Gradients in ion chromatography Optimal separation with shorter analysis time Gradients yield precise results faster The goal of ion chromatography – in a nutshell – reads: Three versions to fit your needs 02 optimum separation within an acceptable time. It is not Metrohm offers three types of gradients: high-pressure, always possible to have both at once: late-eluting ions low-pressure and Dose-in Gradients. may delay results. These could be the analytes that are to be determined or they might simply be other ionic com- • High-pressure gradients achieve the highest precision ponents that must be flushed from the column prior to and accuracy the next injection. • Low-pressure gradients have the most compact gradient module Gradients provide an elegant solution to this problem: • Dose-in Gradients are universally applicable systems depending on the elution behavior of the individual ions, that can be retrofitted anytime gradients alter the strength of the eluent shortening re-tention times. All three versions have in common that they can be used with eluents of any composition, concentration of salts or This offers practical advantages, particularly for routine acids, and proportion of organic modifiers. The Dose-in analyses, since measurement results are available faster, Gradient can be used with mixtures of up to five eluents, enabling higher sample throughput. while the high-pressure and low-pressure systems can be used with up to four or three eluents, respectively. Separation of 17 organic 36 and inorganic anions within 35 minutes. The concentration 32 gradient profile used is shown in red. Column: Metrosep A Supp 28 16 - 150/4.0; eluent A: ultrapure ] water; eluent B: 7.5 mmol/L 24 fluoride chloride Na CO , 0.75 mmol/L NaOH; 2 3 loop: 20 µL; flow rate: 0.8 mL/min; 20 temperature: 40 °C; standard solution, each with: 20 mg/L per anion; detection technique: 16 sequentially suppressed conduc- nitrite tivity; high pressure gradient 12 formate A Conductivity [µS/cm glycolate MS sulfate 8 bromide lactate nitrate oxalate pyruvate malate malonate succinate 4 phosphate maleate 0 0 4 8 12 16 20 24 28 32 36 Time [min] Highlights • Time-optimized separation of anions, cations, sugars, amino acids, and 03 polar substances • Acceleration of late-eluting analytes, and matrix ions • High-pressure, low-pressure, and Dose-in Gradient options, depending on the requirements • Any eluent component and concentration can be used • Solvent stability • Easy to program and modify • Metal-free 940 Professional IC Vario with a 942 Extension Module Vario and 858 Professional Sample Processor for the determination of anions and cations with a binary high-pressure gradient High-pressure gradient – for maximum precision and accuracy The high-pressure gradient makes it possible to achieve The mixing ratio for the two solutions can be adapted in 04 the highest precision and accuracy with eluent mixtures. the method according to the sample requirements and High-pressure gradients are known from HPLC, and are the separation behavior. The selected gradient profi le characterized by their ease of operation. can be visualized in a graphic display. Users can select between several types of concentration transitions from The most frequent application is the binary high-pressure one concentration level to the next, including steps, gradient. For this, the two solutions to be mixed with linear ramps, and concave and convex transition forms. one another are supplied by two individually control-Optimal performance for the high-pressure gradient is lable high-pressure pumps. The two solutions converge with mixing ratios between 10% and 90%. in a T-connector and are subsequently mixed together under high pressure through multiple coils in a mixing capillary (see «Flow Path», page 5). The system can also be upgraded with a 942 Extension Module Vario so that high-precision compositions of up to four solutions can be produced. Possible gradient profi le for a binary high-pressure gradient In addition to concentrations, the flow parameters can The individually adjustable flow and concentration gra-05 also be varied. Flow increments in the range of a few nL dients enable the quantification of results of a multitude can be achieved with maximum accuracy using the pre-of analytes. cise high-pressure pump. This offers even more flexi bi lity required for solving applications with difficult separations. Flow path of a sequentially suppressed ion chromatograph with a binary high-pressure gradient Low-pressure gradient – the most compact gradient module 06 Low-pressure gradients are preferably used when it is eluent profiles are individually adjustable, and a selection necessary to mix more than two solutions within the can be made at each step between linear ramps, steps, or most limited space. In such cases, low-pressure gradients concave or convex concentration changes. offer the best price-performance ratio. The solutions are aspirated through a mixing capillary using a single high-The Metrohm low-pressure gradient is 100% solvent-pressure pump. A low-pressure valve that produces the stable, an advantage that comes with every Metrohm desired mixing ratio is installed upstream from the mixing gradient system. capillary. As in the case of the high-pressure gradient, the Sequentially suppressed ion chromatograph with a ternary low-pressure gradient The low-pressure gradient is particularly well suited for 20% and 80%. The low-pressure gradient is very com-routine applications, but can also be used in method pact, providing consistent and reproducible performance development. The practically maintenance-free gradient in restricted space. offers the best performance at mixing ratios between Multi-sugar analysis with the low-pressure gradient (profile 1600 shown in red). Column: Hamilton glucose RCX-30 - 250/4.6; eluent A: 1400 30 mmol/L NaOH, 7.5 mmol/L sodium acetate; eluent B: 1200 200 mmol/L NaOH, 7.5 mmol/L 1000 sodium acetate; loop: 20 µL; flow rate: 1.5 mL/min; tempe- 800 fructose ra ture: 30 °C; standard solution with 5 or 10 mg/L per sugar; ent [nA] 600 arabinose Inline Sample Preparation urrC Technique: Dialysis; detection sucrose 400 technique: Amperometry (PAD) isomaltose trehalose melezitose raffinose 200 maltose 0 0 4 8 12 16 20 24 28 32 36 40 Time [min] Dose-in Gradient – for universal use The Dose-in Gradient is the most flexible of the three Me-The system uses the patented Dosino technology to feed 07 trohm gradients. It can be used with any of the intelligent additional solutions into the main eluent stream via a Metrohm IC systems. Even if you initially work on a system 6-port adapter. A high-pressure pump controls the flow without gradients, it can always be retrofitted with the rate and ensures a low-pulsation background. The mixing Dose-in Gradient version. ratio for up to five eluents can be adjusted between 5% and 95%, either linearly or stepwise. The Dose-in Gradient The Dose-in Gradient is the latest of the three Metrohm is a particularly low maintenance system. gradients and also operates in the low-pressure range. Sequentially suppressed ion chromatograph with a binary Dose-in Gradient The Dose-in Gradient lives up to its reputation as the uni-no time. In addition, the Dose-in Gradient is compatible versal solution. Not only can it be retrofitted to an existing with organic solvents, and can be used for any type of system fast and without difficulty, it is also so simple to eluent. use that anyone can switch between gradient profiles in Separation of polyphosphates 3.0 (Dose-in Gradient profile in red). 2.8 Column: Metrosep A Supp 2.6 15 - 50/4.0; eluent A: 7.5 mmol/L 2.4 Na CO , 2 mmol/L NaOH; eluent 2 3 ] 2.2 B: 120 mmol/L Na CO , 2 mmol/L 2 3 2.0 NaOH; loop: 20 µL; flow rate: 1.8 tripolyphosphate 0.8 mL/min; temperature: 45 °C; 1.6 10 mL dosing unit for Dose-in pyrophosphate Gradient; Metrohm intelligent 1.4 Partial Loop Injection Technique 1.2 trimetaphosphate (MiPT) and Inline UItrafiltration; 1.0 Conductivity [µS/cm detection technique: sequentially 0.8 suppressed conductivity 0.6 0.4 0.2 0.0 0 2 4 6 8 10 12 14 16 18 Time [min] Ordering information High-pressure gradients 2.940.1140 940 Professional IC Vario HPG 2.940.1240 940 Professional IC Vario ChS/HPG 2.940.1340 940 Professional IC Vario ChS/PP/HPG 2.940.1440 940 Professional IC Vario SeS/HPG 2.940.1540 940 Professional IC Vario SeS/PP/HPG 2.942.0040 942 Extension Module Vario HPG Low-pressure gradients 2.940.1150 940 Professional IC Vario LPG 2.940.1250 940 Professional IC Vario LPG 2.940.1250 940 Professional IC Vario ChS/LPG 2.940.1350 940 Professional IC Vario ChS/PP/LPG 2.940.1450 940 Professional IC Vario SeS/LPG 2.940.1550 940 Professional IC Vario SeS/PP/LPG Dose-in Gradient 2.800.0010 800 Dosino 6.5330.150 IC equipment: Dose-in Gradient 6.3032.210 10 mL Dosing unit 6.3032.220 20 mL Dosing unit 6.3032.250 50 mL Dosing unit The selection of the dosing unit depends on the application, which is why this is not included in the IC equipment: Dose-in Gradient. G, CH-9100 Herisau ohm A witzerland by Metr www.metrohm.com , printed in S SW Subject to change Layout by Ecknauer+Schoch A 8.000.5131EN – 2015-01