Sample handling and contamination encountered when coupling offline normal phase high performance liquid chromatography fraction collection of petroleum samples to Fourier transform ion cyclotron resonance mass spectrometry

Normal phase high performance liquid chromatography (HPLC) is used to separate a gas oil petroleum sample, and the fractions are collected offline and analyzed on a high resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR MS). The separation prior to MS analysis dilutes the sample significantly; therefore the fractions need to be prepared properly to achieve the best signal possible. The methods used to prepare the HPLC fractions for MS analysis are described, with emphasis placed on increasing the concentration of analyte species. The dilution effect also means that contamination in the MS spectra needs to be minimized. The contamination from molecular sieves, plastics, soap, etc. and interferences encountered during the offline fraction collection process are described and eliminated. A previously unreported MS contamination of iron formate clusters with a 0.8 mass defect in positive mode electrospray is also described. This interference resulted from the stainless steel tubing in the HPLC system. Contamination resulting from what has tentatively been assigned as palmitoylglycerol and stearoylglycerol was also observed; these compounds have not previously been reported as contaminant peaks.     

表面特性对PBGA软金丝键合点可焊性的影响

一级封装中最流行的互连技术仍为丝焊。引线键合的效率主要依赖于受表面特性影响的键合点的可焊性。在最近的研究中,我们调查了表面特性对金-金超声压焊系统的影响。表面特性包括金层厚度,表面硬度和粗糙度、有机物杂质及金属杂质。对两个样本间的不同特性进行比较。确定金表面特性的粗糙度依赖于镍层的外形结构。焊料掩膜逸出气体对可焊性具有负面影响,等离子清洗能够有效地去除有机物杂质。金层中的杂质将导致不良的可焊性。     

Scenario-based stochastic programs: Resistance with respect to sample

A contamination technique is presented as a numerically tractable tool to post-optimization and analysis of robustness of the optimal value of scenario-based stochastic programs and of the expected value problems. Detailed applications of the method concern the two-stage stochastic linear programs with random recourse and the corresponding robust optimization problems.This work was supported by the Grant Agency of the Czech Republic under Grant No. 402/93/0631.     

An evaluation of contamination from plasma immersion ion implantation on silicon device characteristics

Silicon devices including diodes, metal oxide semiconductor capacitors, and p-channel metal oxide semiconductor transistors were fabricated by plasma immersion ion implantation (PHI) doping technique using a microwave multipolar bucket plasma system. B₂H₆ diluted in helium (1%) was used as the gas source. The contamination by helium, hydrogen, iron, sodium, and aluminum impurities was evaluated by secondary ion mass spectrometry measurements. During PHI processing in an aluminum chamber with a stainless steel wafer holder, no aluminum and a dose of 4.1 x 10¹²/cm² of Fe were detected. Most of Fe ions were shielded by a thin layer of SiO₂ during the device fabrications. Good quality devices have been demonstrated including low reverse current of 15 nA/cm² (V_R = -5 V) in diodes and reasonable lifetimes of the minority carriers such as t_g = 55.0 μsec and = τ_r 54.2 μsec.     

煤烟对食物、饮水氟污染的研究

测定了云南滇东“燃煤污染型”氟病区新、陈玉米(皮、饭)、饮用水(自然井水、泉水、室内缸水、开水)的含氟量，并对玉米、豆娄、辣椒进行水洗脱氟试验，结果证明由于用煤方式不当，造成室内食物、饮水的污染，发生氟中毒。     

Utilization of TXRF analytical technique in order to improve front-end semiconductor processing

In this paper, we summarize how the introduction of in-line TXRF monitoring provides detailed analytical information on aluminum, titanium and molybdenum contamination levels in order to improve several process steps from front-end processing, minimize product yield loss and make it possible to successfully manufacture multiple products and process geometries in the same fabrication platform.     

Ash characteristics in controlled diode laser pyrolysis of chlorinated rubber

This paper describes the effects of 60 W High Power Diode Laser (HPDL) beams on the removal of chlorinated rubber (CR) paint from concrete surfaces and the ash particles generated from this process. The physical characteristics, including shape and size distribution of the removed and collected airborne CR particles, down to a size of around 1 μm in diameter, were determined using optical microscopy and image analysis. The shape of the particles observed was highly irregular, displaying no symmetry. The size distribution of the collected particles was found to range between 1–2000 μm, with the maximum concentration being found between 29 and 60 μm. The chemical characteristics of the CR ash particles were investigated by means of ESEM and EDX techniques. From a comparative analysis, it was found that the concentration of chlorine within the CR material was significantly reduced after HPDL treatment. This, together with DTA/TGA results indicated a combustive degradation of the CR polymer through the interaction with the process gas, oxygen, and the laser irradiation. Also, a strong correlation between laser power and average particle sizes has been found, with higher powers generally producing larger particle sizes. Opposite effects have been found by changing the oxygen flow rate, with higher oxygen flow producing, on average, smaller particles. An interpretation of the combustion process, as well as a brief discussion on operational safety and environmental impact of the products is attempted.     

A validated method for the determination of traces of UV filters in fish using LC–MS/MS

An analytical method for the determination of UV filter substances in fish tissue has been developed and validated using benzophenone-3, 3-(4-methylbenzylidene)-camphor, 2-ethylhexyl-2-cyano-3,3-diphenyl-2-propenoate and 2-ethylhexyl 3-(methoxyphenyl)-2-propenoate as target analytes. The fish fillets were homogenised and extracted by Soxhlet extraction. The extracts were run through a clean-up process including gel permeation chromatography followed by solid-phase extraction. Quantification of the compounds was performed using liquid chromatography with tandem mass spectrometric detection. Blank fish as well as spiked blank fish were analysed to validate the analytical method. The analytical method developed has the multiple advantages of enabling separation, simultaneous identification and quantification of each of the four selected compounds in a single run. Contamination of blank samples and abnormally high concentrations in spiked samples were avoided by taking extensive precautions during the fish preparation procedure. The method was validated in accordance with internationally accepted criteria, such as specificity, accuracy and repeatability. The combination of LC with tandem mass spectrometry ensures a high level of specificity. The accuracy of the method was reported as the mean recovery rate for the analytes in the sample matrix. Mean recoveries were in the range 86–108%. The precision is expressed as the relative standard deviation, and in all but one of the cases was 20% or below. The accuracy of the method allows residue analyses to be performed on biological matrices at ng/g levels. The determined limit of quantification for each analyte was 8 ng/g fish. For all spiking levels ≥8 ng/g, relative standard deviations were ≤ 20%.     

The use of a portable total reflection X-ray fluorescence spectrometer for field investigation

A newly developed, portable total reflection X-ray fluorescence (TXRF) spectrometer was tested during a field campaign on Chilean lakes and a German river in January 2002. The field measurements were compared with laboratory measurements carried out on a stationary instrument in the German laboratory. For method validation certified reference material (NIST SRM 1640 Trace elements in natural water) and water samples from different freshwater sources were analyzed with both techniques and evaluated statistically. Based on these preliminary results, it could be concluded that the portable TXRF is a useful technique for the quantitative elemental screening of freshwater samples during field campaigns. Future tests with biological samples (e.g. biofilms and zooplankton), and suspended matter will provide information about the suitability of the portable TXRF for these materials.