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WelchromTM Column----Ultimate Performance, Best Value |
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| WelchromTM columns HPLC columns are made from spherical, totally porous, and ultra high purity (>99.999%) type B silica particles. Our proprietary surface modification treatment before bonding generates a very smooth and uniform surface with less acidic surface silanols. We offer a full line of phases including XB-C18, AQ-C18, XB-C8, XB-Phenyl, and XB-CN to provide a wide range of selectivities. These phases were developed using state-of-the-art bonding chemistry technology to provide unique performance characteristics to enable the most demanding separations. All phases are fully end-capped by proprietary techniques to ensure excellent peak shapes and long lifetime. All bonding, end-capping and packing processes are optimized and well-controlled to achieve maximum efficiency, excellent peak shapes for compounds of neutral, polar, acidic and basic, and in particular, strong basic nature, wide pH range (pH 1.5-10.0), excellent batch-to-batch and column-to-column reproducibility, and longer lifetime. |
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Ultra pure and totally porous type B silica |
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1、99.999% Ultra pure silica |
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A useful chromatographic test of trace amount of metal contents in the column is to compare the peak symmetry of two isomers, 4,4¨-dipyridyl and 2,2¨-dipyridyl, and 1,2-dihydroxylnaphthalene. 4,4¨-dipyridyl, which cannot form chelating complex with metal, is used as a reference. 2,2¨-dipyridyl and 1,2-dihydroxylnaphthalene, which are chelating reagents, are sensitive to trace amount of metal in silica. When a C18 column made of type A silica or other so-called type B silica with higher metal content is used, the peaks of 2,2¨-dipyridyl and 1,2-dihydroxylnaphthalene will tail or even totally disappear. Under a pH 7.6 condition, WelchromTM XB-C18 column shows excellent peak shapes, indicating no metal contents in the column at all.
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2、Uniform particle size distribution |
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3、Uniform pore size distribution |
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To ensure the best characteristics for chromatographic performance, the silica are further modified using our proprietary rehydroxylation process to totally eliminate performance-degrading small pores, to generate uniform and inert surface, and to improve particle physical strength. Our silica has a surface area of 320 m2/g with a controlled mean pore size of 120 Å.
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Unique Bonding and Endcapping Technologies |
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Our proprietary surface modification treatment before bonding generates a very smooth and uniform surface with less acidic surface silanols, and totally eliminates performance-degrading small pores. We offer a full line of phases including XB-C18, AQ-C18, XB-C8, XB-Phenyl, and XB-CN to provide a wide range of selectivities. These phases were developed using state-of-the-art bonding chemistry technology to provide unique performance characteristics to enable the most demanding separations. All phases are fully end-capped by proprietary techniques to ensure excellent peak shapes and long lifetime.
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Wide pH Range |
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WelchromTM XB-C18, featuring high surface coverage and exhaustive end-capping, is an excellent choice for a general-purpose C18 column for a wide variety of organic compounds. The bonding chemistry is optimized specifically for our base material. Our proprietary double end-capping leads to optimal performance with neutral, polar, acidic, basic, and chelating compounds. The phase, when used in mid pH, shows the biggest advantage of symmetric peaks for highly basic compounds, which normally show peak tailing on other conventional C18 columns. High surface coverage and exhaustive end-capping make columns suitable over a wide pH range of 1.5 to 10.0 with enhanced stability.
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Longer Lifetime |
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All columns: 4.6 x 150 mm, 5 µm
Column purge condition:
Mobile phase: 50% 1% TFA in water pH 1.3/50% Methanol
Flow rate: 3 mL/min,
Temperature: 80＜C
Run Time: 500 minutes
Column analysis condition:
Mobile phase: 50% 1% TFA in water, pH 1.3/50% Methanol
Flow rate: 1 mL/min,
Temperature: 80＜C
Run Time: 20 minutes
Analyte: toluene
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Purge and Test condition:
Column: 4.6 x 75 mm, 5 µm
Mobile: 30% 20 mM phosphate buffer, pH 10/70% MeOH
Flow rate: 1.5 ml/min,
Temp: 50 0C;
Analyte: Toluene and Naphthalene
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Column lifetime is one of the most important parameters. We compared WelchromTM XB-C18 with other top brand columns under two conditions: (1) 1% TFA at pH 1.3, 80 0C and (2) K3PO4/K2HPO4 buffer solution at pH 10.0, 50 0C. Our XB-C18 has almost no retention drop after 30,000 column volume purge under 1% TFA and 80 0C condition, better than Agilent Eclipse XDB-C18, InertsilTM ODS-3, and Waters XTerraTM MS-C18. At lifetime test at high pH 10.0, our XB-C18 column is better than Agilent Eclipse XDB-C18, and very close to Waters hybrid XTerraTM MS-C18 column. High surface coverage, exhaustive end-capping, and optimized manufacture process provide WelchromTM XB-C18 with longer lifetime at very low or high pH conditions and with high efficiency.
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Excellent Peak Shapes for Acids, Bases, and Polar Compounds |
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Excellent Performance of Strong Basic Compounds |
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The analysis of strong basic compounds at medium pH provides a further evaluation of the quality of C18 phase because strong basic compounds such as tricyclic antidepressants (TCAs) are notorious for poor peak shapes and irreversible adsorption on traditional C18 packings. The separation of TCAs at pH 7.0 can be used to clearly distinguish the quality difference of columns from different manufacturers. WelchromTM XB-C18 shows excellent peak shapes for strong bases because of its high surface coverage, uniform and inert surface silanols. |
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Wide Range of Selectivity |
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WelchromTM XB series are extensively bonded (XB) phases with high coverage and end-capping, including the most popular XB-C18, XB-C8, XB-Phenyl, and XB-CN phases. We also have moderately bonded AQ-C18 phase with moderate coverage for use in highly aqueous mobile phase. The AQ-C18 phase is moderately bonded to avoid so-called ＾phase collapse￣ which conventional C18 columns exhibit at high water contents in the mobile phase, even when 100% water is used. It is fully end-capped to ensure the best peak shapes of polar and basic compounds and longer lifetime. |
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Exceptional Batch-to-Batch Reproducibility |
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The unique surface modification treatment, optimized state-of-art bonding chemistry, proprietary full end-capping technique, and strict manufacture process ensure WelchromTM HPLC columns the ultimate performance and exceptional batch-to-batch reproducibility. |
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