Determination of Doxycycline Residues in Milks and Content in Serum, Tablet and Injection Samples with Self-Ordered Ring Fluorescence Microscopic Imaging Technique

2011 ◽  
Vol 347-353 ◽  
pp. 2356-2359
Author(s):  
Ying Liu ◽  
Yan Min Yu ◽  
Yan Wang
Keyword(s):  
Limit Of Detection ◽  
Imaging Technique ◽  
Signal To Noise Ratio ◽  
Poly Vinyl Alcohol ◽  
Fluorescent Intensity ◽  
Microscopic Imaging ◽  
Dc System ◽  
Glass Slides ◽  
Ordered Ring

A new method of determinating doxycycline residues in milks and content in serum,table and injection samples was established with Self-ordered ring fluorescence microscopic imaging technique. In the presence of hexahydropyridine and poly (vinyl alcohol)-124, Zn2+-doxycycline (DC) system can form a SOR on the hydrophobic glass slides surfaces based on the capillary effect. The maximum fluorescent intensity (Imax) at central ring belt was found to be proportional to DC content. when the droplet volume is 0.5μL, the present SOR method can be used to determine DC in a range of 4.54×10-15–6.81×10-13mol•ring-1, and the limit of detection (LOD) with a threefold signal to noise ratio (S/N = 3) was 4.54×10-15mol•ring-1(2.17×10-8mol•L-1). With the present method, the residues in milks and content in serum, tablet and injection samples were satisfactorily detected with recoveries of 96.3-102.0% and RSD of 1.4-2.2%, respectively, indicating that the method is reliable and practical.

Vortex-Assisted Dispersive Liquid–Liquid Microextraction Coupled with Deproteinization for Determination of Nateglinide in Human Plasma Using HPLC/UV

2020 ◽  
Author(s):  
Mohamed A Hammad ◽  
Amira H Kamal ◽  
Reham E Kannouma ◽  
Fotouh R Mansour
Keyword(s):  
Human Plasma ◽  
High Performance ◽  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Cost Effective ◽  
Salt Addition ◽  
Relative Standard ◽  
Dispersive Liquid Liquid Microextraction ◽  
Liquid Microextraction

Abstract A validated method for preconcentration and determination of nateglinide in plasma was developed using vortex-assisted dispersive liquid–liquid microextraction. Different variables that affect extraction efficiency were studied and optimized, including type and volume of extractant, type and volume of disperser, pH of diluent, salt addition effect, centrifugation and vortex time. Nateglinide was extracted using 30 μL of 1-octanol as an extractant and 200 μL of methanol as a disperser. The enrichment factor reached 330 under the optimum conditions. High-performance liquid chromatography/ultraviolet was used for detection using phosphate buffer (pH 2.5, 10 mM): acetonitrile (45:55, v/v) as a mobile phase at a flow rate of 1 mL/min. The method was linear over the range of 50–20,000 ng/mL with a limit of detection of 15 ng/mL (signal-to-noise ratio = 3). Intra- and inter-day precision had %relative standard deviation <6% (n = 3) and the %recoveries were found to be between 102.5 and 105.9%. The proposed method is simple, sensitive, eco-friendly, cost-effective and powerful for microextraction of nateglinide from human plasma samples.

Determination of trans-phylloquinone in children's serum.

1989 ◽  
Vol 35 (5) ◽  
pp. 874-878 ◽  
Author(s):  
F Moussa ◽  
L Dufour ◽  
J R Didry ◽  
P Aymard
Keyword(s):  
Limit Of Detection ◽  
Signal To Noise Ratio ◽  
Fluorometric Detection ◽  
Vitamin K1 ◽  
Signal To Noise ◽  
Détection Signal ◽  
Coagulation Tests ◽  
Noise Ratio ◽  
Detection Signal

Abstract By optimizing the conditions for determining trans-phylloquinone and its metabolite, K-2,3-epoxide, in serum through a two-step HPLC process combined with fluorometric detection after coulometric reduction, we have been able to develop a method applicable to small volumes of serum (200 to 500 microL). The limit of detection (signal-to-noise ratio of 3) was 15 ng/L for trans-phylloquinone, 30 ng/L for K-2,3-epoxide. The trans-phylloquinone concentrations measured by this method in serum from 82 children, ages one to six years, whose results were normal for overall coagulation tests, ranged from 40 to 880 ng/L (median 175 ng/L). We discuss these findings and compare them with vitamin K1(20) values reported for adults.

scholarly journals Determination of Total Avermectin B1 and 8,9-Z-Avermectin B1 Residues in Wine by Liquid Chromatography

1996 ◽  
Vol 79 (5) ◽  
pp. 1158-1161 ◽  
Author(s):  
Janice A Cobin ◽  
Nelson A Johnson
Keyword(s):  
Liquid Chromatography ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Signal To Noise Ratio ◽  
Reversed Phase ◽  
Liquid Chromatographic Method ◽  
Limit Of Quantitation ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method was developed and validated for determination of avermectin Bi and 8,9-Z-avermectin B1 residues in wine. The sample is extracted with hexane-acetonitrile and the hexane layer containing the avermectins is concentrated/ purified on an aminopropyl solid-phase extraction (SPE) column. The purified extract is derivatized with trifluoroacetic anhydride and the derivatized avermectins are analyzed by reversed-phase liquid chromatography with fluorescence detection. Recoveries of avermectins from wine fortified with approximately 1-25 ng/g avermectin B1a or 8,9-Zavermectin B1a averaged 88 and 102%, respectively. The limit of quantitation is 1 ng/g (signal-to-noise ratio [S/N] > 10) and the limit of detection is 0.5 ng/g (S/N > 3) for each analyte. This procedure provides a simple, rapid, and sensitive method for monitoring the total amount of avermectin residues in wine.

A Novel Electrochemiluminescence Sensor for Sensitive Determination of Carbaryl Based on Solid Phase Microextraction at NH2–Graphene–Nafion Modified Electrode

2015 ◽  
Vol 68 (5) ◽  
pp. 793 ◽  
Author(s):  
Sui Wang ◽  
Shasha Lv ◽  
Wenwen Wu ◽  
Zhiyong Guo
Keyword(s):  
Solid Phase Microextraction ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Signal To Noise Ratio ◽  
Initial Response ◽  
X Ray Diffraction ◽  
Relative Standard ◽  
Sensitive Determination ◽  
Response Current

Sensitive electrochemiluminescence (ECL) detection and solid phase microextraction (SPME) using a NH2–graphene–Nafion modified glassy carbon electrode was developed for carbaryl. The NH2–graphene was synthesised and characterised by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The main parameters that affect the extraction efficiencies, such as the buffer and sample pH, and extraction time were investigated and optimised. The introduction of NH2–graphene into Nafion improves the conductivity of the film because of its electrical conductivity. The electrode enables the determination of carbaryl in the range from 5 × 10–4 to 10 μg mL–1, and the limit of detection was 2 × 10–4 μg mL–1 at a signal-to-noise ratio of 3. The ECL intensity retained 97 % of its initial response current after storage for 10 days, indicating a good storage stability of the sensor. The relative standard deviations (RSDs) of intra-assay and inter-assay were found to be 3.5 and 5.3 %, respectively, indicating an acceptable reproducibility. Furthermore, the ECL sensor was successfully applied to the selective and sensitive quantitative determination of carbaryl in river samples, the recoveries of carbaryl ranged from 99.0 to 108.0 %, and the RSDs were less than 5.0 %, which shows good reproducibility and high precision of analysis.

Low-Cost Synthesis of Gold Nanoparticles from Reused Traditional Gold Leaf and its Application for Sensitive and Selective Colorimetric Sensing of Creatinine in Urine

2020 ◽  
Vol 16 (3) ◽  
pp. 287-297
Author(s):  
Arjnarong Mathaweesansurn ◽  
Nathawut Choengchan ◽  
Putthiporn Khongkaew ◽  
Chutima M. Phechkrajang
Keyword(s):  
Gold Nanoparticles ◽  
Limit Of Detection ◽  
Low Cost ◽  
Poly Vinyl Alcohol ◽  
Colorimetric Determination ◽  
Au Nps ◽  
Urinary Creatinine ◽  
Gold Leaf ◽  
Colorimetric Response

Background: Gold nanoparticles (Au NPs) are normally prepared using standard gold (III) trichloride which is much expensive and irritant. This work is aimed at demonstrating simple and low-cost synthesis of Au NPs from the reused traditional gold leaf which is cost-free and less toxic. Methods: The reused gold leaf was donated by the local temple. It was digested and used as the precursor for the preparation of the Au NPs by Turkevich method. Poly (vinyl alcohol) (PVA) was employed as a stabilizer. The as-prepared Au NPs were applied for the colorimetric determination of creatinine in urine without any sample pretreatment. Results: Long-term stability of the gold colloids was achieved for at least 3 months. Morphology and purity of the as-prepared Au NPs were the same as the ones prepared from standard gold (III) salt and standard gold foil. Colorimetric response of the Au NPs was linear to the standard creatinine up to 200 mg L-1. The limit of detection (0.16 mg L-1 or 1.41 μM) was enough sensitive for urinary creatinine detection in patients with kidney disease. Good recoveries (97-108%) and fast analysis time (3 min) were achieved. The developed method was successfully validated against the HPLC method. Conclusion: Facile and cost-effective synthesis of the Au NPs from the reused traditional gold leaf, was accomplished. The as-prepared Au NPs were successfully applied for the determination of urinary creatinine with high sensitivity and selectivity.

Liquid Chromatographic Method for Determination of Total Avermectin Bi and 8,9-Z-Avermectin B1 Residues in Hops

1996 ◽  
Vol 79 (2) ◽  
pp. 503-507 ◽  
Author(s):  
Janice A Cobin ◽  
Nelson A Johnson
Keyword(s):  
Chromatographic Method ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Signal To Noise Ratio ◽  
Extraction Column ◽  
Assay Procedure ◽  
Liquid Chromatographic Method ◽  
Limit Of Quantitation ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method has been developed and validated for determination of avermectin B1 and 8,9-Z-avermectin B1 residues in dried hops. The dried hops are rehydrated and subsequently extracted with a methanol-water mixture.The aver- mectins are partitioned into hexane and the hexane extract is concentrated (purified) on an amino- propyl solid-phase extraction column. The purified extract is derivatized with trifluoroacetic anhydride, and the derivatized avermectins are analyzed by re versed-phase liquid chromatography with fluorescence detection. Recoveries of the avermectins fromdried hops fortified with approximately 51000 ng/g avermectin B1a or 8,9-Z-avermectin B1a ranged from 73 to 108% with an overall average recovery of 95%. The limit of quantitation is 5 ng/g (signal-to-noise ratio [S/N] > 10), and the limit of detection is 2 ng/g (S/N > 3) for each analyte. The assay procedure provides a simple, rapid, and sensitive method for monitoring the total avermectin residues in hops.

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