Rapid determination of wastewater COD using Mn（H2PO4）2 as catalyst

A new rapid determination method of wastewater COD in mixed acid solution H_2SO_4-H_3PO_4,with Mn(H_2PO_4)_2 as catalyst,has been proposed in this paper. Through orthogonal experiment, the optimal test conditions have been determined: Mn(H_2PO_4)_2:0. 3g,H_2SO_4:H_3PO_4=6:1(V/V),reflux time:5 minutes. The results were similar to that of the standard method, but the test time was only 1/24 of that and the test cost decreased 85%.

THE RAPID DETERMINATION FOR BENZO(a)PYRENE WITH SYNCHRONOUS FLUORESCENCE SPECTROSCOPY SCANNING IN DEFINED RANGE OF DUAL—WAVELENGTHS

A rapid method of determination of BaP in various environmental samples,using synchronous fluorescence spectroscopy scanning in defined range of dual-wavelengths(SFDW)is described in this paper.

RAPID DETERMINATION OF PROTEIN IN MILLET BY FOURIER TRANSFORM NEAR-INFRARED(FTNIR)DIFFUSE REFLECTANCE SPECTROSCOPY

In this paper,the Fourier transform near-infrared(FTNIR)diffuse reflectance spectroscopy is applied for the rapid determination of protein in millet.The partial least-squares(PLS)regression is successfully used as an effective multivariate calibration technique.The calibration set is composed of 20 standard millet samples that the protein contents were determined by the traditional Kjeldahl method.The optimal model dimension is found to be 5 by cross-validation.22 millet samples were determined by the proposed FTNIR-PLS method.The correlation coefficient between the concentration values obtained by the FTNIR-PLS method and the traditional Kjeldahl method is 0.9805.The standard error of prediction(SEP)is 0.28% and the mean recovery is 100.2%.The proposed method has been successfully applied for the routine analysis of protein in about 10,000 grain samples.

Rapid Determination of Pesticide Residues in Fresh Sweet Corn

Objective] This study aimed to detect al organophosphate, organochlorine and pyrethroid pesticide residues in fresh sweet corn in one determination using a gas chromatograph. [Method] The pesticide residues in fresh sweet corn were ex-tracted and loaded to simultaneously the gas chromatograph Agilent 6890N which was equipped with two autosamplers, two columns and two detectors. [Result] Al the 26 pesticides were completely separated and eluted out within 25 min. The re-coveries of standard addition of the 26 pesticides ranged from 76% to 106%, with relative standard deviations （RSD） ranging from 0.5% to 8.9%. The linear regression equation fit wel from 0.050 to 1.500 mg/L corn extract （r2＆gt;0.996）. [Conclusion] The method is accuracy, which meets the requirements of pesticide residue analysis and can be used for the rapid detection, qualitative and quantitative analysis of pesticide residues in fresh sweet corn.

Rapid Determination of Total Content of Five Major Anthraquinones in Rhei Radix et Rhizoma by NIR Spectroscopy

Objective To establish a new method with near-infrared（NIR） spectroscopy to determine the total content of emodin, chrysophanol, rhein, aloeemodin, and physcion. NIR was used in this study to provide rapid and nondestructive analysis results. Methods In the first place, HPLC was used to measure the total content of emodin, chrysophanol, rhein, aloe-emodin and physcion in Rhei Radix et Rhizoma（RR） as a reference. In the second place, the spectral regions, regression methods, pretreatment methods, and partial least squares（PLS） factors were compared to increase the feasibility of the model. In the last, the root mean square error of calibration（RMSEC）, root mean square error of cross validation（RMSECV）, root mean square error of prediction（RMSEP）, and correlation coefficient（r） were used as assessment parameters. Results PLS with first derivative pretreatment in the ranges of 4242-5581 cm^（-1）, 5885-6233 cm^（-1） and 6394-7011 cm^（-1） provided the best results. The RMSEC and RMSEP obtained were 0.134 and 0.226 respectively. The according determination coefficients of the quantitative model were 0.99 and 0.94. Conclusion NIR spectroscopy as a quick and nondestructive analytical method may be used to determine the total content of emodin, chrysophanol, rhein, aloeemodin, and physcion for the quality control of RR.

Rapid determination of histamine concentration in fish(Miichthys Miiuy)by surface-enhanced Raman spectroscopy and density functional theory

Histamine is a type of biogenic amine,which plays a major role in the health problems associated with seafood consumption.Legislative limits of histamine level in seafood have been set in many countries.This study focuses on investigating the feasibility and potentiality of determining histamine concentration in fish(Miichthys miiuy)by surface-enhanced Raman spectroscopy(SERS)combined with density functional theory(DFT).Both a gold colloid and a silver colloid were used to determine the enhancement effect for SERS detection of histamine standard solution,and the gold colloid exhibited more effective as compared to the silver colloid.The protocol on extraction of histamine with 12%trichloroacetic acid and adjustment of pH with NaOH solution(5 mol/L)could significantly shorten sample preparation(20 min)and provide clear SERS spectra of histamine.The peaks of histamine molecules were classified using the DFT and five spectra(953 cm^(-1),992 cm^(-1),1106 cm^(-1),1262 cm^(-1)and 1317 cm^(-1))were selected as the characteristic bands of histamine discrimination.Moreover,the intensity of the peak at 1262 cm^(-1)had a good linear relationship with histamine concentration at 5-400 mg/kg with R^(2)=0.9755.It is concluded that the SERS-DFT approach will be a potential method for rapidly and reliably detecting histamine at levels from 5 mg/kg to 400 mg/kg in fresh fish.

A novel infrared spectrophotometric method for the rapid determination of petroleum hydrocarbons,and animal and vegetable oils in water

To determine the concentrations of total oils,petroleum hydrocarbons,and animal and vegetable oils in water,the conventional analytical methods involve two scans as well as a step of magnesium silicate adsorption to remove the animal and vegetable oils in water samples.In this study,a novel analytical method was developed to determine the above oils in wastewater samples through just one scan—the concentration of animal and vegetable oils,and that of total oils were determined by measuring the absorbance of the 〉C=O bond in the peak area between 1750 cm and 1735 cm^（-1）,and of the C-H bond at 2930 cm^（-1）,2960 cm,and 3030 cm^（-1）,respectively.The concentration of petroleum hydrocarbons was then calculated by subtracting the concentration of animal and vegetable oils from that of total oils.Compared with the well-known analytical method GB/T 16488-1996,the novel approach displayed similar accuracy in the quantitative determination of oils in wastewater samples,but significantly reduced material cost and operation time.

Near-infrared spectroscopy method for rapid proximate quantitative analysis of nutrient composition in Pacific oyster Crassostrea gigas

Glycogen,amino acids,fatty acids,and other nutrient components affect the flavor and nutritional quality of oysters.Methods based on near-infrared reflectance spectroscopy(NIRS)were developed to rapidly and proximately determine the nutrient content of the Pacific oyster Crassostreagigas.Samples of C.gigas from 19 costal sites were freeze-dried,ground,and scanned for spectral data collection using a Fourier transform NIR spectrometer(Thermo Fisher Scientific).NIRS models of glycogen and other nutrients were established using partial least squares,multiplication scattering correction first-order derivation,and Norris smoothing.The R_(C) values of the glycogen,fatty acids,amino acids,and taurine NIRS models were 0.9678,0.9312,0.9132,and 0.8928,respectively,and the residual prediction deviation(RPD)values of these components were 3.15,2.16,3.11,and 1.59,respectively,indicating a high correlation between the predicted and observed values,and that the models can be used in practice.The models were used to evaluate the nutrient compositions of 1278 oyster samples.Glycogen content was found to be positively correlated with fatty acids and negatively correlated with amino acids.The glycogen,amino acid,and taurine levels of C.gigas cultured in the subtidal and intertidal zones were also significantly different.This study suggests that C.gigas NIRS models can be a cost-effective alternative to traditional methods for the rapid and proximate analysis of various slaughter traits and may also contribute to future genetic and breeding-related studies in Pacific oysters.

Rapid and Sensitive Chemiluminescent Enzyme Immunoassay for the Determination of Neomycin Residues in Milk

Immunoassays greatly contribute to veterinary drug residue analysis. However, there are few reports on detecting neomycin residues by immunoassay. Here, a rapid and sensitive chemiluminescent enzyme immunoassay （CLIEA） was successfully developed for neomycin residue analysis. CLIEA demonstrated good cross-reactivity for neomycin, and the IC50 value was 2.4 ng/mL in buffer.

A RAPID FLUORIMETRIC DETERMINATION OF TYROSINE IN SERUM BY THE REACTION WITH CERIUM (Ⅳ)

A fluorimetric method for the determination of tyrosine in serum was proposed. The fluoriscence intensity is a linear function of tyrosine content in the range 0-1. 44ug/ml. The percentage of recovery was satisfactory.

REVERSE VARIABLE-ANGLE SYNCHRONOUS SPECTROFLUORIMETRY FOR RAPID SIMULTANEOUS DETERMINATION OF CHLOROPHYLL A AND CHLOROPHYLL B

Rapid simultaneous determination of chlorophyll a and chlorophyll b by reverse variable-angle synchronous spectrofluorimetry has been studied on a laboratory-constructed microcomputer-controlled versatile spectrofluorimeter.A method in estimation of scan parameters for the determination of two-component system by variable-angle synchronous spectrofluorimetry has been suggested

Rapid satellite-to-site visibility determination based on self-adaptive interpolation technique

Rapid satellite-to-site visibility determination is of great significance to coverage analysis of satellite constellations as well as onboard mission planning of autonomous spacecraft. This paper presents a novel self-adaptive Hermite interpolation technique for rapid satellite-to-site visibility determination. Piecewise cubic curves are utilized to approximate the waveform of the visibility function versus time. The fourth-order derivative is used to control the approximation error and to optimize the time step for interpolation. The rise and set times are analytically obtained from the roots of cubic polynomials. To further increase the computational speed, an interval shrinking strategy is adopted via investigating the geometric relationship between the ground viewing cone and the orbit trajectory. Simulation results show a 98% decrease in computation time over the brute force method. The method is suitable for all orbital types and analytical orbit propagators.

An Ultrastable π-π Stacked Porous Organic Molecular Framework as a Crystalline Sponge for Rapid Molecular Structure Determination

The crystalline sponge method is a pragmatic and promising strategy for molecular structure determination.However,the dominant metal-organic framework crystal sponge platforms always face poor chemical stability,especially solvent instability,hampering their application in a vaster domain.Herein,we report an ultrastable π-π stacked porous organic molecular framework which exhibits permanent porosity,high thermal stability,and good chemical resistance.It can efficiently implement an approach to molecular structure determination via a single-crystal-to-single-crystal transformation.This is the first example utilizing π-π stacked porous organic molecular framework as“crystalline sponge”to determine a wide variety of guests,ranging from hydrophilic to hydrophobic,and from aliphatic to aromatic,which complements the crystalline sponges based on the famous metal-organic frameworks.More importantly,it can achieve rapid structure determination of small molecules within 3 h.

Stability of selenium and its speciation analysis in water using automatic system separation and HR-ICP-MS measurement

A simple and convenient method has been developed for the pre-concentration and separation of inorganic selenium species from environmental water samples using anion exchange chromatographic column combined with high resolution inductively coupled plasma mass spectrometry(HR-ICP-MS)measurement.^(75)Se(Ⅳ) and ^(75)Se(Ⅵ)were prepared and used as tracers during the experiments.The volatility of selenium during solution evaporation was investigated to establish a reliable water samples pretreatment procedure.The parameters which affect the uptake of Se(Ⅳ)and Se(Ⅵ)on Dowex1×8 resin was optimized and the procedure for Se(Ⅳ)and Se(Ⅵ)separation was proposed.Both Se(Ⅳ)and Se(Ⅵ)are retained on the column in natural or alkaline solution with high distribution coefficient.The successive gradient elution of pre-concentrated species of selenium with HNO_(3)solution allows to differentiate between them.Se(Ⅳ)and Se(Ⅵ)finally were eluted with 0.05 mol/L HNO_(3) and 5.0 mol/L HNO_(3),respectively.The proposed method has been successfully verified using the certified reference materials(CRMs)of real water samples,and spiked recoveries for real samples were 98%-104%with 5%relative standard deviations(RSDs).The developed procedure is proved to be reliable and can be used for the rapid determination of selenium species in environmental water samples.