and Zinc in fuel kerosene by FAAS after adsorption and pre-concentration on 2-aminothiazole-modified silica gel

Silica gel chemically modified with 2-Aminotiazole groups, abbreviated as SiAT, was used for preconcentration of copper, zinc, nickel and iron from kerosene, normally used as a engine fuel for airplanes. Surface characteristics and surface area of the silica gel were obtained before and after chemical modification using FT-IR, Kjeldhal and surface area analysis (B.E.T.). The retention and recovery of the analyte elements were studied by applying batch and column techniques. The experimental parameters, such as shaking time in batch technique, flow rate and concentration of the eluent (HCl- 0.25-2.00 mol L-1) and the amount of silica, on retention and elution, have been investigated. Detection limits of the method for copper, iron, nickel and zinc are 0.77, 2.92, 1.73 and 0.097 mg L-1, respectively. The sorption-desorption of the studied metal ions made possible the development of a preconcentration method for metal ions at trace level in kerosene using flame AAS for their quantification.

Amperometric biosensor for ascorbic acid

A L-ascorbic acid biosensor based on ascorbate oxidase has been developed. The enzyme was extracted from the mesocarp of cucumber (Cucumis sativus) by using 0.05 mol L-1 phosphate buffer, pH 5.8 containing 0.5 mol L-1 NaCl. After the dialysis versus phosphate buffer 0.05 mol L-1 pH 5.8, the enzyme was immobilized onto nylon net through glutaraldehyde covalent bond. The membrane was coupled to an O2 electrode and the yielding reaction monitored by oxygen depletion at -600 mV using flow injection analysis optimized to 0.1 mol L-1 phosphate buffer pH 5.8, as the carrier solution and flow-rate of 0.5 mL min-1. The ascorbic acid calibration curve was linear from 1.2x10-4 to 1.0x10-3 mol L-1. The evaluation of biosensor lifetime leads to 500 injections. Commercial pharmaceutical samples were analyzed with the proposed method and the results were compared with those obtained by high-performance liquid chromatography (HPLC).

Determination of carbon monoxide using a coated quartz crystal sensor

Carbon monoxide was detected and determined by a piezoelectric quartz crystal sensor coated with nickel(II)-phthalocyanine 50 % (v/v) solution in glycerine. Studies on the effect of temperature, flow rate, and some possible interferents were carried out. Calibration curves, sensor stability (lifetime) and the precision of measurements were also verified. The resulting selectivity is probably due to the coordinative binding between the electronically unsatured metal complexes and the analyte. The analytical curve is linear in the concentration range 0.10 to 1.0 % (v/v).

Modeling of water/steam circulation in Circulating Fluidized Bed boiler

A distinctive design feature of steam boiler with natural circulation is the presence of the steam drum which plays a role of the separator of vapor from the flow of water-and-steam mixture coming into steam drum from the furnace tubes. Steam drum with unheated downcomer tubes, deducing from it, and riser (screen/furnace tubes) inside the furnace is a closed circulation loop in which movement of water (downcomer tubes) and water-and-steam mixture (riser tubes) is organized. The movement of the working fluid is appears due to occurrence of the natural pressure, determined by the difference in hydrostatic pressure and the mass of water and water-and-steam mixtures in downcomer and riser tubes and called the driving pressure of the natural circulation: S drive = H steam (ρ down + ρ mix) g where: ρ down - density of water in downcomer tubes; ρ mix - density of water in riser tubes; H steam - height of steam content section; g - acceleration of gravity. In steam boilers with natural circulation the circulation rate is usually between 10 and 30. Thus, consumption of water in the circulation circuit “circulation rate times” more than steam output of the boiler. There are two aspects of the design of natural water circulation loops. One is to ensure a sufficient mass flux of circulating water to avoid burnout of evaporator tubes. The other is to avoid tube wall temperature fluctuation and tube vibration due to oscillation of circulation velocity. The design criteria are therefore reduced, in principle, to those of critical heat flux, critical flow rate for burnout, and flow instability. In practical design, however, the circulation velocity and the void fraction at the evaporator tube outlet are used as the design criteria (Seikan I., et. al., 1999). This study has been made with assumption that the heat flux in the furnace of the boiler even all the time. The target of the study was to define the circulation rate of the boiler, thus average heat flux do not change it. I would like to acknowledge professionals from “Foster Wheeler” company for good and comfortable cooperation.

Pumppauksen energiansäästökartoitus teollisuuslaitoksessa

Tässä diplomityössä on suoritettu pumppauksen energiansäästökartoitus Nordkalkin Lappeenrannan teollisuuslaitoksessa. Tavoitteena on kuvata teollisuuslaitoksen nykyistä pumppauksen tarvetta sekä etsiä energiansäästökohteita. Työn valmistelussa on käytetty apuna energiankulutustiedoista koostettuja energiataseita sekä yrityksen valmistelemia pumppulistoja. Energiansäästökohteita haettaessa tässä tarkastelutyössä huomio on kohdistettu pumppujen säätötapoihin ja mahdollisuuksiin vähentää virtaamaa tai pumppujärjestelmän kokonaisnostokorkeutta. Pumppujärjestelmän toiminnan määrittämisessä on käytetty hyväksi tilavuusvirran ja sähkötehon mittauksia sekä teoreettista tarkastelua kokonaisnostokorkeuden ja pumpun toimintapisteen selvittämiseksi. Kaikkien tarkasteltavien pumppujen osalta on hyödynnetty laitevalmistajien tarjoamia tietoja. Pumppujen vuotuisen toiminnan arviointi on suoritettu tuotantotietojen sekä käyttöhenkilökunnan haastatteluilla kerätyn tiedon perusteella. Työn lopussa on esitetty tarkastelukohteiksi valittujen pumppujärjestelmien energiatehokkuuden parantamiseksi suositeltavia toimenpiteitä. Suositeltavien toimenpiteiden sisältäessä investointeja on niille laskettu nykyarvot sekä takaisinmaksuajat. Energiansäästökohteiksi valittujen pumppujärjestelmien yhteenlaskettu vuosittainen energiansäästö on 352 MWh/a (24640 €/a) investointikustannusten (hankintakustannukset) ollessa 12000 €.

Monitoring of centrifugal pump operation by a frequency converter

Centrifugal pumps are widely used in industrial and municipal applications, and they are an important end-use application of electric energy. However, in many cases centrifugal pumps operate with a significantly lower energy efficiency than they actually could, which typically has an increasing effect on the pump energy consumption and the resulting energy costs. Typical reasons for this are the incorrect dimensioning of the pumping system components and inefficiency of the applied pump control method. Besides the increase in energy costs, an inefficient operation may increase the risk of a pump failure and thereby the maintenance costs. In the worst case, a pump failure may lead to a process shutdown accruing additional costs. Nowadays, centrifugal pumps are often controlled by adjusting their rotational speed, which affects the resulting flow rate and output pressure of the pumped fluid. Typically, the speed control is realised with a frequency converter that allows the control of the rotational speed of an induction motor. Since a frequency converter can estimate the motor rotational speed and shaft torque without external measurement sensors on the motor shaft, it also allows the development and use of sensorless methods for the estimation of the pump operation. Still today, the monitoring of pump operation is based on additional measurements and visual check-ups, which may not be applicable to determine the energy efficiency of the pump operation. This doctoral thesis concentrates on the methods that allow the use of a frequency converter as a monitoring and analysis device for a centrifugal pump. Firstly, the determination of energy-efficiency- and reliability-based limits for the recommendable operating region of a variable-speed-driven centrifugal pump is discussed with a case study for the laboratory pumping system. Then, three model-based estimation methods for the pump operating location are studied, and their accuracy is determined by laboratory tests. In addition, a novel method to detect the occurrence of cavitation or flow recirculation in a centrifugal pump by a frequency converter is introduced. Its sensitivity compared with known cavitation detection methods is evaluated, and its applicability is verified by laboratory measurements for three different pumps and by using two different frequency converters. The main focus of this thesis is on the radial flow end-suction centrifugal pumps, but the studied methods can also be feasible with mixed and axial flow centrifugal pumps, if allowed by their characteristics.

A Comparative Study of the Effectiveness of a Prefabricated Appliance and a Stabilization Appliance in the Treatment of Myofascial pain and Headache

The aim of this thesis was to evaluate the short- and long-term effectiveness of a prefabricated occlusal appliance (R) on patients with myofascial pain and headache by comparing it with the treatment of the stabilization appliance (S). Another aim was to evaluate the effect of appliance treatment on stress-related salivary parameters like cortisol and IgA, as well as on flow rate values in these patients. Sixty-five patients diagnosed with myofascial temporomandibular disorder (TMD) pain, of whom 94% suffered concomitantly from headache, at two centres for Stomatognathic Physiology, one in Sweden and one in Finland, were included in this randomized controlled trial using Research Diagnostic Criteria for TMD (RDC/TMD), with history questionnaires and clinical examinations performed at baseline and at 6- and 10-weeks, and 6- and 12-month follow-ups. Patients were randomly assigned either to the R or the S group. Treatment outcome was measured according to IMMPACT (Initiative on Methods, Measurements, and Pain Assessment in Clinical Trials), i.e. four chronic pain outcome domains: pain intensity, overall improvement, physical and emotional functioning. Changes in frequency and intensity of headache were recorded. Thirty-nine patients participated in the saliva study. Salivary analyses were performed at 6 and 10 weeks. The results revealed no differences between groups at baseline. At all follow-ups, all four outcome measures, as well as frequency and intensity of headache, showed statistically significant within-group improvement compared to baseline, without significant differences between groups. No treatment-induced changes in saliva parameters could be registered. In conclusion, the effectiveness of the prefabricated appliance seemed to be similar to that of the stabilization appliance in alleviating myofascial pain, and frequency and intensity of headache, in the short as well as the long term. However, no changes in salivary parameters were observed during treatment.

Water distribuition characteristics and soil loss of LEPA Quad-Spray emitter nozzles

The objective of this study was to characterize water application rate, water application pattern width, flow rate, water distribution uniformity and soil loss caused by nozzles of the Low Energy Precision Aplication (LEPA) type Quad-Spray emitter. The study was carried out at the Hydraulic and Irrigation Laboratory of the Department of Engineering at the Federal University of Lavras, in Lavras, state of Minas Gerais - MG, Brazil. Twenty-two (22) LEPA Quad-Spray emitter nozzles were evaluated, with nozzle diameter ranging from 1.59 to 9.92 mm. The experimental design used was entirely randomized, with three replications.Increasing values of nozzle flow rate ranging from 77.44 up to 3,044 L h-1, were obtained with increasing nozzle diameter sizes. Application pattern width ranged from 0.56 up to 3.24m, according to nozzles diameter size. Low values of CDU (maximum of 35.73%) were observed when using the Quad-Spray nozzles. Observed average water application rates covered the range between 68.05 mm h-1 (the lowest value that was obtained with the 2.38mm nozzle) and 258.15 mm h-1 (the highest value that was observed with the 9.92 mm). Average water application rates increased in a simple non-linear function with the increase of nozzle size diameter. However, the weighted average increase in the amount of soil loss by erosion was not related to the increase of weighted average water application values.