Enrichment and separation of acidic and basic proteins using the centrifugal ultrafiltration followed by nanoparticle-filled capillary electrophoresis

This report describes a method for enrichment and separation of acidic and basic proteins using the centrifugal ultrafiltration followed by nanoparticle-filled capillary electrophoresis. To improve stacking and separation efficiencies of proteins, the separation buffer containing 1.6% poly(diallyldimethylammonium chloride) was added with gold nanoparticles (AuNP), poly(ethylene oxide), cetyltrimethylammonium bromide, and poly(vinyl alcohol). As a result, the use of AuNP as additives exhibited better efficiency in separation, stacking, and analysis time. Even for large-volume samples (110 nL), the separation efficiencies of acidic and basic proteins remained greater than 10(4) and 10(5) plates/m, respectively. To further enhance detection sensitivity, protein samples were enriched using the centrifugal ultrafiltration, followed by our proposed stacking method. The detection sensitivity was improved up to 314-fold compared to normal hydrodynamic injection. Additionally, the limits of detection at a signal-to-noise of 3 for most proteins were down to nanomolar range. We have validated the application of our method by means of analyses of 50 nM lysozyme in saliva samples. The proposed method was also successfully applied to the analyses of egg-white proteins, which have large differences in molecular weight and pI.     

多壁碳纳米管对质谱分析中的血清蛋白富集作用研究

通过多壁碳纳米管(MWCNTs)对临床血清蛋白提取物进行富集处理,经表面增强激光解析离子化飞行时间质谱(SELDI-TOF-MS)检测,发现MWCNTs对血清中小分子量蛋白(<20 kDa)具有很好的富集效果。同时还考察了内径、长度等参数对血清蛋白富集效果的影响。该方法可用于临床血清样本中低丰度的小分子量蛋白的检测。     

Leachability and analytical speciation of antimony in coal fly ash

A new procedure was described with multiwalled carbon nanotubes as solid phase extraction packing material for the trace analysis of nicosulfuron, thifensulfuron and metsulfuron-methyl in water samples. The possible parameters influencing the enrichment were optimized and the optimal conditions were as followed: eluent, sample pH, flow rate and sample volume were acetonitrile containing 1% acetic acid, pH 3, 8 mL min⁻¹ and 500 mL, respectively. Under the optimal chromatographic separation and SPE conditions, the linear range, detection limit (S/N = 3) and precision (R.S.D., n = 6) were 0.04-40 ng mL⁻¹, 6.8 ng L⁻¹ and 2.5% for nicosulfuron, 0.04-40 ng mL⁻¹, 11.2 ng L⁻¹ and 5.4% for thifensulfuron, 0.02-20 ng mL⁻¹, 5.9 ng L⁻¹, 2.1% for metsulfuron-methyl, respectively. The established method was well employed to determine nicosulfuron, thifensulfuron and metsulfuron-methyl in tap water, seawater, reservoir water and well water samples, and satisfactory results were obtained, the spiked recoveries in the range of 87.2-100.7%, 96.5-105.6% and 83.7-111.1% for them each, respectively.     

Elemental compositions of PM2.5 and TSP in Lijiang,southeastern edge of Tibetan Plateau during pre-monsoon period

PM_2.5 and total suspended particulate（TSP） samples were collected at Lijiang,southeastern Tibetan Plateau.China.Sixteen elements（Al,Si,S,K,Ca,Cr,Mn,Ti,Fe,Ni,Zn,As,Br,Sb,Pb and Cu） were analyzed to investigate their elemental compositions during the pre-monsoon period.The results showed that Ca was the most abundant element in both PM_2.5 and TSP samples.The enrichment factors（EFs） of Si,Ti,Ca, Fe,K and Mn were all below 10 for both PM_2.5 and TSP,and these elements also had lower PM_2.5/TSP ratios （0.32-0.34）,suggesting that they were mainly derived from crustal sources.Elements Cu,Zn,S,Br and Sb showed strong enrichment in PM_2.5 and TSP samples,with their PM_2.5/TSP ratios ranging from 0.66 to 0.97,indicating that they were enriched in the fine fractions and influenced by anthropogenic sources. Analysis of the wind field at 500 hPa and calculations of back trajectories indicated that Al,Si,Ca,Ti,Cr, Mn and Fe can be influenced by transport from northwestern China during the dust-storm season,and that S,K,Ni,Br and Pb reached high concentrations during westerly transport from south Asia.Combined with the principle component analysis and correlation analysis,elements of PM_2.5 samples were mainly from crustal sources,biomass burning emissions and regional traffic-related sources.