Development of Fast Sampling and High Recovery Extraction Method for Stable Isotope Measurement of Gaseous Mercury

A method involving fast large-volume sampling and bag extraction of total gaseous mercury (TGM) using a 5 mL acid solution was developed for stable mercury isotope ratio measurements. A big gold-coated sand trap (BAuT)—a 45 (i.d.) × 300 mm (length) quartz tube with 131 times more trapping material than a conventional gold trap—was used for the collection of a large amount of TGM. The collected TGM was extracted using 5 mL inversed aqua regia in a 2 L Tedlar bag followed by isotope measurements using a cold vapor generator coupled with a multicollector inductively coupled plasma mass spectrometer. Sampling tests demonstrated that the collection efficiency of the BAuT was 99.9% or higher during the 1–24 h sampling period under the flow rate of 20–100 L min−1. Recovery tests of 24 h bag extraction using 100 ng NIST SRM 8610 exhibited nearly 100% recovery yields. The five measured stable mercury isotope ratios agreed with reference values within 2σ intervals. The overall methodology tested during the pilot field and laboratory studies demonstrated its successful application in analysis, promising highly precise stable mercury isotopic data with a time resolution of less than 24 h.

Development of a Non-Invasive Dynamic Pulmonary Function Monitor

Characterizing the complexity of airflow limitation in diagnosing and assessing disease severity in asthma, COPD, cystic fibrosis, and other respiratory diseases can help guide clinicians toward the most appropriate treatments. Current technologies allow obstructive lung disease to be measured with about 5%−10% precision. A noninvasive dynamic pulmonary function monitor (DPFM) can quantify ventilation inhomogeneities, such as those originating in partially blocked or constricted small airways, with 1% precision if inert gas concentrations can be measured accurately and precisely over three to four decades of sensitivity. We have studied the precision and linearity of a commercially available mass spectrometer, sampling the gas exhaled by a mechanical lung analog, mimicking a multibreath inert gas washout measurement. The root mean square deviation of the inert gas concentration measured for each “breath,” compared to the expected value for a purely exponential decay, is found to be about 1.1% over three decades of concentration. The corresponding overall impairment, a specific measure of ventilation inhomogeneity, is found to be about 0.2%, which indicates that were inhomogeneities observed, the corresponding impairment could be measured with 1% precision.

Application of a Magnetron Glow Discharge to Direct Solid Sampling for Mass Spectrometry

The behavior of a planar magnetron glow discharge used as a sampling device and ion source for mass spectrometry of conducting solids is examined. Low-pressure operation of the magnetron allows efficient sputtering and ion production from conducting samples. Interfacing the magnetron with the mass spectrometer is simplified by low-pressure magnetron operation. A special sample holder allows up to five sample plugs to be analyzed without the source chamber vacuum being broken. Sample ion current is not found to be a simple function of discharge current, but is a strong function of sample axial position relative to the mass spectrometer sampling cone. The mass spectrometer sampling cone orifice diameter may be varied from 0.5 to 5.0 mm. A cone orifice diameter of 2.0 mm yields optimum analytical conditions. Determination of Al at the 3–5% level in a series of NIST Zn-base alloy standards yields a straight-line analytical curve, suggesting the potential application of the device to high-precision analyses of alloys.

Gas Phase Interactions between Triethylindium and Trimethylgallium

ABSTRACTA study of the room temperature gas-phase interactions between gallium and indium alkyls was undertaken using a mass spectrometer sampling system, mounted on a low pressure organometallic vapor phase epitaxial reactor. Mixtures of triethylindium with triethylgallium or trimethylgallium were investigated. Both combinations formed addition compounds; moreover, the triethylindium-trimethylgallium mixture underwent alkyl exchange. Both admixtures showed reduced reactivity towards arsine. A structure for the addition compound is proposed.