Abstract: Systems, apparatuses, kits, and methods for purification and analysis of analytes having a broad range of hydrophobicities by liquid chromatography-mass spectrometry (LC-MS). Using one set of liquid chromatography columns, one set of mobile phase buffers, and, optionally, a single ionization method (e.g., electrospray ionization), a wide range of analytes can be purified and analyzed on a liquid chromatography-mass spectrometry (LC-MS) system. LC-MS purification and analysis of analytes having a broad range of partition coefficients is accomplished by selecting LC run parameters and MS system parameters that are particular to different classes of analytes without having to make column or buffer changes or any other hardware configuration changes to the LC-MS system.

Abstract: Systems, apparatuses, kits, and methods for purification and analysis of analytes having a broad range of hydrophobicities by liquid chromatography-mass spectrometry (LC-MS). Using one set of liquid chromatography columns, one set of mobile phase buffers, and, optionally, a single ionization method (e.g., electrospray ionization), a wide range of analytes can be purified and analyzed on a liquid chromatography-mass spectrometry (LC-MS) system. LC-MS purification and analysis of analytes having a broad range of partition coefficients is accomplished by selecting LC run parameters and MS system parameters that are particular to different classes of analytes without having to make column or buffer changes or any other hardware configuration changes to the LC-MS system.

Abstract: Systems, apparatuses, kits, and methods for purification and analysis of analytes having a broad range of hydrophobicities by liquid chromatography-mass spectrometry (LC-MS). Using one set of liquid chromatography columns, one set of mobile phase buffers, and, optionally, a single ionization method (e.g., electrospray ionization), a wide range of analytes can be purified and analyzed on a liquid chromatography-mass spectrometry (LC-MS) system. LC-MS purification and analysis of analytes having a broad range of partition coefficients is accomplished by selecting LC run parameters and MS system parameters that are particular to different classes of analytes without having to make column or buffer changes or any other hardware configuration changes to the LC-MS system.

Abstract: Systems, apparatuses, kits, and methods for purification and analysis of analytes having a broad range of hydrophobicities by liquid chromatography-mass spectrometry (LC-MS). Using one set of liquid chromatography columns, one set of mobile phase buffers, and, optionally, a single ionization method (e.g., electrospray ionization), a wide range of analytes can be purified and analyzed on a liquid chromatography-mass spectrometry (LC-MS) system. LC-MS purification and analysis of analytes having a broad range of partition coefficients is accomplished by selecting LC run parameters and MS system parameters that are particular to different classes of analytes without having to make column or buffer changes or any other hardware configuration changes to the LC-MS system.

Abstract: Systems, kits, and methods for quantitation of metabolites of vitamin D by liquid chromatography-mass spectrometry (LC-MS). The systems, kits, and methods described herein stabilize and/or promote the formation of the protonated molecular ion ([M+H]+) for the vitamin D metabolites in the ionization source (e.g., electrospray ionization (“ESI”)). Formation of the molecular ion does not involve loss of a water molecule from the parent molecule. Subsequent fragmentation of the [M+H]+ ion yields product ions that are specific to each molecular ion. The systems, kits, and methods described herein provide for no compromise in specificity and provide for a significant increase in sensitivity relative to previously described methods.

Abstract: Systems, kits, and methods for quantitation of metabolites of vitamin D by liquid chromatography-mass spectrometry (LC-MS). The systems, kits, and methods described herein stabilize and/or promote the formation of the protonated molecular ion ([M+H]+) for the vitamin D metabolites in the ionization source (e.g., electrospray ionization (“ESI”)). Formation of the molecular ion does not involve loss of a water molecule from the parent molecule. Subsequent fragmentation of the [M+H]+ ion yields product ions that are specific to each molecular ion. The systems, kits, and methods described herein provide for no compromise in specificity and provide for a significant increase in sensitivity relative to previously described methods.

Abstract: Systems, apparatuses, kits, and methods for purification and analysis of analytes having a broad range of hydrophobicities by liquid chromatography-mass spectrometry (LC-MS). Using one set of liquid chromatography columns, one set of mobile phase buffers, and, optionally, a single ionization method (e.g., electrospray ionization), a wide range of analytes can be purified and analyzed on a liquid chromatography-mass spectrometry (LC-MS) system. LC-MS purification and analysis of analytes having a broad range of partition coefficients is accomplished by selecting LC run parameters and MS system parameters that are particular to different classes of analytes without having to make column or buffer changes or any other hardware configuration changes to the LC-MS system.

Abstract: The present invention relates to a method and apparatus for chromatographically analyzing each of a plurality of samples in detector, comprising an autosampler to contain a plurality of samples for chromatographic analysis and a pluraltity of chromatographic systems, each system comprising one or more pumps and one or more chromatographic columns. A detector is included for detecting compounds in the samples from each of the chromatography systems along with a valve positioned between the detector and the plurality of chromatography systems, the valve permitting each sample to reach the detector in sequence. A computer control device is included which adjusts the introduction of samples from the autosampler into the plurality of chromatography systems as well as the position of the valve to sequentially separate and deliver compounds within the samples to the detector.

Abstract: A method and system of screening or selecting a mobile phase eluent for a chromatography column is provided. A sample for chromatographic analysis or purification is combined with a solvent and passed through a membrane. A pressure measurement is taken of the sample/solvent combination in the system prior to the membrane. The pressure measurement may be compared to a second pressure and an appropriate solvent may be selected based on the relationship between the first measured pressure and the second pressure.

Abstract: The present invention relates to a method and apparatus for chromatographically analyzing each of a plurality of samples in detector, comprising an autosampler to contain a plurality of samples for chromatographic analysis and a plurality of chromatographic systems, each system comprising one or more pumps and one or more chromatography columns. A detector is included for detecting compounds in the samples from each of the chromatography systems along with a valve positioned between the detector and the plurality of chromatography systems, the valve permitting each sample to reach the detector in sequence. A computer control device is included which adjusts the introduction of samples from the autosampler into the plurality of chromatography systems as well as the position of the valve to sequentially separate and deliver compounds within the samples to the detector.

Abstract: A method and system of screening or selecting a mobile phase eluent for a chromatography column is provided. A sample for chromatographic analysis or purification is combined with a solvent and passed through a membrane. A pressure measurement is taken of the sample/solvent combination in the system prior to the membrane. The pressure measurement may be compared to a second pressure and an appropriate solvent may be selected based on the relationship between the first measured pressure and the second pressure.

Abstract: The present invention relates to a method and apparatus for chromatographically analyzing each of a plurality of samples in detector, comprising an autosampler to contain a plurality of samples for chromatographic analysis and a plurality of chromatographic systems, each system comprising one or more pumps and one or more chromatography columns. A detector is included for detecting compounds in the samples from each of the chromatography systems along with a valve positioned between the detector and the plurality of chromatography systems, the valve permitting each sample to reach the detector in sequence. A computer control device is included which adjusts the introduction of samples from the autosampler into the plurality of chromatography systems as well as the position of the valve to sequentially separate and deliver compounds within the samples to the detector.

Abstract: The present invention relates to a method and apparatus for chromatographically analyzing each of a plurality of samples in detector, comprising an autosampler to contain a plurality of samples for chromatographic analysis and a plurality of chromatographic systems, each system comprising one or more pumps and one or more chromatography columns. A detector is included for detecting compounds in the samples from each of the chromatography systems along with a valve positioned between the detector and the plurality of chromatography systems, the valve permitting each sample to reach the detector in sequence. A computer control device is included which adjusts the introduction of samples from the autosampler into the plurality of chromatography systems as well as the position of the valve to sequentially separate and deliver compounds within the samples to the detector.

Abstract: The present invention relates to a method and apparatus for chromatographically analyzing each of a plurality of samples in detector, comprising an autosampler to contain a plurality of samples for chromatographic analysis and a plurality of chromatographic systems, each system comprising one or more pumps and one or more chromatography columns. A detector is included for detecting compounds in the samples from each of the chromatography systems along with a valve positioned between the detector and the plurality of chromatography systems, the valve permitting each sample to reach the detector in sequence. A computer control device is included which adjusts the introduction of samples from the autosampler into the plurality of chromatography systems as well as the position of the valve to sequentially separate and deliver compounds within the samples to the detector.

Abstract: The present invention relates to a method and apparatus for chromatographically analyzing each of a plurality of samples in detector, comprising an autosampler to contain a plurality of samples for chromatographic analysis and a plurality of chromatographic systems, each system comprising one or more pumps and one or more chromatography columns. A detector is included for detecting compounds in the samples from each of the chromatography systems along with a valve positioned between the detector and the plurality of chromatography systems, the valve permitting each sample to reach the detector in sequence. A computer control device is included which adjusts the introduction of samples from the autosampler into the plurality of chromatography systems as well as the position of the valve to sequentially separate and deliver compounds within the samples to the detector.

Abstract: The present invention relates to a method and apparatus for chromatographically analyzing each of a plurality of samples in detector, comprising an autosampler to contain a plurality of samples for chromatographic analysis and a plurality of chromatographic systems, each system comprising one or more pumps and one or more chromatography columns. A detector is included for detecting compounds in the samples from each of the chromatography systems along with a valve positioned between the detector and the plurality of chromatography systems, the valve permitting each sample to reach the detector in sequence. A computer control device is included which adjusts the introduction of samples from the autosampler into the plurality of chromatography systems as well as the position of the valve to sequentially separate and deliver compounds within the samples to the detector.

Abstract: A method of monitoring performance of liquid chromatography apparatus comprising an elongated chromatography column and having a conduit coupled to the column inlet for introducing a flow of liquid into said column preferably at very high pressure. Variations in a selected electromagnetic property, such as the electrical conductivity, of the liquid flow are measured, preferably in the conduit. Apparatus is configured so that respective volumes of sample liquid and eluant may be introduced into the conduit sequentially or substantially simultaneously with substantially no band-spreading when flowing through the conduit into the column. A pair of electrically conductive electrodes, coupled to metering means, are positioned at two spaced-apart locations within the conduit and are electrically insulated from each other and from the ends of the conduit.

Abstract: A system for separating compounds of relatively low molecular weight substantially not greater than about one kilodalton from compounds having relatively high molecular weights substantially an order of magnitude greater or more than the low molecular weight compounds in a liquid mixture. The system includes a chromatographic column packed with uniformly distributed rigid, solid, porous particles having chromatographically active, hydrophobic surfaces, average diameters of not less than about 30 .mu.m, and average pore diameters sufficiently small to substantially exclude introduction of the compounds of relatively high molecular weight into the pores. The mixture is pumped through the interstitial volume between the particles at a reduced velocity greater than about 5,000, until a band of the high molecular weight compounds exits the column. The low molecular weight compounds are then eluted and are recovered separately from the relatively high molecular weight compounds.

Abstract: A system for separating compounds of relatively low molecular weight substantially not greater than about one kilodalton from compounds having relatively high molecular weights substantially an order of magnitude greater or more than the low molecular weight compounds in a liquid mixture. The system includes a chromatographic column packed with uniformly distributed rigid, solid, porous particles having chromatographically active, hydrophobic surfaces, average diameters of not less than about 30 .mu.m, and average pore diameters sufficiently small to substantially exclude introduction of the compounds of relatively high molecular weight into the pores. The mixture is pumped through the interstitial volume between the particles at a reduced velocity greater than about 5,000, until a band of the high molecular weight compounds exits the column. The low molecular weight compounds are then eluted and are recovered separately from the relatively high molecular weight compounds.