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.

[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.