ABSTRACT
Objective@#To establish analytical method for the determination of vanadium ( V ), chromium ( Cr ), nickel ( Ni ), selenium ( Se ) and arsenic ( As ) in calcium based toothpastes by microwave digestion-inductively coupled plasma tandem mass spectrometry ( ICP-MS/MS ).@*Methods@#The 21 calcium based toothpaste samples from supermarkets and shops in the urban areas of Hangzhou were digested by 6 mL HNO3 and 1 mL H2O2 in microwave digestion system. Then He-SQ mode and O2-MS/MS mode of ICP-MS/MS were respectively used for the determination of Ni and V, Cr, Se, As. Indium ( In ) was used as internal standard for calibration. @*Results@# Good linear relationships were obtained for these five elements from 1.0 to 32.0 μg/L, with the correlation coefficients ranged from 0.999 3 to 1.000 0. The detection limits of the method ranged from 0.000 25 to 0.006 08 mg/kg. The recovery rates of standard spiking were 80.7%-105.7% when set at 0.4, 0.8 and 1.6 mg/kg, the recovery of standard reference material was 102.2%, and the relative standard deviations were 2.6%-4.8%. The concentrations of V, Cr, Ni, Se and As in 21 calcium based toothpaste samples were 0.024-1.935 mg/kg, 0.085-5.759 mg/kg, 0.090-3.673 mg/kg, <0.002 72-0.016 mg/kg and <0.006 08-0.321 mg/kg.@*Conclusion@#Microwave digestion-ICP-MS/MS can effectively reduce the interferences of polyatomic ions and doubly charged ions from the matrix, which is suitable for the determination of V, Cr, Ni, Se and As in calcium based toothpaste.
ABSTRACT
An analytical method was proposed to determine the ultra-trace metal elements in high-purity tetramethylammonium hydroxide ( TMAH).A total of 12 kinds of ultra-trace metal elements in 25% ( w/w) high-purity TMAH aqueous solution were directly determined after simple dilution with ultrapure water by inductively coupled plasma tandem mass spectrometry ( ICP-MS/MS ).In MS/MS mode, the spectral interferences were eliminated by the reaction of target ions with O2 or NH3/He (1:9, V/V) in the collision/reaction cell ( CRC ) of the ICP-MS/MS.Cr, Mn, Ni and Mo were determined using the O2 mass shift method.Cd and Pb were analyZed based on the O2 on-mass method.Fe, Co, Cu and Zn were determined using the NH3/He mass shift method.Mg and Al were determined using the NH3/He on-mass.The detection limits for analytes were in the range of 0.3-57.2 ng/L.The spiked recoveries were in range of 92.0%-106.0%, and the relative standard deviations (RSDs) were less than or equal to 4.6%.The procedure was applied for determining ultra-trace metal elements in 25% high-purity TMAH aqueous solution.
ABSTRACT
An analytical method was developed for determination of low-level uranium isotopes in vegetation samples. Dry ashing method was employed to decompose organic matters of vegetation. The sample ash was further digested using multiple acids. Uranium in the prepared sample solution was separated and purified by an extraction chromatography using UTEVA resin. The chemical recovery of uranium in the separation procedure was more than 94% , and more than 99% of Na, K, Ca and other matrix elements and interfering elements were removed. Three natural uranium isotopes were finally measured with high sensitivity ICP-MS/MS. The detection limits of the method for 238U, 235U, 234U were 3. 05, 0. 34 and 0. 04 pg/g, respectively. The detection limits for 238U and 235U were 10 times better than the reported values. Analysis result of U in GBW-10046 standard reference material was in good agreement with reference value, indicating that this method was reliable. The method was successfully applied to determination of uranium isotopes in the vegetation samples collected in Xi′an region, and it was found that the uranium concentrations and isotopic ratios in these vegetation samples fall well into natural level, and there was no significant artificial uranium contamination. This was the first survey of the three natural uranium isotopes in vegetation samples in this region.
ABSTRACT
An analytical method was developed for determination of P and Si in edible vegetable oil using inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS).The microwave-assisted acid digestion of vegetable oil using HNO3 + H2O2 was carried out in closed vessels.The mass spectral interferences were eliminated by O2 mass shift when promoting reaction with O2 inside the collision reaction cell (CRC), and the monitoring of P as 31P16O+ product ion significantly improved the accuracy of the analysis.H2 was added into the CRC for H2 on-mass reaction.The interferences were eliminated by the quadrupole analyzer to accurately identify 28Si+.The effects of the flow rate of O2 and H2 in ORS3 on the signal intensities and BECs of 31P16O+ and 28Si+ were investigated.The optimum O2 and H2 flow rate was determined.Under the optimized conditions, the limits of detection were 0.043 and 0.66 μg/L for 31P16O+ and 28Si+, respectively.The accuracy of the analytical method was assessed by the analysis of the standard reference materials lubricant oil (SRM 1848) from the National Institute of Standard and Technology.No significant differences were observed between the certified values and measured values.This method was used to analyze 5 kinds of edible vegetable oils (rapeseed oil, sunflower oil, peanut oil, corn oil and soybean oil) from different regions of China, and it was found that the content of P was the highest in peanut oil, and Si showed the highest content in soybean oil.