Rapid Determination of Trace Multiresidues of 18 Sulfonamides in Chicken Eggs Using a Modified QuEChERS Method Coupled with Ultrahigh Performance Liquid Chromatography.

A modified QuEChERS method was used and an ultrahigh performance liquid chromatography (UHPLC) method was developed for the rapid determination of 18 kinds of sulfonamide residues in chicken eggs. Sample preparation and cleanup conditions were carefully evaluated, and factors such as the adsorbent type and adsorption condition were key parameters in improving the cleanup. The modified QuEChERS method removed matrix interferences, and the sensitivity of the method increased about 5% for recovery and efficiency of the method. Under the optimized UHPLC method with UV detection, all 18 sulfonamide residues were simultaneously separated and rapidly identified within 15 min. The qualitative and quantitative method limits of the 18 sulfonamide residues were 2.06 to 4.12 and 6.86 to 13.7 µg·kg-1, respectively. A close linear relationship (R2 = 0.990 to 0.999) was observed within the concentration range of 0.10 to 2.25 µg·ml-1. Recovery was satisfactory (71 to 102%) for all the sulfonamides in three standard spiked levels, with relative standard deviations of <9.7%. After the modified sample pretreatment, the speed of sample pretreatment, purification, and analysis efficiency were all significantly increased. This method is suitable for the rapid detection of multisulfonamide residues in chicken eggs and other animal-derived foods.

Rapid Identification and Quantification of Natural Antioxidants in the Seeds of Rhubarb from Different Habitats in China Using Accelerated Solvent Extraction and HPLC-DAD-ESI-MSn-DPPH Assay.

In this study, the 10 accessions of rhubarb seeds from different habitats in China were investigated. Lipids were removed using petroleum ether, and the effective components were then separated using accelerated solvent extraction with 80% aqueous methanol. An off-line 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging method was used as the marker to evaluate the total antioxidant capability of extracts. On-line high-performance liquid chromatography-diode-array detectors-electrospray ionization-tandem mass spectrometry (HPLC-DAD-ESI-MS(n)) and HPLC-DAD-DPPH assays were developed for rapid identification and quantification of individual free-radical scavengers in extracts of rhubarb seeds. Ten free-radical scavengers from methanolic extracts of the rhubarb seeds were screened, five of which were identified and quantitatively analyzed: epicatechin, myricetin, hyperoside, quercitrin and quercetin. All were identified in rhubarb seeds for the first time and can be regarded as the major potent antioxidants in rhubarb seeds due to representing most of the total free-radical scavenging activity. Preliminary analysis of structures was performed for another five antioxidants. Based on our validation results, the developed method can be used for rapid separation, convenient identification and quantification of the multiple antioxidative constituents in rhubarb seeds, featuring good quantification parameters, accuracy and precision. The results are important to clarify the material basis and therapeutic mechanism of rhubarb seeds.

[Simultaneous determination of gastrodin and eight nucleosides and nucleobases in Tibet cultured gastrodia elata by HPLC method].

This study aims to establish an HPLC method for simultaneous determination of gastrodin and eight nucleosides and nucleobases components in Gastrodia elata. The separation was carried out on an Agilent Zorbax Bonus-RP (4.6 mm x 250 mm, 5 µm) column with a methanol-(0.04% acetic acid) water solution gradient elution program at a flow rate of 1.0 mL x min(-1). The column temperature was 36 degrees C, and the detection wavelength was 254 nm. The volume of injection was 20 µL. The nine components including gastrodin, cytosine, uracil, cytosine, adenine, thymine, uridine, guanosine and adenosine were well separated. The calibration curve was well linear in the range of 2.04-262.00 mg x L(-1), 0.20-24.67 mg x L(-1), 0.18-23.75 mg x L(-1), 0.20-25.83 mg x L(-1), 0.20-26.67 mg x L(-1), 0.16-20.00 mg x L(-1), 0.22-27.71 mg x L(-1), 0.20-24.29 mg x L(-1), 0.24-30.58 mg x L(-1), respectively, and the correlation coefficient was between 0.998 9-0.999 9. The average recovery of gastrodin and eight nucleosides and nucleobases were 96.4%-99.6%, RSD less than 2.7% (n = 6). The contents of gastrodin in all the seven Tibet cultured Gastrodia elata samples were over 2 mg x g(-1). Further, all samples contain higher contents of adenosine, guanosine, uridine and cytidine compared to low contents of cytosine, uracil, adenine and thymine. The established method is accurate, reproducible and suitable for the determination of gastrodin and eight nucleosides and nucleobases comppnents in Gastrodia elata.

[Determination of trace element contents in Urtica laetevirens Maxim. reaped in different months by ICP-MS].

The contents of twenty kinds of trace elements, Al, Ba, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S and Zn, were determined by ICP-MS with microwave digestion in Urtica laetevirens Maxim. The recovery (n=7) is 95.4%-101.2%, and the RSD (n=7) is 1.2%-5.3%. The contents of K, P, S, Ca and Na in the samples were abundant while Fe, Mg, Mn and Zn were less abundant. The contents of Al, Cr and Pb which were harmful to human were kept at low level. The contents of trace elements in Urtica laetevirens Maxim. also showed obvious seasonal dynamics. This result provides some theoretical basis for the study of internal relations between trace elements in Urtica laetevirens Maxim. and its efficacy. It's also useful for better development and utilization of the resource.

[Determination of trace determination of elements in medicinal materials of cultivated and wild Rhizoma et Radix Notopterygii vegetated in different months by flame atomic absorption spectrometry].

The contents of six trace elements Ca, Mg, Fe, Mn, Cu and Zn in the medicinal materials of cultivated and wild Rhizoma et Radix Notopterygii vegetated in different months were determined by flame atomic absorption spectrometry (FAAS) with air-acetylene flame, and the feature of trace elements contents and their seasonal dynamics were analyzed using SPSS16.0 analysis software. The recovery rate obtained by standard addition method ranged between 96.33% and 105.25%, and the relative standard deviation was 0.84%-2.98%. This showed that the method had good precision and definition. The study indicated that there are abundant microelements in medicinal materials of cultivated and wild Rhizoma et Radix Notopterygii. The contents of Ca are both highest in the medicinal materials of cultivated and wild Rhizoma et Radix Notopterygii, and the contents of Cu element are lowest; the contents order is Ca > Mg > Fe > Mn > Zn > Cu; the seasonal dynamics of Ca, Mg, Fe, Mn, Cu and Zn had obvious regularity in the medicinal materials of cultivated and wild Rhizoma et Radix Notopterygii. It is concluded that the amount of six elements in wild Rhizoma et Radix Notopterygii are more than the cultivated; the data can provide reference for artificial cultivation of wild herbs.

[Analysis of total alkaloids in Meconopsis quintuplinervia from different localtites of Qinghai].

The contents of total alkaloids in Meconopsis quintuplinervia Regel, grown in the different localtites of Qinghai Province, are detected by the method of spectrophometry. The result showed that total alkaloid in different localities were 0. 0262% to approximately 0.0788% , its mean was 0.0502%. The content of total alkaloids in the herb increased with elevation, not with latitude.

[Determination of the base contents of liver DNA of rats by reversed-phase high performance liquid chromatography].

The base contents of liver deoxyribonucleic acid (DNA) of rats living at an altitude of 2.3 km were determined by reversed-phase high performance liquid chromatography. At first, 0.05 mol/L KH2PO4(pH 4.0) was used to dissolve the DNA acid hydrolysis products with 8-bromoguanosine (Br8G) as an internal standard. Then the DNA hydrolysis products with Br8G were chromatographed on a Supelcosil LC-18 column with UV detection at 254 nm and eluted by the mobile phase of MeOH-0.05 mol/L KH2PO4(pH 4.0) (20:80, V/V) at the flow rate of 0.8 mL/min. Under these conditions, several bases were separated effectively. From the results, the relatively constant proportions of the bases in DNA were found. The contents were 17.4% of cytosine (C), 28.8% of adenine (A), 23.3% of guanine (G) and 25.3% of thymine (T). RSDs of the determination of these bases were 1.7%, 1.5%, 1.3% and 2.1%, respectively. At the same time the methylation level of liver DNA of the rats determined by the internal standard method was 6.2%.