The purpose of the present work was to evaluate the synergistic effect of ionization type, sample preparation technique, and bio-fluid on the presence of matrix effect in quantitative liquid chromatography (LC)-MS/MS analysis of illicit drugs by post-column infusion experiments with morphine (10-g/mL solution). Three bio-fluids (urine, oral fluid, and plasma) were pretreated with four sample preparation procedures [direct injection, dilution, protein precipitation, solid-phase extraction (SPE)] and analyzed by both LC-electrospray ionization (ESI)-MS/MS and LC-atmospheric pressure chemical ionization (APCI)-MS/MS. Our results indicated that both ionization types showed matrix effect, but ESI was more susceptible than APCI. Sample preparation could reduce (clean up) or magnify (pre-concentrate) matrix effect. Residual matrix components were specific to each bio-fluid and interfered at different time points in the chromatogram. We evaluated matrix effect in an early stage of method development and combined optimal ionization type and sample preparation technique for each bio-fluid. Simple dilution of urine was sufficient to allow for the analysis of the analytes of interest by LC-APCI-MS/MS. Acetonitrile protein precipitation provided both sample clean up and concentration for oral fluid analysis, while SPE was necessary for extensive clean up of plasma prior to LC-APCI-MS/MS. (J

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Fast atom bombardment (FAB) of the lysed cells and crudellpld extracts of bacterla results In the selective desorption of phorphoupkk that are characteristic of bacterlal specks. I n thk paper, constant neutral loss (CNL) llnked scarmlng of the magnetk and electrlc sector flekls of a double focuslng mass spectrometer Is evaluated as an approach to the analysls of bacterla cells that can provlde greater selectlvlty for polar llplds and speclflclty for partlcular phosphollpld classes. I n the metastable t h e frame, neutral losses of phosphorylethanolamlne, phosphorylglycerol, and other polar head groups are be8t obtalned from protonated molecular Ions analyzed In the posltlve Ion mode. SelectlvHy Is Improved (relathre to normal magnetk fleld scans) for phosphollplds of a partlcular class In the presence of more abundant phosphollpMs and the background Ion dgnal characteristk of FAB m a s spectra. I n addklon, CNL scans penntl the observation of momnnethy@hoaphattklylethanolamhre, a mhror pbsphoUpkl prewnt In a few bacterla, such as P. vu&8f/s, but lndlstlngulshabk In mass from fatty acld homologues of PE contalnIng addltlonal methylene groups. Slnce fatty acld content In bacterial lipids (and therefore the masses appearlng In a particular spectrum) reflects growth condltlons as well as specks, the ldenttflcatlon of specllc phosphollpld classes by CNL scans provlcks a promlskrg approach to the klentllicatlon and cladlcatlon of bacterla.Membrane lipids are important biomarkers that can be used to differentiate bacteria from one another (1-3). We have found that desorption mass spectrometry techniques selectively ionize polar membrane lipids directly from lysed bacteria to provide mass spectra that are characteristic of Gram stain and species (4, 5). Both phospholipids and glycolipids are selectively desorbed by these techniques. The most common phospholipids contain two fatty acids, a glycerolphosphate core, and a polar head group which determines the phospholipid class (Scheme I). The variable portions of phospholipids (the head group and the fatty acids) are both found in distribution patterns that are chemotaxonomically significant.Thus, one approach to characterizing bacteria involves the chromatographic analysis of fatty acids extracted from bacteria cultured and harvested under standard conditions (6). Fatty acids are identified by retention times and their distribution is determined from the relative peak areas. While there are limits to the range of fatty acids that a given species will produce, the fatty acid distribution itself can vary significantly in the same species grown on different media, at different Scheme I -CO-O-CH, I CO-0-CH CH, I L/ 0-t-0 R J J R -CHiCH

A sensitive and specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous quantification of opioids, cocaine, and metabolites in urine was developed and validated. A 10-mL aliquot of urine was injected directly onto the LC/MS/MS system. The lack of sample preparation substantially reduced total analysis time. Separation was performed by reversed-phase chromatography with gradient elution for all analytes in 26 min. Atmospheric pressure chemical ionization (APCI) was a rugged and efficient ionization technique for basic drugs. Identification and quantification was based on selected reaction monitoring (SRM). Calibration, with deuterated internal standards, was performed by linear regression analysis (weighting factor 1/x). Limits of quantitation (LOQ) were established between 10-100 ng/mL and linearity was obtained up to a maximum of 10 000 ng/mL with an average correlation coefficient (R 2 ) > 0.99. Analytical validation criteria for specificity, precision, accuracy, dilution integrity, matrix effect, and stability were fulfilled. The method proved to be simple and time efficient, and was applicable for illicit drug use monitoring and methadone treatment compliance in clinical research projects