Liquid chromatography/mass spectrometry columns

A liquid chromatography-mass spectrometry (LC-MS) method that can quantitatively analyze urinar y normal and modified nucleosides in less than 30 min with a good resolution and sufficient sensitivity has been developed. Nineteen kinds of normal and modified nucleosides were determined in urine samples from 10 healthy persons and 18 breast cancer patients. Compounds were separ ated on a reverse phase Kromasil C18 column (2.1 mm I.D.) by isocratic elution mode using 20 mg/1 ammonium acetate - acetonitrile (97 3 % v/v) at 200 p.l/min. A higher sensitivity was obtained in positive atmospheric pressure chemical ionization mode APCI(-i-). 

Figure 5.6 Positive-ion electrospray spectrum obtained from the major component in the LC-MS analysis of a purified recombinant 62 kDa protein using a Cig microbore 50 X 1 mm column and a flow rate of 50 p.lmin . The starting buffer (buffer A ) was 0.1% TEA in water, while the gradient buffer (buffer B ) consisted of 0.1% TEA in acetonitrile-water (9 1 vol/vol). The running conditions consisted of 0% B for 5 min, followed by a linear gradient of 100% B for 55 min. Reprinted from J. Chromatogr., B, 685, McAtee, C. P., Zhang, Y., Yarbough, P. O., Fuerst, T. R., Stone, K. L., Samander, S. and Williams, K. R., Purification and characterization of a recombinant hepatitis E protein vaccine candidate by liquid chromatography-mass spectrometry , 91-104, Copyright (1996), with permission from Elsevier Science.

Ethylenethiourea (ETU) is a toxic decomposition product/metabolite of alky-lenebis(dithiocarbamates). This compound could be generated during processing of treated crops at elevated temperature. Different chromatographic methods to determine the residue levels of ETU have been published. After extraction with methanol, clean-up on a Gas-Chrom S/alumina column and derivatization (alkylation) with bro-mobutane, ETU residues can be determined by GC with a flame photometric detector in the sulfur mode. Alternatively, ETU residues can also be determined by an HPLC method with UV detection at 240 nm or by liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/tandem mass spectrometry (LC/MS/MS) (molecular ion m/z 103). ... 

Liquid chromatography/mass spectrometry (LC/MS) analysis Quantitation system Agilent Series 1100 liquid chromatograph Chromsep Omnispher 3 Cig HPLC column, 100 x 4.6-mm i.d., 3- am diameter particle size... 

Volmer, D.A., Brombacher, S., Whitehead, B. (2002). Studies on azaspiracid biotoxins. I. Ultrafast high-resolution liquid chromatography/mass spectrometry separations using monolithic columns. Rapid Commun. Mass Spectrom. 16, 2298-2305. 

All gas chromotography/mass spectrometry (GC/MS) analyses of monomers and intermediates were performed on a Finnigan 1020 GC/MS using a 30-m RSL-150 fused silica capillary column. Liquid chromatography/mass spectrometry (LC/NS) was performed on a Finnigan 4500 mass spectrometer using acetonitrile-water eluent and a moving belt LC/MS interface. 

Other combinations are available. For example, liquid chromatographs connected to mass spectrometers (known as liquid chromatography-mass spectrometry [LC-MS]) are fairly common. Almost any combination of two instruments that can be thought of has been built. In addition, two of the same instruments can be connected so that the output from one is fed directly into the other for further separation and analysis. Examples include two mass spectrometers in an MS-MS arrangement and two different gas chromatography columns connected in a series, known as GC-GC. To keep up with these advances, one needs to have a working knowledge of the fundamental principles involved in the techniques and of the abbreviations used for the various instrumentation methods. 

When the mobile phase is a gas, the technique is called gas chromatography-mass spectrometry (GC-MS). In this case, the mixture is in the gas phase as it moves through the column, and the individual separated mixture components emerge in the gas phase and mix with the gaseous mobile phase, which is usually helium. When the mobile phase is a liquid, or a mixture of liquids, the technique is called liquid chromatography-mass spectrometry (LC-MS). In this case, the mixture is in the liquid phase as it moves through the column and individual separated mixture components emerge dissolved in this liquid phase. 

Kang, W. et ah. Analysis of benidipine enantiomers in human plasma by liquid chromatography—mass spectrometry using a macrocyclic antibiotic (vancomycin) chiral stationary phase column, J. Chromatogr. B, 814, 75, 2005. 

Miki A, Tatsuno M, Katagi M, Nishikawa M, Tsuchihashi H. 2002. Simultaneous determination of eleven benzodiazepine hypnotics and eleven relevant metabolites in urine by column-switching liquid chromatography-mass spectrometry. J Anal Toxicol 26 87. 

Black, R. Henion, J. High-throughput selected reaction monitoring liquid chromatography-mass spectrometry determination of methylphenidate and its major metabolite, ritalinic acid, in rat plasma employing monolithic columns. J Chromatogr B Anal Technol Biomed Life Sci 2003, 783, 73-83. 

Liquid chromatography/mass spectrometry analyses were performed with an ion trap mass spectrometer (LCQ, Thermo Fisher Scientific Inc., MA) equipped with an HPLC system (Agilent, CA Model 1100) connected with a diode-array detector (DAD, G1315A). The sample solution (1-5 p,L) was applied on an Inertsil ODS-3 column (2.1 x 150 mm, 3 p,m, GL... 

Figure F2.4.1 Liquid chromatography/mass spectrometry (LC/MS) analysis of isomeric carotenes in a hexane extract from 0.5 ml human serum. Positive ion electrospray ionization MS was used on a quadrupole mass spectrometer with selected ion monitoring to record the molecular ions of lycopene, p-carotene, and a-carotene at m/z (mass-to-charge ratio) 536. A C30 HPLC column was used for separation with a gradient from methanol to methyl-ferf-butyl ether. The a -trans isomer of lycopene was detected at a retention time of 38.1 min and various c/ s isomers of lycopene eluted between 27 and 39 min. The all-frans isomers of a-carotene and P-carotene were detected at 17.3 and 19.3 min, respectively.

T Gomyo, M Ozawa, S Kobayashi. Analytical method for determining the total content of methyl benzimidazole carbamate fungicides in water by column switching liquid chromatography mass spectrometry. Anal Sci 8 687-690, 1992. 

G. S. Rule, A. V. Mordehai and J. Henion, Determination of carbofuran by on-line immunoaffinity chromatography with coupled-column liquid chromatography/mass spectrometry , Anal. Chem. 66 230-235 (1994). 

To establish a sensitive and specific liquid chromatography-mass spectrometry (time-of-flight) [LC-MS (TOF)] method for the determination of donepezil in human plasma after an oral administration of 5 mg donepezil hydrochloride tablet [29]. Alkalized plasma was extracted with isopropa-nol-n-hexane (3 97) and loratadine was used as internal standard (IS). Solutes were separated on a Cis column with a mobile phase of metha-nokacetate buffer (pH 4.0) (80 20). Detection was performed on a TOF mass spectrometry equipped with an electrospray ionization interface and operated in positive-ionization mode. Donepezil quantitation was realized by computing the peak area ratio (donepezil-loratadine) (donepezil m/z 380 [M + H]+ and loratadine m/z 383[M + H]+) and comparing them with calibration curve (r = 0.9998). The linear calibration curve was obtained in the concentration range of 0.1-15 jUg/1. The detection limit of donepezil was 0.1 /zg/1. The average recovery was more than 90%. The intra- and inter-run precision was measured to be below 15% of RSD... 

Y. Odd, H. Ohe, S. Tanaka, N. Asakawa, Direct determination of E2020 enantiomers in plasma by liquid chromatography-mass spectrometry and column-switching techniques, J. Chromatogr. A. 694 (1995) 209-218. 

For metabolite isolation, 1.5 liters of pooled urine were applied to a XAD-2 resin column first. The ethyl acetate extract obtained containing 85 % of the radioactivity was applied upon evaporation to semipreparative HPLC on a Zorbax RX C18 column (9.4 x 250 mm, 5 pm) using gradient elution. Fractions obtained were further separated by isocratic elution on the semipreparative column. The metabolite fractions obtained were finally purified by preparative thin-layer chromatography. Liquid chromatography/mass spectrometry (LC/MS) and LC/MS/MS analysis was applied to the isolated metabolite fractions for structure elucidation. 

---