scholarly journals Gold Nanoparticles with Different Particle Sizes for the Quantitative Determination of Chlorpyrifos Residues in Soil by SERS

2019 ◽  
Vol 20 (11) ◽  
pp. 2817 ◽  
Author(s):  
Yong He ◽  
Shupei Xiao ◽  
Tao Dong ◽  
Pengcheng Nie
Keyword(s):  
Gold Nanoparticles ◽  
Limit Of Detection ◽  
Soil Surface ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sers Substrate ◽  
Least Squares Regression ◽  
Simple Method ◽  
Good Linear ◽  
Relative Standard

Chlorpyrifos (CPF) is widely used in the prevention and control of crop pests and diseases in agriculture. However, the irrational utilization of pesticides not only causes environmental pollution but also threatens human health. Compared with the conventional techniques for the determination of pesticides in soil, surface-enhanced Raman spectroscopy (SERS) has shown great potential in ultrasensitive and chemical analysis. Therefore, this paper reported a simple method for synthesizing gold nanoparticles (AuNPs) with different sizes used as a SERS substrate for the determination of CPF residues in soil for the first time. The results showed that there was a good linear correlation between the SERS characteristic peak intensity of CPF and particle size of the AuNPs with an R2 of 0.9973. Moreover, the prepared AuNPs performed great ultrasensitivity, reproducibility and chemical stability, and the limit of detection (LOD) of the CPF was found to be as low as 10 μg/L. Furthermore, the concentrations ranging from 0.01 to 10 mg/L were easily observed by SERS with the prepared AuNPs and the SERS intensity showed a good linear relationship with an R2 of 0.985. The determination coefficient (Rp2) reached 0.977 for CPF prediction using the partial least squares regression (PLSR) model and the LOD of CPF residues in soil was found to be as low as 0.025 mg/kg. The relative standard deviation (RSD) was less than 3.69% and the recovery ranged from 97.5 to 103.3%. In summary, this simple method for AuNPs fabrication with ultrasensitivity and reproducibility confirms that the SERS is highly promising for the determination of soil pesticide residues.

scholarly journals Voltammetric determination of dopamine in the presence of ascorbic and uric acids using partial least squares regression: determination of dopamine in human urine and plasma

2009 ◽  
Vol 7 (3) ◽  
pp. 524-531 ◽  
Author(s):  
Morteza Bahram ◽  
Khalil Farhadi ◽  
Farzin Arjmand
Keyword(s):  
Least Squares ◽  
Partial Least Squares ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Limit Of Detection ◽  
Relative Standard Error ◽  
Carbon Electrode ◽  
Least Squares Regression ◽  
Relative Standard

AbstractA new differential pulse voltammetric method for dopamine determination at a bare glassy carbon electrode has been developed. Dopamine, ascorbic acid (AA) and uric acid (UA) usually coexist in physiological samples. Because AA and UA can be oxidized at potentials close to that of DA it is difficult to determine dopamine electrochemically, although resolution can be achieved using modified electrodes. Additionally, oxidized dopamine mediates AA oxidation and the electrode surface can be easily fouled by the AA oxidation product. In this work a chemometrics strategy, partial least squares (PLS) regression, has been applied to determine dopamine in the presence of AA and UA without electrode modification. The method is based on the electrooxidation of dopamine at a glassy carbon electrode in pH 7 phosphate buffer. The dopamine calibration curve was linear over the range of 1–313 μM and the limit of detection was 0.25 μM. The relative standard error (RSE %) was 5.28%. The method has been successfully applied to the measurement of dopamine in human plasma and urine.

Determination of diltiazem based on the reduction of Cu(II)–BCA complexes in micellar medium

2010 ◽  
Vol 88 (6) ◽  
pp. 533-539 ◽  
Author(s):  
Larissa Zuppardo Lacerda Sabino ◽  
Daniele Cestari Marino ◽  
Horacio Dorigan Moya
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Confidence Level ◽  
Limit Of Detection ◽  
Calibration Graph ◽  
Micellar Medium ◽  
Solution Ph ◽  
Simple Method ◽  
Relative Standard

A simple method was developed for determining microquantities of diltiazem, based on the reduction of copper(II) in buffered solution (pH 7.0) and the use of a micellar medium containing 4,4′-dicarboxy-2,2′-biquinoline acid. The copper(I) produced reacts with 4,4′-dicarboxy-2,2′-biquinoline acid and the complexes formed are spectrophotometrically measured at 558 nm. A typical calibration graph shows good linearity (r = 0.993) from 20 to 100 μg mL–1 of diltiazem. The limit of detection and relative standard deviation were calculated as 12 μg mL–1 (99% confidence level) and 3.5% (40 μg mL–1; n = 6), respectively, with a mean recovery value of 96.5% found in pharmaceutical dosages. A straightforward and effective way to recycle the reagents is addressed. The hazardous aspects of the Cu(I)–BCA reaction are presented as well.

scholarly journals A simple method for determination of deoxynivalenol in cereals and flours

2011 ◽  
Vol 20 (No. 2) ◽  
pp. 63-68 ◽  
Author(s):  
F. Kotal ◽  
Z. Radová
Keyword(s):  
Regression Analysis ◽  
Standard Deviation ◽  
Limit Of Detection ◽  
Linear Regression Analysis ◽  
Fast Method ◽  
Immunoaffinity Column ◽  
Simple Method ◽  
Relative Standard ◽  
Certified Value

An effective and fast method for determination of deoxynivalenol (DON) in cereals and flours has been developed. The immunoaffinity column was used for the isolation of DON from wheat, corn, rice and flour extract. The determination was carried out by using the HPLC/UV method. The limit of detection was 0.02 mg/kg. The recoveries for the assay range 0.1 to 2 mg/kg were generally higher than 80%, ranging from 83 to 96% with an average relative standard deviation of 3.8%. The trueness of the method using the DON test – HPLC column was established by use of certified reference material CRM 379. The certified value was 0.67 mg/kg. The result obtained from three replicates was 0.68 ± 0.05 mg/kg. The corresponding confidence interval at 95% probability ranged from 0.63 to 0.73 mg/kg. A comparative study of the DON testTM – HPLC/UV and the Mycosep 225 – GC/ECD methods was carried out. Six naturally contaminated wheat samples were analysed by both methods. Linear regression analysis demonstrates that DON testTM – HPLC is a statistically significant predictor of the GC/ECD method using the Romer Mycosep 225 column.  

scholarly journals Determination of the Immunoglobulin G Spectrum by Surface-Enhanced Raman Spectroscopy Using Quasispherical Gold Nanoparticles

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Alejandra Ortiz-Dosal ◽  
Elizabeth Loredo-García ◽  
Ana Gabriela Álvarez-Contreras ◽  
Juan Manuel Núñez-Leyva ◽  
Luis Carlos Ortiz-Dosal ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Raman Spectroscopy ◽  
Raman Spectrum ◽  
Surface Enhanced Raman Spectroscopy ◽  
Protein Quantification ◽  
Acquisition Time ◽  
Sers Substrate ◽  
Surface Enhanced ◽  
Surface Enhanced Raman

Background. Immunoglobulins (Ig) are glycoprotein molecules produced by plasma cells in response to antigenic stimuli involved in various physiological and pathological conditions. Intravenous immunoglobulin (IVIG) is a compound whose composition corresponds to Ig concentrations in human plasma, predominantly IgG. It is used as a replacement treatment in immunodeficiencies and as an immunomodulator in inflammatory and autoimmune diseases. The determination of IgG concentrations is useful in the diagnosis of these immunodeficiencies. Surface-enhanced Raman spectroscopy (SERS) is a technique that allows protein quantification in a fast and straightforward way. Objective. This study is aimed at determining the Raman spectrum of IgG at physiological concentrations using quasispherical gold nanoparticles as a SERS substrate. Methods. We initially determined the Raman spectrum of IVIG at 5%. Subsequently, for SERS’ characterization, decreasing dilutions of the protein were made by adding deionized water and an equal volume of the 5 nm gold quasispherical nanoparticle colloid. For each protein concentration, the Raman spectrum was determined using a 10x objective; we focused the 532 and 785 nm laser on the sample surface, in a range of 500-1800 cm-1, with five acquisitions and an acquisition time of 30 seconds. Results. We obtained the IVIG spectrum using SERS up to a concentration of 75 mg/dl. The Raman bands correspond to aromatic amino acid side chains and the characteristic beta-sheet structure of IgG. Conclusion. The use of 5 nm quasispherical gold nanoparticles as a SERS substrate allows for detecting the Raman spectrum of IVIG at physiological concentrations.

scholarly journals Rapid and Quantitative Determination of Sildenafil in Cocktail Based on Surface Enhanced Raman Spectroscopy

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1790 ◽  
Author(s):  
Lei Lin ◽  
Fangfang Qu ◽  
Pengcheng Nie ◽  
Hui Zhang ◽  
Bingquan Chu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Limit Of Detection ◽  
Surface Enhanced Raman Spectroscopy ◽  
Alcoholic Beverages ◽  
Relative Standard ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Accurate Scheme ◽  
Related Compounds

Sildenafil (SD) and its related compounds are the most common adulterants found in herbal preparations used as sexual enhancer or man’s virility products. However, the abuse of SD threatens human health such as through headache, back pain, rhinitis, etc. Therefore, it is important to accurately detect the presence of SD in alcoholic beverages. In this study, the Opto Trace Raman 202 (OTR 202) was used as a surface-enhanced Raman spectroscopy (SERS) active colloids to detect SD. The results demonstrated that the limit of detection (LOD) of SD was found to be as low as 0.1 mg/L. Moreover, 1235, 1401, 1530, and 1584 cm−1 could be qualitatively determined as SD characteristic peaks. In a practical application, SD in cocktail could be easily detected using SERS based on OTR 202. Also, there was a good linear correlation between the intensity of Raman peaks at 1235, 1401, 1530, and 1584 cm−1 and the logarithm of SD concentration in cocktail was in the range of 0.1–10 mg/L (0.9822 < R2 < 0.9860). The relative standard deviation (RSD) was less than 12.7% and the recovery ranged from 93.0%–105.8%. Moreover, the original 500–1700 cm−1 SERS spectra were pretreated and the partial least squares (PLS) was applied to establish the prediction model between SERS spectra and SD content in cocktail and the highest determination coefficient (Rp2) reached 0.9856. In summary, the SD in cocktail could be rapidly and quantitatively determined by SERS, which was beneficial to provide a rapid and accurate scheme for the detection of SD in alcoholic beverages.

scholarly journals Application of chemometrics for modeling and optimization of ultrasound-assisted dispersive liquid–liquid microextraction for the simultaneous determination of dyes

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Siroos Shojaei ◽  
Saeed Shojaei ◽  
Arezoo Nouri ◽  
Leila Baharinikoo
Keyword(s):  
Water Samples ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
World Population ◽  
Simple Method ◽  
Relative Standard ◽  
Ultrasound Assisted ◽  
Dispersive Liquid Liquid Microextraction ◽  
Liquid Microextraction

AbstractAs the world population continues to grow, so does the pollution of water resources. It is, therefore, important to identify ways of reducing pollution as part of our effort to significantly increase the supply of clean and safer water. In this study, the efficiency of ultrasound-assisted dispersive liquid–liquid microextraction (UA-DLLME) as a fast, economical, and simple method for extraction malachite green (MG) and rhodamine B (RB) dyes from water samples is investigated. In optimal conditions, the linear dynamic range (LDR) for RB and MG is 7.5–1500 ng mL−1 and 12–1000 ng mL−1, respectively. The limit of detection (LOD) is 1.45 ng mL−1 and 2.73 ng mL−1, and limit of quantification (LOQ) is 4.83 ng mL−1 and 9.10 ng mL−1 for RB and MG, respectively. Extraction efficiency is obtained in the range of 95.53–99.60%. The relative standard deviations (RSD) in real water and wastewater samples are less than 3.5. The developed method is used successfully in the determination of RB and MG dyes from water samples and there are satisfactory results.

scholarly journals A Sensitive SERS Method for Determination of Pymetrozine in Apple and Cabbage Based on an Easily Prepared Substrate

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1874
Author(s):  
Ting-Tiao Pan ◽  
Mei-Ting Guo ◽  
Wang Guo ◽  
Ping Lu ◽  
De-Yu Hu
Keyword(s):  
Limit Of Detection ◽  
Surface Enhanced Raman Spectroscopy ◽  
Detection Range ◽  
Linear Detection ◽  
Relative Standard ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Liquid Chromatography Tandem Mass ◽  
Highly Correlated

Residual pesticides are one of the major food safety concerns around the world. There is a demand for simple and reliable methods to monitor pesticide residues in foods. In this study, a sensitive method for determination of pymetrozine in apple and cabbage samples using surface-enhanced Raman spectroscopy (SERS) based on decanethiol functionalized silver nanoparticles was established. The proposed method performed satisfactorily with the linear detection range of 0.01–1.00 mg/L and limit of detection (LOD) of 0.01 mg/L in methanol. In addition, it was successfully used to detect pymetrozine in apple and cabbage samples, the LOD was 0.02 and 0.03 mg/L, respectively, and the recoveries of spiked cabbage and apple ranged 70.40–104.00%, with relative standard deviations below 12.18% and 10.33% for intra-day and inter-day tests. Moreover, the results of the correlation test with real cabbage samples of liquid chromatography-tandem mass spectrometry showed that they were highly correlated (slope = 0.9895, R2 = 0.9953). This study provides a sensitive approach for detection of pymetrozine in apple and cabbage, which has great potential for determination of pymetrozine residues in food products.

scholarly journals Facial Fabrication of Large-Scale SERS-Active Substrate Based on Self-Assembled Monolayer of Silver Nanoparticles on CTAB-Modified Silicon for Analytical Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3250
Author(s):  
Juanjuan Guo ◽  
Yang Xu ◽  
Caili Fu ◽  
Longhua Guo
Keyword(s):  
Single Molecule ◽  
Large Scale ◽  
Limit Of Detection ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sers Substrate ◽  
Self Assembled Monolayer ◽  
Single Molecule Level ◽  
Analytical Technique ◽  
Relative Standard ◽  
Surface Enhanced Raman

Surface-enhanced Raman spectroscopy (SERS) has been proven to be a promising analytical technique with sensitivity at the single-molecule level. However, one of the key problems preventing its real-world application lies in the great challenges that are encountered in the preparation of large-scale, reproducible, and highly sensitive SERS-active substrates. In this work, a new strategy is developed to fabricate an Ag collide SERS substrate by using cetyltrimethylammonium bromide (CTAB) as a connection agent. The developed SERS substrate can be developed on a large scale and is highly efficient, and it has high-density “hot spots” that enhance the yield enormously. We employed 4-methylbenzenethiol(4-MBT) as the SERS probe due to the strong Ag–S linkage. The SERS enhancement factor (EF) was calculated to be ~2.6 × 106. The efficacy of the proposed substrate is demonstrated for the detection of malachite green (MG) as an example. The limit of detection (LOD) for the MG assay is brought down to 1.0 × 10−11 M, and the relative standard deviation (RSD) for the intensity of the main Raman vibration modes (1620, 1038 cm−1) is less than 20%.

Indirect Determination of Amikacin by Gold Nanoparticles as Redox Probe

2020 ◽  
Vol 17 ◽  
Author(s):  
Mansureh Alizadeh ◽  
Mandana Amiri ◽  
Abolfazl Bezaatpour
Keyword(s):  
Gold Nanoparticles ◽  
Bacterial Infections ◽  
Limit Of Detection ◽  
Pharmaceutical Preparation ◽  
Cathodic Peak ◽  
Easy Method ◽  
Peak Current ◽  
Indirect Determination ◽  
Tract Infections

: Amikacin is an aminoglycoside antibiotic used for many gram-negative bacterial infections like infections in the urinary tract, infections in brain, lungs and abdomen. Electrochemical determination of amikacin is a challenge in electroanalysis because it shows no voltammetric peak at the surface of bare electrodes. In this approach, a very simple and easy method for indirect voltammetric determination of amikacin presented in real samples. Gold nanoparticles were electrodeposited at the surface of glassy carbon electrode in constant potential. The effect of several parameters such as time and potential of deposition, pH and scan rates on signal were studied. The cathodic peak current of Au3+ decreased with increasing amikacin concentration. Quantitative analysis of amikacin was performed using differential pulse voltammetry by following cathodic peak current of gold ions. Two dynamic linear ranges of 1.0 × 10−8–1.0 × 10-7 M and 5.0 × 10−7–1.0 × 10-3 M were obtained and limit of detection was estimated 3.0× 10−9 M. The method was successfully determined amikacin in pharmaceutical preparation and human serum. The effect of several interference in determination of amikacin was also studied.

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