Rapid determination of products of phenol hydrogenation in a supercritical water system using headspace gas chromatography

2015 ◽  
Vol 69 (5) ◽  
Author(s):  
Qing-Qing Guan ◽  
Xiao-Dian Huang ◽  
Yan-Hua Zeng ◽  
Chao-Hai Wei ◽  
Ping Ning ◽  
...  
Keyword(s):  
Supercritical Water ◽  
Rapid Determination ◽  
Reaction System ◽  
Headspace Analysis ◽  
Water System ◽  
Anhydrous Calcium Chloride ◽  
Crystal Water ◽  
Phenol Hydrogenation ◽  
Relative Standard

AbstractThis paper reports a headspace analysis technique for the determination of products, i.e., cyclohexanone (CE) and cyclohexanol (CL), of phenol hydrogenation in a supercritical water reaction system (SWRS) with water removal by hydrate formation. An addition of anhydrous calcium chloride leads to water absorption resulting in crystal water; thus, the samples can be quantitatively measured without the influence of water. After achieving equilibrium at 150­°C and maintaining it for 5 min, the obtained results showed a relative standard deviation of less than 5.3 % and the recovery ranged from 93 % to 104 %. The presented method is simple and accurate for the analysis of CL, CE and phenol in samples from phenol conversion in SWRS.

scholarly journals Rapid Determination of Ethylene Oxide and 75 VOCs in Ambient Air with Canister Sampling and Associated Growth Issues

Separations ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 35
Author(s):  
Jason Hoisington ◽  
Jason S. Herrington
Keyword(s):  
Ethylene Oxide ◽  
Rapid Determination ◽  
Complex Mixture ◽  
Ambient Air ◽  
Gas Chromatography Mass Spectrometry ◽  
Average Accuracy ◽  
Relative Standard ◽  
Wide Range ◽  
Us Epa

A canister-based sampling method along with preconcentrator-Gas chromatography-Mass Spectrometry (GC-MS) analysis was applied to ethylene oxide (EtO or EO) and 75 other volatile organic compounds (VOCs) in ambient air. Ambient air can contain a large variety of VOCs, and thorough analysis requires non-discriminatory sampling and a chromatographic method capable of resolving a complex mixture. Canister collection of whole air samples allows for the collection of a wide range of volatile compounds, while the simultaneous analysis of ethylene oxide and other VOCs allows for faster throughput than separate methods. The method presented is based on US EPA Method TO-15A and allows for the detection of EtO from 18 to 2500 pptv. The method has an average accuracy of 104% and precision of 13% relative standard deviation (RSD), with an instrument run time of 32 min. In addition, a link between canister cleanliness and ethylene oxide growth is observed, and potential mechanisms and cleaning strategies are addressed.

Rapid Determination of Sulfite by Flow Injection Analysis Based on Fuchsin′s Addition

2013 ◽  
Vol 295-298 ◽  
pp. 950-953 ◽  
Author(s):  
Dong Yuan ◽  
Da You Fu ◽  
Wen Yuan Tan
Keyword(s):  
Flow Injection ◽  
Addition Reaction ◽  
Rapid Determination ◽  
Sampling Rate ◽  
Optimum Conditions ◽  
Linear Calibration ◽  
Relative Standard ◽  
Replicate Measurements ◽  
Good Agreement

A rapid spectrophotometric method for flow injection determination of sulfite in tan wastewater is described. The proposed method was based on the addition reaction of sulfite with fuchsin in Na2B4O7-NaOH medium. The optimum conditions allow a linear calibration range of 0.01-1.20 μg ml-1 SO32-. The detection limit is 0.0023μg ml-1 (S/N=3), and the relative standard deviation for night replicate measurements is 1.1% for 0.5μg ml-1 of sulfite. The sampling rate is 60 samples h-1. The procedure has been applied to the determination of sulfite in tan wastewater. The results were in good agreement with those obtained by pararosaniline method.

Simultaneous Determination of Eight New Generation Amide Insecticide Residues in Complex Matrix Agri-food by Multi-walled Carbon Nanotube Cleanup and UPLC-MS/MS

2021 ◽  
Author(s):  
Tao Lin ◽  
Xinglian Chen ◽  
Li Wang ◽  
Haixian Fang ◽  
Maoxuan Li ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Simultaneous Determination ◽  
High Performance ◽  
Rapid Determination ◽  
Complex Matrix ◽  
Limit Of Quantification ◽  
Relative Standard ◽  
The Matrix ◽  
Multi Walled Carbon Nanotubes

Abstract The simultaneous determination method of 8 amide pesticides by multi-walled carbon nanotubes (MWCNs) cleanup, combined with QuEChERS method and ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry has been developed and successfully applied in complex matrix such as green onions, celery, leeks, citrus, lychees, avocado. The matric effect of MWCNs is optimized and compared with QuEChERS materials. The results show that MWCNs can effectively reduce the matrix effect in sample extraction. The mass spectrometry is optimized, through their chemical structure skeletons, the ESI+ and ESI- mode are simultaneously scanned in the method. The coefficient (r) is greater than 0.9990, the limit of quantification ranges from 0.03 to 0.80 μg/kg, the recovery rate ranges from 71.2% to 120%, and the relative standard deviation (RSD) ranges from 3.8% to 9.4%. The method is fast, simple, sensitive, and has good purification effect. It is suitable for the rapid determination of amide pesticides in complex matrix agri-food.

scholarly journals Direct Determination of Free Methionine in Soy-Based Infant Formula

2004 ◽  
Vol 87 (1) ◽  
pp. 123-128
Author(s):  
Paul Johns ◽  
Rosalyn Phillips ◽  
Lobat Dowlat
Keyword(s):  
Infant Formula ◽  
Mobile Phase ◽  
Method Comparison ◽  
Water System ◽  
Direct Determination ◽  
Reversed Phase ◽  
Intermediate Precision ◽  
Relative Standard ◽  
Limit Of Quantitation

Abstract A method was developed for the direct determination of free methionine in soy-based infant formula, with analyte separation and quantitation by reversed-phase liquid chromatography (LC), and UV absorbance at 214 nm, respectively. Sample preparation required only dilution with mobile phase and syringe filtration. Using a 0.02M KH 2 PO 4 mobile phase (pH adjusted to 2.9 with 85% o-phosphoric acid) and 0.7 mL/min flow rate, methionine eluted at approximately 8 min, and total run time was 14 min after column regeneration with acetonitrile–water. System linearity was demonstrated as peak area versus analyte concentration, ranging from 80 to 120% of the formula specification for free methionine (r > 0.999, and all residuals <0.45%). Intermediate precision relative standard deviation values were <1.5% for ready-to-feed and reconstituted powder samples, and recoveries ranged from 98.0 to 103.5% for inter-method comparison with an amino acid analyzer method. The limit of quantitation was 3 mg methionine/L in the “as fed” infant formula. Despite the relatively weak UV absorptivity of methionine, the 214 nm signal was sufficiently intense in the 30–65 mg/L (201–436 μM) range to afford quantitation by peak area proportionation versus a 2-point external standard calibration. This direct UV detection after reversed-phase LC separation provides a simple and accurate method for determining free methionine without derivatization.

Gas Chromatography Mass Spectrometry Method of Rapid Determination of Trichloroacetaldehyde in Water Optimization

2013 ◽  
Vol 448-453 ◽  
pp. 359-362
Author(s):  
Mo Jie Sun ◽  
Ling Zhang ◽  
Ruo Kun Jia
Keyword(s):  
Human Error ◽  
Rapid Determination ◽  
Water Source ◽  
Gas Chromatography Mass Spectrometry ◽  
Drinking Water Source ◽  
Purge And Trap ◽  
Relative Standard ◽  
Before And After ◽  
The Difference

Chloral alkali at room temperature Can be quickly converted into chloroform completely, Application of this principle, By Purge and Trap GC/MS method , Determination of the alkali content of chloroform in water before and after the difference, Inverse to get the water content of chloral. NaOH were added to different volumetric flask. It is flask with standard solutions in different concentrations. Aside a certain amount of determination, error is larger. NaOH was injected directly into the injector. This was the method. It completely transformed in Purge and Trap, greatly reduces human error. The linear range is 0.5-20ug/L, the minimum detection limit can reach 0.05ug/L, the relative standard deviation is less than 2.3%, the average recovery was 97.5%. This method is simple and quick,the results are accurate and reliable, which is able to meet the drinking water source in the analytical needs of chloral.

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 Smartphone-based molecularly imprinted sensors for rapid detection of thiamethoxam residues and applications

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0258508
Author(s):  
Sihua Peng ◽  
Aqiang Wang ◽  
Yuyang Lian ◽  
Xi Zhang ◽  
Bei Zeng ◽  
...  
Keyword(s):  
Pesticide Residues ◽  
Rapid Detection ◽  
Rapid Determination ◽  
Detection System ◽  
Residue Analysis ◽  
Differential Pulse ◽  
Detection Technology ◽  
Screen Printed Carbon Electrode ◽  
Relative Standard

In order to achieve rapid detection of thiamethoxam residues in mango, cowpea and water, this study modified the screen printed carbon electrode (SPCE) to make a specific molecular imprinting sensor (Thiamethoxam-MIP/Au/rGO/SPCE) for thiamethoxam. An integrated smartphone platform was also built for thiamethoxam residue analysis. The performance of the complete system was analyzed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The system was then applied for the rapid determination of thiamethoxam residues in water, mango and cowpea samples. The results showed that the molecular sensor showed good linearity in the range 0.5–3.0 μmol/L of thiamethoxam. The detection limit of thiamethoxam was 0.5 μmol/L. Moreover, the sensor had good reproducibility and anti-interference performance. The average recovery rates of the pesticide residues in water, mango and cowpea samples were in the range of 90–110% with relative standard deviations < 5%. The rapid detection system for thiamethoxam residue constructed in this study was simple, reliable, reproducible and had strong anti-interference. It has broad application prospects in the field detection of thiamethoxam residue, and serves as a valuable reference for the further development of rapid detection technology of pesticide residues in the field of environment and food safety.

Time-Resolved Laser-Induced Breakdown Spectrometry for the Rapid Determination of Beryllium in Beryllium-Copper Alloys

1986 ◽  
Vol 40 (4) ◽  
pp. 491-494 ◽  
Author(s):  
John A. Millard ◽  
Robert H. Dalling ◽  
Leon J. Radziemski
Keyword(s):  
Local Thermodynamic Equilibrium ◽  
Rapid Determination ◽  
Signal To Noise Ratio ◽  
Copper Alloys ◽  
Copper Matrix ◽  
Time Resolved ◽  
Beryllium Copper ◽  
Relative Standard ◽  
Laser Induced Breakdown

Time-resolved laser-induced breakdown spectrometry has been combined with the long spark technique and applied to the rapid determination of beryllium in beryllium-copper alloys. A calibration curve was developed which related the beryllium concentration in a solid copper matrix to the Be(I) 234.9-nm to Cu(II) 235.7-nm intensity ratio. The beryllium concentrations ranged from 0.001 to 0.22%. For the lowest concentration the relative standard deviation of replicate samples was 7%, implying a detection limit of 0.0002% (2 ppm) at a signal-to-noise ratio of 3. The excitation temperature was determined from Boltzmann plots on Cu(I) and Cu(II), assuming local thermodynamic equilibrium. The values from the two spectra agreed well, and averaged to 13,850 K at 1 μS into the plasma lifetime.

Rapid Determination of Formaldehyde in Dried Bean Milk Cream by HPLC with Pre-Column Derivatization

2012 ◽  
Vol 554-556 ◽  
pp. 1493-1497
Author(s):  
Qi Tong ◽  
Jian Zheng Song ◽  
Qiu Rong Li
Keyword(s):  
High Performance ◽  
Rapid Determination ◽  
Rapid Test ◽  
Chromatography Method ◽  
System A ◽  
Controlling System ◽  
Relative Standard ◽  
Liquid Chromatography Method ◽  
Set Up

A high-performance liquid chromatography method was set up for rapid determination of formaldehyde in dried bean milk cream. This thesis studies the Nash derivatization, derivative solubility, reaction time, amounts of Nash and derivative stability. The derivative is chromatographic separated by Agilent Zorbax Eclipse XDB-C18 column (4.6mm× 250mm, 5μm) and detected by index detector with VWD (412nm). The heater does not need the temperature-controlling system. A mobile phase was composed of acetonitrile and water (50:50, V/V) at a flow rate of 0.8 mL/min. Under the conditions of the above-mentioned test, the developed calibration curves displayed good linearity over a concentration range of 0.00 to 0.80mg/L, with a correlation coefficient exceeding 0.9998. Average spike recovery was found in a range of 88% to 91%, with a relative standard deviation (RSD) between 1.1% and 4.0%.The minimum detection limit of source is 0.013mg/Kg. The method can be used for rapid test on formaldehyde preservative in dried bean milk cream.

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