scholarly journals A Low Cost and Simple Lab-on-a-Chip for Spectrophotometric Determination of Ethanol

2017 ◽  
Vol 15 (7) ◽  
pp. 529-539
Author(s):  
Thanyaluck SOMSAENG ◽  
Kem PUMSA-ARD ◽  
Piyada JITTANGPRASERT
Keyword(s):  
Limit Of Detection ◽  
Rapid Determination ◽  
Low Cost ◽  
Colorimetric Detection ◽  
Lab On A Chip ◽  
Ceric Ammonium Nitrate ◽  
Alcoholic Beverages ◽  
Manufacturing Cost ◽  
Relative Standard

A simple lab-on-a-chip system was developed for the rapid determination of ethanol in different sample matrices, including gasohol and various alcoholic beverages. The colorimetric detection of ethanol using a spectrophotometer was based on the reaction between ethanol with 0.12 M ceric ammonium nitrate in acidic medium to produce a red colored product which gave a maximum absorption at 470 nm. A non-lithographic method was used for creating lab-on-a-chip molds to reduce  manufacturing cost and preparation steps. The lab-on-a-chip device was fabricated from polydimethylsiloxane which consisted of a simple Y-shaped working channel. Under optimum conditions, a linear calibration graph was obtained in the concentration range of 0.20 - 20 % (v/v) (r2> 0.999). The limit of detection (3 SD) and limit of quantification (10 SD) were 0.039 and 0.13 % (v/v), respectively. The precision reported in terms of relative standard deviation (RSD) values was less than 1.40 % (n = 15). To demonstrate the lab-on-a-chip’s performance, the determination of ethanol in gasohol and various alcoholic beverages was applied. The results obtained from the developed method compared with a standard gas chromatographic method were well correlated using the paired t-test and linear regression test. The results indicate that the proposed method has shown potential to extend the use of this simple lab-on-a-chip analytical device, due to its simplicity, low cost, lower reagent and sample consumption and high analytical performance. Moreover, the method of fabrication would be an additive manufacturing technique featuring a low equipment cost with no need for clean rooms.

scholarly journals Miniaturized Fluorimetric Method for Quantification of Zinc in Dry Dog Food

2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Rute C. Martins ◽  
Ana M. Pereira ◽  
Elisabete Matos ◽  
Luisa Barreiros ◽  
António J. M. Fonseca ◽  
...  
Keyword(s):  
Limit Of Detection ◽  
Rapid Determination ◽  
Low Cost ◽  
Food Samples ◽  
Dog Food ◽  
Fluorimetric Assay ◽  
Relative Standard ◽  
The Stability ◽  
Cost Determination

Zinc is an essential trace element for animals in several biological processes, particularly in energy production, and it is acquired from food ingestion. In this context, a microplate-based fluorimetric assay was developed for simple, fast, and low-cost determination of zinc in pet food using 2,2′-((4-(2,7-difluoro-3,6-dihydroxy-4aH-xanthen-9-yl)-3-methoxyphenyl)azanediyl)diacetic acid (FluoZin-1) as fluorescent probe. Several aspects were studied, namely, the stability of the fluorescent product over time, the FluoZin-1 concentration, and the pH of reaction media. The developed methodology provided a limit of detection of 1 μg L−1 in sample acid digests, with a working range of 10 to 200 μg L−1, corresponding to 100–2000 mg of Zn per kg of dry dog food samples. Intraday repeatability and interday repeatability were assessed, with relative standard deviation values < 3.4% (100 μg L−1) and <11.7% (10 μg L−1). Sample analysis indicated that the proposed fluorimetric assay provided results consistent with ICP-MS analysis. These results demonstrated that the developed assay can be used for rapid determination of zinc in dry dog food.

scholarly journals Rapid and Sensitive Spectrophotometric Method for the Determination of the Trace Amount of Thallium (III) in Water and Urine Samples by New Oxidative Coupling Reaction

2019 ◽  
Vol 53 (4) ◽  
Author(s):  
Padmarajaiah Nagaraja ◽  
Naef Ghllab Saeed Al-Tayar ◽  
Anantharaman Shivakumar ◽  
Ashwinee Kumar Shresta ◽  
Avinash K. Gowda
Keyword(s):  
Spectrophotometric Method ◽  
Limit Of Detection ◽  
Rapid Determination ◽  
Coupling Reaction ◽  
Molar Absorptivity ◽  
Urine Samples ◽  
Oxidative Coupling Reaction ◽  
Relative Standard ◽  
Student’S T

A very simple, sensitive and fairly selective direct spectrophotometric method is presented for the rapid determination of thallium(III) at trace level. The method is based on the oxidation of 2-hydrazono-3-methyl-2,3-dihydrobenzo[d]thiazole hydrochloride (MBTH) by thallium(III) in phosphoric acid medium to form a diazoniumcation, which couples immediately with 10,11-dihydro-5Hdibenzo[b,f]azepine (IDB) at room temperature giving a blue colored species having a maximum absorption at 660 nm. The reaction conditions and other important analytical parameters were optimized.The calibration curve was found to be linear over the range of 0.1-4 μg/mL with molar absorptivity of 4.5 × 104 L mol- cm-1 and Sandell’s sensitivity of 0.00454 μg cm-2. The relative standard deviation and limit of detection have been found to be 0.58% and 0.0147 μg/mL respectively. Almost all common anions and cations are found notto interfering in matrix level of the analytical process. The method has been successfully applied for the determination of thallium(III) in synthetic standard mixtures, water and human urine samples. The performance of proposed method was evaluated in terms of student’s t-test and variance ratio F-test, to find out the significance of proposed method over the reported methods.    

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.

A rapid in vitro assay of cobalamin in human urine and medical tablets using ICP-MS

2009 ◽  
Vol 63 (3) ◽  
Author(s):  
Gai Zhang ◽  
Jianbo Liu ◽  
Zuchao Meng ◽  
Xin Wang
Keyword(s):  
Human Urine ◽  
Inductively Coupled Plasma ◽  
Limit Of Detection ◽  
Rapid Determination ◽  
Vitro Assay ◽  
Cobalt Ions ◽  
Icp Ms ◽  
Relative Standard

AbstractA rapid and simple as well as sensitive inductively coupled plasma mass spectrometry (ICP-MS) method for the determination of cobalamin is described. Cobalamin in human urine and medicine tablet solutions was converted on-line into free cobalt ions in acid medium, the cobalt ions were then detected by ICP-MS. Cobalamin was determined by measuring the increase of integral counts per second intensity, which was linear over the cobalamin concentration range of 1.0 × 10−10 g mL−1 to 8.0 × 10−5 g mL−1, and the limit of detection was 0.05 ng mL−1 (3σ). At the pump rate of 30 rotations per minute, one analysis cycle of cobalamin, including sampling and washing, could be accomplished in 0.5 min with the relative standard deviations of less than 5 %. The proposed procedure was applied successfully in monitoring cobalamin in human urine without any pretreatment process and in rapid determination of cobalamin in multivitamin tablets.

Rapid determination of fosetyl-aluminium in commercial pesticide formulations by high-performance liquid chromatography

2014 ◽  
Vol 68 (6) ◽  
Author(s):  
Helen Karasali ◽  
Konstantinos Kasiotis ◽  
Kyriaki Machera
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
High Performance ◽  
Limit Of Detection ◽  
Rapid Determination ◽  
Hplc Method ◽  
Negative Ion ◽  
Rp Hplc ◽  
Relative Standard

AbstractAn isocratic reversed-phase high-performance liquid chromatographic (RP-HPLC) method with diode array detection (DAD) was developed for the determination of aluminium tris(ethyl phosphonate) (fosetyl-aluminium, fosetyl-Al) in plant-protection products. The method involves extraction of the active ingredient by sonication of the sample with water and direct measurement by RPHPLC. The isocratic RP-HPLC method for the analysis of fosetyl-Al thus developed was then validated for specificity, linearity, precision, and accuracy. The chromatographic peak confirmation was performed by LC-MS using electron spray ionisation in the negative-ion mode. The repeatability of the method, expressed as relative standard deviation (RSD, %), was found to be 0.5 % and the limit of detection was 0.035 mg mL−1. The average recoveries of the three fortification levels varied from 96.7 % to 100.6 % and the RSDs ranged between 2.6 % and 6.3 %. The precision of the method was also considered to be acceptable as the experimental repeatability relative standard deviation (RSDr) was lower than the RSDr, calculated using the Horwitz equation. The method is rapid, simple, accurate, cost-effective, and provides a new and reliable means for the analysis of fosetyl-Al in formulated products.

scholarly journals Determination of four naphthalenediols in cosmetic samples by sweeping-micellar electrokinetic chromatography and a comparison with HPLC

2021 ◽  
Author(s):  
Qian Wang ◽  
Xiaobin Li ◽  
Zhihan Zheng ◽  
Huitao Liu ◽  
Yuan Gao
Keyword(s):  
Micellar Electrokinetic Chromatography ◽  
Limit Of Detection ◽  
Low Cost ◽  
Hplc Method ◽  
National Standards ◽  
Sample Introduction ◽  
Electrokinetic Chromatography ◽  
Relative Standard ◽  
Limit Of Quantitation

Abstract A sweeping micellar electrokinetic chromatography (sweeping-MEKC) method was developed for the determination of 1,7-naphthalenediol, 2,3-naphthalenediol, 1,5-naphthalenediol and 2,7-naphthalenediol in cosmetics. Several parameters affecting sweeping-MEKC method were studied systematically and the separation conditions were optimized as 20 mM NaH2PO4–110 mM SDS and 40% (v/v) MeOH (pH 2.4), with −22 kV applied voltage and UV detection at 230 nm. The sample matrix is 60 mmol L−1 NaH2PO4 and sample introduction was performed at 3 psi for 6 s. Separation of the four naphthalenediols was completed in less than 17 min. Limit of detection (LOD) and limit of quantitation (LOQ) are 0.0045∼0.0094 μg mL−1 and 0.015∼0.031 μg mL−1. Linear relationship (r 2 > 0.999) is satisfactory at the range of 0.1–10 μg mL−1. The developed method has been successfully applied to the determination of the four naphthalenediols in real cosmetic samples, with recoveries in foundation, sun cream and lotion in the range of 92.3%∼106.8% and relative standard deviation (RSD) less than 4.15%. A HPLC method described in the National Standards of the People’s Republic of China was carried out for the comparison with the proposed method. The results showed that the proposed sweeping-MEKC method has the advantages of fast, low cost with comparative sensitivity.

Rapid Determination of Total Cholesterol in Homogenized Milk

1989 ◽  
Vol 72 (3) ◽  
pp. 421-424 ◽  
Author(s):  
Ida C Tsui
Keyword(s):  
Total Cholesterol ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Rapid Determination ◽  
Internal Standard ◽  
Gas Chromatograph ◽  
Relative Standard ◽  
Aoac Method ◽  
Normal Work

Abstract A rapid method that is amenable to automation has been developed for the determination of total cholesterol in homogenized milk. The milk sample is saponified in ethanolic KOH in the presence of an internal standard, cholestane. Cholesterol and the internal standard are then isolated by solid-phase extraction on a nonpolar adsorbent and eluted with organic solvent. The evaporated extract is derivatized and analyzed by capillary gas chromatography. Average recovery of cholesterol acetate added to milk prior to saponification was 95%. The average relative standard deviation for repeated analyses was 2%. The limit of detection for this method is 2 mg/100 g. Twenty samples can be analyzed by one analyst in a normal work day if the gas chromatograph is equipped with an autosampler. This method has been compared with a modified AOAC method for the determination of total cholesterol. At a confidence level of 95%, no difference was observed between the 2 methods.

A Carbon Nanodots-Based Fluorescent Turn-On Probe for Iodide

2015 ◽  
Vol 68 (10) ◽  
pp. 1479 ◽  
Author(s):  
Qi Wang ◽  
Yuehuan Wu
Keyword(s):  
Limit Of Detection ◽  
Rapid Determination ◽  
Low Cost ◽  
Good Health ◽  
Food Chains ◽  
Carbon Nanodots ◽  
Competitive Reaction ◽  
Turn On ◽  
Excellent Selectivity

The human body requires iodine to develop and maintain proper metabolic balance. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability. Small amounts of iodine are needed for good health. However, large doses can eventually cause iodide goitre, hypothyroidism or myxedema. Children are especially sensitive to the effects of iodine. Because humans can be exposed to iodide via several different food chains, the development of on-site, real-time and reliable sensors for iodide is of great interest to ensure early diagnosis and improve management. We propose here a simple and low cost, yet sensitive and selective fluorescent ‘turn-off-on’ assay for rapid determination of iodide based on a combined carbon nanodots (CDs) and Hg2+ system. The fluorescence of CDs that was quenched by Hg2+ was restored and ‘turned on’ in the presence of iodide, which triggered a competitive reaction among CDs, Hg2+ and iodide. The recovered fluorescence intensity varied linearly with the concentration of iodide in the range of 0.05–5 μmol L–1, with a limit of detection as low as 46 nmol L–1. This approach shows excellent selectivity for iodine over the other anions.

scholarly journals Determination of Trace Levels of Nickel(II) by Adsorptive Stripping Voltammetry Using a Disposable and Low-Cost Carbon Screen-Printed Electrode

Chemosensors ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 94
Author(s):  
Víctor Padilla ◽  
Núria Serrano ◽  
José Manuel Díaz-Cruz
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
Stripping Voltammetry ◽  
Differential Pulse ◽  
Adsorptive Stripping Voltammetry ◽  
Carbon Surface ◽  
Complexing Agent ◽  
Relative Standard ◽  
Screen Printed

A commercial and disposable screen-printed carbon electrode (SPCE) has been proposed for a fast, simple and low-cost determination of Ni(II) at very low concentration levels by differential pulse adsorptive stripping voltammetry (DPAdSV) in the presence of dimethylglyoxime (DMG) as complexing agent. In contrast with previously proposed methods, the Ni(II)-DMG complex adsorbs directly on the screen-printed carbon surface, with no need of mercury, bismuth or antimony coatings. Well-defined stripping peaks and a linear dependence of the peak area on the concentration of Ni(II) was achieved in the range from 1.7 to 150 µg L−1, with a limit of detection of 0.5 µg L−1 using a deposition time of 120 s. An excellent reproducibility and repeatability with 0.3% (n = 3) and 1.5% (n = 15) relative standard deviation, respectively, were obtained. In addition, the suitability of the SPCE as sensing unit has been successfully assessed in a wastewater certificated reference material with remarkable trueness and very good reproducibility.

scholarly journals Rapid Determination of Fosetyl-Aluminum Residues in Lettuce by Liquid Chromatography/Electrospray Tandem Mass Spectrometry

2003 ◽  
Vol 86 (4) ◽  
pp. 832-838 ◽  
Author(s):  
Félix Hernández ◽  
Juan V Sancho ◽  
Óscar J Pozo ◽  
Carme Villaplana ◽  
María Ibáñez ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Limit Of Detection ◽  
Rapid Determination ◽  
Tandem Mass ◽  
Electrospray Tandem Mass Spectrometry ◽  
Relative Standard ◽  
Limit Of Quantitation

Abstract This paper describes a new method for the sensitive and selective determination of fosetyl-aluminum (Al) residues in vegetable samples. The method involves extraction with water by using a high-speed blender and subsequent injection of the 5-fold diluted extract into the liquid chromatograph. Fosetyl-Al is determined by liquid chromatography with electrospray tandem mass spectrometry after the addition of tetrabutylammonium acetate as the ion-pairing re-agent. The method has been used to assay lettuce samples spiked at 2 and 0.2 mg/kg. Recoveries were satisfactory, with mean values of 98 and 106%, respectively, and relative standard deviations were &lt;10%. The limit of quantitation was 0.2 mg/kg, and the limit of detection was as low as 0.05 mg/kg. Matrix-matched calibration was used for quantitation, and the addition of an internal standard improved repeatability. The developed method allows the accurate and rapid determination of low levels of fosetyl-Al residues in lettuce with very little sample handling and good sensitivity; it was shown to be robust by the analysis of almost 100 samples.

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