Split flow and bypass flow systems for monolithic capillary columns in liquid chromatography

Takeuchi, Toyohide; Tatsumi, Shinichi; Masuoka, Shinichi; Hirose, Katsuaki; Uzu, Hideyuki; Jin, Jiye; Fujimoto, Chuzo; Ohta, Kazutoku; Lee, Kwang-Pill; Ryoo, Je-Jeong; Choi, Sung-Jin

doi:10.1016/j.chroma.2003.08.087

Cited by 10 publications

(4 citation statements)

References 18 publications

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“…Earlier off-chip pumping approaches split the flow produced by a conventional LC pump using a flow splitter to compensate for flow resistance (due to viscosity, etc.) of different solvent compositions. , If a gradient elution is performed, the majority of the solvents are not utilized for the separation. Thus, the “split” approach becomes uneconomical and contradicts the advantages of miniaturization.…”

Section: Pumps: Low Flow High Pressurementioning

confidence: 99%

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Advances in Microchip Liquid Chromatography

Yuan

Oleschuk

2017

Anal. Chem.

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Section: Pumps: Low Flow High Pressurementioning

confidence: 99%

“…of different solvent compositions. 67,68 If a gradient elution is performed, the majority of the solvents are not utilized for the separation. Thus, the "split" approach becomes uneconomical and contradicts the advantages of miniaturization.…”

mentioning

confidence: 99%

Advances in Microchip Liquid Chromatography

Yuan

Oleschuk

2017

Anal. Chem.

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“…Monolithic silica capillary columns were prepared as previously reported [2,4] with some modifications in the preparation conditions. A 2-mL volume of TMOS and 0.53 g PEG 10,000 were dissolved in 0.01 M acetic acid by agitating the solution for 30 min at 08C.…”

Section: Monolithic Capillary Columnsmentioning

confidence: 99%

Separation of benzene and deuterated benzenes by reversed‐phase and recycle liquid chromatography using monolithic capillary columns

Lim¹,

Uzu²,

Takeuchi³

2004

J of Separation Science

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An alternate pumping-recycle system utilizing a commercially available low dead-volume switching valve was developed for microcolumn LC. The recycle system had two separation columns, and the dead volume of the recycling lines was kept to a minimum by avoiding passage of the sample through the pump chamber, sample injector, and the normal path length of a conventional UV detector. The drawback of the high total back pressure caused by the second column that is placed after the detector was overcome by on-column detection, and this eliminated the need for a high pressure flow cell. The system was used for the separation of an authentic mixture of benzene, benzene-1,3,5-d3, and benzene-d6. Baseline separation was accomplished after six cycles and the calculated theoretical plate number for benzene was 230,000. It was observed that the theoretical plate number (N) increased linearly with increasing number of cycles, and the N per unit time increased with increasing inlet pressure. The separation conditions were optimized and the separation of benzene and benzene-d6 was accomplished within 75 min at 2.5 MPa inlet pressure.

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“…according to the sol-gel method previously reported. 6,10 Fused-silica capillary tubes with 0.1 mm i.d. (GL Sciences, Tokyo, Japan) were treated with 1 M sodium hydroxide at 60˚C for 2 h, followed by washing with 1 M hydrochloric acid and methanol.…”

Section: Preparation Of Monolithic Capillary Columnsmentioning

confidence: 99%

Rapid Separation of Inorganic Anions by Capillary Ion Chromatography Using Monolithic Silica Columns Modified with Dilauryldimethylammonium Ion

2007

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The determination of trace ions contained in seawater is one of the most difficult tasks in ion chromatography owing to the effect of a high concentration of matrix ions. Various stationary phases have been reported for ion chromatographic determination of trace ions in seawater samples, involving lowcapacity anion-exchange columns as well as C18 reversedphase columns coated with cetyltrimethylammonium ion, 1 a semi-microcolumn (35 × 1 mm i.d.) packed with styrenedivinylbenzene copolymer, 2 conventional-size monolithic ODS columns coated with cetyltrimethylammonium ion, 3 a reversedphase C18 packed column modified with Zwittergent-3-14 micelles, 4 and reversed-phase C30 stationary phase coated with poly(ethylene glycol). 5 We have found that monolithic silica capillary columns dynamically modified with cetyltrimethylammonium ion also allowed the determination of bromide in seawater without tedious pretreatments. 6 The stability of the retention time of analyte anions could be improved by adding 0.1 mM cetyltrimethylammonium chloride (CTAC) into the eluent. Monolithic silica capillary columns achieved rapid separation at lower inlet pressures owing to the unique pore structures. However, when the eluent contained no cetyltrimethylammonium ion in the eluent, the retention time of anions gradually deceased. More hydrophobic modifiers are preferred to obtain more stable stationary phases.Using a dilauryldimethylammonium bromide (DDAB) coated short (30 × 4.6 mm) ODS analytical column (3-μm particle size) and a 5 mM phthalate eluent (pH 7.5), the isocratic separation of nine common anions in 160 s was possible. 7 A reversedphase monolithic ODS column was permanently coated with DDAB to perform ultrafast separations of iodate, chloride, nitrite, bromide, nitrate, phosphate, and sulfate in as little as 30 s. 8 Separations were performed using 6 mM o-cyanophenol (pH 7.0) at flow rates of up to 10 mL/min and suppressed conductivity detection. It is reported that columns coated with DDAB were stable for up to 12 h of continuous use at 5 mL/min when a DDAB-coated guard column was placed upstream from the injector. 8 Very short silica-based monolithic columns (0.5 -1 cm) coated with DDAB were also used for achieving rapid low-pressure ion chromatographic separations of inorganic anions. 9 The present work tried to obtain stable stationary phases for ion chromatography. DDAB was examined for the modification of monolithic silica gel to obtain an anionexchange stationary phase. The prepared columns were applied to the rapid determination of bromide in seawater samples. Experimental ApparatusAn eluent was supplied by applying pressure from a nitrogen gas cylinder, or by using a Model MF2 Microfeeder (Azumadenki Kogyo, Tokyo, Japan) equipped with a 0.5-mL MS-GAN050 gas-tight syringe (Ito, Fuji, Japan). In the former case the eluent was filled in a 0.8-mL loop attached to a Model 7000 6-way switching valve (Rheodyne, Cotati, CA, USA). A sample was loaded by using a CN4-4344-.02 nanovolume sample injector with an injection volume ...

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Split flow and bypass flow systems for monolithic capillary columns in liquid chromatography

Cited by 10 publications

References 18 publications

Advances in Microchip Liquid Chromatography

Advances in Microchip Liquid Chromatography

Separation of benzene and deuterated benzenes by reversed‐phase and recycle liquid chromatography using monolithic capillary columns

Rapid Separation of Inorganic Anions by Capillary Ion Chromatography Using Monolithic Silica Columns Modified with Dilauryldimethylammonium Ion

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