Application of Near Infrared Spectroscopy Coupled with Fluidized Bed Enrichment and Chemometrics to Detect Low Concentration of ß-Naphthalenesulfonic Acid.

A fluidized bed enrichment technique was developed to improve sensitivity of near infrared (NIR) spectroscopy with features of rapidness and large volume solution. D301 resin was used as an adsorption material to preconcentrate ß-naphthalenesulfonic acid in solutions in a concentration range of 2.0-100.0 µg/mL, and NIR spectra were measured directly relative to the ß-naphthalenesulfonic acid adsorbed on the material. An improved partial least squares (PLS) model was attained with the aid of multiplicative scatter correction pretreatment and stability competitive adaptive reweighted sampling wavenumber selection method. The root mean square error of cross validation was 1.87 µg/mL at PLS factor of 7. An independent test set was used to assess the model, with the relative error (RE) in an acceptable range of 0.46 to 10.03% and mean RE of 3.72%. This study confirmed the viability of the proposed method for the measurement of a low content of ß-naphthalenesulfonic acid in water.

Determination of triazine herbicides in milk by cloud point extraction and high-performance liquid chromatography.

High-performance liquid chromatography with UV detection was used to detect four triazines in milk. An efficient pretreatment method known as cloud point extraction (CPE) was proposed for extracting and preconcentrating analytes. The parameters of CPE including surfactant type and concentration, electrolyte, sample pH, incubation temperature and duration were investigated. Under optimal conditions, satisfying recoveries in the range of 70.5-96.9% were achieved for four triazines. The limits of detection ranged from 6.79 to 11.19µg L(-1). The linear range of quantitation for the four triazines was 50-2000µg L(-1), and the correlation coefficients of the calibration curves were all 0.9999. The results demonstrated that the proposed method was efficient and reliable for the determination of triazine herbicides in milk samples.

[Simultaneous determination of 11 quinolones in hotpot ingredients by dispersive solid-phase extraction and ultra performance liquid chromatography-tandem mass spectrometry].

A method for the simultaneous determination of the residues of 11 quinolones in hotpot ingredients by quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction and ultra performance liquid chromatography-tandem mass spectrometric method (UPLC-MS/MS) was established. The sample was extracted with acetonitrile (containing 5% formic acid) and followed by stratifying with a salting-out agent. Clean-up of the extracts was processed by C18 and PSA, a modified QuEChERS procedure. The analytes were then separated on a Poroshell 120 EC-C18 column, and finally detected by tandem mass spectrometry in positive ESI mode. The linearity of all the 11 quinolones in the range from 1.0 to 100.0 microg/kg had correlation coefficients greater than 0.998. The limits of detection (LOD) of the method were from 1.8 to 3.1 microg/kg and the limits of quantification (LOQ) were from 6.0 to 10.3 microg/kg. The average recoveries of the 11 quinolones were in the range from 70.1% to 100.3%, with relative standard deviations from 2.42% to 10.88%. The established method is sensitive and of good recoveries. It can be applied as a rapid and reliable method for the determination of the 11 quinolones in hotpot ingredients.

[Identification of irradiated abalone by ESR spectroscopy].

OBJECTIVE: To establish an analytical method for the detection and identification of irradiated abalone by electron spin resonance spectroscopy. METHODS: Electron spin resonance (ESR) was used to study the spectral characteristics of abalone and the characteristic peak for quantitation. RESULTS: There were obvious different ESR spectra between unirradiated and irradiated abalone. The g factor for unirradiated abalone was 2.0055-2.0060, the g1 and g2 factor for irradiated abalone were (2.0027 +/- 0.0001) and (1.9994 +/- 0.0001), respectively. The ESR signal intensity of characteristic peak was positively correlated with absorbed dose in the range of 0.5 - 10 kGy, left peak was the characteristic peak for quantitation and the detection limit was < or = 0.5 kGy. It was difficult to quantitate when the absorbed dose was over 10 kGy. ESR characteristic peak and g factor were able to qualitatively determine the irradiation of abalone. CONCLUSION: ESR spectroscopy is an effective method to determine whether the abalone being irradiated or not.

[Infrared spectroscopy investigation on conformational change of silk fiber induced by gaseous organic acids existing in museum].

Study on the impact of pollutants on cultural materials in storing or displaying micro-environment in museum is considered as very important for the preservation of cultural relics and its aging prevention. This paper applied the Fourier transform infrared (attenuated total reflection) technique to assess silk structural changes under volatile organic acids (formic acid/acetic acid), which usually come from decorative materials emission and commonly exist in the surface or around cultural materials. The focus of this work was on investigating the changes of peptide bond in the area of amide I-amide III, as well as the peptide chains (GlyAla), characteristic region. The structural and conformational changes in silk fiber treated with gaseous formic and acetic acid were assessed. The results indicate that both the gaseous acids can weaken the intermolecular hydrogen bond in fiber peptide, based on the spectral changes in the increased intensity of amide I (1 617 cm(-1)), the narrowing amide II peak (1 515 cm(-1)), the increased intensity of random coil conformation in amide III peak (1 230 cm(-1)), and the decreased fiber crystallinity as well. The obvious secondary structural conformation occurred when the concentration of gaseous formic acid reached 8.1 mg x m(-3) in simulated environment. The conformational transformation was supported by the observation of the rapidly reduced random coil conformation, the increased short peptide chains (GlyAla)n with beta-sheet conformation characteristic peak (1 000, 975 cm(-1)), and the enhanced fiber crystallinity degree as well. In contrast, gaseous acetic acid has less impact on the amide I and amide II bond based on the spectral changes, but it did promote random coil conformation and decreased fiber crystallinity. This work also provides a potential application of the infrared spectroscopy in non-destructive investigation of silk in-situ.

Determination of tricyclazole content in paddy rice by surface enhanced Raman spectroscopy.

An ultrasensitive method based on Surface enhanced Raman scattering (SERS) has been developed to determine content of a pesticide which is tricyclazole in paddy rice using sliver colloid as a substrate and pyridine as an internal standard. The peaks at 424 and 1035 cm(-1) in a SERS spectrum were selected as analytic and internal peaks, respectively, and their intensity ratio I(t)/I(p) was used to calculate the regression concentration of tricyclazole. The correlation between I(t)/I(p) and concentration showed significant linear relationship with a correlation coefficient of R(2)= 0.995 in a concentration range of 0.05 to 0.70 mg/L and the tricyclazole solution can be detected to be low as 0.002 mg/L by SERS. The method was applied to determine tricyclazole contents of 3 real rice samples with a standard addition method in order to eliminate interference of matrix. The errors of SERS measurements for the 3 samples were 0.0008 to 0.0246, 0.0013 to 0.0028, and 0.0129 to 0.0304 mg/kg, respectively, compared with the results obtained by high performance liquid chromatography method. This also showed a good reproducibility with low values of relative standard deviation (n= 3) for the 3 samples ranged from 3.63% to 4.64%.