Rapid qualitative and quantitative analysis of methamphetamine, ketamine, heroin, and cocaine by near-infrared spectroscopy.

Rapid and nondestructive near infrared spectroscopy (NIR) methods have been developed for simultaneous qualitative and quantitative analysis of methamphetamine, ketamine, heroin, and cocaine in seized samples. This is the first systematic report regarding a qualitative and quantitative procedure of applying NIR for drug analysis. A total of 282 calibration samples and 836 prediction samples were used for the building and validating of qualitative and quantitative models.

[Multivariate Calibration Combined with Mass Spectrometry for Rapid Analysis].

A mixture of four substances of benzaldehyde, iso-octane, butyl acetate, acetophenone were quantitatively analyzed by mass spectrometry combined with chemometrics. The mass chromatogram data of mixture were proceeded with two methods for quantitative analysis. One is feature selection--Multiple Linear Regression (MLR) and the other is full spectrum--Partial Least Squares (PLS).

[Simultaneous determination of instant coffee, plant fat and sugar content in liquid coffee beverage by diffuse reflectance near-infrared spectroscopy].

The diffuse reflectance near-infrared spectra of 20 liquid coffee beverage samples were collected by FT-NIR spectrometer combined with integral sphere in this thesis. The quantitative calibration models of instant coffee, plant fat and sugar were developed respectively. The result indicated that for the calibration models of instant coffee, plant fat and sugar, the dimensions of the calibration models are 4, 5 and 4 respectively; the determination coefficients (R2) are 98.

[Near-infrared spectroscopy quantitative analysis model based on inverse regression].

In the present paper, an inverse regression method is used in near infrared (NIR) spectroscopy analysis to reduce dimension of predictor at first, then estimate linear regression function using the new derived low dimensional data. A real data set of 103 corn samples was used for analysis with this new inverse regression method. Taking 103 corn samples as experiment materials, seventy samples were chosen randomly to establish predicting model, the remaining thirty-three corn samples were viewed as prediction set.

[Fast determination of the proportion of metalaxyl-M enantiomers by UV spectroscopy].

In the present study, beta-cyclodextrin(betaCD) was used as chiral selector to detect the proportion of chiral isomers of metalaxyl. The proportion of metalaxyl enantiomers can be detected by ultraviolet (UV)spectroscopy since the interaction between the R, S isomer of metalaxyl with beta-CD is different. The quantitative models were established by partial least squares regression (PLS) and the robust of models was evaluated by independent validation samples.

[Rapid detection of dichlorvos in chlorpyrifos by mid-infrared and near-infrared spectroscopy].

In the present study, the content of dichlorvos in chlorpyrifos was rapidly determined by mid-infrared and near-infrared spectroscopy. The quantitative models were established by partial least squares (PLS) method and optimized. The independent validation sets and 7 test samples were used to evaluate the model accuracy.

[Quantitative analysis of the content of deltamethrin in agrochemicals by near-infrared, attenuated total reflectance infrared and raman spectroscopy].

The method of near-infrared, attenuated total reflectance infrared and Raman spectroscopy was used for the rapid determination of the content of deltamethrin in agrochemicals. The quantitative models were established by PLS (partial least squares) method and optimized. The independent validation sets were used to evaluate the model accuracy.

[Near-infrared spectrum quantitative analysis model based on principal components selected by elastic net].

Elastic net is an improvement of the least-squares method by introducing in L1 and L2 penalties, and it has the advantages of the variable selection. The quantitative analysis model build by Elastic net can improve the prediction accuracy. Using 89 wheat samples as the experiment material, the spectrum principal components of the samples were selected by Elastic net.

[Spectrofluorimetric study of supramolecular inclusion between rodenticide brodifacoum and beta-cyclodextrin and application].

The supramolecular interaction between beta-cyclodextrin and brodifacoum, an anticoagulant rodenticide of the second generation, was studied by spectroscopy. The results showed that brodifacoum and beta-cyclodextrin could form an inclusion complex with an association constant of 1.048 x 10(4) L x mol(-1) and a 1 : 1 stoichiometry based on Benesi-Hildebrand equation.

[Spectroscopic study on interaction of rodenticide brodifacoum with bovine serum albumin].

The mutual interaction of bovine serum albumin (BSA) with brodifacoum (3-[3-(4'-bromophenyl-4) 1,2,3,4-tetralin-10]-4-hydroxyl-coumarin), an anticoagulant rodenticide, was investigated by ultra-violet spectroscopy, flurorescence spectroscopy and synchronous fluorescence spectroscopy under physiological conditions. It was proved that the intrinsic fluorescence quenching of BSA by brodifacoum was the result of the formation of brodifacoum-BSA complex. And this quenching is mainly due to static fluorescence quenching.

[Comparison of the models of mixed liquid samples under different near-infrared spectral resolutions].

Models of near-infrared spectra under different resolutions, 1, 4, 16, 32 and 64 cm(-1), were studied with the mixed liquid samples of 4 components. The calibration models were developed by the method of partial least square and the validations of the models were carried out by the method of full cross. The value of target function was used to estimate the models performance.

[Study of the interaction mechanism between brodifacoum and DNA by spectroscopy].

The interaction between brodifacoum (3-[3-(4'-bromophenyl-4) 1,2,3,4-tetralin-10]-4-hydroxyl-coumarin) (BDF), an anticoagulant rodenticide, and calf thymus DNA (ct-DNA) was studied by UV spectrum and fluorescence spectrum. The results were summarized as follows: There was a hypochromic effect of low concentration ct-DNA on the UV spectra. The fluorescence quenching studies showed a regular decrease in the fluorescence intensity after addition of ct-DNA by the static quenching mode with a quenching constant (Ksv) of 1.

[Applications of near-infrared spectroscopy to analysis of traditional Chinese herbal medicine].

Analysis of traditional Chinese herbal medicine is of great importance to its quality control Conventional analysis methods can not meet the requirement of rapid and on-line analysis because of complex process more experiences or needed. In recent years, near-infrared spectroscopy technique has been used for rapid determination of active components, on-line quality control, identification of counterfeit and discrimination of geographical origins of herbal medicines and so on, due to its advantages of simple pretreatment, high efficiency, convenience to use solid diffuse reflection spectroscopy and fiber. In the present paper, the principles and methods of near-infrared spectroscopy technique are introduced concisely.

[Study on the interaction of carbaryl and ctDNA by resonance light scattering spectra and its application].

Interaction modes of carbaryl and DNA were studied by resonance light scattering (RLS) spectra and absorption spectra. Experiments show that at pH 1.97, there are two interaction modes between carbaryl and ctDNA, namely surface assembly mode and intercalative mode.

[Study on the methods and applications of near-infrared spectroscopy chemical pattern recognition].

Near infrared spectroscopy pattern recognition technique is an important part of modern near infrared spectroscopy technique. In the present paper, main methods of near infrared spectroscopy chemical pattern recognition and some recent developments are introduced. Basic principles of the methods in cluster analysis, discriminant analysis and latent projection are discussed, including some new methods such as support vector machines (SVM), bubble agglomeration algorithm (BA) and focal eigen functions (FEF) etc.

[Interaction between carbaryl and calf thymus DNA enhanced via Cu2+].

The interaction between carbaryl and calf thymus DNA with Cu2+ was studied using fluorescence spectroscopy (FS) and UV spectrum. The quenching process was proved to be single static quenching and the quenching constant decreases with temperature increasing. The experimental results showed that the carbaryl can be intercalated into the twin-screw structure of calf thymus DNA, forming ctDNA-carbaryl adducts.

[The mechanism of carbofuran interacts with calf thymus DNA].

Carbofuran is an insecticide used on a variety of corps. Acute and chronic occupational exposure of humans to carbofuran has been observed to cause cholinesterase inhibition, but little is known about the interaction of carbofuran with DNA. Using the technique of UV spectrum and fluorescence quenching respectively, the interaction between carbofuran and ct DNA was studied.

[Nondestructive analysis of protein and fat in whole-kernel soybean by NIR].

Near-infrared diffusion reflectance spectroscopy is a fast technique that can provide component information about intact soybean samples. We have combined this technique with partial least-squares (PLS) regression to perform a quantitative determination of protein and fat contents in soybean samples. In calibration set, the NIR model determination coefficient R2 of protein and fat is 0.

[Outlier diagnosis and calibration model optimization for near infrared spectroscopy analysis].

Outlier diagnosis is a very important step in building near infrared calibration model. Data outlier includes spectral outlier and chemical value outlier. Mahalanobis' distance, ratio of spectral residual and spectral variable leverage test were used to evaluate sample spectral outlier.