Quadrupole mass spectrometer,triple methods

Currently, HPLC/fiuorescence is still the most common technique for the determination of residues of oxime carbamates. With the introduction of ESI and APCI MS interfaces, HPLC/MS analysis for oxime carbamates in various sample matrices has become widespread. However, for a rapid, sensitive, and specific analysis of biological and environmental samples, HPLC/MS/MS is preferred to HPLC/MS and HPLC/fiuorescence. With time, improved and affordable triple-quadrupole mass spectrometers will be available in more analytical laboratories. With stricter regulatory requirements, e.g., highly specific and conclusive methods with lower LOQ, HPLC/MS/MS will be a method of choice for oxime carbamates and their metabolites. 

The results thus show that ammonia DCI-MS/MS using a triple quadrupole mass spectrometer is a convenient method for the detection of additives in PE samples. The softness and selectivity provided by ammonia DCI in combination with the specificity provided by CID, demonstrate great potential for identification of additives directly from PE extracts. The utility of DCI in the quantitative analysis of additives has still to be explored. DCI-MS/MS (B/E) with high collision... 

Selection of a suitable ionisation method is important in the success of mixture analysis by MS/MS, as clearly shown by Chen and Her [23]. Ideally, only molecular ions should be produced for each of the compounds in the mixture. For this reason, the softest ionisation technique is often the best choice in the analysis of mixtures with MS/MS. In addition to softness , selectivity is an important factor in the selection of the ionisation technique. In polymer/additive analysis it is better to choose an ionisation technique which responds preferentially to the analytes over the matrix, because the polymer extract often consists of additives as well as a low-MW polymer matrix (oligomers). Few other reports deal with direct tandem MS analysis of extracts of polymer samples [229,231,232], DCI-MS/MS (B/E linked scan with CID) was used for direct analysis of polymer extracts and solids [69]. In comparison with FAB-MS, much less fragmentation was observed with DCI using NH3 as a reagent gas. The softness and lack of matrix effect make ammonia DCI a better ionisation technique than FAB for the analysis of additives directly from the extracts. Most likely due to higher collision energy, product ion mass spectra acquired with a double-focusing mass spectrometer provided more structural information than the spectra obtained with a triple quadrupole mass spectrometer. 

Yang, L. et al. 2001. Evaluation of a four-channel multiplexed electrospray triple quadrupole mass spectrometer for the simultaneous validation of LC/MS/MS methods in four different preclinical matrixes. Anal. Chem. 73 1740. 

Personnel Choosing an appropriate technique sometimes comes down to having the right person on your staff to perform the technique. If you, or no one in the lab, had had experience with the hydroxyl value titration, it might not have been an option in the Bulging Drum Problem. Certainly, if the operator of your triple quadrupole mass spectrometer is on vacation and there is no back-up operator, another method, or sending the samples to another lab, may be necessary. Should the method need to be transferred to another lab, does that lab have the requisite people for the job ... 

Liquid chromatography combined with triple-quadrupole mass spectrometers has been used extensively as the analytical method of choice to determine the plasma concentration of compounds. 

Both of the above examples illustrate that the sensitivity of the MDF method, in general, is comparable to PIS analysis and better than NLS methods (Figs 6.9 and 6.10). The sensitivity of the MDF method is attributed at least in part to the full-scan capability of high-resolution mass spectrometers such as the Q-TOF and LTQ-FTICR, which could be several times more sensitive than full-scan analysis by a triple-quadrupole mass spectrometer (Kostiainen et al., 2003). 

Determination of MS/MS conditions using the MALDI ion source coupled to the triple-quadrupole mass spectrometer takes a different approach (Kovarik et al., 2003) which at present is not as easily automated. As mentioned earlier, some product ion spectra will contain additional fragment ions not related to the analyte due to isobaric matrix peaks. However, MS/MS conditions previously obtained by using an ESI-MS/MS system can be directly ported over to the MALDI triple-quadrupole mass spectrometer. These conditions provide the advantage of product ion selection for SRM of the analyte. In the typical high-throughput environment, individual methods for each chemical entity are not normally utilized. Rather, the semioptimized template-style methods referred to above are often used wherein a few values of collision energy are combined with the appropriate SRM and polarity. These methods are ported to the MALDI triple quadmpole mass spectrometer, and no further... 

Stenhoff et al. [117] determined enantiomers of omeprazole in blood plasma by normal-phase liquid chromatography and detection by atmospheric-pressure ionization tandem mass spectrometry. The enantioselec-tive assay of omeprazole is using normal-phase liquid chromatography on a Chiralpak AD column and detection by mass spectrometry. Omeprazole is extracted by a mixture of dichloromethane and hexane and, after evaporation, redissolution and injection, separated into its enantiomers on the chiral stationary phase. Detection is made by a triple quadrupole mass spectrometer, using deuterated analogs and internal standards. The method enables determination in plasma down to 10 nmol/1 and shows excellent consistency suited for pharmacokinetic studies in man. 

Martens-Lobenhoffer et al. [119] used chiral HPLC-atmospheric pressure photoionization tandem mass-spectrometric method for the enantio-selective quantification of omeprazole and its main metabolites in human serum. The method features solid-phase separation, normal phase chiral HPLC separation, and atmospheric pressure photoionization tandem mass spectrometry. The internal standards serve stable isotope labeled omeprazole and 5-hydroxy omeprazole. The HPLC part consists of Agilent 1100 system comprising a binary pump, an autosampler, a thermo-stated column component, and a diode array UV-VIS detector. The enantioselective chromatographic separation took place on a ReproSil Chiral-CA 5 ym 25 cm x 2 mm column, protected by a security guard system, equipped with a 4 mm x 2-mm silica filter insert. The analytes were detected by a Thermo Scientific TSQ Discovery Max triple quadrupole mass spectrometer, equipped with an APPI ion source with a... 

Detection of imatinib is performed by triple quadrupole mass spectrometer with an electrospray ionization (ESI) interface operated in positive ion mode [103, 104, 106,107,109,110]. Except the methods published by Parise et al. for imatinib and its main metabolite [108], and for nilotinib [111], where a single quadrupole mass spectrometer was used, most TKIs are analyzed in plasma by atmospheric pressure ionization (electrospray or turbo ion spray) coupled to triple stage mass spectrometer. Expectedly, higher limit of quantifications for imatinib (30 ng/ml) [108], and nilotinib (5 ng/ml) [111], are obtained for the assays using single quadrupole MS (see Table 2). 

Smith, C.J., Wilson, I.D., Abou-Shakra, F., Payne, R., Parry, T.C., Sinclair, P., Roberts, D. W. A comparison of the quantitative methods for the analysis of the platinum-containing anticancer drug cii-amminedichloro(2-methylpyridine)]-platinum(II) (ZD0473) by HPLC coupled to either a triple quadrupole mass spectrometer or an inductively coupled plasma mass spectrometer. Anal. Chem. 75, 1463-1469 (2003)... 

Positive ion thermospray LC/MS and LC/MS/MS methods carried out on a triple quadrupole mass spectrometer have been successfully utilized in our laboratory to elucidate the structures of metabolites of several compounds currently undergoing development as drug candidates. Samples were obtained from both in vivo sources (urine, bile, or plasma) and analyzed directly from the biological fluid or from in vitro enzymatic/chemical methods. In all cases, buffer ionization mode using ammonium acetate in the HPLC mobile phase was employed for ionization of the metabolites of interest. 

A. Low-Resolution CE-MS AND CE-MS/MS Methods Using Triple Quadrupole Mass Spectrometers or Quadrupole Ion Traps... 

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