共查询到20条相似文献,搜索用时 500 毫秒
1.
《Analytical letters》2012,45(7):1279-1289
Abstract Based on the fact that nonionic surfactant polyethylene glycol-400 (PEG-400) catalyzed the chemiluminescence of luminol-H2O2 system, a novel and simple chemiluminescence method has been developed for the determination of PEG-400. Under the optimal conditions, the standard curve was Y = 198835X–2091.8, where the correlation coefficient (R) was 0.9999. The detection limit was 4 × 10?5 g·ml?1 PEG-400 and the linear range was 1.0 × 10?4–4.0 × 10?2g·ml?1. The relative standard deviation was 3.2% at 2.0 × 10?3 g·ml?1 PEG-400 (n = 7). This method has been applied to the determination of PEG-400 in cosmetic samples with satisfactory results. Furthermore, the dynamics characteristic curve of PEG-400 in luminol-H2O2 system was compared to typical metallic ion and other surfactants. Moreover, the mechanism of the luminol-H2O2-PEG-400 chemiluminescence system was studied, assisted by fluorescence spectra and UV spectra. 相似文献
2.
《Analytical letters》2012,45(10):1242-1253
Detection of tuberculosis and related diseases caused by mycobacteria is costly, time-consuming, and labor-intensive. Here a new phage-modified piezoelectric system for rapid and specific detection of mycobacteria was developed. In this system, interdigital gold electrode immobilized with lytic phage was used as a probe in place of a steel electrode in the multi-channel series piezoelectric quartz crystal (MSPQC) system. The probe was directly connected to the piezoelectric detection system. Mycobacterium was specifically captured to the phage-modified electrode and then lysed by immobilized phage, which caused the electrode electrical properties change. This change can be sensitively monitored by the piezoelectric detection system. The detection time of Mycobacterium smegmatis was less than 2 hours and a detection limit of 103cfu mL?1 was obtained. Additionally, it was successfully used to detect Mycobacterium tuberculosis. The developed system using phage-modified interdigital electrode showed high specificity and reproducibility for mycobacterium detection. Compared with the MSPQC system, the proposed system was faster and more specific. 相似文献
3.
《Analytical letters》2012,45(8):1375-1386
Abstract A novel chemiluminescence method for the quantitative assay of the organophosphorus pesticide chlorpyrifos in vegetable samples is presented. The determination is based on the reaction of chlorpyrifos with luminol-H2O2 in alkaline medium with sodium chloride being enhancer. Under the optimum conditions, the increased CL intensity was proportional with the concentration of chlorpyrifos in the range of 1.0 × 10?8 g · ml?1 ? 1.0 × 10?6 g · ml?1 and the detection limit was 3.5 × 10?9 g · ml?1 (3σ). The relative standard is less than 3.9% for 5.0 × 10?7g · ml?1 chlorpyrifos (n = 7). This method has been successfully applied to the determination of chlorpyrifos residue in vegetable sample. Further study was focused on the mechanism of chlorpyrifos and the possible mechanism was proposed. 相似文献
4.
《Analytical letters》2012,45(5):837-852
Abstract A simple, rapid, sensitive, and reproducible procedure for assaying norfloxacin (NOR), ciprofloxacin (CIP), and ofloxacin (OFL) was investigated. The procedure is based on the reaction of selected drugs with Sudan II (I), Congo red (II), and Gentian violet (III) in universal buffer to give soluble ion‐pair complexes. The effects of various parameters have been studied. Beer's law plots were obeyed in the concentration ranges 0.5–11 µg ml?1, whereas Ringbom optimum ranges were 0.7–9.5 µg ml?1. The apparent molar absorptivity (6.4×104 L mol?1 cm?1), Sandell sensitivity (4.99 ng cm?2), detection (0.13 µg ml?1), and quantification (0.44 µg ml?1) limits were calculated. The relative standard deviation for ten determinations, for samples containing 4.0 µg ml?1, was found to be 1.40%. The influence of commonly employed excipients in the determination of the studied drugs was examined. There was no interference from degradate product results from thermal and hydrolytic treatments. The results obtained by the proposed procedure were statistically validated. The developed procedure was successfully applied to the determination of the studied drugs in dosage forms and biological fluids. 相似文献
5.
《Analytical letters》2012,45(12):2295-2300
Abstract A direct fluorimetric method for the determination of chlorodesmethyldiazepam was proposed. The fluorescence process was pH dependent. The dynamic range for the method was 1.6–12 µg ml–1. A linear relationship between the fluorescence intensity and the concentration of chlorodesmethyldiazepam solution was obtained with r 2 of 0.9958. The detection limit for the method was found to be 0.224 µg ml–1. The method has successfully applied to the determination of chlorodesmethyldiazepam in pure, authentic, and aqueous samples. 相似文献
6.
《Analytical letters》2012,45(12):2384-2390
Abstract A novel spectrophotometric method for the determination of titanium(IV) by using a new reagent, water extract of slippery elm leaf is developed. In 0.05 M hydrochloric acid, titanium(IV) reacts with this reagent to form a yellow product. The formed product shows maximum absorbance at 415 nm with a molar absorptivity value of 0.68×104 l mol–1 cm–1 and the method was linear in the 0.2–6 µg ml?1 concentration range. The detection limit value was found to be 0.0131 µg ml?1. The proposed method was simple, low cost, selective, and sensitive. It was applied to the analytic samples with satisfactory results. 相似文献
7.
《Analytical letters》2012,45(18):3405-3416
Abstract A post‐chemiluminescence (PCL) was observed when loperamide hydrochloride solution was injected into the reaction mixture after the finish of CL reaction of alkaline N‐Chlorosuccinimide (NCS) and dichlorofluorescein. Based on this phenomenon, a simple, sensitive and fast flow injection PCL method was established for the determination of loperamide hydrochloride. The possible mechanism for the PCL reaction was discussed via the investigation of the CL kinetic characteristics, the CL spectra, the fluorescence spectra. The PCL intensity responded linearly to the concentration of loperamide hydrochloride in the range 8.0×10?10 to 6.0×10?7 g · ml?1 with a linear correlation of 0.9995. The detection limit was 4×10?10 g · ml?1. The relative standard deviation was 2.4% for 4.0×10?8 g · ml?1 loperamide hydrochloride (n=11). This method has been applied to the determination of loperamide hydrochloride in human plasma and pharmaceutical samples with satisfactory results. 相似文献
8.
《Analytical letters》2012,45(3):417-423
Abstract A spectrofluorimetric method was developed for the determination of gatifloxacin. The emission peak for gatifloxacin was recorded at 495 nm upon excitation at 291 nm. The fluorescence process was pH dependent. The dynamic range for the method was 16–80 ng ml?1with detection limit of 3.97 ng ml?1. A linear relationship between the fluorescence intensity and the concentration of gatifloxacin solution was obtained with r 2 of 0.9968. The method has successfully applied to the determination of gatifloxacin in pure, authentic and aqueous samples. 相似文献
9.
《Analytical letters》2012,45(8):1622-1631
Abstract Catalyzed determination of glucose with mimic glucose oxidase is constructed by the reaction of β‐cyclodextrin, maleic anhydride, and chloroacetic acid with iron trichloride in hydrogen peroxide. The method is simple and convenient, and sensitivity and repeatability are ideal. Beer's law is obeyed in a concentration range of 30–197 µg · ml?1 glucose with an excellent correlation coefficient (r=0.9994), while the detection limit is 4.10 µg · ml?1, the RSD is 0.98% (n=8). The recovery of sample is 95.8–103.1%. 相似文献
10.
The complexes [Zn(phenylacetato)2(2-aminopyridin)2] (3), [Zn(phenylacetato)2(1,10-phenanthroline)]·H2O (4), and [Zn(phenylacetato)2(2,9-dimethyl-1,10-phenanthroline)]·0.5 H2O (5) were prepared and characterized by IR-, UV–Visible, 1H and 13C NMR spectroscopy, and single crystal X-ray diffraction. BNPP hydrolysis of the complexes and their parent nitrogen ligands showed that the hydrolysis rate of bis-(4-nitrophenyl) phosphate (BNPP) was 1.7 × 105 L mol?1 s?1 for 3, 3.1 × 105 L mol?1 s?1 for 4 and 4.3 × 104 L mol?1 s?1 for 5. Antibacterial activities show the effect of complexation on activity against Gram-positive (S. epidermidis, S. aureus, E. faecalis, M. luteus and B. subtilis) and Gram-negative (K. pneumonia, E. coli, P. mirabilis and P. aeruginosa) bacteria using the agar well diffusion method. Complex 4 showed good activity against G? bacteria except P. aeruginosa, and against G+ bacteria except E. ferabis. Complex 5 showed no activity against G? bacteria, low activity against M. luteus and B. subtilis bacteria and high activity against S. epidemidis and S. aureus. Complex 3 did not show any activity against G? or G+ bacteria. 相似文献
11.
《Analytical letters》2012,45(13):2207-2216
Abstract A simple and selective spectrophotometric method has been developed for the determination of trace amounts of arsenic using azure B as a chromogenic reagent. The proposed method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine. The liberated iodine bleaches the violet color of azure B and is measured at 644 nm. This decrease in absorbance is directly proportional to the As(III) concentration, and Beer's law is obeyed in the range 0.2–10 µg ml?1 of As(III). The molar absorptivity, Sandell's sensitivity, detection limit, and quantitation limit of the method were found to be 1.12×104 l mol?1cm?1, 6.71×10?3 µg cm?2, 0.02 µg ml?1 and 0.08 µg ml?1, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples. 相似文献
12.
《Analytical letters》2012,45(7):935-947
Abstract A high sensitive, accurate and simple kinetic method has been developed for determination of trace of Co(II) ions, based on its strongly catalytic effect in the reaction oxidation of disodium-6-hydroxy-5-[(4-sulfophenyl)azo]-2-naphtalenesulfonic acid (artificial color, Sunset Yellow FCF, E110 in text selected as SY) by hydrogen peroxide in borate buffer at pH of 9.5, by monitoring the rate of disappearance of SY. Reaction rate was monitored spectrophotometrically, at λmax of the SY at 478.4 nm. The optimum operating conditions regarding reagents concentration and temperature were established. The tangent method was adopted for constructing the calibration curve, which was found to be linear over the concentration range 1.18–17.67 ng ml?1 and 17.67–58.90 ng ml?1 of Co(II). The limit of detection (3σ) is 0.15 ng ml?1, and limit of quantification (10σ) is 0.5 ng ml?1. The effects of the other ions on the reaction rate were determined for an assessment of the selectivity of the method. The developed kinetic procedure was successfully applied for the determination of Co(II) in pharmaceutical and urine samples. The unique features of this procedure are that the determination can be performed at room temperature, and the analysis time is short. The newly developed method is high sensitive, simple, inexpensive and efficient for use in the analysis of a large number of samples. 相似文献
13.
《Analytical letters》2012,45(17):2690-2704
A disposable immunosensor for the detection of Escherichia coli O157:H7 based on a multiwalled carbon nanotube–sodium alginate nanocomposite film was constructed. The nanocomposite was placed on a screen-printed carbon electrode, and horseradish peroxidase-labeled antibodies were immobilized to E. coli O157:H7 on the modified electrode to construct the immunosensor. The modification procedure was characterized by atomic force microscopy and cyclic voltammetry. Under optimal conditions, the proposed immunosensor exhibited good electrochemical sensitivity to E. coli O157:H7 in a concentration range of 103–1010 cfu/mL, with a relatively low detection limit of 2.94 × 102 cfu/mL (S/N = 3). This immunosensor exhibited satisfactory specificity, reproducibility, stability, and accuracy, making it a potential alternative tool for early assessment of E. coli O157:H7. 相似文献
14.
《Analytical letters》2012,45(14):2234-2245
A novel chemiluminescence (CL) method is developed for determination of ofloxacin and levofloxacin with Ag(III) complex in H2SO4 solution medium. The CL intensity is proportional to drug concentration in a wider range with a correlation coefficient of 0.999. The limit of detection (s/n = 3) for ofloxacin and levofloxacin was 5.3 × 10?9 g ml?1 and 8.3 × 10?9 g ml?1, respectively, and their recoveries from urine and serum samples were in the range of 90.1–112% with the RSDs of 1.0–2.8%. The proposed method was applied for analysis of real samples with satisfactory result. The possible CL mechanism was discussed. 相似文献
15.
《Analytical letters》2012,45(10):1893-1903
Abstract Sunset Yellow (SY), Carmoisine (C), Ponceau 4R (P), and Patent Blue V (PB) are synthetic organic dyes which are under governmental regulations all over the world because of their toxicity and carcinogenicity. In this study, a simple and fast analytical procedure was proposed for the simultaneous determination of food dyes (SY, C, P, and PB) in powder drinks by means the partial least‐square treatment of spectrophotometric absorbance between 450 –730 nm, taken at 10 nm intervals. The experimental calibration matrix was constructed with 27 samples. The concentration ranges considered were 2, 3, 4 µg · ml?1 for SY, 7, 8, 9 µg · ml?1 for C, 9, 10, 11 µg · ml?1 for P, and 0.3, 0.4, 0.5 µg · ml?1 for PB. The method was applied to the determination of dyes in different commercially available powder drinks. The results obtained by the application of the PLS‐2 method were statistically compared with those obtained by an HPLC method using the F and t tests. Very similar values were found by two methods. No time consuming pretreatment was needed and this method also provides rapid, accurate and economical analysis of these colors. 相似文献
16.
《Analytical letters》2012,45(6):1047-1062
Abstract The study was directed to the development of generic immunoenzyme assay for sulfonamides. N‐sulfanil‐4‐aminobutyric acid which mimics the common part of sulfonamides was used as immunogenic hapten. The obtained rabbit polyclonal antibodies allowed detection of the N‐sulfanil‐4‐aminobutyric acid in indirect competitive immunoenzyme assay down to 0.03 ng ml?1. The lowest detection limit for the sulfonamides tested, 0.1 ng ml?1, was observed for sulfamethoxypyridazine. Eleven other sulfonamides could be determined at concentrations ranging from 1–37 ng ml?1. Thus, the proposed technique can be used in class‐specific sulfonamides detection in products of animal origin. 相似文献
17.
《Analytical letters》2012,45(7):989-999
Abstract A new method for flow-injection analysis (FIA) for the determination of penicillins based on the extraction and spectrophotometric determination of ion associates with selected thiazine dyes (methylene blue, azure A, and azure B) is proposed. The reaction conditions (cdye = 2 × 10?4 mol l?1, cKCl = 1 mol l?1, pH ? 6, λ = 635 nm) were found. The factorial design has been carried out to determine the optimum flow conditions. A wide linear dynamic range of calibration curves (5.1–700 µg ml?1 for penicillin V with all dyes, R = 0.9985) and good repeatability (e.g., relative standard deviation [RSD] = 4.6–0.6% in this concentration range for the reaction with azure B) were found. The detection limit for penicillin V is 1.5 µg ml?1, and the determination limit is 5.1 µg ml?1. The maximum analysis rate is 35 samples per h. The practical samples of pharmaceutics were tested. There are no interferences from the additives in pharmaceutics. 相似文献
18.
《Analytical letters》2012,45(7):1128-1143
Abstract The spectrophotometric behavior of uranium (VI) with L-3-(3, 4-dihydroxy phenyl) alanine (LDOPA) reagent revealed that the uranium can form a ML2 complex with LDOPA in solution. Thus a highly sensitive adsorptive stripping voltammetric protocol for measuring of trace uranium, in which the preconcentration was achieved by adsorption of the uranium-LDOPA complex at hanging mercury drop electrode (HMDE), is described. Optimal conditions were found to be a 0.02 M ammonium buffer (pH 9.5) containing 2.0 × 10?5 M (LDOPA), an accumulation potential of ? 0.1 V (versus Ag/AgCl) and an accumulation time of 120 sec. The peak current and concentration of uranium accorded with linear relationship in the range of 0.5–300 ng ml?1. The relative standard deviation (at 10 ng ml?1) is 3.6% and the detection limit is 0.27 ng ml?1. The interference of some common ions was studied. Applicability to different real samples is illustrated. The attractive behavior of this reagent holds great promise for routine environmental and industrial monitoring of uranium. 相似文献
19.
《Analytical letters》2012,45(16):2559-2570
A sensitive electrochemical DNA biosensor based on a mixed monolayer structure self-assembled at nanoporous gold (NPG) electrode surface was prepared for Escherichia coli (E. coli) detection. The NPG was fabricated on gold electrode, onto which thiolated oligonucleotides (SH-DNA) and mercaptohexanol (MCH) were covalently linked forming a mixed self-assembled monolayer (SAM). The hybridization between the SH-DNA/MCH modified biosensor and E. coli DNA was monitored with differential pulse voltammetry measurement using methylene blue (MB) as the hybridization indicator. The biosensor can detect 1 × 10?12 M DNA target and 50 cfu/μL E. coli without any nucleic acid amplification steps. The detection limit was lowered to 50 cfu/mL after 5.0 h of incubation. 相似文献
20.
《Analytical letters》2012,45(12):2279-2288
Abstract An integrated-sensor method for the determination of formaldehyde based on retention of the reaction product of the analyte with p-rosaniline and sulfite in a flow-cell packed with Dowex 1-X-8 anion exchange resin was developed. The method has a good selectivity with a detection limit of 0.3 μg ml?1 (1 ml sample) or 75 ng ml?1 (2 ml sample), and a linear range between 1–30 μg ml?1. The relative standard deviations (n = 11) were 2.8 and 1.3% for 2 and 20 μg ml?1 formaldehyde, respectively. Depending on the working conditions, the sampling frenquency ranged between 10 and 18 h?1. The method was applied to the determination of formaldehyde in well water. 相似文献