Ion mobility spectrometry peak width data are fitted by a least-squares procedure to a semiempirical model having three adjustable parameters. Peaks are wider than contributions from initial pulse width and diffusion predict, and it is suggested that the additional width is due mainly to electric field inhomogeneity and Coulombic repulsion. The effects of operating conditions and instrument dimensions on resolving power are discussed. It is proposed that increased inhomogeneity of the electric field results in lower measured mobility values, as well as lower resolving power.

Continuous subcutaneous infusions offer a safe, simple, effective alternative to intravenous or intramuscular injections when oral medications cannot be used. They are extremely useful for cancer patients suffering from pain, vomiting, seizures, and other symptoms. Hydromorphone or morphine may be combined with metoclopramide, methotrimeprazine, or haloperidol (in D5W only), in the same pump to control both pain and nausea. Seizures can be controlled by subcutaneous infusion of phenobarbital or midazolam. If proper doses are prescribed and skin irritation is watched for, they can be used safely in the patient's home.

Abstract:The purpose of the current study was to explore and assess the potential of high resolution electrospray ionization atmospheric pressure ion mobility spectrometry (ESI-AP-IMS) as a field analytical method for the detection and identification of mixtures of sulfonylurea (SU) herbicides in aqueous samples. Because of increased usage, persistent behavior, and potential for crop damage, an environmental method of analysis capable of evaluating SU herbicides in a swift and effective manner is necessary. Eight SU herbicides were evaluated using ESI-AP-IMS quadrupole mass spectrometry. The selected herbicides were chosen based upon availability and scope of use. The SU herbicide species were qualitatively identified using quadrupole mass spectrometry, followed by the determination of reduced mobility values for characteristic ions. Various mixtures of rimsulfuron, metsulfuron-methyl, prosulfuron, sulfometuron-methyl, tribenuron-methyl, and primisulfuron-methyl could be revealed using AP-IMS. The ease of use, ability to operate under ambient conditions, and relatively rapid data acquisition times make ESI-AP-IMS an attractive candidate for the analysis of aqueous environmental field samples. C

Ion mobility spectrometry (IMS) is recognized as one of the most sensitive and robust techniques for the detection of narcotics, explosives and chemical warfare agents. IMS is widely used in forensic, military and security applications. Increasing threat of terrorist attacks, the proliferation of narcotics, Chemical Weapons Convention (CWC) treaty verification as well as humanitarian de-mining efforts have mandated that equal importance be placed on the time required to obtain results as well as the quality of the analytical data.[1] In this regard IMS is virtually unrivaled when both speed of response and sensitivity have to be considered.[2] The problem with conventional (signal averaging) IMS systems is the fixed duty cycle of the entrance gate that restricts to less than 1%, the number of available ions contributing to the measured signal. Furthermore, the signal averaging process incorporates scan-to-scan variations that degrade the spectral resolution contributing to misidentifications and false positives. With external second gate, Fourier Transform ion mobility spectrometry (FT-IMS) the entrance gate frequency is variable and can be altered in conjunction with other data acquisition parameters (scan time and sampling rate) to increase the spectral resolution to reduce false alarms and improve the sensitivity for early warning and contamination avoidance. In addition, with FT-IMS the entrance gate operates with a 50% duty cycle and so affords a seven-fold increase in sensitivity. Recent data on high explosives are presented to demonstrate the parametric optimization in sensitivity and resolution of our system.