Phosphorimetric Method Research Articles

Determination of enrofloxacin by room-temperature phosphorimetry after solid phase extraction on an acrylic polymer sorbent

A phosphorimetric method was developed to enable the determination of enrofloxacin using photochemical derivatization which was used to both improve detection limits and to minimize the uncertainty of measurements. Phosphorescence was induced on cellulose containing TlNO3. Absolute limit of detection at the ng range and linear analytical response over three orders of magnitude were achieved. A metrological study was made to obtain the combined uncertainty value and to identify that the precision was mainly affected by the changing of substrates when measuring the signal from each replicate. Pharmaceutical formulations containing enrofloxacin were successfully analyzed by the method and the results were similar to the ones achieved using a HPLC method. A solid phase extraction on an acrylic polymer was optimized to separate enrofloxacin from interferents such as diclofenac and other components from biological matrices, which allowed the successful use of the method in urine analysis.

A new analytical application of nylon-induced room-temperature phosphorescence: Determination of thiabendazole in water samples

This paper discusses the first analytical determination of the widely used fungicide thiabendazole by nylon-induced phosphorimetry. Nylon was investigated as a novel solid-matrix for inducing room-temperature phosphorescence of thiabendazole, which was enhanced under the effect of external heavy-atom salts. Among the investigated salts, lead(II) acetate was the most effective in yielding a high phosphorescence signal. An additional enhancement of the phosphorescence emission was attained when the measurements were carried out under a nitrogen atmosphere. There was only a moderate increase in the presence of cyclodextrins. The room-temperature phosphorescence lifetimes of the adsorbed thiabendazole were measured under different working conditions and, in all cases, two decaying components were detected. On the basis of the obtained results, a very simple and sensitive phosphorimetric method for the determination of thiabendazole was established. The analytical figures of merit obtained under the best experimental conditions were: linear calibration range from 0.031 to 0.26 μg ml −1 (the lowest value corresponds to the quantitation limit), relative standard deviation, 2.4% ( n = 5) at a level of 0.096 μg ml −1, and limit of detection calculated according to 1995 IUPAC Recommendations equal to 0.010 μg ml −1 (0.03 ng/spot). The potential interference from common agrochemicals was also studied. The feasibility of determining thiabendazole in real samples was successfully evaluated through the analysis of spiked river, tap and mineral water samples.

Simple and rapid determination of the active metabolite of nabumetone in biological fluids by heavy atom-induced room temperature phosphorescence

A simple, selective and sensitive heavy atom induced-room temperature phosphorimetric method is described for the determination of 6-methoxynaphthylacetic acid, main metabolite of nabumetone, in biological fluid. The phosphorescence signals are a consequence of intermolecular protection when analytes are, exclusively, in presence of heavy atom salt and sodium sulfite as an scavenger to minimize room temperature phosphorescence quenching. This technique enables us to determine analytes in complex matrices without the need for a tedious prior separation process. Optimized conditions for the determination were 0.12 M TlNO 3. An amount of 0.025 M sodium sulfite and pH 7.5 (adjusted with 0.1 M sodium hydrogen phosphate-dihydrogen phosphate buffer solution). The delay time, gate time and time between flashes were 180, 1500 μs, and 5 ms, respectively. The maximum phosphorescence signal appeared instantly and the intensity was measured at λ ex = 328.4 nm and λ em = 544.4 nm. The response obtained was linearly dependent on concentration in the range of 20–1000 ng mL −1. The detection limit, according to error propagation theory, was 11.6 ng mL −1 and the detection limit as proposed by Clayton, was 17.4 ng mL −1. The repeatability was studied by using 10 solutions of 100 and 800 ng mL −1 of metabolite; if the theory of error propagation is assumed the relative error is 4.3 and 0.66%. The S.D. of replicates was found to be 2.2 and 11.0 ng mL −1. This method was successfully applied to the analysis of 6-methoxynaphthylacetic acid in human serum and urine.

A simple and rapid phosphorimetric method for the determination of the fungicide fuberidazole in water samples

The applicability of heavy-atom induced room-temperature phosphorescence to determine pesticides in real samples is demonstrated in this work. Thus a new, simple, rapid and selective phosphorimetric method for fuberidazole determination is proposed. The phosphorescence signals are a consequence of intermolecular protection when analytes are found exclusively in the presence of heavy atom salts and sodium sulphite when used as an oxygen scavenger to minimize RTP quenching, so protective media (such as cyclodextrines, micellar media, etc) are not necessary to use for obtaining phosphorescence in solution. The determination was performed in 0.4 M KI and 8 mM sodium sulphite at a measurement temperature of 20°C. The phosphorescence intensity was measured at 515 nm exciting at 308 nm. Phosphorescence was easily and rapidly obtained, showing a linear concentration range between 0 and 25 ng mL−1 with a detection limit of 95 ng L−1. The method has been successfully applied to the analysis of fuberidazole in water.

Simple determination of the herbicide napropamide in water and soil samples by room temperature phosphorescence

A new, simple, rapid and selective phosphorimetric method for determining napropamide is proposed which demonstrates the applicability of heavy-atom-induced room-temperature phosphorescence for analyzing pesticides in real samples. The phosphorescence signals are a consequence of intermolecular protection and are found exclusively with analytes in the presence of heavy atom salts. Sodium sulfite was used as an oxygen scavenger to minimize room-temperature phosphorescence quenching. The determination was performed in 1 M potassium iodide and 6 mM sodium sulfite at 20 degrees C. The phosphorescence intensity was measured at 520 nm with excitation at 290 nm. Phosphorescence was easily developed, with a linear relation to concentration between 3.2 and 600.0 ng ml(-1) and a detection limit of 3.2 ng ml(-1). The method has been successfully applied to the analysis of napropamide in water and soil samples and an exhaustive interference study was also carried out to display the selectivity of the proposed method.

Flow-through optosensing of 1-naphthaleneacetic acid in water and apples by heavy atom induced–room temperature phosphorescence measurements

A sensitive and selective phosphorimetric method for the determination of 1-naphthaleneacetic acid (1-NAA) based on a flow-injection system connected to a flow cell packed with a solid support and placed in the sample compartment of a conventional luminescence spectrometer is described. A non-ionic solid polymeric resin Amberlite XAD-7 is used for the packing. After injection of the sample, 1-NAA is on-line retained in the packed resin and measurements of the heavy atom induced (HAI)–room temperature phosphorescence (RTP) emission ( λ ex/ λ em = 292/490 nm) from this native luminescent compound are taken. The optimum experimental conditions were investigated by injecting 2 ml samples of an aqueous solution of 1-NAA in the flow system. A concentration 0.15 mol l −1 of thallium(I) ions, as heavy atom, both in the samples and the carrier flow, was finally selected. Also, a concentration of 6 mmol l −1 of sulphite was optimal for ensuring the necessary deoxygenation of the system at the selected flow rate of 0.8 ml min −1. After measurement, the solid support was efficiently regenerated by injecting 1 ml of a mixture water:acetone in a ratio 1:1 (v/v) into the flow. The detection limit (3 σ criterion) was 1.2 ng ml −1 of 1-NAA. The repeatability (R.S.D.) for five replicates of a sample containing 50 ng ml −1 of analyte turned out to be ±3% and the calibration graphs proved to be linear up to 500 ng ml −1 of 1-NAA (maximum concentration assayed). The effect of potential interferences from other organic species which can be also used as plant growth regulators, as well as from various inorganic cations and anions, has been investigated as well. The method was successfully applied to the determination of low levels of this plant growth regulator in natural waters (river and fountain waters) and apples.

Determination of naproxen with solid substrate room temperature phosphorimetry based on an orthogonal array design

A solid substrate room temperature phosphorimetric method (SSRTP) for the determination of naproxen in pharmaceutical products was developed. The experimental conditions were optimized by a L 25 (5 6) orthogonal array design (OAD) with five factors at five levels using statistical analysis. The five factors contained pH value of the sample solution, drying time ( t d) and drying temperature ( T d) of solid substrate paper in the oven, concentration ( c I − ) of heavy atom (I −), and exposure time ( t e) of solid substrate paper after being dried. The pH value, t d, c I − and t e had significant influences on the measurement of phosphorescence intensity. The optimization for sample preparation improved greatly the analytical performance of SSRTP. Under the optimal conditions, naproxen can be determined in a linear range from 10 to 400 ng ml −1 with a detection limit of 2.7 ng ml −1 at 3 σ. The method has been applied satisfactorily to the determination of naproxen in a commercial product.

FACILE ANALYSIS OF CARBAZOLE IN COMMERCIAL ANTHRACENE BY HEAVY ATOM–INDUCED ROOM TEMPERATURE PHOSPHORESCENCE

The applicability of heavy atom–induced room temperature phosphorescence (HAI-RTP) in real samples is demonstrated in this work. In this methodology only two reagents, potassium iodide as heavy atom salt and sodium sulfite as oxygen scavenger, were used to obtain the phosphorescent signal of carbazole in solution while anthracene did not show phosphorescence under these experimental conditions. In this study a new simple, rapid, and selective phosphorimetric method is proposed, using HAI-RTP methodology for the determination of carbazole in high-purity anthracene. The phosphorescence intensity was measured at 438 nm with excitation at 290 nm. Phosphorescence was fully developed instantly. A linear concentration range between 0 and 250 ng/mL−1 with a detection limit of 1.05 ng/mL−1 (10.5 ng of CBZ in 600 ng of anthracene), an analytical sensitivity of 1.7 ng/mL−1, and standard deviation of 0.71% at 150 ng/mL−1 concentration level was obtained. The method has been successfully applied to the analysis of carbazole in spiked anthracene samples.

Sensitive and simple determination of the vasodilator agent dipyridamole in pharmaceutical preparations by phosphorimetry.

The applicability of heavy atom-induced room-temperature phosphorescence to pharmaceutical samples is demonstrated in this work. Thus a new, simple, rapid, and selective phosphorimetric method for dipyridamole determination is proposed. The phosphorescence signals are a consequence of intermolecular protection when analytes are exclusively in the presence of heavy atom salts and sodium sulfite as an oxygen scavenger to minimize RTP quenching. The determination was performed in 0.1 mol L(-1) thallium(I) nitrate and 8 mmol L(-1) sodium sulfite at a measurement temperature of 20 degrees C. The phosphorescence intensity was measured at 635 nm, with excitation at 305 nm. Phosphorescence was easily developed; a linear concentration range was obtained between 0 and 100 ng mL(-1) with a detection limit of 940 ng L(-1), an analytical sensitivity of 2.5 ng mL(-1), and a standard deviation of 2.7% at 60 ng mL(-1) concentration. The method has been successfully applied to the analysis of dipyridamole in a unique Spanish commercial formulation containing 100 ng mL(-1) per capsule. The recovery was 101.6% with 6.5% standard deviation of analytical measurement. The method using the standard addition methodology has been validated.

Solid-phase spectrophosphorimetric determination of the pesticide o-phenylphenol in water and vegetables.

A phosphorimetric method for the determination of o-phenylphenol (OPP) using filter paper as solid support and Tl(I) as heavy metal enhancer of the phosphorescent signal is proposed. The phosphorescence measurements were carried out by placing the paper with the sample between two plates of quartz, thus avoiding the quenching effect produced by atmospheric oxygen and moisture. The linear dynamic range of the method was 0.5-4.0 mg L(-1) and the detection and quantification limits were 0.03 and 0.11 mg L(-1), respectively. The precision of the method (expressed as relative standard deviation) was 1.7% for a sample containing 2.0 mg L(-1) of analyte. The method has been applied to the determination of OPP in different types of water, lettuce, string beans and peppers, with recoveries ranging between 97.1 and 100.7%

Simple determination of propranolol in pharmaceutical preparations by heavy atom induced room temperature phosphorescence

The applicability of heavy atom induced room temperature phosphorescence in real samples is demonstrated in this work. In this methodology only two reagents, potassium iodide as heavy atom salt and sodium sulphite as oxygen scavenger, were used to obtain phosphorescent signal of propranolol in solution. Thus a new simple, rapid and selective phosphorimetric method is proposed for propranolol determination in pharmaceutical preparations. The phosphorescence intensity was measured at 492 nm exciting at 294 nm. Phosphorescence was fully developed instantly, obtaining a linear concentration range between 0 and 500 ng ml −1 with a detection limit of 14.4 ng ml −1, an analytical sensitivity of 6.7 ng ml −1 and a standard deviation of 1.4% at a 300 ng ml −1 concentration level. The method has been successfully applied to the analysis of propranolol in an antidepressive pharmaceutical preparation and it was validated using standard addition methodology.

Direct determination of naftopidil by non-protected fluid room temperature phosphorescence.

A selective and sensitive room temperature phosphorimetric method for the direct determination of naftopidil in biological fluids is described. The method is based on obtaining a phosphorescence signal from this antihypertensive drug using TlNO3 as a heavy atom perturber and Na2SO3 as a deoxygenator agent without a protective medium. This technique is named non-protected room temperature phosphorescence (NP-RTP), and enables us to determine analytes in complex matrices without the need for a tedious prior separation process. The optimization of Na2SO3 (8.5 x 10(-3) M) and the accurate value of pH (9.0) were determined using a simplex as a method of optimization. Sodium carbonate-hydrogencarbonate buffer solution (5.0 x 10(-2) M) was used to adjust the suitable pH. The optimum concentration of Tl+ (8.5 x 10(-2) M) was also determined. The delay time, gate time and time between flashes selected were 200 microseconds, 200 microseconds and 5 ms, respectively. Under the above conditions we propose a method to determine naftopidil by direct measurement of phosphorescence intensity with an emission wavelength of 526 nm and an excitation wavelength of 296 nm in the concentration range 0.05-1.00 mg L-1. Under these conditions the phosphorescence signal appears in 3 min once the sample has been prepared. Optimization of the various conditions permitted the establishment of an NP-RTP method for the determination with a detection limit, according to the error propagation theory, of 21.0 ng mL-1. The repeatability was studied using 10 solutions of 0.20 mg L-1 of naftopidil; if error propagation is assumed, the relative error is 1.39%. The standard deviation for replicate samples was 1.1 x 10(-2) mg L-1. This method was successfully applied to the determination of naftopidil, in human urine with recoveries between 106 and 112%.

Direct determination of 1-naphthoxylactic acid in biological fluids by non-protected fluid room temperature phosphorimetry.

A selective and sensitive room-temperature phosphorimetric method for the direct determination of 1-naphthoxylactic acid (NA) in biological fluids is described. It is based on obtaining a phosphorescence signal from NA using TlNO3 as a heavy atom perturber and Na2SO3 as a deoxygenator without a protective medium. This technique is named non-protected room-temperature phosphorescence (NP-RTP), which allows to determine analytes in complex matrices without the need for tedious prior separation. Optimization of the operational conditions resulted in a detection limit for NA of 9.6 ng/mL according to the error propagation theory. The repeatability and standard deviation were also determined. This method was successfully applied to the determination of NA in urine and human serum.

Determination of nafcillin by room temperature phosphorescence

Room-temperature phosphorescence, as a very high selective and sensitive method, was applied to the determination of nafcillin in pharmaceutical preparations. The use of phosphorescence enhancer such as sodium dodecyl sulfate (micellar agent), thallium (I) nitrate (external heavy atom), and sodium sulfite (deoxygenation agent) was studied and optimized to obtain maximum sensitivity and adequate selectivity. The determination was performed in 0.092 M sodium dodecyl sulfate, 0.023 M thallium nitrate and 0.01 M sodium sulfite. A pH value of 7.2 was selected as adequate for phosphorescence development. The phosphorescence was totally developed in 15 min, after that the intensity was measured at λ ex=284 nm and λ em=540 nm. The response obtained was linear for the concentration range from 0.2 to 1.5 mg l −1. The detection limit, according to the error propagation theory was 0.18 mg l −1. The repeatability and relative standard deviation were also determined according to this theory. The specificity of the method was studied by adding excipients and other penicillins to a solution of nafcillin with the result that only two penicillins, methicillin and penicillin G procaine, cause interference in the nafcillin quantification. The method has been validated with a fluorimetric method and HPLC method. A commercial pharmaceutical preparation was successfully analyzed using this method. In order to determine the ability of the phosphorimetric method proposed, nafcillin in a pharmaceutical preparation was analyzed and the results were compared with the certificated values by turbidimetry and by high pressure liquid chromatography (HPLC); there was an excellent agreement between values obtained by all techniques.

Simple and rapid determination of the drug naproxen in pharmaceutical preparations by heavy atom-induced room temperature phosphorescence

A simple, selective and sensitive heavy atom-induced room temperature phosphorimetric method (HAI-RTP) is described for the determination of naproxen (NAP) in pharmaceutical preparations. The phosphorescence signals are a consequence of intermolecular protection when analytes are, exclusively, in presence of a heavy atom salt and sodium sulfite as an oxygen scavenger to minimize RTP quenching. These variables selection constitute the basis of a HAI-RTP method for the determination of naproxen (detection limit 17.6 ng ml −1; 1.71% relative standard deviation at 250 ng ml −1). The method has been applied satisfactorily to the analysis of pharmaceutical preparations.

A Simple and Rapid Phosphorimetric Method for the Determination of α-Naphthaleneacetamide in Fruit Samples

A simple and rapid phosphorimetric method for the determination of α-naphthaleneacetamide residues in fruit samples is presented. The method is based on a new, simple and sensitive methodology: Heavy Atom Induced Room Temperature Phosphorescence (HAI-RTP). The effect of different heavy atom salts and sodium sulfite concentration over the phosphorescence signals was investigated. The resultant HAI-RTP spectra were successfully applied for determining α-naphthaleneacetamide concentrations in the range of 7.8 to 100 μg·L−1, with relative standard deviations between 2.6 and 5.7%.

Synchronous-derivative phosphorimetric determination of 1- and 2-naphthol in irrigation water by employing β-cyclodextrin

A room-temperature phosphorimetric (RTP) study of the inclusion process between 1- and 2-naphthol, β-cyclodextrin (β-CD) and 3-bromo-1-propanol as heavy atom pertuber has been performed. Experimental conditions were optimized for the formation of trimolecular complexes with lifetimes of 10.82 and 9.41 ms for 1- and 2-naphthol, respectively. A synchronous-derivative room-temperature phosphorimetric method has been proposed to the analysis of both naphthols in synthetic mixtures and irrigation water in the ratio 1:10 to 10:1; the limit of detection is 0.02 μg ml −1 and the relative standard deviation (RSD) is about 6%.

Determination of the Drug Naphazoline in Pharmaceutical Preparations by Heavy Atom-Induced Room-Temperature Phosphorescence

A simple, selective, and sensitive heavy atom-induced room-temperature phosphorimetric method (HAI-RTP) is described for the determination of naphazoline (NPZ) in pharmaceutical preparations. The phosphorescence signals are a consequence of intermolecular protection when analytes are, exclusively, in the presence of a heavy atom salt and sodium sulfite as an oxygen scavenger to minimize RTP quenching. This variable selection constitutes the basis of the HAI-RTP method for the determination of naphazoline (detection limit 43.5 ng/mL; 2.39% relative standard deviation at 500 ng/mL). The method has been applied to the analysis of pharmaceutical preparations.

Rapid screening method for cocaine and benzoylecgonine in saliva samples

We are presenting a new method for cocaine and benzoylecgonine analysis in saliva samples based on room temperature phosphorimetry. The determination of the drugs is performed on filter paper, which is a suitable substrate for most saliva collection procedures. Extraction from the solid substrate is not necessary, since both compounds are detected on the paper substrate. Complete analysis can be performed with only a few microliters of saliva, which is an attractive feature in cases of limited sample availability. The limits of detection are estimated at the sub-ng level, which shows the feasibility of detecting cocaine and benzoylecgonine at the cut-off levels stipulated by the National Institute on Drug Abuse (300 ng/ml). When compared to the existing methodology, the phosphorimetric method presents several advantages which include simplicity, short analysis time, low cost, and the viability of interfacing it with portable instrumentation for field screening applications.

Heavy Atom Induced Room Temperature Phosphorescence Method for the Determination of the Plant Growth Regulator β-Naphthoxyacetic Acid

A simple, selective, and sensitive heavy atom induced room temperature phosphorimetric method (HAI-RTP) is described for the determination of the plant growth regulator β-naphthoxyacetic acid (NOA) in spiked apple samples. A careful selection of the different variables (heavy atom and sodium sulfite) to obtain the phosphorescence signal constitutes the basis of a HAI-RTP method for the determination of NOA. The analytical curve of NOA gives a linear dynamic range of 0−625 ng mL-1 and a detection limit of 30.5 ng mL-1. A recovery of 108.8% was obtained for 500 ng mL-1 NOA in spiked apple samples. Keywords: β-Naphthoxyacetic acid; heavy atom induced room temperature phosphorescence (HAI-RTP)