Fluorimetric determination of proteins using 4‐chloro‐(2′‐hydroxylophenylazo)rhodanine–Ti(IV) complex as a spectral probe

A novel method for the determination of proteins was developed, based on the enhancement of fluorescence with 4‐chloro‐(2′‐hydroxylophenylazo)rhodanine–Ti(IV) [ClHARP–Ti(IV)] complex as a fluorescence probe. The excitation and emission wavelengths of the system were 335 nm and 376 nm, respectively. The presence of bis(2‐ethylhexyl)sulphosuccinate sodium salt (AOT) microemulsion greatly increased the sensitivity of the system. Under optimal conditions, four kinds of proteins, including bovine serum albumin (BSA), human serum albumin (HSA), egg albumin (Ova), and γ‐globin (γ‐G) were studied. The detection limits were 0.182 µg/mL for BSA, 0.0788 µg/mL for HSA, 0.216 µg/mL for Ova and 0.484 µg/mL for γ‐G. The linear ranges of the calibration were 0–12.0, 0–10.0, 0–18.0 and 0–18.0 µg/mL, respectively. The method possessed high sensitivity, good selectivity and was applied to the analysis of protein in milk powder and cornmeal with satisfactory results. Copyright © 2008 John Wiley & Sons, Ltd.     

Chemiluminescence determination of promazine in human serum and drug formulations using Ru(phen)32+–Ce(IV) system and a chemometrical optimization approach

A new chemiluminescence (CL) method using flow injection has been described for the rapid and sensitive determination of promazine hydrochloride (PMH). The method is based on the CL reaction of PMH with tris(1,10 phenanthroline)ruthenium(II), [Ru(phen)₃²⁺] and Ce(IV) in sulfuric acid medium. Effects of chemical variables were investigated employing central composite design and response surface methodology. Under the optimum conditions, the CL intensity was proportional to the concentration of the drug in solution over the ranges 0.020–0.32 and 0.32–32 µg/mL. The limit of detection (signal‐to‐noise ratio = 3) was 0.012 µg/mL. The method was applied successfully to the determination of PMH in drug formulations and human serum (recovery percentages between 96.7 and 105.0%). The relative standard deviation for 11 replicate determinations of 1.5 µg/mL of PMH was 1.7%. The minimum sampling rate was 100 samples per hour. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of oxytetracycline hydrochloride in milk and egg white samples using Ru(bipy)32+–Ce(SO4)2 chemiluminescence

A novel, rapid and sensitive chemiluminescence (CL) method for the determination of oxytetracycline hydrochloride (OTCH) is described in this paper. The presented method was based on the fact that OTCH could immensely enhance the CL of the reaction of cerium sulfate and tris(2,2‐bipyridyl) ruthenium (II) in acidic medium. Under optimal experimental conditions, CL intensity was favorably linear for OTCH in the range 5.0 × 10^?7 to 5.0 × 10^?5 g/ml, with a detection limit of 1.5 × 10^?7 g/ml (S/N = 3). The relative standard detection was 4.76% for 5.0 × 10^?6 g/ml (n = 11). This method was successfully applied to the analysis of OTCH in milk and egg white samples. According to the results of the kinetic curves for OTCH in the Ru(bipy)₃²⁺–Ce(SO₄)₂ CL system, together with CL and ultraviolet (UV)–visible spectra, the possible mechanism of the CL reaction is discussed briefly.     

Cupric oxide nanoparticles‐enhanced chemiluminescence method for measurement of β‐lactam antibiotics

A simple, sensitive cupric oxide nanoparticles (CuO NPs) enhanced chemiluminescence (CL) method was developed for the measurement of β‐lactam antibiotics, including amoxicillin and cefazolin sodium. The method was based on suppression of the CuO NPs–luminol–H₂O₂ CL reaction by β‐lactam antibiotics. Experimental parameters that influenced the inhibitory effect of the antibiotic drugs on the CL system, such as NaOH (mol/L), luminol (µmol/L), H₂O₂ (mol/L) and CuO NPs (mg/L) concentrations, were optimized. Calibration graphs were linear and had dynamic ranges of 1.0 × 10^–6 to 8.0 × 10^–6 mol/L and 3.0 × 10^–5 to 5.0 × 10^–3 mol/L for amoxicillin and cefazolin sodium, respectively, with corresponding detection limits of 7.9 × 10^–7 mol/L and 1.8 × 10^–5 mol/L. The relative standard deviations of five replicate measurements of 5.0 × 10^–6 amoxicillin and 5 × 10^–4 cefazolin sodium were 5.43 and 5.01%, respectively. The synthesized CuO NPs were characterized by X‐ray diffraction (XRD) and transmission electronmicroscopy (TEM). The developed approach was exploited successfully to measure antibiotics in pharmaceutical preparations. Copyright © 2014 John Wiley & Sons, Ltd.     

Chemiluminescence of non‐differentiated THP‐1 promonocytes: developing an assay for screening anti‐inflammatory milk proteins and peptides

Human leukemic THP‐1 promonocytes are widely used as a model for peripheral blood monocytes. However, superoxide production during respiratory burst (RB) of non‐differentiated THP‐1 (nd‐THP‐1) cells is very low. Here we present a rapid and low‐cost method for measuring the chemiluminescence (CL) of opsonized zymosan (OZ) induced RB which allows detection of Escherichia coli lipopolysaccharide (LPS) induced priming of nd‐THP‐1 cells on the basis of CL reaction kinetics. Maximum CL intensity obtained was 2.20 ± 0.25 and 1.30 ± 0.11 relative light units, while CL peak time was achieved at 18.1 ± 2.6 and 28.7 ± 1.3 min in primed and non‐primed cells, respectively. The priming of nd‐THP‐1 cells with LPS evoked typical TNF‐α and IL‐6 production. We tested the effects of bovine lactoferrin and protein fractions from Lactobacillus helveticus BGRA43 fermented milk for potential anti‐inflammatory effects on LPS primed nd‐THP‐1 cells. Four fractions were found to inhibit the OZ‐induced CL in a dose‐dependent manner (IC₅₀ 3–30 µg/mL), while lactoferrin inhibited CL to a lesser extent (IC₅₀ 270 µg/mL). These results suggest that measuring CL response of nd‐THP‐1 cells can serve as a method for screening anti‐inflammatory compounds which could be used in reducing the risk of phagocyte‐mediated inflammatory diseases. Copyright © 2010 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescent determination of estrogen benzoate using the tris(1,10‐phenanthroline) ruthenium(II)–permanganate system

Chemiluminescence (CL) detection for the determination of estrogen benzoate, using the reaction of tris(1,10–phenanthroline)ruthenium(II)–Na₂SO₃–permanganate, is described. This method is based on the CL reaction of estrogen benzoate (EB) with acidic potassium permanganate and tris(1,10–phenanthroline)ruthenium(II). The CL intensity is greatly enhanced when Na₂SO₃ is added. After optimization of the different experimental parameters, a calibration graph for estrogen benzoate is linear in the range 0.05–10 µg/mL. The 3 s limit of detection is 0.024 µg/mL and the relative standard deviation was 1.3% for 1.0 µg/mL estrogen benzoate (n = 11). This proposed method was successfully applied to commercial injection samples and emulsion cosmetics. The mechanism of CL reaction was also studied. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of ampicillin sodium using the cupric oxide nanoparticles–luminol–H2O2 chemiluminescence reaction

A simple and sensitive chemiluminescence (CL) method has been developed for the determination of ampicillin sodium at submicromolar levels. The method is based on the inhibitory effect of ampicillin sodium on the cupric oxide nanoparticles (CuO NPs)–luminol–H₂O₂ CL reaction. Experimental parameters affecting CL inhibition including concentrations of CuO NPs, luminol, H₂O₂ and NaOH were optimized. Under optimum conditions, the calibration plot was linear in the analyte concentration range 4.0 × 10^‐7–4.0 × 10^‐6 mol/L. The limit of detection was 2.6 × 10^‐7 mol/L and the relative standard deviation (RSD) for six replicate determinations of 1 × 10^‐6 mol/L ampicillin sodium was 4.71%. Also, X–ray diffraction (XRD) and transmission electron microscopy (TEM) analysis were employed to characterize the CuO NPs. The utility of the proposed method was demonstrated by determining ampicillin sodium in pharmaceutical preparation. Copyright © 2013 John Wiley & Sons, Ltd.     

Flow injection determination of diclofenac sodium based on its sensitizing effect on the chemiluminescent reaction of acidic potassium permanganate–formaldehyde

A sensitive and simple chemiluminescent (CL) method for the determination of diclofenac sodium has been developed by combining the flow injection technique and its sensitizing effect on the weak CL reaction between formaldehyde and acidic potassium permanganate. A calibration curve is constructed for diclofenac sodium under optimized experimental parameters over the range 0.040–5.0 µg/mL and the limit of detection is 0.020 µg/mL (3σ). The inter‐assay relative standard deviation for 0.040 µg/mL diclofenac sodium (n = 11) is 2.0%. This method is rapid, sensitive, simple, and shows good selectivity and reproducibility. The proposed method has been successfully applied to the determination of the studied diclofenac sodium in pharmaceutical preparations with satisfactory results. Furthermore, the possible mechanism for the CL reaction has been discussed in detail on the basis of UV and CL spectra. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination of clomipramine by flow‐injection analysis with acidic potassium permanganate–formic acid chemiluminescence detection

A sensitive and simple chemiluminescent (CL) method for the determination of clomipramine has been developed by combining the flow‐injection analysis (FIA) technique, which is based on the CL intensity generated from the redox reaction of potassium permanganate (KMnO₄)–formic acid in sulphuric acid (H₂SO₄) medium. Under the optimum conditions, the linear range for the determination of clomipramine was 0.04–4 µg/mL, with a correlation coefficient of 0.9988 (n = 10) and a detection limit of 0.008 µg/mL (3σ), and the relative standard deviation (RSD) for 2.0 µg/mL clomipramine (n = 11) is 1.26%. The proposed method has been successfully applied to the determination of the studied clomipramine in pharmaceutical preparations. The possible reaction mechanism is discussed. Copyright © 2011 John Wiley & Sons, Ltd.     

Trace analysis of N‐acetyl‐L‐cysteine using luminol–H2O2 chemiluminescence system catalyzed by silver nanoparticles

N‐Acetyl‐L‐cysteine (NAC) can inhibit the luminol–H₂O₂, reaction, which is catalyzed by silver nanoparticles. Based on this phenomenon a new method was developed for NAC determination. Under optimum conditions, a linear relationship between chemiluminescence intensity and NAC concentration was found in the range 0.034–0.98 µg/mL. The detection limit was 0.010 µg/mL (S/N =3), and the relative standard deviation (RSD) was <5% for 0.480 µg/mL NAC (n =5). This simple, sensitive and inexpensive method has been applied to measure the concentration of NAC in pharmaceutical tablets. Copyright © 2014 John Wiley & Sons, Ltd.     

Sensitive and selective determination of fluvoxamine maleate using a sensitive chemiluminescence system based on the alkaline permanganate–Rhodamine B–gold nanoparticles reaction

A high‐yield chemiluminescence (CL) system based on the alkaline permanganate–Rhodamine B reaction was developed for the sensitive determination of fluvoxamine maleate (Flu). Rhodamine B is oxidized by alkaline KMnO₄ and a weak CL emission is produced. It was demonstrated that gold nanoparticles greatly enhance this CL emission due to their interaction with Rhodamine B molecules. It is also observed that sodium dodecyl sulfate, an anionic surfactant, can strongly increase this enhancement. In addition, it was demonstrated that a notable decrease in the CL intensity is observed in the presence of Flu. This may be related to Flu oxidation with KMnO₄. There is a linear relationship between the decrease in CL intensity and the Flu concentration over a range of 2–300 µg/L. A new simple, rapid and sensitive CL method was developed for the determination of Flu with a detection limit (3s) of 1.35 µg/L. The proposed method was used for the determination of Flu in pharmaceutical and urine samples. Copyright © 2014 John Wiley & Sons, Ltd.     

A validated HPLC method for the determination of dimethyl‐4,4′‐dimethoxy‐5,6,5′,6′‐dimethylene dioxybiphenyl‐2,2′‐dicarboxylate (DDB) with fluorescence detection in raw material and pill form: application to an in vitro dissolution test and a content uniformity test

A simple, sensitive and rapid HPLC method with fluorescence detection for the determination of dimethyl‐4,4′‐dimethoxy‐5,6,5′,6′‐dimethylene dioxybiphenyl‐2,2′‐dicarboxylate (DDB) in the raw material and pill form was developed. Liquid chromatography was performed on a C₁₈ column (250 × 4.6 mm i.d., 5 µm particle size), the mobile phase consisted of methanol and 0.05 M sodium dihydrogen phosphate buffer (80 : 20, v/v), and the apparent pH of the mobile phase was adjusted to 3. The fluorescence detector was operated at excitation/emission wavelengths of 275/400 nm. The proposed method allows the determination of DDB within concentration range 0.1–1.5 µg/mL with a limit of detection of 0.032 µg/mL, a limit of quantification of 0.097 µg/mL and a correlation coefficient of 0.9997. The proposed method has been successfully applied for the analysis of DDB in its pills with a percentage recovery of 98.45 ± 0.32. The method was fully validated according to ICH guidelines. Moreover, the high sensitivity of the method permits its use in an in vitro dissolution test for DDB under simulated intestinal conditions. In addition, the proposed method was extended to a content uniformity test according to USP guidelines. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination of alkaloids in Sinomenium acutum by field‐amplified sample stacking in capillary electrophoresis with chemiluminescene detection

A simple and rapid capillary electrophoresis (CE) with an acidic potassium permanganate chemiluminescence (CL) detection method was developed to determine three alkaloids (curine, sinomenine and magnoflorine) simultaneously. A laboratory‐built CE–CL detection interface was used. The field‐amplified sample stacking technique was applied to the online concentration of alkaloids. Experimental conditions for CE separation and CL detection were investigated in detail to acquire optimum conditions. Under optimal conditions, the three alkaloids were baseline separated within 6 min, and the detection limits (S/N = 3) ranged from 0.03 µg/mL to 0.49 µg/mL. This method was successfully applied to determine the above three alkaloids in Sinomenium acutum, and the result of the determination of sinomenine was in good agreement with those given by high‐performance liquid chromatography and CE methods. In addition, a possible CL reaction mechanism of sinomenine–KMnO₄–H₂SO₄ was proposed. Copyright © 2013 John Wiley & Sons, Ltd.     

Chemiluminescence method for the determination of piroxicam by the enhancement of the tris‐(4,7‐diphenyl‐1,10‐phenanthrolinedisulphonic acid) ruthenium(II) (RuBPS)–cerium(IV) system and its application

A simple, rapid chemiluminescence (CL) method was described for the determination of piroxicam, a commonly used analgesic agent drug. A strong CL signal was detected when cerium(IV) sulphate was injected into tris‐(4,7‐diphenyl‐1,10‐phenanthrolinedisulphonic acid) ruthenium(II) (RuBPS)–piroxicam solution. The CL signal was proportional to the concentration of piroxicam in the range 2.8 × 10^–8–1.2 × 10^–5 mol/L. The detection limit was 2 × 10^–8 mol/L and the relative standard deviation (RSD) was 3.7% (c = 7.0 × 10^–7 mol/L piroxicam; n = 11). The proposed method was applied to the determination of piroxicam in pharmaceutical preparations in capsules, spiked serum and urine samples with satisfactory results. Copyright © 2008 John Wiley & Sons, Ltd.     

A lab‐on‐a‐chip device for analysis of amlodipine in biological fluids using peroxyoxalate chemiluminescence system

A highly sensitive, rapid and economical method for the determination of amlodipine (AM) in biological fluids was developed using a peroxyoxalate chemiluminescence (CL) system in a lab‐on‐a‐chip device. Peroxyoxalate‐CL is an indirect type of CL that allows the detection of native fluorophores or compounds derivatized with fluorescent labels. Here, fluorescamine was reacted with AM, and the derivatization product was used in a bis‐(2,4,6‐trichlorophenyl)oxalate‐CL system. Fluorescamine reacts selectively with aliphatic primary amine at neutral or basic pH. As most of the calcium channel blocker and many cardiovascular drugs do not contain primary amine, the developed method is highly selective. The parameters that influenced the CL signal intensity were studied carefully. These included the chip geometry, pH, concentration of reagents used and flow rates. Moreover, we confirmed our previous observation about the effects of imidazole, which is commonly used in the bis‐(2,4,6‐trichlorophenyl)oxalate‐CL system as a catalyst, and found that the signal was significantly improved when imidazole was absent. Under optimized conditions, a calibration curve was obtained with a linear range (10–100 µg/L). The limit of detection was 3 µg/L, while the limit of quantification was 10 µg/L. Finally the method was applied for the determination of AM in biological fluids successfully. Copyright © 2014 John Wiley & Sons, Ltd.     

Simultaneous determination of isoniazid and p‐aminosalicylic acid by capillary electrophoresis using chemiluminescence detection

It was found that isoniazid (ISO) or p‐aminosalicylic acid (PAS) could enhance the chemiluminescence (CL) emission from Cu (II)‐luminol‐hydrogen peroxide system, and the increased chemiluminescence signals were proportional to their concentrations, respectively. Based on this phenomenon, a chemiluminescence method coupled to capillary electrophoresis (CE) was established for simultaneous determination of ISO and PAS. The CE conditions including running buffer and running voltage were investigated in detail. The effects of the pH of H₂O₂ solution and the concentrations of luminol, H₂O₂ and Cu (II) on the CL signal were also investigated carefully. Under the optimized conditions, the analysis could be accomplished within 10 min, with the limits of detection of 0.3 µg mL^–1 for ISO and 1.1 µg mL^–1 for PAS, corresponding to 7.2 and 26.4 pg per injection (24 nL), respectively. Finally, the method was validated by determining the two analytes in pharmaceutical preparation and spiked human serum samples. The results of pharmaceutical tablet analysis were in good agreement with the labeled amounts. The recoveries for ISO and PAS in human serum were in the range of 92–104% and 90–113%, respectively. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of manganese‐ and manganese‐containing fungicides with lucigenin–Tween‐20‐enhanced chemiluminescence detection

A flow‐injection (FI) method is reported for the determination of Mn(II), maneb and mancozeb fungicides based on the catalytic effect of Mn(II) on the oxidation of lucigenin and dissolved oxygen in a basic solution. The Tween‐20 surfactant has been reported for first time to enhance lucigenin chemiluminescence (CL) intensity in the presence of Mn(II) (53%) and maneb and mancozeb (89%). The calibration graphs were linear in the concentration range of 0.001–1.5 mg L^–1 (R² = 0.9982 (n = 11) with a limit of detection (S/N = 3) of 0.1 µg L^–1 for Mn(II) and 0.01–3.0 mg L^–1 [R² = 0.9989 and R² = 0.9992 (n = 6)] with a limit of detection (S/N =3) of 1.0 µg L^–1 for maneb and mancozeb respectively. Injection throughputs of 90 and 120 h^–1 for Mn(II) and maneb and mancozeb respectively, and relative standard deviations of 1.0–3.4% were obtained in the concentration range studied. The experimental variables, e.g., reagents concentrations, flow rates, sample volume, and photomultiplier tube voltage, were optimized and potential interferences were investigated. The analysis of Mn(II) in river water reference materials (SLRS‐4 and SLRS‐5) showed good agreement with the certified values incorporating an on‐line 8‐hydroxyquinoline chelating column in the manifold for removing interfering metal ions. Recoveries for maneb and mancozeb were in the range of 92 ± 5 to 104 ± 3% and 91 ± 2 to 100 ± 4% (n = 3) respectively. The effect of 30 other pesticides (fungicides, herbicides and insecticides) was also examined in the lucigenin–Tween‐20 CL system. Copyright © 2015 John Wiley & Sons, Ltd.     

Luminescent and hydrophilic LaF3–polymer nanocomposite for DNA detection

Luminescent LaF₃–Ce³⁺/Tb³⁺ nanocrystals have been successfully prepared via a simple wet chemical technique. For the next bioapplication, these nanoparticles dispersed in cyclohexane have also been functionalized with poly(St‐co‐MAA), based on a designed oil‐in‐water microemulsion system. These polymer‐coated nanospheres are water‐soluble and bioconjugable. Unlike semiconductor quantum dots, the as‐prepared lanthanum fluoride nanocrystals possess non‐size‐dependent emissions and completely stable photocycles. With functionalized LaF₃ nanospheres as fluorescence probes, a fluorescence method was developed for the rapid quantitative analysis of DNA, due to the quenching effect of fluorescence by the DNA. Under optimum conditions, the fluorescence intensity was proportional to the concentration of the introduced DNA over the range 2.5–35 µg/mL for calf thymus DNA (ctDNA) and 2.5–30 µg/mL for fish sperm DNA (fsDNA), respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

Determination of phenformin hydrochloride using molecular imprinting technology coupled with flow-injection chemiluminescence

A novel method was developed using molecular imprinting technology (MIT) coupled with flow‐injection chemiluminescence (FI‐CL) for highly sensitive detection of phenformin hydrochloride (PH). The phenformin imprinted polymer was synthesized with methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross‐linker. Newly synthesized molecularly imprinted polymer (MIP) particles were packed into a column as a selective recognition element for determination of PH. A CL method for the determination of PH was developed based on the CL reaction of PH with N‐bromosuccinimide sensitized by eosin Y in basic media. The optimization of detection conditions was investigated. The CL intensity responded linearly to the concentration of PH in the range 0.09–2.0 µg/mL, with a correlation coefficient of 0.9920. The detection limit was 0.031 µg/mL. The relative standard deviation for the determination of 1.0 µg/mL PH solution was 1.0% (n = 11). The method was applied to the determination of PH in urine samples, with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.