Miniaturized mass spectrometers are becoming increasingly capable, enabling the development of many novel field and laboratory applications. However, to date, triple quadrupole tandem mass spectrometers, the workhorses of quantitative analysis, have not been significantly reduced in size. Here, the basis of a field-deployable triple quadrupole is described. The key development is a highly miniaturized ion optical assembly in which a train of six microengineered components are employed to generate ions at atmospheric pressure, provide a vacuum interface, effect ion guiding, and perform pre-filtering, fragmentation and mass analysis. Despite its small dimensions, the collision cell efficiently fragments precursor ions and yields product ion spectra that are very similar to those recorded using conventional instruments. The instrument has been used to detect Thiabendazole, a common pesticide, in apple pulp at a level of 10 ppb.3

A miniature mass spectrometer capable of detecting analytes eluting from a high-performance liquid chromatography (HPLC) system is described and demonstrated for the first time. The entire instrument, including all pumps and the computer, is contained within a single enclosure that may be conveniently accommodated at the base of the HPLC stack. The microspray ion source, vacuum interface, ion guide, and quadrupole ion filter are all microengineered. These components are fabricated in batches using microelectromechanical systems (MEMS) techniques and considered to be consumables. When coupled to a standard HPLC system using an integrated passive split, the limit of detection for reserpine while scanning the full mass range is 5 ng on-column (1 pg of which is passed to the microspray). The mass range is m/z 100-800, and each spectrum is typically acquired at a rate of 1 scan per second.

Microwave plasma chemical vapour deposition (MPCVD) has been used to deposit diamond films with H 2 S additions of 0-5000 ppm to a 51% CH 4 /49% CO 2 plasma, with growth carried out for two different substrate temperatures (620 and 900 C). Film morphology, growth rate and quality are all observed to deteriorate with increased H 2 S addition, as investigated by scanning electron microscopy (SEM) and laser Raman spectroscopy (LRS). H 2 S addition also appears to alter the resistivity of films, as measured by the four-point probe method, however X-ray photoelectron spectroscopy (XPS) revealed little incorporation of sulfur. The plasma chemistry leading to film deposition has been investigated using optical emission spectroscopy (OES), in which H 2 S addition leads to a reduction in C 2 * and CH* intensities. Molecular beam mass spectrometry (MBMS) measurements have detected a build-up in CS, CS 2 , SO and SO 2 concentrations with addition of H 2 S. Experimental results have been compared to CHEMKIN simulations of plasma chemistry and S-incorporation has been investigated in terms of the product of CHEMKIN predicted mole fractions of CH 3 and CS, [CH 3