Development of Vaginal Carriers Based on Chitosan-Grafted-PNIPAAm for Progesterone Administration

Chitosan-based hydrogels possess numerous advantages, such as biocompatibility and non-toxicity, and it is considered a proper material to be used in biomedical and pharmaceutical applications. Vaginal administration of progesterone represents a viable alternative for maintaining pregnancy and reducing the risk of miscarriage and in supporting the corpus luteum during fertilization cycles. This study aimed to develop new formulations for vaginal administration of progesterone (PGT). A previously synthesized responsive chitosan-grafted-poly (N-isopropylacrylamide) (CS-g-PNIPAAm) was formulated in various compositions with polyvinyl alcohol (PVA) as external crosslinking agent to obtain pH- and temperature-dependent hydrogels; the hydrogels had the capacity to withstand shear forces encountered in the vagina due to its mechanism of swelling once in contact with vaginal fluids. Three different hydrogels based on grafted chitosan were analyzed via Fourier-transform infrared spectroscopy (FTIR), swelling tests, in vitro drug release, and bioadhesion properties by TA.XTplus texture analysis. A higher amount of PVA decreased the swelling and the bioadhesion capacities of the hydrogel. All hydrogels showed sensitivity to temperature and pH in terms of swelling and in vitro delivery characteristics. By loading progesterone, the studied hydrogels seemed to possess even higher sensitivity than drug-free matrices. The release profile of the active substance and the bioadhesion characteristics recommended the CS-g-PNIPAAm/PVA 80/20 +PGT (P1) hydrogel as a proper constituent for the vaginal formulation for progesterone administration.

Design, Synthesis, In Silico and In Vitro Studies for New Nitric Oxide-Releasing Indomethacin Derivatives with 1,3,4-oxadiazole-2-thiol Scaffold

Starting from indomethacin (IND), one of the most prescribed non-steroidal anti-inflammatory drugs (NSAIDs), new nitric oxide-releasing indomethacin derivatives with 1,3,4-oxadiazole-2-thiol scaffold (NO-IND-OXDs, 8a-p) have been developed as a safer and more efficient multitarget therapeutic strategy. The successful synthesis of designed compounds (intermediaries and finals) was proved by complete spectroscopic analyses. In order to study the in silico interaction of NO-IND-OXDs with cyclooxygenase isoenzymes, a molecular docking study, using AutoDock 4.2.6 software, was performed. Moreover, their biological characterization, based on in vitro assays, in terms of thermal denaturation of serum proteins, antioxidant effects and the NO releasing capacity, was also performed. Based on docking results, 8k, 8l and 8m proved to be the best interaction for the COX-2 (cyclooxygense-2) target site, with an improved docking score compared with celecoxib. Referring to the thermal denaturation of serum proteins and antioxidant effects, all the tested compounds were more active than IND and aspirin, used as references. In addition, the compounds 8c, 8h, 8i, 8m, 8n and 8o showed increased capacity to release NO, which means they are safer in terms of gastrointestinal side effects.

Synthesis and Structural Characterization of Some 1,3-Dithiol-2-ylium Salts

A new series of 2-(dialkylamino)-1,3-dithiol-2-ylium cations derived from acetophenones and propiophenones was synthesized by the intramolecular condensation of appropriate substituted dithiocarbamates. The structural characterization of the new compounds has been performed by NMR and IR analysis. The structure of 1,3-dithiol-2-ylium perchlorate 3e has been proved by X-Ray analysis.

Study of Physico-chemical Characteristics and Pharmacological Effects of 1-Ethyl-Salicyldene-bis-Ethylene-Diamine and Its Complex with Mn(II)

The paper presents the synthesis of a new complex combination of a Bis-Schiff base with Mn(II) ions with great potential for antimicrobial and anti-inflammatory activity. A new complex of the Salen-type ligand, 1-ethyl-salicylidene-bis-ethylene diamine was synthetized using Mn(II) ions. The chemical structure was confirmed through 1H-NMR and IR spectroscopy. The antimicrobial activities of the Bis-Schiff base and its complex were tested in comparison with Ampicillin, Chloramphenicol, Tetracycline, Ofloxacin and Nystatin. Those compounds were found to be active against Gram-positive or Gram-negative bacteria, and had an anti-inflammatory effect comparable to that of Indomethacin.

Reversed-Phase High Performance Liquid Chromatographic Analysis of Three First Line Anti-Tuberculosis Drugs

Active pharmaceutical ingredients such as isoniazid, pyrazinamide and rifampicin are among the most important first-line anti-tuberculosis drugs. A simple, rapid and sensitive reversed phase-high performance liquid chromatographic assay method for the simultaneous determination of isoniazid, pyrazinamide and rifampicin has been developed. Separation of the interest compounds was achieved in a 10 min chromatographic run in gradient elution mode on a Zorbax SB-C18 stainless steel column (150 � 4 mm, 5 mm) using a guard column containing the same stationary phase. The gradient elution was carried out with a mobile phase of 10% CH3CN aqueous solution for channel A and 50% CH3CN in pH = 6.8 phosphate buffer (20 mM), to which 1.5 mL triethylamine were added for channel B. Quantification of the analyzed substances was carried out spectrophotometrically at 269 nm. Detection limits of 0.48 mg/L for isoniazid, 0.52 mg/L for pyrazinamide and 0.48 mg/L for rifampicin were established for the developed assay method. The present work showed that the proposed analysis method was advantageous for simple and rapid analysis of the active pharmaceutical ingredients in pharmaceuticals and biological fluids.

Aniline Derived Bis-Schiff Base - Analytical Reagent for the Assay of Fe (III)

A new spectrophotometric method for the quantitative determination of Fe (III) was established based on the complexation reaction with a new bis-Schiff base, 4,4`-methylenebis-salicylidene aniline, when a stable complex with an absorption maximum at 520 nm was obtained. The conditions of the complexation reaction were established and the method was validated according to ICH guidelines in terms of linearity, accuracy, precision of the method and the limits of detection and quantification were determined. The method was applied with good results for the quantitative determination of Fe (III) in pharmaceutical products.

Studies on Chromatographic Fractioning by Cations Exchangers of a Bovine Hemoglobin Hydrolysate

A peptidic hydrolysate has been obtained through hydrolysis of bovine hemoglobin using pepsin. The fractioning of the hydrolysate was performed on a column packed with CM-Sepharose Fast Flow. The hydrolysate and each fraction was filtered and then injected into a HPLC system equipped with a Vydak C4 reverse phase column (0.46 x 25 cm), suitable for the chromatographic separation of large peptides with 20 to 30 amino acids. The detection was done using mass spectrometry, and the retention time, size and distribution of the peptides were determined.

Validation and Application of an Analysis Method of Four Metabolites of Nitrofurans in Honey

Although nitrofurans are supposed to be absent in foods, they are still used in veterinary medicine for the treatment of infections in animals not bred for consumption. That meant that there are still samples of honey contaminated with residues of nitrofurans because of bees treated with those pharmaceutical substances. Developing accessible methods to detect them is of high interest to food residue monitoring and regulation programs. We propose an immunochemical method as an alternative to detect four toxic metabolites of nitrofurans (1-aminoimidazolidine-2,4-dione, 3-amino-5-morpholinomethyl-2-oxazolidinone, 3-amino-2-oxazolidone and semicarbazide) in honey. The new method has been optimized and validate for the simultaneous determination of the four metabolites of the nitrofurans honey using biochip technology, and it has been used for the quantitative determination of the residues in 16 Romanian honey samples. The evaluated validation parameters included: linearity, sensitivity (IC50 �2.32 mg/kg), specificity and selectivity, precision (intermediate and reproducibility) and accuracy, decision limit (CCa between 0.37 and 1.05 mg/kg), detection capability (CCb between 0.42 and 1.14 mg/kg), and recovery coefficient (64�192%).

Study of the Presence of Lead in a Series of Foods of Plant Origin

The objective of the study was to evaluate the presence of lead in several food products of plant origin. An atomic absorption spectroscopic quantitative method for the analysis of Pb+2 was developed and validated using an Analytik Jena ContrAA 300 apparatus equipped with an air-acetylene flame and a high-resolution continuum source. The analyzed food products were wheat, wheat flour, onions, corn, corn flour, carrots, beans, potatoes and cabbage grown in three geographical areas, on three soil types. The results obtained were in line with the limits laid down in Commission Regulation (EC) No 1881/2006 - Consolidated acts as far as the maximum admissible level of Pb+2 in foods.

Parameters of Chemical Composition of Phaseolus coccineus L. Pods Grown in Protected Areas

Runner beans are an important source of carbohydrates, fibers, vitamins and minerals that play an important part in the cardiovascular and gastrointestinal tract physiology. The aim of the study was the identification of crop specificities of four varieties of Phaseolus coccineus L. homologated in the Great Britain: Lady Di, Desiree, Polestar and White Apollo, which are less cultivated in Romania, although during the study they proved a remarkable crop production. Another objective of the study was the determination of some chemical composition parameters of the pods harvested from protected areas, in order to highlight the particularities that could determine the expansion of their cultivation in our country.

Influence of Hydroxypropyl Methylcellulose on Flowing and Swelling Parameters in Biomucoadhesive Tablets with Miconazole Nitrate

Original pharmaceutical formulations have been produced as oral biomucoadhesive tablets for antifungal medication. They have been obtained through direct compression using as matrix forming polymers various sorts of hydroxypropyl methylcellulose. The main goal of the study was determining the swelling index of the new mucobioadhesive formulations with miconazole nitrate in order to correctly evaluate the time of contact with mucosa, and the prolongation of drug release. For each formulation, the flowing parameters have been determined: flowing time, friction coefficient, repose angle, Haussner ratio, Carr index, and the swelling index for 6 formulations containing various sorts of hydroxypropyl methylcellulose as matrix molders, while the formulation variables studied were time and association ratio between those polymers. Though results analysis, we noticed that the values of the swelling index depended on the type and quantity of polymer, results that could also be explained by the proportionality relationship to flowing and compressibility parameters.

Fast HPLC Method for the Determination of Piroxicam and its Application to Stability Study

A fast and robust RP-HPLC isocratic method was developed for determination of piroxicam in bulk materials and pharmaceutical formulations. Optimum separation of piroxicam and stress induced degradation a product was achieved using a SB-C18 Eclipse column (150x4.6; 5�m). The mobile phase was a mixture of water: acetonitrile (50:50) with a flow rate of 0.5mL/min. The UV detection was performed at 360nm. The method was validated in accordance with the current ICH guidelines in terms of linearity, limit of detection, limit of quantification, precision, accuracy, recovery and system suitability. The retention time for piroxicam was 2.55 min. The calibration graph was linear in the concentration range 5-90�g/mL. The assay proved to be sensitive, specific and reproducible. The method was applied for the determination of piroxicam in tablets.

Evaluation of in Vitro Reducing Effect of Several Vegetable Extracts on the Digestive Bioavailability of Heavy Metals

The study aimed at assessing the in vitro digestive bioavailability of heavy metals in the presence of plant extracts under simulated digestive system conditions. The complexing ability of aqueous herbal extracts of Crataegus sp., Tilia spp., Rosa canina, Vaccinium myrtillus, Geranium robertianum, Mentha piperita, Cynara cardunculus subsp. Scolymus, Plantago sp., and Coriandrum sativum was researched on Cu+2, Cd+2, Ni+2, Pb+2 and Hg+2 cations. The quantitative determination of the fraction of free metal left, available for absorption, was achieved by atomic absorption spectroscopy (AAS) or potentiometry using an ion-selective electrode (ISE).

Synthesis and Biological Evaluation of a New Schiff Base and its Cu(II) Complex

A new Schiff base ligand, N-hydroxy-N�-salicylidene-urea was synthesized through the condensation of salicylaldehyde with hydroxyurea. The copper(II) complex of the Schiff base has been also obtained. Their structure has been proven using spectral methods such as UV-Vis, FT-IR, 1H-NMR and elemental analysis. The antimicrobial activity of the copper(II) complex was evaluated through comparison to the activity of the Schiff base on various bacterial strains. All tested compounds were very active against both gram-positive and gram-negative bacteria.

Toxicity, Biocompatibility, pH-Responsiveness and Methotrexate Release from PVA/Hyaluronic Acid Cryogels for Psoriasis Therapy

Poly(vinyl alcohol)/hyaluronic acid cryogels loaded with methotrexate were studied. The physical⁻chemical characterization of cryogels was performed by FT-IR spectroscopy, scanning electron microscopy, differential scanning calorimetry and dynamic mechanical thermal analysis. Acute toxicity and haematological parameters were determined by "in vivo" tests. The biocompatibility tests proved that the obtained cryogels showed significantly decreased toxicity and are biocompatible. The pH-responsiveness of the swelling behaviour and of the methotrexate release from the poly(vinyl alcohol)/hyaluronic acid (PVA/HA) cryogels were studied in a pH interval of 2⁻7.4. A significant change in properties was found at pH 5.5 specific for treatment of affected skin in psoriasis disease.

Novel Multiresidue Method for the Determination of Eight Trichothecene Mycotoxins in Pollen Samples Using QuEChERS-Based GC-MS/MS

A simple multi-residue method based on QuEChERS-sample preparation was developed for the determination of eight trichothecene mycotoxins (nivalenol, fusarenon-x, diacetoxyscirpenol, 3-acetyl-deoxynivalenol, neosolaniol, deoxynivalenol, T-2 and HT-2 toxins) in pollen, using gas chromatography coupled with mass spectrometry. The developed method was validated by evaluating the following parameters: linearity, limit of quantification, matrix effect and precision of measurements. All mycotoxins showed good linearity. The method gave good recoveries (91-104%) with RSDs ] 11% for most of the analites (6 out of 8). The limits of quantification varied from 1 to 4�g�kg--1.

Fast RP-HPLC Method for the Determination of Bisoprolol

AIM

To develop and validate a fast, robust, isocratic reversed-phase high performance liquid chromatographic method for the determination of bisoprolol in bulk and pharmaceutical formulations.

MATERIAL AND METHOD

Optimum separation of bisoprolol was achieved using as stationary phase a Zorbax SB-C18 column (100×3 mm; 5µm). The mobile phase was a mixture of phosphate buffer (pH = 3.5) and acetonitrile (70:30) with a flow rate of 1mL/min. The UV detection was performed at 225nm. The temperature of the column and autosampler was 25°C. The specificity was assessed by using metoprolol as internal standard. The method was validated in accordance with the current ICH guidelines in terms of linearity, limit of detection, limit of quantification, precision, accuracy, recovery and system suitability.

RESULTS

The retention time for bisoprolol was 1.158 minute. The calibration graph was linear in the concentration range 5-90 µg/mL. The LOD and LOQ of bisoprolol were 1.63 μg/mL and 4.94 μg/mL, respectively. The intra and interday precision of measurements were lower than the accepted criteria (RSD ≤ 2%). The recovery values of HPLC determination of bisoprolol from tablets proved that none of the excipients influenced the results of the analysis.

CONCLUSIONS

The assay it was found to be accurate, reproducible, sensitive and less time consuming. The proposed method can be successfully applied to quality control studies of pharmaceutical products.

ANTINFLAMMATORY ACTIVITY OF AN N, N'-DISALICYLIDENEMETHYLENDIAMINE-DERIVED SCHIFF BIS BASE AND ITS COPPER(II) COMPLEX

AIM

The cooper(II) complex combination of N, N'-disalicylidenemethylenediamine and the Schiff bis base were investigated for anti-inflammatory activity.

MATERIAL AND METHODS

In vivo, the anti-inflammatory activity of the metallic complex in comparison with the activity of the Schiff bis base was tested by the method of Winter and co-workers using the Levy technique.

RESULTS AND DISCUSSIONS

Our study on the anti-inflammatory activity of a new Schiff bis base and its complex cooper(II) combination showed that the Schiff bis bases exhibited significant anti-inflammatory action in acute experimental inflammation when compared to the control group. The copper cation from the complex combination enhanced the anti-inflammatory effect of the Schiff bis base, the effect being stronger at doses of 10 mg/kg cooper(II) complex.

CONCLUSIONS

The Schiff bis base and its cooper(II) complex had an anti-inflammatory effect comparable to that of indomethacin.

A NEW SPECTROPHOTOMETRIC METHOD FOR THE ASSAY OF LISINOPRIL

AIM

A new spectrophotometric method for the assay of lisinopril using 2,4-dinitrophenol as reagent is described.

MATERIAL AND METHODS

The method involved the addition of 2,4-dinitrophenol to lisinopril in methanol followed by absorbance measurement at 400 nm. Experimental conditions that provide wide linear range, maximum sensitivity, selectivity, accuracy and precisions were optimized.

RESULTS AND DISCUSSIONS

Beer's law was obeyed in the concentration range 2.0-14.0 μg/mL. Linear regression equation of calibration graph was A = 0.005 + 0.045 x concentration, with a regression coefficient (r) of 0.9995 (n = 8). The limits of detection (LOD) and quantification (LOQ) calculated according to the ICH guidelines were 0.42 and 1.42 μg/mL, respectively. Accuracy and precision of the assays were determined by computing the intra-day and inter-day variations at three different lisinopril concentrations; the intra-day and inter-day RSD was < 1.43% and accuracy was better than 1.72%.

CONCLUSIONS

The proposed method is simple, easy to perform, sensitive, linear, precise, accurate and robust.

Spectrophotometric method for estimation of bisoprolol fumarate in tablets

Bisoprolol fumarate is prescribed for the treatment of hypertension and angina pectoris.

AIM

The purpose of this study was to develop a simple, sensitive, accurate, and reproducible method for estimation of bisoprolol fumarate in tablets.

MATERIAL AND METHODS

The proposed method was based on a yellow colored complex formed with tropaeolin 00, extractable in dichloromethane with maximum absorbance at 412 nm. The method was validated statistically.

RESULTS

The linearity domain was observed in the concentration of 5-30 microg/ml. The recovery studies confirmed the accuracy of the proposed method.

CONCLUSIONS

The proposed method can be applied for the routine analysis of bisoprolol from formulations.

Effect of apitherapy products against carbon tetrachloride-induced toxicity in Wistar rats

The present paper aimed to evaluate the influence of apitherapy diet in Wistar rats with carbon tetrachloride induced hepatotoxicity, by the means of biochemical determinations and histopathological changes of liver, spleen, pancreas and testicular tissue. The experiment was carried out on six groups of male Wistar rats. Hepatic lesions were induced by intraperitoneal injection of carbon tetrachloride (dissolved in paraffin oil, 10% solution), 2 mL per 100 g, every two days, for two weeks. Hepatoprotection was achieved with two-apitherapy diet formulations (containing honey, pollen, propolis, Apilarnil, with/without royal jelly), that have been administered for six up to nine weeks. The biochemical results revealed that the two-apitherapy diet formulations had a positive effect improving the enzymatic, lipid, and protein profiles, coagulation, mineral parameters and also the bilirubin levels, after six weeks of treatment. The histopathological results demonstrated the benefit of the two-apitherapy diet formulations on reducing the toxicity of liver, spleen and pancreas in laboratory animals, after six and nine weeks, respectively. In conclusion, apitherapy products have a hepatoprotective effect in carbon tetrachloride-induced hepatopathy.

Validation of a spectrophotometric assay method for bisoprolol using picric acid

Bisoprolol is a drug belonging to beta blockers drugs used primarily for the treatment of cardiovascular diseases.

AIM

A spectrophotometric method for quantitative determination of bisoprolol was developed based on the formation of a complex combination between bisoprolol and picric acid.

MATERIAL AND METHODS

The complex combination of bisoprolol and picric acid has a maximum absorbance peak at 420 nm. Optimum working conditions were established and the method was validated.

RESULTS

The method presented a good linearity in the concentration range 5-120 microg/ml (regression coefficient r2 = 0.9992). The RSD for the precision of the method was 1.74 and for the intermediate precision 1.43, and recovery values ranged between 98.25-101.48%.

CONCLUSIONS

The proposed and validated spectrophotometric method for the determination of bisoprolol is simple and cost effective.

Spectrometric method for the assay of ramipril using molybdophosphoric acid

Ramipril is a drug of the angiotensin converting enzyme inhibitor class.

AIM

A new molecular absorbance spectrometric method was developed for the assay of ramipril using molybdophosphoric acid in acidic medium.

MATERIAL AND METHODS

The reaction product showed a maximum absorbance at 361 nm. The optimum conditions of the reaction were established. The developed method was validated.

RESULTS

The method showed a good linearity in the range of 8 - 36 microg/ml (correlation coefficient r = 0.9996). The detection limit (LD) was 0.86microg/ml and the quantification limit (LQ) 2.88 pg/ml. Precision and accuracy were determined (RSD = 1.15%); mean recovery was 98.90% in the 97.13-101.03% concentration range.

CONCLUSIONS

The proposed method is simple, easy to perform, sensitive, linear, precise, accurate and robust.

[Construction and characterisation of a selective membrane electrode for the assay of lisinopril]

In order to analyze lisinopril using a selective membrane electrode, the electro-active compound was obtained and included in the selective membrane. The new analysis method was developed and validated.

MATERIAL AND METHOD

The electro-active compound was obtained through the precipitation of lisinopril in acidic media using silicowolframic acid solution. The membrane was obtained by mixing the electro-active compound with polyvinylchloride using tetrahydrofurane as solvent. The solution was evaporated in order to obtain a thick membrane, which was then attached at one end of a polyvinylchloride tube. The internal Ag/AgCl reference electrode was inserted in that tube. The assembly was filled with a lisinopril internal solution. The electrode was characterized by establishing the following characteristics: electrode slope, selectivity, optimal pH range, response time and life-time period. The developed method was validated.

RESULTS

The method showed a good linearity in the range of 10(-7) and 10(-2)M (the correlation coefficient r = 0.9991). The detection limit (LD) was 8,66 x 10(-8)M and the quantification limit (LQ) was 7,8 x 10(-7)M. There were established the precision (RSD = 1.73%) and the accuracy (mean recovery was 99.92%)

CONCLUSIONS

The experimental results demonstrated a good sensibility.

Evaluation of some pharmaceutical formulations of lisinopril through dissolution testing

AIM

Lisinopril is a drug of the angiotensin converting enzyme (ACE) inhibitor class that is primarily used in treatment of hypertension, congestive heart failure, heart attacks and also in preventing renal and retinal complications of diabetes. We compared the dissolution profiles of Lisinopril 20 mg tablets (Antibiotice S.A. laşi) and Zestril 20 mg tablets (Astra Zeneca).

MATERIAL AND METHOD

Because lisinopril is a third class active substance, we performed dissolution tests in standard media at three pH values: 1.2, 4.5 and 6.8 using the paddle apparatus at 75 rpm.

RESULTS

Both pharmaceutical formulations present a dissolution percentage more than 85% (Q) of the labeled amount.

CONCLUSION

Both pharmaceutical formulations present similar dissolution profile. Key words:

[Quantitative determination of adrenaline by visible spectrophotometric method]

A sensible and rapid spectrophotometric assay for adrenaline was developed.

MATERIAL AND METHOD

The method is based on the reaction with ammonium molybdate and sodium nitrite in acid medium.

RESULTS

The obtained compound is stable, soluble in water and has the absorbtion maximum at 405 nm. Beer's law is valid within a concentration range of 20-160 microg/mL. The validity of the method was tested by statistical analysis of the experimental data using the linearity, the scale's calibration factor, the detection limit, the quantification limit and the precision.

CONCLUSIONS

A new method for the assay of adrenaline in pharmaceutical products has been developed.

[Analytical application of phosphotungstic acid complexes. Synthesis and characterisation]

Phosphotungstic acid forms salt type ionic association complexes with a large number of medicinal drugs that contain cation forming proton acceptor moieties.

MATERIAL AND METHOD

Ranitidine, nizatidine and famotidine complexes with phosphotungstic acid were synthesized and subsequently characterized by their melting point, water solubility, specific absorbance, UV spectra and IR spectra.

RESULTS

These sparingly soluble complexes were applied for the fabrication of membrane selective electrodes for quantitative potentiometric determination of ranitidine, nizatidine and famotidine.

CONCLUSIONS

There have been synthesized phosphotungstic acid complexes with uses in fabrication of membrane selective electrodes for quantitative potentiometric determination of ranitidine, nizatidine and famotidine.

[Turbidimetric assay of famotidine]

This paper proposes a new method for the quantitative determination of famotidine, based on its reaction with phosphomolybdic acid. The measurements were carried out at wavelength of 400 nm. This method has been validated and it has been applied to the determination of famotidine in pharmaceutical products.

[UV spectrophotometric assay of famotidine in combination with picrolonic acid, picrolinate]

Famotidine, belonging to H2-antagonist group, is a compound containing a thiazolic moiety and it is used in peptic ulcer therapy. This paper debates the possibility of developing a new ultraviolet spectrophotometric assessment by using the reaction between famotidine and picrolonic acid. We carried out our determinations at 362 nm, where the absorbency of famotidine - picrolonic acid complex is maximal, and we have established the optimal reaction conditions. This method was successfully applied for famotidine assay from pharmaceutical dosage forms.

[Membrane-selective electrodes for drug analysis. Note II]

Seven membrane-selective electrodes with PVC matrix and liquid-membrane for N-butylscopolamine with different electroactive materials are presented. These electrodes have a linear response in the concentration range of 10(-6) - 10(-2) M N-butylscopolamine bromide, with a detection limit between 4.58 x 10(-7)M and 1.09 x 10(-6)M. These electrodes were used with good results for quantitative assay by direct potentiometry and potentiometric titration of N-butylscopolamine bromide from pharmaceutical formulations. Recovery was between 95.50% and 99.20% for N-butylscopolamine bromide of injectable solutions.

[Schiff base type onno spectrophotometric determination of magnesium]

By condensing hydrazide salicylic acid with o-hydroxy carbonilic compounds it was obtained 2--hydroxy acetophenon--salicyl hidrazina, Schiff base--type ONNO. These Schiff bis bases present a good capacity of complexing the Mg (II) ions. The above mentioned Schiff base forms complex with Mg (II) cation, with maximum absorbance at 386 nm, and molar absorbtivity (epsilon) = 6.27 x 10(4) mol-1.L.cm-1. The complex with Mg (II) presents a maximum stability at pH = 9.6 - 10.0. The calculated apparent stability constant is K = 3.18 x 10(3). The absorbance is proportional to Mg (II) concentration in the range of 10-60 mg/mL. In this range, the Lambert--Beer law is respected, the linearity coefficient being 0.9818, SD = 0.83, RSD = 0.84 (n = 6). The results obtained for spectrophotometric determination of Mg (II) using this Schiff base as reagent were successfully applied to pharmaceutical products containing Mg (II) cation.

[Visible spectrophotometric assay of ranitidine]

Ranitidine, belonging to H2-antagonist group, is a compound containing a furanic moiety and is used in peptic ulcer therapy. This paper debates the possibility of developing a new visible spectrophotometric assessment by using the reaction between ranitidine and eosine. We carried out our determinations at 505 nm, where the absorbency of ranitidine-eosine complex is maximal, and we have established the optimal reaction conditions. This method was successfully applied for ranitidine assay from pharmaceutical dosage forms.

[Membrane-selective electrode for atropine assay]

One membrane-selective electrode with PVC matrix for atropine is described, with atropine tetraphenylborate as electroactive material. This electrode has a linear response in the concentration range of 10(-2)-10(-5) M atropine sulphate, with a detection limit of 3.29 x 10(-6) M. This electrode was used with good results for quantitative assay by direct potentiometry and potentiometric titration of atropine sulphate from pharmaceutical formulations.

Study on the Enzymatic Activity of the Soil in Racos Protected Area from Brasov

Soil enzymes are vital for maintaining soil fertility and health, as they play a crucial role in initiating and maintaining the biogeochemical cycles of the nutrients, in providing fundamental support for fertility for healthy plant growth, and for protecting the environment by degrading pollutant molecules. The aim of the study was the characterization of the soil from the Racos volcano area situated in the southern part of the East Carpathian Mountains, from the point of view of the enzymatic activities of invertase, urease, catalase and dehydrogenase. The values of the index of the total enzymatic activity � TEI, and of the geometric mean of the enzymatic activities - GME, were calculated using the experimental results of the determinations of the enzymatic activity of invertase as μg glucose/g soil/h, of urease as μg NH4+-N/g soil/h, of dehydrogenase as μg triphenylformazan/g soil/h, and of catalase as mL 0,02M KMnO4 solution/g soil/h.

[Ion-selective electrodes with a liquid membrane for determining N-butylscopolammonium bromide]

Two ion-selective electrodes with liquid membrane for N-butylscopolamonium bromide are described, with N-butylscopolamonium tetraphenylborate (I) and N-butylscopolamonium reineckate (II), respectively, solved in benzylic alcohol as electroactive material. These electrodes have a linear response in the concentration range of 10(-2)-10(-6) M N-butylscopolamonium bromide, with the detection limit of 10(-7) M for both electrodes. These electrodes were used with good results for quantitative assay by direct potentiometry of injectable solutions of N-butylscopolamonium bromide.