Advancing Ion Chromatography with High Pressure

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with with o I Sponsored content from Sponsored February 2016 I ntroDuction igh pressures and columns with small particle sizes have been used in high performance liquid chromatography (HPLC) for a long time, and HPLC practitioners know that working with small particle sizes and high pressures can provide significant advantages. In ion chromatography (IC), however, the moveH to higher pressures has taken much longer, but is finally ready to take off, as the articles in this e-book make clear.

First, Mike Doyle explains the advantages of small column particle size and the benefits of high-pressure IC, and illustrates these benefits with examples from the analysis of food and beverages, such as cranberry juice, orange juice, and beer.

In the next piece, Peter Bodsky outlines the hardware considerations involved in high- pressure IC. He then provides example of the advantages of this technique—and particularly the speed it can provide—in environmental applications, such as the analysis of drinking water and treated wastewater.

We wrap up the e-book with an interview with Chris Pohl. He puts the trend to high- pressure IC in context, and discusses the accompanying move to high-capacity IC columns. He also explains the features that Thermo Fisher Scientific has included in its new high-pressure IC instrument that make it easier to use.

We hope you find this new e-book informative and helpful in your work. TOC Adv ancing Ion Chromatography Table of contents with High Pressure

Food & Beverage Applications H igh-Pressure Ion Chromatography Applications in Food and Beverage Analysis 4 Mike Doyle

E nvironmental Applications Fast Ion Chromatography for High Throughput with Environmental Samples 13 Peter Bodsky

Trends T rends in Ion Chromatography: User-Friendly Instruments, Higher-Capacity Columns, and the Move to High Pressure 20 An interview with Chris Pohl 4 | February 2016 |LCGC 4 |February Bever in Applic C essure essure gh- H Mike Doyle Mike h i rom Food Food P a a r a g t t ions ions a e An e and easier peak integration. into analysis faster times resolution with better flowrates. The use of higher flow translatesrate narrower peaks acrossawider rangeof usable sizes; in other words, smaller sizes particle yield 1, becomessmaller flatter with the curve particle of graph Figureincreases. shownin the left As column size particle decreases, peak efficiency separation times. resolving peaks of interest involve can long improve peak resolution. complex With samples, and resolution—that is, flowrate is lowered to often,most involves speed between atradeoff ofdetermined column by and, used the type Chromatographic analysis time is largely Advantages Size Column Particle of Small increase yield and improve troubleshooting. throughput, monitoring process and fast to turnaroundrapid of sample results, high sample help meet analytical scientists demands for (4-μm) advantages to columns distinct offers combined with the of use small-particle-size High-pressure ion chromatography (IC) The van Deemter equation tells us that as ogr n d a a l p I ysis o hy hy Sponsor’s content Sponsor’s n

Getty Images/aristotoo Food & Beverage E nvironmental T rends Applications Applications

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10-µm particles 5-µm particles 3-µm particles 2-µm particles

Optimal ﬂow rate for maximum separation efﬁciency and resolution Column pressure (bar) Theoretical plate height (µm )

Linear velocity u (mm/s) Linear velocity u (mm/s)

Figure 1: Influence of the particle diameter on efficiency and pressure..

Reducing the particle size, however, allows for higher flow rates and faster dramatically increases column back analysis times at a lower back pressure pressure (Figure 1, right), which presents a than a 4-μm, 250-mm column. Using the challenge in the design of chromatography shorter column will improve resolution for systems that can operate reliably at higher less complex samples, while providing a pressures. fast analysis. The longer column will help maximize resolution for more complex Benefits of High-Pressure samples, but the maximum usable flow Ion Chromatography rate, and therefore analysis speed, is High-pressure ion chromatography uses limited by high back pressure. smaller-particle-size resin columns on Thermo Fisher Scientific has developed systems that support high operating a range of both standard and 4-μm pressures and thus facilitates faster runs high-pressure IC columns in a variety without sacrificing resolution. Working of dimensions to allow analysts to tailor with small-particle-size resins in various the column to the application by finding column lengths helps optimize speed the right balance between speed and and resolution relative to column back resolution. In this article, we examine a pressure. series of high-pressure IC applications to A 4-μm, 150-mm column, for example, food and beverage analyses, where high

5 | February 2016 | LCGC Sponsor’s content Food & Beverage E nvironmental T rends Applications Applications

25 Dionex IonPac AG11-HC-4µm/AS11-HC-4µm column

3600 psi 21 22

Peaks mg/L mg/L 13 17 1. Quinate 5.0 16. Bromide 5.0 8 16 24 26 2. Fluoride 1.5 17. Nitrate 5.0 6 12 14 3. Lactate 5.0 18. Carbonate 23 27 29 --- 9 19 11 4. Acetate 5.0 19. Malonate 7.5

Conductivity (µS) 25 2 15 5. Propionate 5.0 20. Maleate 7.5 5 7 6. Formate 5.0 21. Sulfate 7.5 4 10 18 1 3 28 7. Butyrate 5.0 22. Oxalate 7.5 8. Methylsulfonate 5.0 23. Tungstate 10.0 0 9. Pyruvate 5.0 24. Phosphate 10.0 10. Valerate 5.0 25. Phthalate 10.0 Dionex IonPac AG11-HC/AS11-HC 11. Monochloro- 5.0 26. Citrate 10.0 2200 psi acetate 27. Chromate 10.0 12. Bromate 5.0 28. cis-Aconitate --- 13. Chloride 2.5 29. trans-Aconitate 10.0 14. Nitrite 5.0

Conductivity (µS) 15. Triﬂuoroacetate 5.0

-15 0 6 12 18 24 30 36 Time (min)

Figure 2: Separations obtained using a Dionex IonPac AS11-HC column (bottom) and a 4-µm Dionex IonPac AS11-HC column (top). Eluent source: Thermo Scientific Dionex EGC-KOH eluent generator cartridge (capillary); gradient (potassium hydroxide): 1 mM from 0 to 5 min, 1–15 mM from 5 to 14 min, 15–30 mM from 14 to 23 min, 30–60 mM from 23 to 31 min; flow rate: 15 µL/min; injection volume: 0.40 µL; temperature: 30 °C; detection: suppressed conductivity, Thermo Scientific Dionex ACES 300 anion capillary electrolytic suppressor, recycle mode.

resolving power in relatively fast runs is a column with 4-μm particles. The 4-μm valuable tool. column yields better resolution and peak efficiency improvement for many of the Examples of High-Pressure IC peaks by as much as 50–60%. Applications in Food Figure 3 illustrates a real-life example of and Beverage Analysis identification of spoilage in orange juice. The Thermo Scientific Dionex IonPac A 250-mm column and a flow rate of 15 μL AS11-HC (HC = high capacity) column were used, so pressure is high at 3600 psi, is a workhorse column that is useful in but resolution is achieved between early profiling applications. Figure 2 compares eluted inorganic and organic peaks such as an orange juice separation using the lactate and acetate, which are important in standard packing material in the AS11-HC determining sample freshness. with a separation made using a similar The separations in Figure 4 are

6 | February 2016 | LCGC Sponsor’s content Food & Beverage E nvironmental T rends Applications Applications

6 7 Peaks 15 µL/min, 3600 psi 1. Quinate 11. Maleate 2. Fluoride 12. Sulfate 3. Lactate 13. Oxalate 4. Acetate 14. Unknown* 15 5. Formate 15. Phosphate 6. Unknown 16. Citrate 3 9 7. Chloride 17. cis-Aconitate 8. Unknown 18. trans-Aconitate 9. Malate-succinate 19. Unknown 4 10 10. Carbonate 6 16 Conductivity (µS) 13

1 11 2 8 12 14 17 18 19 5

0 0 10 20 30 42 Time (min)

Figure 3: Spoilage identification in beverages. Column: 250 mm X 0.4 mm Dionex IonPac AS11-HC-4µm; eluent source: Dionex EGC-KOH cartridge (capillary); gradient (potassium hydroxide):1 mM from 0 to 8 min, 1–30 mM from 8 to 28 min, 30–60 mM from 28 to 38 min, 60 mM from 38 to 42 min; flow rate: 15 µL/min; injection volume: 0.4 µL; column temperature: 30 °C; detection: suppressed conductivity, Dionex ACES 300 suppressor, recycle mode; sample preparation: 1:40 dilution with deionized water.

high-resolution fingerprints showing carbonate response. Chloride and sulfate differences in organic profiles of are monitored because they affect the hops cranberry and apple juice obtained by extraction process. The organic acids, listed high-presssure IC. Such fingerprints are in blue, are the fermentation products, highly useful in sample identification and in which are of particular interest in monitoring determining the differences between juices. the process. Phosphate is monitored for pH In the production of beer, it’s important adjustment. As can be seen in this example, to monitor inorganic and organic content in high-pressure IC is a powerful tool that the formulation and fermentation process. provides a detailed profile of the sample Figure 5 illustrates three beer samples in just 35–40 min to determine how the run by high-pressure IC. The carbonate fermentation process is progressing. peak is high, which is typical for a beer The Thermo Scientific Dionex sample. The use of a carbonate removal CarboPac SA10 column was developed device after the suppressor minimizes for fast analysis of common mono- and

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Peaks (Standard)mg/L mg/L 10 1. Quinate 1 13. Glutarate 2 2. Fluoride 0.6 14. Succinate 2 3. Lactate 1 15. Malate 2 4. Acetate 1 16. Carbonate -- 5. Propionate 1 17. Tartrate 2 6. Formate 1 18. Sulfate 2 18 20 7. Butyrate 1 19. Fumarate 2 15 8. Pyruvate 2 20. Oxalate 2 10 21. Phosphate 3 22 9. Galacturonate 2 16,17 21 10. Chloride 1 22. Citrate 3 2 14 19 23 25 8 11. Bromide 1 23. Isocitrate 3 1112 24 Standard 3 6,7 9 13 12. Nitrate 1 24. cis-Aconitate -- 1 4 5 25. trans-Aconitate 3 Conductivity (µS) Cranberry

Apple

15 µL/min, 3600 psi

-10 0 10 20 30 40 45 Time (min)

Figure 4: Characterization of beverage samples. Column: Dionex IonPac AG11-HC-4µm/AS11-HC-4µm (250 mm X 0.4 mm); gradient + 10% methanol (added to deionized water: 1 mM KOH for 8 min, 1–15 mM KOH in 10 min, 15–30 mM KOH in 10 min, 30–60 mM KOH in 10 min; eluent source: Dionex EGC-KOH cartridge (capillary); flow rate: 15 µL/min; injection volume: 0.4 µL; temperature: 30 ˚C; detection: suppressed conductivity, Dionex ACES 300 suppressor, external water mode; sample: juice,1:50 sample dilution.

disaccharides in foods, beverages, detection of nonderivatized sugars; this and biofuels. To meet the challenge of is also a useful tool for detecting amino achieving fast, high-capacity runs, we acids and amines and other electroactive developed a 4-μm version of the Dionex species. SA10 column with a supermacroporous The Dionex CarboPac SA10 column is substrate coated with latex nanoparticles. very stable. Figure 7 shows an overlay Figure 6 compares the separation of of 1000 injections (every 100th run mono- and disaccharides on the 4-μm shown) without a shift in retention times Dionex SA10 column (top chromatogram) or problems with capacity loss. A long and a standard SA10 column (bottom column lifetime is maintained by using chromatogram). As can be seen, simple eluent cleanup steps. resolution and efficiency are significantly Figure 8 illustrates the high capacity improved on the 4-µm column. Pulsed of the Dionex CarboPac SA10 4-μm amperometric detection is used for direct column in a separation of a concentrated

8 | February 2016 | LCGC Sponsor’s content Food & Beverage E nvironmental T rends Applications Applications

6 9 12 10 Peaks 1. Quinate 8. Carbonate Beer sample-3 2. Fluoride 9. Sulfate 3. Lactate 10. Oxalate 7 13 4. Acetate 11. Fumarate 5 8 2 5. Pyruvate 12. Phosphate 3 10 4 14 6. Chloride 13. Citrate 11 1 7. Succinate+malate* 14. Isocitrate *Malate and succinate are coeluted under these conditions Beer sample-2 Conductivity (µS)

Beer sample-1

15 µL/min, 3600 psi

-20 0 10 20 30 40 45 Time (min) Figure 5: Beverage process control. Column: Dionex IonPac AG11-HC-4µm/AS11-HC-4µm, 0.4 mm; eluent source: Dionex EGC- KOH cartridge (capillary); gradient (potassium hydroxide): 1 mM for 8 min, 1–15 mM in 10 min, 15–30 mM in 10 min, 30–60 mM in 10 min; flow rate: 15 µL/min; injection volume: 0.4 µL; temperature: 30 ˚C; detection: suppressed conductivity, Dionex ACES 300 suppressor, Thermo Scientific Dionex CRD Carbonate Removal Device, recycle mode; samples: beer samples diluted 1:25 with deionized water.

corn stover hydrolysate with a 1:200 operating at high pressures and nominally dilution. Excellent resolution is achieved higher flow rates. High pump pressures without column overload. The detector demand valves and fittings that function is configured using a 15-mil (0.015-in.) reliably when generating the eluent. For gasket to increase the volume of the flow electrolytic eluent generation, Thermo path through the electrochemical cell, Fisher Scientific has developed cartridges which essentially desensitizes the cell and able to handle pressures up to 5000 psi, allows for running higher concentration which is significant for inert, polymeric samples. (PEEK) systems. Gradient capabilities— using Electrolytic Eluent Generation, Instrumentation for as well as low-pressure mechanical High-Pressure IC gradients—are essential for taking full What’s common to these applications advantage of the resolving power of high- is the high-pressure IC approach of efficiency columns.

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30 4-µm 2 mm 1 Thermo Scientiﬁc™ Dionex™ 3 CarboPac™ SA10-4µm column Number Peak Name Ret. Time Plates Resolution Column pressure = 2160 psi (min) (EP) 4 6 5 1 Fucose 2.7 11,602 6.13 2 Sucrose 3.5 9055 2.44

7 3 Arabinose 3.8 13,729 2.05

Response (nC) 4 Galactose 4.1 12,105 2.84 2 8 5 Glucose 4.5 11,377 3.15 6 Xylose 5.1 14,128 1.73 7 Mannose 5.4 14,337 1.95 -5 8 Fructose 5.7 13,416 n.a. 0 2 4 6 8 10 Time (min)

30 Std 2 mm Dionex CarboPac SA10-6µm column Column pressure = 1240 psi Number Peak Name Ret. Time Plates Resolution (min) (EP) 1 3 1 Fucose 2.7 7103 4.71 2 Sucrose 3.5 5391 1.84 4 5 6 3 Arabinose 3.8 7706 1.53

Response (nC) 4 Galactose 4.1 6862 2.07 7 5 Glucose 4.5 6720 2.37 6 Xylose 5.1 7803 1.21 2 8 7 Mannose 5.4 7901 1.63

-2 8 Fructose 5.8 7211 n.a.

Figure 6: Separation of carbohydrates using 4-µm (top) and standard (bottom) CarboPac SA10 columns.

The Thermo Scientific Dionex ICS- as needed because it can be left on 24/7. 5000+ universal high-pressure IC system With waste generation of only 15 mL/day, runs microbore, standard bore, and the system can run off 1 L of deionized capillary flow rates. The system can be water eluent over 2 months. used for continuous operation at pressures In addition to conductivity and as high as 5000 psi when it’s configured electrochemical detection, a newer as a Reagent-Free (RFIC) system. The technology called charge detection is system has versatile detection options, available with capillary systems. Charge including conductivity for organic acids detection has a different response and inorganic anions, electrochemical factor than conductivity and is useful for carbohydrate separations, as well as for detecting weakly ionic species. It absorbance detection. has better linearity for weakly ionized The Thermo Scientific Dionex ICS- components such as organic acids and 4000 is a dedicated capillary ion amines. As seen in the pomegranate juice chromatography system designed example of Figure 9, the charge detector for ease-of-use for practical process (blue) is able to provide better response monitoring. The instrument can be used for some of the key organic acids that are as a walk-up system to run applications important in profiling this juice.

10 | February 2016 | LCGC Sponsor’s content Food & Beverage E nvironmental T rends Applications Applications

1 3

4 5 6 22 11 Peaks 7 2 8 Inj. 1000 11 1. Quinate 2. Lactate 10 3. Acetate 9 4. Valerate 5. Chloride 8 6 6. Nitrate Conductivity (µS) 7 7. Carbonate 8. Sulfate Inj. 500 6 9. Oxalate

Response ( nC ) 4 13 3 7 8 10 12 9 A 10. Phosphate 5 1 2 5 B 11. Citrate 4 -2.0 12. trans-Aconitate 0.0 10 20 30 42 13. Unknown 3 Time (min) 2 Inj. 10 1 Figure 9: Analysis of pomegranate juice using charge and conductivity detection. Column: Dionex IonPac AS11-HC- 0 2 4 6 8 10 Time (min) 4µm capillary (250 mm X 0.4 mm); instrument: Dionex ICS- 5000 system; eluent source: EGC-EG; gradient (potassium Figure 7: Separation of carbohydrates using a 4-µm Dionex hydroxide): 1 mM from 0 to 8 min, 1–30 mM from 8 to CarboPac SA10 column (1000 runs were performed, and every 28 min, 30–60 mM from 28 to 38 min, 60 mM from 38 100th run is shown). Column: Dionex CarboPac SA10-4µm, to 42 min; flow rate: 0.015 mL/min; injection volume: 0.4 guard + analytical (250 mm X 2mm); eluent: 1 mM KOH; µL; column temperature: 30 °C; detection: suppressed eluent source: Dionex EGC 500 KOH cartridge; flow rate: 0.38 conductivity; suppressor: Dionex ACES 300 suppressor, mL/min; injection volume: 2.5 µL; gasket: 2 mil; temperature: AutoSuppression recycle mode; sample preparation: 1:40 45 ˚C; detection: integrated amperometry, quadruple dilution with deionized water. A = charge detection, B = pulse waveform working electrode: PTFE gold, disposable conductivity detection. electrode; reference electrode: silver/silver chloride. Peaks (10 mg/L): 1 = fucose, 2 = sucrose, 3 = arabinose, 4 = galactose, 5 = glucose, 6 = xylose, 7 = mannose, 8 = fructose. Conclusion High-pressure IC, with its use of smaller

ED_1 particle columns, provides more 140 4 information, better peak efficiency, 1:200 Dilution and the possibility of better speed and resolution—or finding the best balance

3 of those. Better peak shapes improve

Response ( nC ) 1 2 peak integration for more accurate and 5 reliable results. Sample throughput is -20 increased without compromising data 0 2 4 6 8 10 Time (min) quality. The ability of high-pressure IC to Figure 8: Separation of a corn stover sample (diluted yield high-resolution results quickly for 1:200) using a 4-µm CarboPac SA10 column. Column: Dionex CarboPac SA10-4µm guard + analytical, 250 mm X profiling applications is particularly useful 2mm; eluent : 1 mM KOH; eluent source: Dionex EGC 500 in industries such as food and beverage KOH cartridge; flow rate: 0.38 mL/min; injection volume: 2.5 µL; gasket: 15 mil; temperature: 45 ˚C; detection: where answers are needed quickly in integrated amperometry, quadruple pulse waveform; working electrode: PTFE gold, disposable electrode; process monitoring. reference electrode: silver/silver chloride; sample: corn stover, 43 g/L, 1:200 dilution. Peaks: 1 = arabinose, 2 = Mike Doyle is the Product Manager for Ion Chromatography and galactose, 3 = glucose, 4 = xylose, 5 = fructose. Sample Preparation Products at Thermo Fisher Scientific.

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13 | February 201613 |LCGC | February E n PeterBodsky t f F a o n s r vironment H I o i gh C T h h rom roughput with A good generalA good definition of high-pressure IC High-Pressure IC Defined dealing with matrix issues. challenges of running complex samples and High-pressure IC is also useful in meeting the more control and improved troubleshooting. toanswers changes in the stream process mean semiconductor manufacturing. Fast analytical food processes, as well as for ultrapure water for streams for wastewater, drinking water, and is also agrowing need in monitoring process maximum sample throughput. Analysis speed biopharmaceutical laboratories that require environmental, industrial, pharmaceutical, and analysis times, benefit whichto is an attractive separations onthe fly. enhanced selectivity, and even modification of control of the analysis through increased speed, provide tools toinstruments powerful enhance pressure IC. Recent innovations in columns and ICpressures and in of high- the form fast chromatography (HPLC) by moving to higher offootsteps liquid high performance Ion chromatography (IC) is following the High-pressure IC and fast IC offer very fast fast very IC offer High-pressure IC and fast a l a

S t a ogr m ples a Sponsor’s content Sponsor’s p hy

Getty Images/Atomic Imagery Food & Beverage E nvironmental T rends Applications Applications

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10-µm particles 5-µm particles 3-µm particles 2-µm particles

Optimal ﬂow rate for maximum separation efﬁciency and resolution Column pressure (bar) Theoretical plate height (µm )

Linear velocity u (mm/s) Linear velocity u (mm/s) Figure 1: The influence of particle diameter on efficiency (left) and pressure (right).

is that it is the practice of using smaller- overcoming these limitations and offering particle-size resins in combination with excellent separation control for both hardware capable of high pressure to routine and complex samples. achieve better chromatographic control. The two key parameters controlled Hardware Considerations in high-pressure IC are speed and The greatest benefit from high-pressure resolution. On standard IC systems, IC comes from the use of decreased samples can be pushed through the particle size of the columns combined column at a faster rate, of course, with hardware that can tolerate the but resolution may erode as a result. elevated pressures these columns Approaches such as using a shorter produce. The pumps and electrolytic column or a faster flow rate with the eluent generators used must operate same resin or increasing mobile phase reliably under these pressures over the strength are useful, but they offer limited lifetime of the instrument. Gradient success when working with complex or capabilities, although not always poorly resolved samples. Resolution can necessary, provide extraordinary resolving be improved using smaller-particle-size characteristics, flexibility, and control. columns, but systems must be able to A fundamental concept in HPLC is that handle the high pressures involved to decreasing column particle size increases take full advantage of these columns. separation efficiency. For example, High-pressure IC, however, is capable of reducing an 8-μm particle size resin to

14 | February 2016 | LCGC Sponsor’s content Food & Beverage Environmental T rends Applications Applications

25 Dionex IonPac AG11-HC-4µm/AS11-HC-4µm column

3600 psi 21 22

Peaks mg/L mg/L 13 17 1. Quinate 5.0 16. Bromide 5.0 8 16 24 26 2. Fluoride 1.5 17. Nitrate 5.0 6 12 14 3. Lactate 5.0 18. Carbonate 23 27 29 --- 9 19 11 4. Acetate 5.0 19. Malonate 7.5

Conductivity (µS) 15. Triﬂuoroacetate 5.0

-15 0 6 12 18 24 30 36 Time (min)

Figure 2: Separations obtained using a 4-µm Dionex IonPac AS11-HC column (top) and a standard AS11-HC column (bottom). Eluent source: Thermo Scientific Dionex EGC-KOH eluent generator cartridge (capillary); gradient (potassium hydroxide): 1 mM from 0 to 5 min, 1–15 mM from 5 to 14 min, 15–30 mM from 14 to 23 min, 30–60 mM from 23 to 31 min; flow rate: 15 µL/ min; injection volume: 0.40 µL; temperature: 30 °C; detection: suppressed conductivity, Thermo Scientific Dionex ACES 300 anion capillary electrolytic suppressor, recycle mode.

4-μm doubles efficiency, although with a The left graph of Figure 1 shows that consequent fourfold increase in column as particle size decreases, in this case, pressure. Like HPLC, IC is moving toward from 10 μm to 2 μm, the optimal flow column technology using smaller particles, rate actually increases. For maximum and, now, newer instrumentation exists that efficiency and resolution, smaller-particle- can handle the pressures of these small size columns give you the best flexibility particles, even at high flow rates. These and control with respect to flow rate. smaller particle (4-μm) resins provide high As the 3-μm particle size line shows, efficiency and, when packed in 150-mm as linear velocity or flow rate increases, columns, offer extremely fast separation theoretical plate height remains the speeds. For complex samples, 4-μm same. This means that the separation particles in longer columns run at standard can be run at even higher flow rates flow rates yield excellent resolving power. without degradation of the efficiency and The van Deemter equation describes resolution. This is the essence of fast IC and several relationships in chromatography. HPLC.

15 | February 2016 | LCGC Sponsor’s content Food & Beverage Environmental T rends Applications Applications

Thermo Scientiﬁc™ Dionex™ IonSwift ™ MAX-100 column: 11 minutes 10000:1 Na : Ammonia 4.5 15,16 5 24 L/min – 3900 psi 17

19 11 3 12 1 6 7 1 8 13 14 2 9 2 18 4 5 10 Conductivity (µS)

B Conductivity (µS) 1 2 -0.5 -2 0 5 10 15 Time (min) 0 Time (min) 16

Figure 3: Separations showing the high-pressure capabilities of IC. Left: Separation of 18 ions on a Thermo Scientific Dionex IonSwift MAX-100 column. Right: Separation of a 10,000:1 mixture of sodium and ammonia using two Dionex IonPac CS16 columns (upper trace) and one CS16 column (lower trace).

The right side of Figure 1 illustrates HC column (bottom). The 4-μm column the dramatic effect on pressure of produced narrower peaks, which results using smaller particle sizes, and, thus, in improved integration and more reliable the importance of using high-pressure- quantification. A number of critical peak compatible systems. pairs in this separation, such as lactate– High-pressure IC systems with 4-μm acetate, valerate–monochloroacetate, particle-size columns deliver significant bromide–nitrate, and maleate–sulfate, performance advantages, including more show distinctly better resolution. efficient peaks, improved speed and High-pressure capabilities. Hardware resolution, increased sample throughput designed to handle high pressures greatly without compromising data quality, and expands the range and flexibility of improved quality of analytical results. separations. The separation on the left in Figure 3 was run on a high-capacity High-Pressure IC Applications ion-exchange column (Dionex IonSwift Improved resolution. Figure 2 illustrates MAX-100 anion-exchange column) at the improvement in resolution that can be high pressure. Monolith columns contain achieved using 4-μm particle size capillary a network of large separation pores and, columns. This separation was run on the thus, exhibit high permeability for fast Dionex ICS-5000 high-pressure IC system mass transfer and provide high-speed, under gradient conditions for the 4-μm high-resolution performance. As shown in Dionex IonPac AS11-HC column (top) the figure, 18 peaks are resolved at high and the standard Dionex IonPac AS11- resolution in 15 min.

16 | February 2016 | LCGC Sponsor’s content Food & Beverage Environmental T rends Applications Applications

35.0 (a) 20 1 2

4 1 Concentration Overlay of 20 consecutive runs 3 5 Peaks (mg/L)

Conductivity (µS) 6 Retention time RDS (n = 20): -1 0.053% (calcium) to 0.28% (sodium) (b) +! Peak area RSD (n = 20): 20 0.5% (sodium) to 0.9% (magnesium) 2 Conductivity (µS) 4 3 1 2 4 3 5 6 Conductivity (µS) -1 -2.0 0.0 2.5 5.0 0 1 2 3 4 5 Time (min) Time (min)

Figure 4: Rapid determination of cations in treated Figure 5: Analysis of municipal drinking water samples from wastewater. Column: 150 mm X 0.4 mm Dionex IonPac CS12A- (a) San Francisco and (b) Sunnyvale, California. Column: 5µm; eluent source: Dionex EGC-MSA capillary cartridge; Dionex IonPac AG18-Fast, AS18-Fast, 2 mm; eluent source: eluent: 28 mM MSA; flow rate: 18 µL/min; temperature: 30 °C; Thermo Scientific Dionex EGC III KOH cartridge; eluent: suppressor: electrolytic capillary anion suppressor; sample: 23 mM potassium hydroxide; column temperature: 30 °C; treated wastewater (1:10 dilution). Peaks: 1 = sodium (19.6 flow rate: 0.55 mL/min; injection volume: 5 µL; detection: mg/L), 2 = potassium (0.8 mg/L), 3 = magnesium (3.5 mg/L), 4 Thermo Scientific Dionex ASRS 300 Anion Self Regenerating = calcium (3.1 mg/L). Suppressor, 2 mm, 32 mA, recycle mode.

R eproducibility. Figure 4 shows an capacity to maintain resolution even in a overlay of 20 consecutive runs of a short-column format, as shown here. When treated wastewater sample on a CS12A the short column is packed with smaller- 5-µm column. Retention time relative particle resin, back pressures produced at standard deviations (RSDs) and peak area higher flow rates are reduced and shorter RSDs are very low, indicating that this is overall run times can be achieved. Anions an extremely reproducible separation. can be determined with high resolution Speed. The Dionex IonPac AS22-Fast even in drinking, surface, groundwater, and 4-μm column was designed for monitoring wastewater matrices, all in less than 5 min. inorganic anions in accordance with The Dionex IonPac AS18 column also US EPA Method 300.1 (A) and 300.1. now comes in a 4-μm format. The column The column is used with an isocratic offers the same selectivity as the standard carbonate, bicarbonate eluent and Dionex IonPac AS18-Fast column but the suppressed conductivity detection. The reduced particle size allows separation of column works well with Reagent-Free common inorganic anions in significantly ion chromatography, or from eluent less time without loss of chromatographic concentrates that can be manually resolution. prepared. The column is ideal for fast IC Convenience. Figure 5 shows a because it is designed to have sufficient comparison of two municipal drinking

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IC (Table I) and significantly improve Dionex IonPac Anion-Exchange Columns separation efficiency and resolution. For Dionex IonPac AS22-IC columns high-pressure IC, analysts now have the Dionex IonPac AS22-Fast choice of running fast separations on short Dionex IonPac AS19-4μm 150-mm columns and high-resolution Dionex IonPac AS18-4μm separations with standard-length 250-mm Dionex IonPac AS18-4μm Fast Dionex IonPac AS11 HC-μm columns and finding the optimum balance Dionex IonPac Cation-Exchange Columns between resolution and throughput. Dionex IonPac CS19-4μm Dionex IonPac CS12A-5μm Conclusion High pressure IC and fast IC systems Table I: Dionex IonPac high-capacity, ion-exchange, and small-particle resin columns provide flexibility and a high degree of separation control, even for challenging water samples from California, one from samples. With high-pressure PEEK Sunnyvale and one from San Francisco. flow paths and the ability to operate The samples were run on a Dionex continuously at pressures as high as IonPac AS18-Fast 2-mm column with 5000 psi, these reagent-free systems an eluent generation cartridge. The represent a significant improvement in IC samples are similar in composition, as capabilities. The systems are designed would be expected, and the run time is to tolerate high pressures, which allows less than 5 min. The system was able to the analyst to increase flow rate to generate ultrapure potassium hydroxide maximize throughput while benefiting electrolytically with only the addition of from the advantages of electrolytic eluent water, combining speed with ease of use. generation and suppression. The small Thermo Fisher Scientific offers three 4-μm particle size columns used with high-pressure IC systems, the Thermo these systems allow fast run times while Scientific Dionex Integrion HPIC system, maintaining excellent resolution. the Dionex ICS-4000, and the Dionex Peter Bodsky is the Regional Marketing Manager for the Ameri- ICS-5000+. The Dionex IonPac 4-μm cas for Ion Chromatography and Sample Preparation Products at columns are designed for high-pressure Thermo Fisher Scientific.

18 | February 2016 | LCGC Sponsor’s content

20 | February 2016 |LCGC 20 |February An interview with Chriswith Pohl interview An er-FriendlyH U ends in T the C s i r gher- h M rom o ve to C a p a a c H ity t without sacrificing resolution. of equivalent allow efficiency faster foranalysis increased column plate count, columns shorter water,high-purity which don’t benefitfrom of low as such complexity drinking water or Alternatively, of in the well-definedsamples case common in foods and environmental samples. dozens species; of are distinct mixtures such the analysis of complex that mixtures contain be canused to advantageHigher in efficiency willof two increase of pressure by four. afactor words, reducing diameter particle by afactor diameter particle between and pressure. In other therebecause is an inverse square relationship requireparticles significantly higherpressures columns, all other things being equal. Smaller (LC), smaller produce higher-efficiency particles with otherAs modes of liquid chromatography pressurehigh IC? in shouldWhy we move to chromatography (IC). Scientific,talkscurrent about trends in ion of Chromatography at Fisher Thermo Chemistry In this interview, Chris Pohl, the Vice President I i n gh ogr struments, C I o o P r lumns, n essure a p hy: Sponsor’s content Sponsor’s a n d

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Why is it taking so long to move enabled a significant increase in IC to high-pressure IC, given that operating pressure, making high-pressure high pressures have been used IC feasible. in high performance LC (HPLC) for so long? There is also a trend to move to In IC, the preferred eluent species are higher-capacity columns for IC. hydroxide in the case of anion analysis Why? and hydronium in the case of cation High-capacity columns offer the ability analysis. These ions produce the lowest to handle diverse sample matrices background conductivity when operating with analytes present at a wide range in the suppressed mode. However, they of concentrations. In IC, it is not tend to be corrosive to the metallic uncommon to find analytes of interest components commonly used to achieve that are eluted immediately adjacent the high pressures associated with to a ubiquitous matrix ion. When the ultrahigh-pressure LC (UHPLC). Such concentration ratio of the matrix ion eluent species are especially problematic to the analyte ion becomes extreme, it when exposing metallic surfaces to can be difficult to quantitate the analyte extremes of pH in an alternating fashion. in the presence of the matrix species, This exposure can strip the protective especially if the concentration of the passivation layer from the metal surface matrix species exceeds the loading at high pH followed by corrosion of the capacity of the analytical column. metal surface upon return to low pH. As a Dilution of the sample can overcome result, nonmetallic materials are required problems with sample overload but for IC instrumentation to ensure long- can compromise the analyte limit of term reliability with such eluent systems. detection (LOD). It is preferable to use Unfortunately, the tensile strength of high-capacity columns for such samples polymeric materials commonly used in as this enables determination of analyte IC is much lower than that of metallic species without the necessity of sample materials, which limits the maximum dilution, providing superior analyte LODs. pressure rating of the IC system. To In the early days of ion chromatography, increase the operating pressure of the suppressors had limited capacity and thus IC system it has been necessary to re- IC columns typically had correspondingly engineer most of the chromatographic low ion-exchange capacity. The components of the IC instrument so as development of modern continuous to maximize the upper pressure limit suppressors compatible with high mobile- of the system with available materials. phase concentrations enables the use Only recently has this combination of of IC columns of much higher capacity, component design and material science greatly expanding the utility of IC for the

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analysis of trace analytes in the presence use in UHPLC and are available in an IC- of large molar excesses of matrix ions. compatible format for the first time. These new fittings make small-diameter columns With its new instrument, Thermo as easy to use as 4-mm columns. Fisher Scientific is focusing a lot on ease of use. Have IC instruments Why are you now providing not been very user friendly to date? a new system for consumable Previous IC instruments have been identification? How does it work? designed so as to maximize analytical It’s long been my goal to incorporate performance. Achieving high performance automatic consumable identification in IC involves a number of components as part of the instrument. Automatic not present in a conventional HPLC identification ensures that 100% of the system, such as the suppressor, the eluent consumable utilization record is tracked generator, the electrolytic trap column, as part of the identification system. and the high-pressure degasser. We Identification is achieved using either have found that the greater operational radio-frequency identification (RFID) complexity of these IC-specific tags on consumables without electrolytic components makes an IC instrument more control or electronic tags embedded in the difficult to use than an HPLC instrument, control cable for electrolytic consumables. especially for those who are new to IC. These tags allow for keeping records of With our newest IC instrument, the up to 20 different parameters associated Thermo Scientific Dionex Integrion HPIC with each consumable, such as number system, we worked hard to make sure of injections, maximum temperature that all of these components are easy to exposure, volume of mobile phase passed use through the use of built-in plumbing through the column, column pressure diagrams, an intuitive fluidic layout, and history, suppressor voltage history, a simple, easy-to-use tablet control panel and eluent generator ion count, along available in 11 languages. Taken together, with device parameters such as column these features combine to make the diameter, column type, and suppressor Dionex Integrion IC system the easiest-to- type. It can also be used to identify when use instrument we’ve ever made, without the performance of a component has sacrificing performance drifted outside recommended operating In addition, we have developed new a IC parameters and the component needs PEEK Viper finger-tight fitting system that replacement. Because the information guarantees a perfect zero dead volume is stored on a tag attached to the connection every time, minimizing issues consumable rather than being stored in commonly seen with conventionally tubing software, the information stays with the and fittings. Viper fittings are in wide consumable even if the consumable is

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moved to a new instrument. Furthermore, and warn about improperly configured the information stored on the consumable components such as an anion-exchange helps technical support personnel column in combination with a cation troubleshoot issues that customers report suppressor or an anion eluent generator by providing key information about the in combination with a cation-exchange way the consumable was operated and column. In addition, the instrument performance trends over the life of the uses a new chemical barcode standard consumable. system for improved peak identification tracking. Unlike conventional software Can the new system that uses retention time windows for be controlled remotely? each analyte in the chromatogram, this The instrument is available with a WiFi new analyte tracking system uses the interface that allows for remote control area percent of each peak relative to the of the instrument with any WiFi-enabled largest peak in the chromatogram as the tablet or mobile device that has been basis for identifying each of the peaks connected to the instrument and loaded in the chromatogram. Even as retention with a suitable control app. Although time shifts over the life of the column, the tablet interface is not a requirement peak identifications remain accurate, to operate the instrument, the tablet whereas under similar conditions the use can either be magnetically mounted to of retention time windows may result in the front of the instrument or can be erroneous peak identifications. detached from the instrument; in the latter case, the tablet can be used to What if users still need more help? remotely control the instrument as long Because control of the instrument uses as it is within WiFi communication range. a tablet interface with considerable The interface is compatible with mobile memory capacity, it is feasible to provide devices with Android, iOS, and Windows much more information in the tablet operating systems. interface than has been available in previous instruments. The instrument The new instrument includes manual in its entirety is stored in tablet features to help prevent user memory. In addition, installation guides, error. Can you tell us about those? installation videos, and troubleshooting Because all of the consumables used guides are available through the tablet- in the instrument contain tags that are based instrument control interface to automatically identified by the instrument, help the chromatographer each step of the instrument can immediately identify the way. incompatible combinations. For Chris Pohl is the Vice President of Chromatography Chemistry at example, the instrument will identify Thermo Fisher Scientific.

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