Determination Of Such Compounds Research Articles

Facile green spectrophotometric approaches for the determination of three natural edible antioxidant polyphenols in different matrices

The combination of Curcumin (CRN), resveratrol (RSV), and quercetin (QRN) has significant antioxidant effects and is found to be more effective than a single polyphenol. Spectrophotometric methods are considered one of the most common analytical techniques for the determination of the drugs due to their sensitivity, rapidness, low cost, and reproducibility. Therefore, the presence of new, and simple methods for the determination of such compounds will be highly valuable, specially in the presence of spectral overlap. In this research, five different facile spectrophotometric methods were investigated for the simultaneous determination of that ternary mixture for the first time, including zero order (I), first derivative (II), ratio difference double divisor (III), first derivative ratio spectra (IV), and mean centering (V) methods. The designed approaches were linear over the concentration ranges of (1.0–10.0), (0.5–8.0), and (1.0–14.0) μg/mL, respectively for curcumin, resveratrol, and quercetin. The different methods were then validated as stated by the International Council of Harmonization. The accuracy and precision have been evaluated by statistical analysis including student t-test, variance ratio F-test, and ANOVA. Moreover, the greenness and whiteness of the proposed methods were assessed to ensure the adherence to the greenness characters.

Study of Cytotoxic Responses of Anticancer Drug Cyclophosphamide

It is widely accepted that cancer, the second leading cause of death, is a morbidity with big impacts on the global health. In the last few years, chemo- therapeutic treatment continually induces alone most lengthy consequents, which is extremely harmful for the physiological and psychological health of the patients. In the present research, we discuss the recent techniques for employed for extraction, and quantitative determination of such compounds in pharmaceutical, and biological specimens. In the frame of this information, this review aims to provide basic principles of chromatography, spectroscopy. Anticancer drugs research and development have been largest market area in pharmaceuticals industry in terms of the numbers of project and clinical trials and spending. Our goals to improve cancer treatment by increasing our understanding of the mechanism by which anti-cancer treatments kill susceptible tumor cells. This articles provides an overview of current knowledge of anticancer drug their pharmacology, mechanism of action, uses, side effects,precautions, and contraindication. This mini review outlined the current status of anticancer drugs development and hinted the opinions of how to further increase the accuracy and efficacy of discovery for cancer treatment.

Analytical Approaches and Trends in the Determination of Psychoactive Drugs in Air

Understanding of the levels of psychoactive drugs in air is important for assessing both occupational and environmental exposure. Intelligence on the usage and manufacture of illegal drugs can also be gained. Environmental analysis and determination of air quality has recently expanded from its traditional focus to new pollutant categories that include illicit and psychoactive drugs. This is attributed to a greater part on the development of new, advanced techniques, such as liquid chromatography/mass spectrometry (LC/MS), allowing for the trace determination of such compounds down to the parts-per-trillion (ng/L) levels generally reported in air. Studies have also investigated the effects of firsthand and secondhand smoking of drugs, such as cocaine, cannabis and opium. Generally, these have shown secondhand smoke effects to be limited, apart from in the case of opium. Some studies have highlighted ill effects resulting through the exposure of vapors and dusts from the storage of drugs, but this has been shown to result from mould and other fungal contaminates. Investigations into the possible occupational exposures resulting from the use of anesthetic drugs in surgery and accident and emergency have focused on nitrous oxide, sevoflurane, methoxyflurane, isoflurane, propofol and fentanyl. This review focuses on developments and applications for the determination of psychoactive drugs in air.

Patterns of estrogenic activity in the Baltic Sea

Compounds such as estradiol and ethinylestradiol belong to contaminants of emerging concern, as they can disrupt the endocrine system of an organism with a hormonal system. The determination of such compounds is still challenging due to required low detection and quantification limits. Bioassays have proved to be sensitive tools for investigating the full potential of all compounds that can elicit an estrogenic response. In this study, surface water samples from different sampling sites and seasons in the Baltic Sea were analyzed for estrogenic activity with the Arxula adeninivorans yeast estrogen screen. Observed estradiol equivalent concentrations were in the range of <LOD – 0.38ngL−1. In general, a seasonal trend was observed, i.e., with an increase in water temperature in late spring, estradiol equivalent concentrations rose suddenly and decreased as abruptly when the temperature declined in autumn. An initial risk assessment shows that observed estradiol equivalent concentrations potentially affect organisms at a medium risk level based on determined risk quotients.

Development and validation of a GC\u2013MS/MS method for the determination of 11 amphetamines and 34 synthetic cathinones in whole blood

PurposePsychoactive compounds that contain a phenylethylamine structure (such as amphetamine-type stimulants and synthetic cathinones) are one of the major classes of stimulants on the recreational drug market. Approximately 670 new psychoactive substances (NPS) are monitored only in Europe; however, new psychoactive compounds are being developed for illicit trade each year. In this context, the development of new analytical procedures for the determination of such compounds in biological specimens for forensic toxicology is of great importance.MethodsGas chromatography–tandem mass spectrometry (GC–MS/MS) technique was applied for analysis of amphetamines and synthetic cathinones. The volumes of 200 µL of each whole blood sample and 1 mL of liquid-liquid extraction solvent were used for extraction, followed by pentafluoropropionyl derivatization.ResultsA high-throughput, robust, rapid, and sensitive procedure involving a simple liquid-liquid extraction for the simultaneous determination of 45 amphetamine-type stimulants and synthetic cathinones in whole blood was developed. The assay was validated based on its recovery (83.2–106%), interday accuracy (89.0–108%), and interday precision (≤ 8.1%). In view of the low limits of detection (ranged between 0.02 and 0.72 ng/mL) and limits of quantification (1 and 2.5 ng/mL), the developed method can serve as a less expensive and more ecologically friendly alternative to the liquid chromatography–tandem mass spectrometric methods.ConclusionsTo the best of our knowledge, this is the first work presenting a GC–MS/MS method for the determination of NPS in blood samples. The presented procedure was applied to authentic samples from forensic cases, demonstrating its utility in the quantification of a wide number of psychoactive substances in routine toxicological analyses. The developed procedure can also be easily expanded to additional compounds.

A Simple and Sensitive LC-MS/MS Method for the Simultaneous Determination of Cyclophosphamide and Doxorubicin Concentrations in Human Plasma

Background: The combination of cyclophosphamide and doxorubicin is commonly used in the adjuvant treatment of breast cancer in women with a high risk of recurrent disease. It is essential to devise dosing strategies for such drugs in order to minimise their in-use toxicity and to maximise their efficacy. Data have shown that concentration directed rather than dose targeted therapy provides better clinical outcomes. Therefore, analytical methods that permit the simple, sensitive and accurate determination of such compounds in human plasma will assist in drug dosing strategies Methods: We report herein a method for the LC-MS/MS determination of cyclophosphamide and doxorubicin concentrations in patient plasma, following intravenous chemotherapy using protein precipitation without time-consuming supernatant drying and reconstitution steps, at the same time using a HILIC pre-column to further remove residual phospholipids. Results: The method has a less than 15% RE and less than 5% RSD both intra- and inter- day. It has following principal advantages over recently published LC-MS/MS methods for cyclophosphamide and doxorubicin in human plasma: 1) the sample preparation method is very simple and rapid; 2) the method has a very low LLOQ (cyclophosphamide 0.5 ng/mL and doxorubicin 1.0 ng/mL) at the same time the precision and accuracy meeting the primary requirements established by the FDA; and 3) the procedure only requires a very small plasma volume (30 µL). Conclusion: Such a methodology, when applied in close temporal and geographical proximity to patients will permit a short turn-around time and thereby facilitate the clinical interpretation and feedback to improve patient outcomes. Keywords: Cyclophosphamide, doxorubicin, LC-MS/MS, human, plasma, protein.

Simultaneous determination of naproxen, ibuprofen and diclofenac in wastewater using solid-phase extraction with high performance liquid chromatography

The occurrence and removal efficiency for naproxen, ibuprofen and diclofenac in two of eThekwini Municipality’s wastewater treatment plants (WWTPs), Kingsburgh and Umbilo, were investigated. This paper describes a simple method that can be used routinely for the simultaneous determination of such compounds in the influent and effluent of the WWTPs. Target compounds were extracted from wastewater and pre-concentrated using the optimized Oasis MAX solid-phase extraction (SPE) method. During SPE, the pH of wastewater samples was adjusted to 2.5; then 100 mL of each sample was loaded onto a pre-conditioned cartridge. The SPE cartridge was rinsed with methanol:water (10:90%, v:v) prior to sequential elution of retained analytes with 2 mL methanol, followed by 2 mL methanol and acetic acid (90:10, v:v) and 2 mL of 2% (v:v) formic acid diluted using a mixture of methanol and acetic acid (40:60, v:v). The eluted analytes from the SPE cartridge were quantified using high performance liquid chromatography (HPLC) equipped with photo diode array detection. The analytical method was validated by spiking deionized water with 5 and 50 μg·L -1 of target compounds, for which the recovery range of 76 to 98% was achieved with good precision. The instrument quantification limits obtained were 0.1 μg·L -1 , for naproxen and 0.4 μg·L -1 for both ibuprofen and diclofenac. The detected concentrations for naproxen, ibuprofen and diclofenac in the influent of both WWTPs were in the ranges of 15–20 μg·L -1 , 55–69 μg·L -1 and 6.4–16 μg·L -1 , respectively. In effluent, the detected concentrations for naproxen, ibuprofen and diclofenac were in the ranges of 0.6–1.1, 2.1–4.2 and 1.4–2.0 μg·L -1 , respectively. Overall, the employed SPE-HPLC method led to rapid pre-concentration of target compounds prior to their trace quantification in wastewater samples. Keywords: solid-phase extraction, wastewater treatment plants, ibuprofen, naproxen, diclofenac

Determination of Quinine and its Derivatives with High-Performance Liquid Chromatography

This article presents the results deriving from research made on the development of optimal conditions for chromatographic separation and determination of such compounds as: quinine, quinidine, and acetylquinidine. The compounds subject to analysis are used in the treatment of malaria. Three stationary phases were used in the examination: octadecyl, which is perceived by analysts as the standard one, and two aryl phases (benzylpropyl and naphthylpropyl). For the mobile phases, the following compounds were adopted: methanol, acetonitrile, and a mixture of acetonitrile/water/formic acid. The best separation of quinine, quinidine, and acetylquinidine was observed in the naphthylpropyl column with the application of methanol as the mobile phase. The coefficients of separation of these compounds with the flow of methanol of 0.8 mL min−1 were 1.17 and 1.14, respectively. However, no proper separation of the compounds was observed in the octadecyl column, regardless of the mobile form applied.

Trace determination of acaricides in honey samples using XAD-2 adsorbent and gas chromatography coupled with an ion trap mass spectrometer detector

Various infectious/parasitic diseases affect beekeeping (e.g., Varroa destructor) and substances like acaricides are largely used as pesticides to tackle this problem, in particular tau-fluvalinate, fipronil, bromopropylate, amitraz, and coumaphos. A key issue in their use though is potential ingress into the human food chain, and in this regard accurate residue determination of such compounds in honey foods at trace concentration levels is critical. This paper describes an analytical methodology for determining qualitatively and quantitatively the acaricide residues in such foods. A solid-phase extraction method has been developed for the extraction and analysis of five acaricides in honey-foods using XAD-2 sorbent. Gas Chromatography coupled with an Ion Trap Mass Spectrometer detector (GC-IT/MS) was used for the analysis. The isotherm and breakthrough curves for XAD-2 solution are reported here. The developed procedure allows efficient acaricide recoveries, ranging from 81–96% with relative standard deviations (RSDs) of ≤6.9 for honey-food samples. The linearity (R2) of each acaricide has been investigated in the range 0.030–10.0 μg g−1 for evaluating the whole analytical protocol, R2 values are ≥0.945. The intraday and interday repeatabilities for honey samples were between 4.1–9.2 and 2.4–5.6, respectively. Special note has been made to the determination of the Limits of Detection (LODs) and the Limits of Quantification (LOQs) and their relative comparison with those reported in literature and those in International regulations: for GC/IT-MS (SIM mode), LODs vary between 3 ng g−1 and 18 ng g−1 (RSD ≤ 4.9), whereas LOQs range between 8 ng g−1 and 48 ng g−1 (RSD ≤ 8.3). The analytical method developed here has been applied to several commercial honey-foods (Millefiori, molasses, royal jelly). The investigated method is simple, selective, reproducible, reliable, and inexpensive.

Two new dinuclear copper(II) complexes as efficient catalysts of luminol chemiluminescence

Abstract The present study, introduces the beneficial catalyze effects of dinuclear copper(II) complexes on the luminol chemiluminescence (CL) reaction. Two new dinuclear copper(II) complexes ([Cu 2 (L) 2 (TAE)]X 2 and [Cu 2 (L′) 2 (TAE)]X 2 ), where TAE = tetraacetylethane; L = N,N′-dibenzyl ethylenediamine and L′ = N,N-dimethyl-N′-benzylethylenediamine; X = ClO 4 , have exhibited highly efficient catalytic activity of luminol CL as an artificial peroxidase model at pH as low as 7.5 in water in the presence of H 2 O 2 and dissolved O 2 even in the absence of H 2 O 2 at elevated pH (∼12). The effects of the reactant concentrations and some amino acids on luminol CL were also investigated. Among them, l -cysteine (CySH) containing -SH group was observed to inhibit the CL signal of the luminol-H 2 O 2 -dinuclear copper(II) complex. A similar phenomenon also was observed for glutathione (GSH), which made CL probe of peroxidase-like dinuclear copper(II) complexes applicable for the determination of such compounds in biological media.

Quantitative Determination of Cucurbitane-Type Triterpenes and Triterpene Glycosides in Dietary Supplements Containing Bitter Melon (Momordica charantia) by HPLC-MS/MS

Momordica charantia L. (Cucurbitaceae), commonly known as bitter melon, is widely cultivated in many tropical and subtropical areas of the world. It is a common food staple; its fruits, leaves, seeds, stems, and roots also have a long history of use in traditional medicine. In the United States, dietary supplements labeled as containing bitter melon can be purchased over-the-counter and from Internet suppliers. Currently, no quantitative analytical method is available for monitoring the content of cucurbitane-type triterpenes and triterpene glycosides, the major constituents of bitter melon, in such supplements. We investigated the use of HPLC-electrospray ionization (ESI)-MS/MS for the quantitative determination of such compounds in dietary supplements containing bitter melon. Values for each compound obtained from external calibration were compared with those obtained from the method of standard additions to address matrix effects associated with ESI. In addition, the cucurbitane-type triterpene and triterpene glycoside contents of two dietary supplements determined by the HPLC-ESI-MS/MS method with standard additions were compared with those measured by an HPLC method with evaporative light scattering detection, which was recently developed for quantification of such compounds in dried fruits of M. charantia. The contents of five cucurbitane-type triterpenes and triterpene glycosides in 10 dietary supplements were measured using the HPLC-ESI-MS/MS method with standard additions. The total contents of the five compounds ranged from 17 to 3464 microg/serving.

A fast and reliable method for the quantitative determination of benzimidazoles and metabolites in milk by LC-MS/MS with on-line sample treatment

This work reports the development of a simple, reliable and automated method based on LC-MS/MS for the quantitative determination of benzimidazole residues and some of their metabolites in milk. The method involves the use of an extraction cartridge coupled on-line to the chromatographic system for the clean-up of the milk samples, efficiently eliminating matrix macromolecules and providing appropriate selectivity for the determination of such compounds. In the online method developed here, only a reduced manual sample manipulation was required (protein precipitation and filtration) prior to injection into the chromatographic system. The limits of detection of the target anthelmintics ranged from 0.1 to 0.8 ng mL(-1) in milk samples, these values being below the maximum residue limit established for these compounds. The whole method developed was validated in real samples according to the requirements set by the Commission Decision 2002/657/EC. The optimized method was successfully applied to commercial and raw milk samples of different origin demonstrating that the proposed method may find application in routine laboratory analyses of food control safety.

Bioanalytical chromatographic methods for the determination of catechol- O-methyltransferase inhibitors in rodents and human samples: A review

In the past years, it has been recognised that the levodopa therapy may be improved with therapeutic regimens including a catechol- O-methyltransferase (COMT) inhibitor. At the present time, tolcapone and entacapone are the only two COMT inhibitors available in the market. However, further COMT inhibitors are under development for Parkinson's disease, namely nebicapone and opicapone (formerly known as BIA 9-1067). In addition, the nitecapone, another well-known COMT inhibitor, is also in preclinical development but for neuropathic pain. Since the 1990s different liquid chromatography methods have been developed and validated to quantify tolcapone, entacapone, nitecapone, nebicapone and some metabolites in biological samples, particularly in plasma samples obtained from rodent and human species. These bioanalytical methods have been primarily used to support pharmacokinetic assays with such COMT inhibitors in non-clinical and clinical studies. As these inhibitors present hydrophobic groups in their chemical structures, reversed-phase liquid chromatography has been used as the major approach for the determination of such compounds, especially high-performance liquid chromatography coupled to ultraviolet detection (HPLC-UV), electrochemical detection (HPLC-ECD) and mass spectrometry detection (HPLC–MS). Regarding the sample preparation, the traditional liquid–liquid extraction (LLE) and solid-phase extraction (SPE) were also the most widely used procedures for extraction of the analytes of interest prior to the analysis of samples. Thus, this review aimed to gather, for the first time, sufficient background information about the bioanalytical chromatographic methods which have been already developed and applied for the determination of tolcapone, entacapone, nitecapone, nebicapone and their metabolites. Moreover, some pharmacokinetic aspects of the COMT inhibitors with interest from a bioanalytical perspective were also addressed.

An Enzyme‐Linked Immunosorbant Assay Using Monoclonal Antibody Against Bacoside A3 for Determination of Jujubogenin Glycosides in Bacopa monnieri (L.) Wettst

In Ayurvedic medicines, Bacopa monnieri (L.) Wettst. (brahmi) is known as a medicinal plant used for memory enhancement. Its active compounds are classified as pseudojujubogenin and jujubogenin glycosides. Owing to the lack of chromophore in the saponin glycoside structures, HPLC-UV-vis gives low sensitivity for determination of such compounds. In the case of the detection of small amounts of saponin glycosides, immunological assay could be a suitable method. To develop and validate a sensitive enzyme-linked immunosorbant assay (ELISA) using monoclonal antibody (MAb) against bacoside A₃, the major jujubogenin glycoside found in brahmi. An immunogen was prepared by conjugating bacoside A₃ with a bovine serum albumin (BSA). To determine its immunogenicity, the ratio of hapten in bacoside A₃-BSA conjugate was determined by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS). After immunisation in mice, hybridomas secreting MAbs against bacoside A₃ were produced by fusing the immunised splenocytes with SP2/0- Ag14 myeloma cells. The antibody was raised specifically against jujubogenin glycosides. The ELISA using anti-bacoside A₃ MAb was developed. Bacoside A₃ in the range of 3.05-97.70 ng mL⁻¹ could be detected by ELISA using anti-bacoside A₃ MAb. The assay showed a detection limit of 0.48 ng mL⁻¹ (0.517 nm). The validation study showed that the method was precise, accurate and sensitive. Interestingly, the MAb showed cross-reactivity with the other jujubogenin glycosides, bacopaside X and IV. However, it did not show cross-reactivity with any of pseudojujubogenin glycosides. The study demonstrated that ELISA using anti-bacoside A₃ MAb can be used for determination of total jujubogenin glycosides in brahmi.

Automated sample treatment with the injection of large sample volumes for the determination of contaminants and metabolites in urine

This work reports the development of a simple and automated method for the quantitative determination of several contaminants (triazine, phenylurea, and phenoxyacid herbicides; carbamate insecticides and industrial chemicals) and their metabolites in human urine with a simplified sample treatment. The method is based on the online coupling of an extraction column with RP LC separation-UV detection; this coupling enabled fast online cleanup of the urine samples, efficiently eliminating matrix components and providing appropriate selectivity for the determination of such compounds. The variables affecting the automated method were optimized: sorbent type, washing solvent and time, and the sample volume injected. The optimized sample treatment reported here allowed the direct injection of large volumes of urine (1500 microL) into the online system as a way to improve the sensitivity of the method; limits of detection in the 1-10 ng/mL range were achieved for an injected volume of 1500 microL of urine, precision being 10% or better at a concentration level of 20 ng/mL. The online configuration proposed has advantages such as automation (all the steps involved in the analysis - injection of the urine, sample cleanup, analyte enrichment, separation and detection - are carried out automatically) with high precision and sensitivity, reducing manual sample manipulation to freezing and sample filtration.

Chemiluminescence reactions of luminol system catalyzed by nanoparticles of a gold/silver alloy

The chemiluminescence (CL) of luminol–H2O2 system is strongly enhanced on addition of nanoparticles composed of a gold/silver alloy (ratio 5:4). The effect is attributed to a catalytically enhanced decomposition of H2O2 to produce reactive oxygen species. A reaction mechanism is proposed. Organic compounds containing hydroxy, amino, or thiol groups (such as amino acids, dopamine, pyrocatechol) can inhibit the CL signal of the system. It is concluded that the system has a large potential in terms of the determination of such compounds.

Chemiluminescence Reactions of a Luminol System Catalyzed by ZnO Nanoparticles

Colloidal ZnO nanoparticles were synthesized by the sol−gel method and were characterized by UV−visible spectroscopy and photoluminescence spectroscopy. The effect of ZnO nanoparticles on the luminol−H2O2 chemiluminescence (CL) system, a popular model CL system, was investigated. It was found that ZnO nanoparticles with a size regime from 6 to 21 nm could enhance the CL of the luminol−H2O2 system, and the strongest CL signal was obtained when the mean diameter of ZnO nanoparticles was 6 nm. To investigate the enhancement mechanism of the CL, we used UV−visible spectroscopy, FT-IR spectroscopy, and CL spectroscopy to study optical properties before and after the CL reaction in the presence/absence of ZnO nanoparticles. The CL enhancement of the luminol−H2O2 system by ZnO nanoparticles should originate from the catalysis of ZnO nanoparticles, which could catalyze the decomposition of H2O2 to produce some reactive intermediates such as hydroxyl radical and superoxide anion. Then, the resulting hydroxyl radical reacted with luminol to form luminol radical, which rapidly reacted with superoxide anion or monodissociated hydrogen peroxide. As a result, the emission was enhanced. Experimental results showed that some organic compounds containing -OH, -NH2, and -SH groups, such as amino acid, ascorbic acid, and dopamine, could inhibit the CL signal of the luminol−H2O2−ZnO system. The above facts indicated that the present system had a wide application for the determination of such compounds.

Enrichment of pyrethroid residues in environmental waters using a multiwalled carbon nanotubes cartridge, and analysis in combination with high performance liquid chromatography

A sensitive method was developed using new carbon nanomaterial, multiwalled carbon nanotubes, as solid phase extraction adsorbents followed by high performance liquid chromatography with UV detection for determination of six pyrethroid pesticides at trace level in environmental water samples. Parameters influencing the extraction efficiency were investigated in detail. Under the optimal conditions, detection limits of 0.7–5.0 ng L−1 were obtained for six pyrethroid pesticides, the linear ranges were between 0.1 and 40 μg L−1 and the precisions were in the range of 2.0–5.8%. The method has been applied to determine the six target compounds in tap water, well water, river water and reservoir water. Good recoveries were obtained for all target analytes and these results indicated that the method developed can be used in the determination of such compounds at trace levels in environmental water samples.

Sensitized chemiluminescence of CdTe quantum-dots on Ce(IV)-sulfite and its analytical applications

Water-soluble CdTe quantum-dots (QDs) of different sizes capped with thioglycolic acid (TGA) were synthesized via a microwave-assisted method. It was found that CdTe QDs, as a kind of sensitizer, could enhance the chemiluminescence (CL) emission from the redox reaction of SO 3 2− with Ce(IV) in acidic medium. In combination with the flow injection technique, the effects of reactant concentrations, the sizes of CdTe QDs, some organic compounds, and several electron transfer proteins on the CL emission were investigated in detail. The sensitized CL displayed the size-dependent effect and increased along with increasing the QDs sizes. Organic compounds containing OH, NH 2, or SH groups, and some electron transfer proteins such as cytochrome c, hemoglobin and myoglobin, which readily interact with CdTe QDs, were observed to inhibit the CL signal of the Ce(IV)–SO 3 2−–CdTe QDs system, which made it applicable for the determination of such compounds and proteins. The CL enhancement mechanism was also discussed briefly on the basis of the photoluminescence (PL) and CL spectra. This work is not only of importance for gaining a better understanding of the unique optical and physical chemistry properties of semiconductor nanocrystals but also of great potential to find applications in many fields such as luminescence devices, bioanalysis, and multicolor labeling probes.

Sub-second adsorption for the fast sub-nanomolar monitoring of Clindamycin in its pure and pharmaceutical samples by fast Fourier transformation with the use of continuous cyclic voltammetry at an Au microelectrode in a flowing system

For the first time the fast Fourier adsorptive stripping voltammetry at a microgold electrode for the determination of Clindamycin in flow injection systems has been developed. The principal advantages of the method are that it is rapid, simple, and possesses low detection limit. Some investigations were also done, to find the effects of various parameters on the sensitivity of the proposed method. The conditions producing the performance were the pH value of 2, the scan rate value of 40 V/s, accumulation potential of (300 mV), and accumulation time of 0.3 s. Some of the advantages of the proposed method are as follows: the removal of oxygen from the test solution is not required any more, the detection limit of the method is sub-nanomolar and finally, the method is fast enough for determination of such compounds, in a wide variety of chromatographic methods. We also introduce a special computer based numerical method, for calculation of the analyte signal and noise reduction. After subtracting the background current from noise, the electrode response was calculated, based on partial and total charge exchanges at the electrode surface. The integration range of currents was set for all the potential scan ranges, including oxidation and reduction of the Au surface electrode, to obtain a sensitive determination. The waveform potential was continuously applied on an Au disk microelectrode (with a 12.5 μm in radius). The method was linear over the concentration range of 4–42,498,400 pg/ml ( r = 0.9957) with a limit of detection and quantitation 1.3 and 4 pg/ml, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay Clindamycin in capsules.