Biological Fluid Samples Research Articles

H-point standard additions method for simultaneous determination of sulfamethoxazole and trimethoprim in pharmaceutical formulations and biological fluids with simultaneous addition of two analytes

The applicability of H-point standard additions method (HPSAM) to the resolving of overlapping spectra corresponding to the sulfamethoxazole and trimethoprim is verified by UV–vis spectrophotometry. The results show that the H-point standard additions method with simultaneous addition of both analytes is suitable for the simultaneous determination of sulfamethoxazole and trimethoprim in aqueous media. The results of applying the H-point standard additions method showed that the two drugs could be determined simultaneously with the concentration ratios of sulfamethoxazole to trimethoprim varying from 1:18 to 16:1 in the mixed samples. Also, the limits of detections were 0.58 and 0.37 μmol L −1 for sulfamethoxazole and trimethoprim, respectively. In addition the means of the calculated RSD (%) were 1.63 and 2.01 for SMX and TMP, respectively in synthetic mixtures. The proposed method has been successfully applied to the simultaneous determination of sulfamethoxazole and trimethoprim in some synthetic, pharmaceutical formulation and biological fluid samples.

Identification of several basic nitrogen-containing compounds in the presence of coextracted substances of urine and blood by capillary electrophoresis

Preparation conditions for samples of biological fluids (urine, blood) for electrophoretic identification of basic nitrogen-containing compounds with the aid of a Kapel-105 capillary electrophoresis system have been studied. It is demonstrated that bupivacaine, lidocaine, and azaleptine can be identified in biological fluids in the presence of coextracted substances using electrophoretic spectra and quantitative indices (pKa).

Simultaneous Determination of Dextromethorphan and Quinidine Contents in Biological Fluid Samples Using Excitation-Emission Matrix Fluorescence Coupled with Second-Order Calibration Methods

This paper presents a novel method for simultaneous determination of dextromethorphan and quinidine contents in biological fluid samples using excitation–emission matrix fluorescence (EEM) coupled with second-order calibration methods. The adopted calibration methods, i.e., parallel factor analysis (PARAFAC), self-weighted alternating tri-linear decomposition (SWATLD), and alternating penalty trilinear decomposition (APTLD), could adequately exploit the second-order advantage. The accuracy of the three methods was evaluated through figures of merit and elliptical joint confidence region (EJCR) tests. It has been found that all the methods could give good results. But, with correct number of factors, the PARAFAC model performed slightly better than the others.

Grafting of poly[1-(N,N- bis-carboxymethyl)amino-3-allylglycerol- co-dimethylacrylamide] copolymer onto siliceous support for preconcentration and determination of lead (II) in human plasma and environmental samples

A method is reported for surface grafting of polymer containing a functional monomer for metal chelating, poly[1-(N,N- bis-carboxymethyl)amino-3-allylglycerol- co-dimethylacrylamide] (poly(AGE/IDA- co-DMAA) onto silica modified by silylation with 3-mercaptopropyltrimethoxysilane. Monomer 1-(N,N- bis-carboxymethyl)amino-3-allylglycerol (AGE/IDA) was synthesized by reaction of allyl glycidyl ether with iminodiacetic acid. The resulting sorbent has been characterized using FT-IR, elemental analysis, thermogravimetric analysis (TGA), FT-Raman and scanning electron microscopy (SEM) and evaluated for the preconcentration and determination of trace Pb(II) in human biological fluid and environmental water samples. The optimum pH value for sorption of the metal ion was 5.5. The sorption capacity of functionalized resin was 15.06 mg g −1. The chelating sorbent can be reused for 15 cycles of sorption–desorption without any significant change in sorption capacity. A recovery of 96.2% was obtained for the metal ion with 0.5 M nitric acid as eluting agent. The profile of lead uptake by the sorbent reflects good accessibility of the chelating sites in the poly(AGE/IDA- co-DMAA)-grafted silica gel. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The equilibrium adsorption data of Pb(II) by modified resin were analyzed by Langmuir, Freundlich, Temkin and Redlich–Peterson models. On the basis of equilibrium adsorption data the Langmuir, Freundlich and Temkin constants were determined as 0.70, 1.35 and 2.7, respectively at pH 5.5 and 20 °C. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption.

Clearance and disposition of indometacin in chronically instrumented fetal lambs following a 3-day continuous intravenous infusion.

Indometacin is used in pregnancy for the treatment of premature labour, but there are limited data on the disposition of the drug in the fetus. In order to elucidate fetal indometacin pharmacokinetics at plasma levels and duration comparable with those occurring with use of the drug for tocolysis in humans, indometacin was administered at doses of 1.9 (low dose, LD; n = 5) or 7.5 (high dose, HD; n = 9) microg min(-1) to steady state over a 3-day period in chronically instrumented fetal lambs. Indometacin concentrations in biological fluid samples were analysed by a sensitive capillary gas chromatography-electron capture detection method. The mean steady-state fetal arterial plasma indometacin concentrations were 68.6+/-16.5 ng mL(-1) in the LD infusion and 230.3+/-28.8 ng mL(-1) in the HD infusion. Indometacin concentrations in amniotic fluid were approximately 10% of those in fetal plasma, and below assay detection limits in tracheal fluid. Total body clearance (TBC) in the LD and HD infusions were not different and the overall mean was 11.3+/-1.2 mL min(-1) kg(-1). In the 11 experiments where paired fetal arterial and umbilical venous samples were collected, the extraction of indometacin across the placenta averaged only 5.2+/-1.1%, indicating low placental permeability to the drug in sheep. However, fetal placental clearance (CLpl) of indometacin (10.0+/-2.5 mL min(-1) kg(-1), n = 10) averaged 115.1+/-41.2% of TBC in these animals and the calculated value for fetal non-placental clearance (0.6+/-2.8 mL min(-1) kg(-1)) was not significantly different from zero. Fetal renal clearance of intact indometacin (3.8+/-1.1 microL min(-1) kg(-1); n = 12) was also very low. However, treatment of fetal urine with glucuronidase indicated the presence of glucuronide conjugates and these comprised 69.9+/-8.2% of the total drug concentration (i.e. intact+conjugated) in urine. Thus, the fetal lamb appears to be able to glucuronidate indometacin, but the contribution of this and other non-placental routes to overall fetal elimination of the drug appear minimal. CLpl of the drug is also low owing to the physicochemical properties of indometacin (high polarity) and the permeability characteristics of the sheep placenta.

Presence of hepcidin-25 in biological fluids: Bile, ascitic and pleural fluids

To examine body fluids such as ascitic fluid (AF), saliva, bile and pleural effusions for the presence of hepcidin using a novel radioimmunoassay (RIA). Serum samples were collected from 25 healthy volunteers (mean age: 36 +/- 11.9 years, 11 males, 14 females). In addition bile was obtained from 12 patients undergoing endoscopic retrograde cholangiopancreatography (mean age: 66.9 +/- 16.7 years, M:F = 5:7). Saliva was collected from 17 healthy volunteers (mean age: 35 +/- 9.9 years, M:F = 8:9). Pleural and AF were collected from 11 and 16 patients [(mean age: 72 +/- 20.5 years, M:F = 7:4) and (mean age: 67.32 +/- 15.2 years, M:F = 12:4)], respectively. All biological fluid samples (serum, exudative and transudative fluids) were tested for the presence of hepcidin-25 molecule using RIA. Hepcidin-25 was detected in all biological fluids tested. The mean +/- SD hepcidin-25 in serum was 15.68 +/- 15.7 ng/mL, bile 7.37 +/- 7.4 ng/mL, saliva 3.4 +/- 2.8 ng/mL, exudative fluid 65.64 +/- 96.82 ng/mL and transudative fluid 14.1 +/- 17.8 ng/mL. We provide clear evidence that hepcidin-25 is present in bile, saliva, pleural and ascitic fluids. Hepcidin is likely to play a role here in innate immunity.

Microporation techniques for enhanced delivery of therapeutic agents.

Perhaps the greatest barrier to development of the field of transmembrane drug delivery is that only a limited number of drugs are amenable to administration by this route. The highly lipophilic nature and barrier function of the uppermost layer of the skin, the stratum corneum, for example, restricts the permeation of hydrophilic, high molecular weight and charged compounds into the systemic circulation. Other membranes in the human body can also present significant barriers to drug permeation. In order to successfully deliver hydrophilic drugs, and macromolecular agents of interest, including peptides, DNA and small interfering RNA, many research groups and pharmaceutical companies Worldwide are focusing on the use of microporation methods and devices. Whilst there are a variety of microporation techniques, including the use of laser, thermal ablation, electroporation, radiofrequency, ultrasound, high pressure jets, and microneedle technology, they share the common goal of enhancing the permeability of a biological membrane through the creation of transient aqueous transport pathways of micron dimensions across that membrane. Once created, these micropores are orders of magnitude larger than molecular dimensions and, therefore, should readily permit the transport of hydrophilic macromolecules. Additionally, microporation devices also enable minimally-invasive sampling and monitoring of biological fluids. This review deals with the innovations relating to microporation-based methods and devices for drug delivery and minimally invasive monitoring, as disclosed in recent patent literature.

New biomimetic sensors for the determination of tetracycline in biological samples: Batch and flow mode operations

New potentiometric membrane sensors with cylindrical configuration for tetracycline (TC) are described based on the use of a newly designed molecularly imprinted polymer (MIP) material consisting of 2-vinylpyridine as a functional monomer in a plasticized PVC membrane. The sensor exhibited significantly enhanced response towards TC over the concentration range 1.59 × 10−5–1.0 × 10−3 mol L−1 at pH 3–5 with a lower detection limit of 1.29 × 10−5 mol L−1. The response was near-Nernstian, with average slopes of 63.9 mV decade−1. The effect of lipophilic salts and various foreign common ions were tested and were found to be negligible. The possibility of applying the proposed sensor to TC determination in spiked biological fluid samples was demonstrated.

New potentiometric sensors based on two competitive recognition sites for determining tetracycline residues using flow-through system

New potentiometric membrane sensors for tetracycline (TC) are described based on the use of a newly designed molecularly imprinted polymer (MIP) material based on 2-vinylpyridine as a functional monomer, AmION (I) [Calix-4-arene tetraacetic acid ester] as neutral ionophore in plasticized PVC membranes. Effects of lipophilic salts and various foreign common ions are tested. The sensors exhibit significantly high sensitivity, stability and selectivity for TC+ ions over many common ions and are successfully used for determining TC+ ions in spiked biological fluid samples under static and hydrodynamic mode of operations.

Polarographic reduction of pralidoxime and obidoxime at hanging mercury drop electrode

The polarographic reduction behavior of Pralidoxime (PRL) and Obidoxime (OBD) at a Hanging Mercury Drop Electrode (HMDE) was exploited for their determination in different samples. Based on the obtained differential pulse polarograms, standard addition method was used to determine these drugs in pharmaceutical formulations and biological fluid samples. Linearity in the peak currents was achieved in the concentration ranges of 5.4 x 10 -8

Restricted-Access Media Supports for Direct High-Throughput Analysis of Biological Fluid Samples: Review of Recent Applications

This review presents an update on the use of restricted-access materials (RAMs) for direct injection of biological samples. The fundamental improvements in the preparation of tailored RAMs and the diversity of applications with these phases are presented. Insights into diminishing the matrix effect by the use of RAM supports in methods by LC-MS and into the low number of methods for enantiomeric separations by direct injections of biological samples are addressed. The diversity of systems that incorporate RAMs for selective sample clean-up or fractionation in proteome and peptidome analysis is also covered.

An isotropic chemical shift–chemical shift anisotropic correlation experiment using discrete magic angle turning

An isotropic–anisotropic shift 2D correlation spectroscopy is introduced that combines the advantages of both magic angle turning (MAT) and magic angle hopping (MAH) technologies. In this new approach, denoted DMAT for “discrete magic angle turning”, the sample rotates clockwise followed by an anticlockwise rotation of exactly the same amount with each rotation less or equal than 360° but greater than 240°, with the rotation speed being constant only for times related to the evolution dimension. This back and forth rotation is repeated and synchronized with a special radio frequency (RF) pulse sequence to produce an isotropic–anisotropic shift 2D correlation spectrum. For any spin-interaction of rank-2 such as chemical shift anisotropy, isotropic magnetic susceptibility interaction, and residual homo-nuclear dipolar interaction in biological fluid samples, the projection along the isotropic dimension is a high resolution spectrum. Since a less than 360° sample rotation is involved, the design potentially allows for in situ control over physical parameters such as pressure, flow conditions, feed compositions, and temperature so that true in situ NMR investigations can be carried out.

Temperature and Denaturing Substances Influence on Lab-on-a-Chip Electrophoresis

Temperature and Denaturing Substances Influence on Lab-on-a-Chip Electrophoresis Qualitative and quantitative determination of proteins in different biological fluids is of great significance in medicine, due to their importance in diagnosis and treatment of some diseases. Nowadays, different methods for protein analysis are available. Lab-on-a-chip electrophoresis is a relatively new technique, based on microfluidics, which allows samples of biological fluids to be analyzed within a microchip. This paper describes the optimization of performance of the chip-based protein analyses in serum samples from patients with different neurological disorders. Using microchip technology, serum proteins with the molecular mass from 4.5 to 240 Kb were separated and sized. The fluorescence detection method in the analysis was used to follow the influence of the temperature and the type and concentration of denaturing substances on the electrophoresis protein profiles. It was noted that, depending on incubation temperature and denaturing substances, different electrophoresis patterns can be obtained from the proteins of one specimen. Significant change of the fluorescence intensity was observed when different incubation temperatures were used, probably due to fluorescence quenching. In some cases, the band intensity was changed several times. Lab-on-a-chip electrophoresis is a very efficient method for the separation and determination of different serum proteins in a very short time. However, to obtain comparable results for the analysis, the denaturing agent concentration and temperature must be observed and maintained carefully.

Single-drop micro-extraction and diffuse reflectance Fourier transform infrared spectroscopic determination of chromium in biological fluids

The present paper deals with a new micro-extraction procedure for selective separation of Cr(VI) in the form of a metaloxy anionic species namely dichromate (Cr 2O 7 2−) with N 1-hydroxy- N 1, N 2-diphenylbenzamidine (HOA) in to dichloromethane and its subsequent and rapid diffuse reflectance Fourier transform infrared spectroscopic (DRS-FTIR) determination employing potassium bromide matrix. The diffuse reflectance Fourier transform infrared spectroscopy gives both qualitative and quantitative information about the dichromate. The determination of chromium is based on the analytical peak selection, among the various vibrational peaks, at 902 cm −1. The micro-extraction was based on the liquid–liquid solvent extraction (LLSE) principle. The dichromate binds with the nitrogen and oxygen atoms of N 1-hydroxy- N 1, N 2-diphenylbenzamidine (HOA) and forms 1:2, Cr(VI):HOA complex in 0.1 mol L −1 HCl medium. The formation of above complex, in the acidic medium, is confirmed by the appearance of chocolate-brown color in the micro-extract. The speciation studies of Cr(III) and Cr(VI) is done by conversion of Cr(III) into Cr(VI) utilizing H 2O 2 as an oxidizing agent. The chemistry of pure dichromate and that of its HOA complex is discussed. The limit of detection (LoD) and the limit of quantification (LoQ) of the method are found to be 0.01 μg g −1 Cr 2O 7 2− and 0.05 μg g −1 Cr 2O 7 2−, respectively. The standard deviation value and the relative standard value at a level of 10 μg Cr 2O 7 2−/0.1 g KBr for n = 10 is found to be 0.26 μg Cr 2O 7 2− and 2.6%, respectively. The relative standard deviation ( n = 8 and 6) for the determination of dichromate (Cr 2O 7 2−) in real human biological fluid samples is observed to be in the range 3.1–7.8%.

Determination of prednisolone, dexamethasone and hydrocortisone in pharmaceutical formulations and biological fluid samples by voltammetric techniques using β β β β-cyclodextrin modified carbon paste electrode

A simple, sensitive and accurate voltammetric studies on prednisolone (PE), dexamethasone (DE) and hydrocortisone (HC) were carried out by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at bare carbon paste electrode (CPE) and β-cyclodextrin modified carbon paste electrode (CDMCPE) in Britton-Robinson (BR) buffer solution. PE, DE and HC show marked enhancement of peak currents at CDMCPE when compared to CPE due to the inclusion complex between keto-group from the drug and β-cyclodextrin (modifier). All these compounds exhibit a well-defined single peak in the studied pH range which is attributed to the reduction of keto-group. BR buffer of pH 3.0 was found to be reliable supporting electrolyte for the analytical estimation of these compounds. CV studies indicate that the process was irreversible and adsorption controlled. The reduction peak currents at CDMCPE for PE, DE and HC changes linearly over the concentration range from 5.6 × 10-7 M to 2 × 10-5 M (PE), 4.1 × 10-7 M to 2 × 10-5 M (DE) and 4.2 × 10-7 M to 2.5 × 10-5 M (HC) with a correlation co-efficient of 0.9991, 0.9986 and 0.9995 for the respective compounds. DPV technique is used for the determination of PE, DE and HC in pharmaceuticals and biological fluid samples. For quantification, standard addition method was carried out in both pharmaceutical formulations and biological fluid samples. Key words: Prednisolone, dexamethasone, hydrocortisone, b-cyclodextrin modified carbon paste electrode, pharmaceutical formulations, biological samples, voltammetric techniques.

Determinação voltamétrica de metais em águas e fluidos biológicos empregando mineralização de amostras com radiação ultravioleta

This work describes the optimization of pretreatment steps for the destruction of organic matter in samples of waters and biological fluids, by using an UV irradiation system with a high power UV radiation source (400 W). The efficiency of the system constructed for the photo-decomposition of samples of model waters, natural waters and biological fluids was investigated by performing recovery experiments of the metallic species Zn(II), Cd(II), Pb(II), Cu(II), Al(III) and Fe(III). The use of UV irradiation allowed the liberation of metals bound to the organic matrix and the determination of the total content of elements in the samples.

Microstructured Devices for Transdermal Drug Delivery and Minimally-Invasive Patient Monitoring

Transdermal drug delivery offers certain advantages over conventional oral or parenteral administration. However, the excellent barrier function of the skin, accomplished almost entirely by the stratum corneum, restricts the number of drug substances that can be administered transdermally to those with very specific physicochemical properties. Several approaches have been used to enhance the transport of drugs through the stratum corneum. However, in many cases, only moderate success has been achieved and each approach is associated with significant problems. Microstructured devices, consisting of a plurality of microprojections attached to a support, can be used to painlessly bypass the stratum corneum barrier and thus achieve successful transdermal delivery. Moreover, microprojection devices also enable minimally-invasive sampling and monitoring of biological fluids. Much activity is currently focussed in this area. Accordingly, this article deals with the innovations pertaining to microprojection-based devices for transdermal drug delivery and minimally-invasive monitoring as disclosed in recent patent literature.

Electrophoretic determination of biogenic amines in biological fluids

The capabilities of the electrophoretic separation of biogenic amines (adrenalin, noradrenalin, dopamine, serotonin, metanephrine, and normetanephrine) under conditions of capillary zone electrophoresis and micellar electrokinetic chromatography with the introduction of complex-forming agents (18-crown-6, 4,13-diaza-18-crown-6, and sodium dodecyl sulfate as an ion-pair reagent) and acetonitrile as the constituents of a working electrolyte were demonstrated. A technique for the sampling of biological fluids (urine, blood plasma, and serum) with the use of solid-phase extraction on aluminum oxide and a C18 reversed-phase sorbent was developed. The capabilities of various versions of the preconcentration of biogenic amines were determined, which allowed us to decrease the limits of detection by a factor of hundreds.

Design of an Advanced Temporary Hip Prosthesis for an Effective Recovery of Septic Mobilizations: A Preliminary Study

The purpose of this study was the design and preliminary feasibility study of an advanced temporary hip prosthesis acting as an in-site drug dispensing system. An interactive device was designed to improve the recovery of bone infections compared to the mechanical spacers currently used in septic mobilizations. A commercial device was chosen and modified specifically for the purpose. First of all, the device was provided with a hydraulic multi-channel system connected via catheter to a subcutaneous valve, refillable with a drug aqueous solution from the outside. Moreover, since it allows samples of biological fluids for analyses to be drawn directly from the implantation site, this chemical dispensing system was designed to allow the course of infections to be monitored and customized therapies to be dosed. The insertion of biocompatible membranes inside the channel ends was considered essential to prevent their occlusion by fibrous tissue growth, thereby preserving the device functionality. Moreover, a biodegradable spongy ring was designed to be fixed onto the stem in distal position both to give primary stability to the implant and to act simultaneously as a scaffold for bonelike cell growth.

A comparison of three solvent-free techniques coupled with gas chromatography for determining trihalomethanes in urine samples

The analysis of volatile organic compounds in samples of biological fluids characterized by complex matrices is highly challenging. This paper presents a comparison of the results obtained in this field using three solvent-free techniques: thin-layer headspace with autogenous generation of liquid sorbent (TLHS) and membrane separation of the trace substances (pervaporation, PV), both of which are coupled to direct aqueous injection gas chromatography-electron capture detection (TLHS-DAI-GC-ECD and PV-DAI-GC-ECD), as well as conventional static headspace analysis followed by GC analysis with ECD detection (HS-GC-ECD). Basic validation parameters of the HS-GC-ECD, TLHS-DAI-GC-ECD and PV-DAI-GC-ECD procedures were calculated for water and urine samples. The calibration curves for all procedures were linear within the concentration range examined. The intermediate precisions of the procedures were good and reached about 10% (for all analytes) for HS-GC-ECD and TLHS-DAI-GC-ECD. The poorest results were obtained for PV-DAI-GC-ECD: about 20% for all analytes. The lowest method detection limits were obtained for the TLHS-DAI-GC-ECD procedure: below 0.0022 microg/L for all analytes. The enrichment factors did not differ significantly between water and urine samples, indicating little or no matrix effect in all procedures.