Magnetic metal-organic frameworks for fast and efficient solid-phase extraction of six Sudan dyes in tomato sauce.

Magnetic solid-phase extraction is an effective and useful technique to preconcentrate trace analytes from food samples. In this study, a magnetic trimeric chromium octahedral metal-organic framework (Fe3O4-NH2@MIL-101) was fabricated and characterized. Fe3O4-NH2@MIL-101 was applied as an adsorbent of magnetic solid-phase extraction combined with high performance liquid chromatography to effectively isolate and simultaneously determine six Sudan dyes (Para Red, Sudan I-IV, and Sudan Red 7B) from tomato sauce. Potential factors affecting the MSPE were investigated in detail, and adsorption efficiency of Fe3O4-NH2@MIL-101 was compared with those of conventional adsorbents, such as neutral alumina, HLB, and C18. The developed method facilitated the extraction with using only 3 mg of adsorbent in 2 min. In addition, enhancement factors of 50, linear range of 0.01-25 µg/mL, and detection limit (S/N = 3) of 0.5-2.5 µg/kg were obtained. The intra-day and inter-day recoveries for spiked Sudan dyes were in the range of 72.6%-92.9% and 69.6%-91.6%, respectively, with relative standard deviations of ≤9.2%.

Effective extraction and simultaneous determination of Sudan dyes from tomato sauce and chili-containing foods using magnetite/reduced graphene oxide nanoparticles coupled with high-performance liquid chromatography.

A simple, effective, and robust magnetic solid-phase extraction method was developed using magnetite/reduced graphene oxide nanoparticles as the adsorbent for the simultaneous determination of Sudan dyes (I, II, III, and IV) in foodstuffs. The magnetite/reduced graphene oxide nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. The extraction parameters including extraction time, elution solution, and elution time and volume were investigated in detail. Such magnetite/reduced graphene oxide nanoparticles based magnetic solid-phase extraction in combination with high-performance liquid chromatography and variable wavelength detection gave the detection limits of 3-6 µg/kg for Sudan I-IV in chili sauce, tomato sauce, chili powder, and chili flake samples. The recoveries were 79.6-108% at three spiked levels with the intra- and inter-day relative standard deviations of 1.2-8.6 and 4.5-9.6%, respectively. The feasibility was further performed by a comparison with commercial alumina-N. This method is suitable for the routine analysis of Sudan dyes due to its sensitivity, simplicity, and low cost.

[The change of pulmonary surfactant protein of rat following silica exposure].

OBJECTIVE: To investigate the change of lung surfactant protein (SP) A,B,C,D of rats following silica dust exposure in order to provide the evidences for the early diagnosis indices or therapy of silicosis. METHODS: 60 male SD rats were randomly divided into silica group, and corresponding controls group. Rats in silica group were administrated 1 ml silica solution by intratracheal instillation at dose of 50 mg/ml. Rats in control group were administrated the same amount saline. At 3rd, 7th, 14th, 21st, 28th after silica exposure, serum and bronchoalveolar lavage fluid (BALF) samples were obtained. The concentration of SP-A, SP-B, SP-C, SP-D in serum and BALF were measured by using enzyme immunoassay (ELISA). Meanwhile the levels of total anti-oxidative activity (T-AOC) and hydroxyproline (HYP) in lung tissue were also detected. The pathology of lung tissue was conducted. RESULTS: Compared with control group, SP-A concentration in BALF of silica exposed rat for 3, 14, 21, 28d was significant lower and SP-D concentration in BALF of silica exposed rat for all time points was also lower. The differences were significant (P < 0.05). Meanwhile SP-B level in 7, 14, 21, 28 d silica exposed rats BALF and SP-C level in 14, 21, 28 d silica exposed rats markedly decreased (P < 0.05). In addition compared with control group, SP-A, SP-B and SP-C concentration in serum of silica exposed rat were higher when SP-A for 14, 21, 28 d silica exposure, SP-B for 7, 14, 21 d silica exposure and Sp-C for 7, 14, 21, 28 d exposure. And all difference were significant (P < 0.05). As silica exposure time increased, SP-C concentration in serum showed an increase trend, which showed a time-response relationship (r = 0.618, P = 0.042). However, SP-D concentration in serum of rat for 7, 14, 21, 28d silica exposure were significant lower than that of control group (P < 0.005). And there was a decrease trend with time point exposure regarding of SP-D (r = -0.731, P = 0.016). The HYP content in lung tissue of experiment rats increased at 3rd, 7th, 14th, 21st and 28th day time point and The T-AOC activity in lung tissue decrease at, 7th, 14th, 21st and 28th day time point. The differences were significant (P < 0.05). There was a positive correlation (P = 0.803, P = 0.045) between SP-C in BALF and HYP of silica exposed rats and a negative correlation between SP-D in BALF and HYP (r = -0.867, P = 0.033). No significant correlation were seen between SP-A, SP-B BALF and HYP (y = 0.416, P = 0.28; r = 0.592, P = 0.071). SP-C concentration in BALF and serum all showed an increased trend and a positive correlation was seen (r = 0.539, P = 0.046). The same decrease trend was seen between SP-D in BALF and serum and correlation value was 0.870 (P = 0.034). CONCLUSION: The silica exposure did cause the change of SP content both in BALF and serum. The SP-C and SP-D content in serum might be served as an early effective biomarker of silicosis.

[Effects of acrylamide on the permeability of blood cerebrospinal fluid barrier in rats].

OBJECTIVE: To explore the effects of acrylamide on the permeability of blood cerebrospinal fluid barrier (BCB) and tight junction protein ZO-1 of choroid plexus in rats and to provide a theoretical basis for explaining the mechanism of nerve injury induced by acrylamide. METHODS: Thirty two male Sprague-Dawley rats were randomly divided into ACR and control groups. ACR group was exposed to 20 mg/kg ACR daily for 5 days a week by intraperitoneal injection (i.p.) for 4 weeks. Control group was exposed to normal saline. The neurobehavioral tests (including sensatory and motor functions) were performed every week. At the end of exposure, Evan blue (EB) and Sodium fluorescein (NaFI) content in rat CSF were detected for determining the BCB permeability, Real-time PCR was used to measure the expression levels of ZO-1 mRNA in the epithelium cells of choroid plexus, and laser scanning confocal microscope (LSCM) was utilized to observe the distribution of ZO-1 protein. RESULTS: Neurobehavioral tests showed that the tail-flick latencies of ACR group were 27.77% and 53.71% as long as control group in the 3rd week and 4th week, respectively (P < 0.05). The hind lamb splay distances of ACR group were 131.76% and 153.77% as long as control group in the 3rd week and 4th week, respectively (P < 0.05). Evan blue (EB) and Sodium fluorescein (NaFI) content of ACR group were significantly higher than those of control group (P < 0.05). In the 4th week, the expression level of ZO-1 mRNA in ACR group was 0.21 +/- 0.07, which was significantly lower than that (0.31 +/- 0.11) in control group (P < 0.05). In the 4th week, the ZO-1 protein expression level of choroid plexus in ACR group was significantly lower than that in control group (P < 0.05). CONCLUSION: Acrylamide could increased the BCB permeability of rats, which may be involved in the central nervous injury induced by ACR.

[Preliminary study of biomarker in blood or cerebrospinal fluid of rat following manganese exposure].

OBJECTIVE: To explore the biomarkers of manganese exposure by measuring the manganese (Mn) and iron (Fe) level as well as the mRNA change of Hepcidin, divalent metal-ion transporter-1 (DMT1) and Parkin-2, one of genes related to Parkinson disease in body fluid and brain tissues of rat. METHODS: Male Sprague-Dawley rats were administered (i.p) either MnCl2 solution (6 mg Mn/kg) or the same volume saline, 5 times per week and for 4 weeks. Graphic furnace Atom Absorption Spectrum (AAS) was applied to measure the concentration of Mn and Fe in brain tissue and body fluids. Meanwhile Hepcidin, DMT1 and Parkin-2 mRNA expression were detected by real-time RT-PCR. RESULTS: Mn concentration in erythrocytes of rats was the 86.9 folds of that in control; No significant change was found in plasma. However the trend and range of Mn increase in cerebrospinal fluid (CSF) was the same as that in brain tissue including striatum, cortex, hippocampus and choroid plexus. Meanwhile Fe concentration in brain tissue of Mn exposed rats was also higher than that of control, whose trend was as same as that in CSF. However iron concentration in plasma decreased. The real-time RT-PCR data also showed that Hepcidin mRNA expression in Mn-exposed rat decreased 56% in blood, which was in line with its expression in cortex(67%). Similarly, Parkin-2 mRNA expression decreased both in blood (42%) and in striatum. However DMT1 mRNA expression increase 38% in striatum of Mn-exposed rats but decreased in blood. CONCLUSION: Hepcidin and Parkin-2 mRNA expression in blood might be serves as the effective biomarkers following manganese exposure, certainly which needs to be further explored.

[In situ resonance Raman spectra of organic pigments in freshwater cultured pearls].

In situ resonance Raman spectra of Chinese freshwater pearls were collected and analysed systematically with three different excitation wavelengths at lambda = 514, 633 and 785 nm. At the same time, the Raman spectra of eggshells of Pomacea canaliculata were also collected under the same experimental conditions in order to compare with pearls' Raman spectra. The conclusions were as follows: (1) Frequency dispersions of Raman spectra of organic pigments were obviously observed in Raman spectra of pearls. In contrast, Raman spectra of organic pigments in eggshells of Pomacea canaliculata showed no frequency dispersion phenomena; (2) It was considered that the organic pigments in pearls were polyacetylenic materials but not carotenoids which was proposed by previous researchers, and the organic pigments in eggshells of Pomacea canaliculata were carotenoids; (3) The conjugated (>=C number of polyacetylenic material in pearls was calculated to be about 10 and 16, and the conjugated C[double bond]C number of carotenoid in eggshells of Pomacea canaliculata was about 13 based on the Raman shifts caused by conjugated C[double bond]C double bonds.