945 Professional Detector Vario IC Amperometric Detector Amperometric detection for determining electroactive components Amperometric detection: the answer for complex analytical tasks 02 Amperometric detectors are an alternative to conductiv-The user-friendly measuring cells are intelligent, require ity and UV/VIS detectors. They may always be used when little maintenance, and are optimized for the various electroactive − i.e., oxidizable or reducible − components app lications. Their three-electrode configuration ensures are to be de ter mined. The IC Amperometric Detector re markably low noise levels and excellent signal strength. excels by its high selectivity and measurement sensitivity. Depending on the particular application, the instrument It can be used for sensitive and accurate determination can be operated in direct current mode (DC), in pulsed of concentrations down to the ng/L range. amperometric mode (PAD), in flexible integrated pulsed amperometric mode (flexIPAD), or in cyclic voltammetric The amperometric detector is available as a detector block mode (CV). The flexibility of the detector includes the (the IC Amperometric Detector) and as a stand-alone choice of measurement signal: no matter whether current detector (the 945 Professional Detector Vario). Both or charge is selected, users always obtain a reliable result. instruments can be operated either with a 940 Pro fessional IC Vario or with a 930 Compact IC Flex. Con trol, data recording, and data evaluation are carried out by the proven ion chromatography software MagIC Net. The amperometric detector of the Professional IC Vario generation: irrespective of whether the 945 Professional Detector Vario or the IC Amperometric Detector is used, the amperometric detector can be incorporated in any Metrohm IC system and helps users to perform even the most demanding analytical tasks. 03 Highlights • Amperometric detector for determining electroactive components • Flexible setup as stand-alone detector or detector block for IC and HPLC • Outstanding selectivity due to different measuring modes: DC, PAD, flexIPAD, CV • High sensitivity through excellent signal/noise ratio • Large measuring range for demanding applications • Easy to use due to intelligent and robust measuring cells with wall-jet and thin-layer design • Large variety of working electrodes: Au, Ag, Pt, Cu, GC • Different maintenance-free reference electrodes • Very fast start-up without long conditioning times • Leak sensor in the cell compartment • Fully compliant with Metrohm Inline Sample Preparation techniques • Control and monitoring by MagIC Net − the proven software for ion chromatography Direct current amperometry: DC mode The most well-known method of amperometric mea-04 (e.g., glacial acetic acid, urine, wastewater). To ensure surement is direct current amperometry, which is also optimum analysis of samples, Metrohm offers a wide se - known as DC mode. It is used primarily to determine in - lec tion of working electrode materials: gold (Au), silver or ganic anions, but can also be used to determine or ga- (Ag), platinum (Pt), copper (Cu), and glassy carbon (GC). nic substances such as phenols or catecholamines. When Complete cell equipments with an intelligent measuring a constant working potential is applied between the cell, including the permanently installed auxiliary elec-working electrode and the reference electrode, the ana-trode, suitable working electrode, and reference elec-lytes are, for example, oxidized. Depending on their con-trode, are also available to users for the standard DC centration, a current flows to the auxiliary electrode, mode applications, such as cyanide determination, and which provides the measurement signal. In DC mode it is for the analysis of inorganic anions. possible to measure without a specific range. For this, auto range is available. Typical DC applications DC amperometry is a highly sensitive analytical method • Anions, such as cyanide, sulfide, nitrite, sulfite, that is characterized by detection limits in the lowest ng/L thiosulfate, iodide, chlorite, hypochlorite, bromide, range. Another outstanding feature is its high selectivity, arsenite, ... which enables matrix effects to be suppressed in the • Cations such as amines and aromatic amino acids, ... chromatogram, so reliable analysis can be carried out • Organic substances such as phenols, catecholamines, successfully even in the most difficult sample matrices ascorbic acid, alcohols, vitamins, ... 25 23 21 19 17 15 sulfide; 4 µg/L 13 ent [nA] 11 cyanide; 4 µg/L urrC 9 7 5 3 1 0 1 2 3 4 5 Time [min] Fast, extremely sensitive (detection limits below 10 ng/L), and reliable determination of cyanide and sulfide is possible with DC amperometry. Analysis of a standard solution containing 4 µg/L cyanide and 4 µg/L sulfide; column: Metrosep A Supp 10 - 100/2.0; eluent: 100 mmol/L NaOH + 7 µmol/L EDTA, flow: 0.25 mL/min; column temperature: 35 °C; detector: DC mode, WE: Ag, RE: Ag/AgCl, working potential: 0 V, temperature: 35 °C; sample volume: 20 µL Pulsed amperometry: PAD mode Pulsed amperometry is used when analytes form a de - In PAD mode, all working and reference electrodes are 05 posit on the surface of the working electrode as a result available to the user. Specifically for carbohydrate analy-of the electrochemical reaction, making detection in DC sis, however, Metrohm offers a complete cell equipment mode impossible. In PAD mode, a constant working po - comprising intelligent measuring cell, gold working elec-tential is applied at the beginning. However, unlike in DC trode, palladium reference electrode, and appropriate amperometry, the surface of the working electrode is accessories. then cleaned continuously through the application of cleaning potentials. A total of up to 40 different poten-Typical PAD applications tials can be app lied for this «potential wave». In this way, • Sugars, e.g., mono-, di-, oligo-, and polysaccharides ... the application can be optimized, so there is always a • Sugar alcohols, polyols, glycols, aliphatic alcohols, ... fresh working elec trode surface available. Robust and • Sugar amines, e.g., glucosamine, galactosamine, ... reliable detection is guaranteed. • Anhydrosugars, e.g., levoglucosan, galactosan, mannosan, ... PAD mode is used primarily to detect carbohydrates and • Sugar acids, e.g., glucuronic acid, gluconic acid, their derivatives. Multiple potential profiles make it pos-sialic acids, ... sible to find the optimum working conditions for each • Substituted sugar compounds, e.g., glucose-6-phos-analyte. phate, 2-fluoro-2-deoxy-D-glucose, ... • Amino acids All separations are achieved on Metrosep Carb 2 - 150/4.0 column Analysis of sugar alcohols, mono- & disaccharides Quality control of fruit juices 1400 10000 1300 9000 1200 1100 8000 1000 7000 fructose; 60331 mg/L 900 inositol; 1 mg/L 800 6000 700 arabitol; 1 mg/L 5000 600 glucose; 19367 mg/L Current [nA] sorbitol; 1 mg/L 500 4000 Current [nA] 400 glucose; 1 mg/L xylose; 1 mg/L 3000 300 fructose; 1 mg/L 2000 200 lactose; 1 mg/L sucrose; 1 mg/L 100 1000 sucrose; 18417mg/L 0 0 0 2 4 6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 16 18 20 22 24 Time [min] Time [min] Eluent: 100 mmol/L sodium hydroxide / 10 mmol/L sodium acetate, Eluent: 100 mmol/L sodium hydroxide / 10 mmol/L sodium ace-column temperature: 30 °C; sample volume: 20 µL, flow rate: tate, co lumn temperature: 30 °C; sample volume: 20 µL, flow rate: 0.5 mL/min, amperometric detector: PAD mode, WE: Au, RE: Pd, 0.5 mL/min, amperometric detector: PAD mode, WE: Au, RE: Pd, working potential: 50 mV working potential: 50 mV, dilution 1:1000 Anhydrosugars as air quality indicators Production monitoring of lactose free milk products 5500 1600 5000 4500 1400 4000 arabitol; 1.28 mg/L 1200 3500 glucose; 13820 mg/L sorbitol; 1.27 mg/L 1000 galactose; 14154 mg/L 3000 mannitol; 1.28 mg/L inositol; 0.64 mg/L 2500 800 erythritol; 0.647 mg/L Current [nA] mannosan; 3.23 mg/L galactosan; 3.24 mg/L 2000 levoglucosan; 3.13 mg/L Current [nA] 600 1500 rhamnose; 3.17 mg/L xylose; 3.18 mg/L 400 lactose; 110.7 mg/L 1000 glucose; 3.16 mg/L 200 500 sucrose; 3.04 mg/L 0 Systempeak 0 0 4 8 12 16 20 24 28 32 36 40 0 2 4 6 8 10 12 14 16 18 20 Time [min] Time [min] Eluent: 10 mmol/L sodium hydroxide, column temperature: 45 °C; Eluent: 5 mmol/L sodium hydroxide / 2 mmol/L sodium acetate, sample volume: 100 µL, flow rate: 1.0 mL/min, amperometric column temperature: 40 °C; sample volume: 20 µL, flow rate: detector: PAD mode, WE: Au, RE: Pd, working potential: 50 mV 0.8 mL/min, amperometric detector: PAD mode, WE: Au, RE: Pd, working potential: 50 mV. Sample: diluted 1:100, spiked with 100 mg/L lactose Flexible integrated pulsed amperometry: flexIPAD mode 06 In flexIPAD mode the focus is entirely on flexibility. This enables a potential-time pattern to be preset at will. Up to 40 constant potentials (steps) and linear potential changes (ramps) can be combined. Whatever the require-ments of the application are, they can be fulfilled in this working mode. The range over which the measurement signal is to be integrated can be defined at the user’s dis cretion. Either charge or current can be chosen as the mea surement signal. The fast switches of the amperometric detector enable the potential to be applied very rapidly. Consequently there is hardly any need for conditioning steps; the potential wave can be made short, so a higher data rate is possible. The range of uses of the flexIPAD mode comprises all applications of the PAD mode and a few more besides, including the determination of sulfur-containing analytes, for example, in electroplating baths, in pharmaceu-tical products, or in food and beverage. In addition, the flexIPAD mode is ideal for research applications owing to Complete flexibility in the creation of the potential wave the freedom one has to choose the po tential profile. of the sweetener Stevia (see chromatogram below). Typical flexIPAD applications • Carbohydrates and their derivatives, sweeteners • Amino acids and sugar amines • Organosulfur compounds • Antibiotics • Biogenic amines • Research applications 1800 1750 1700 1650 1600 1550 rebaudioside A; 41 mg/L stevioside; n.q. 1500 1450 Charge [nC] 1400 rebaudioside C; n.q. 1350 1300 1250 1200 0 2 4 6 8 10 12 14 16 18 20 Time [min] Glycoside analysis in sweetener – flexIPAD mode. Noncaloric stevia glycosides are widely used in food and beverages to replace calorie-rich sugars. One of the main stevia glycosides is rebaudioside A. The chromatogram shows the rebaudioside and stevioside peaks detected in a highly diluted sweetener sample (41 mg/L). Column: Luna 5 µm C18, 250 × 4.6 mm (Phenomenex); eluent: 10 mmol/L NaH PO , pH = 4.5 / acetonitrile 70:30 (v/v), flow: 1.0 mL/min; column temperature: 40 °C; PCR solution: 2 4 400 mmol/L NaOH, 0.3 mL/min; detector: flexIPAD mode (see Fig. above), WE: Au, RE: Pd, working potential: -1.0 to 0.6 V, temperature: 35 °C; sample volume: 20 µL Cyclic voltammography: CV mode The method development for determining unknown 07 ana lytes is complex, especially when work is done using PAD or flexIPAD mode. CV mode helps the user to meet this challenge. Through interpretation of a cyclic voltammogram it is possible to arrive at the optimum working potential for the particular application. The cyclic voltammogram also shows the potentials with which the surface of the working electrode can be oxidized and re - duced, in order to achieve continuous cleaning. In this way the optimum potential profile for each analyte can be discovered. In addition, working, reference, and auxiliary electrodes can be characterized with the help of cyclic voltammograms. Changes over a prolonged period can be docu-mented. Furthermore, it is possible to read off from cyclic voltammograms the potential range within which work A multiple number of cyclic voltammograms in combina-can be done (depending on the electrode configuration tion with a few preparing cycles guarantees that one actu-being used). Thus users can get a better understanding ally measures what one is supposed to measure. Artifacts and interferences can be ruled out. Variable settings are possible of the electrochemical reactions under the respective for the start and end potential, the sweep rate, the measurement application conditions. range, and also whether full or half cycles should be scanned. Typical CV applications • Determination of the optimum working potential • Determination of regeneration potentials for PAD and flexIPAD modes • Characterization of electrodes 80000 60000 40000 20000 0 ent [nA] -20000 urrC -40000 -60000 -80000 -100000 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Voltage [V] In CV mode voltammograms are recorded that show the resulting current as a function of the working potential. This can also be done in a peak − during chromatographic separation. Thus, the electrochemical reaction in the cell can be followed exactly as it takes place during detection. The example shows a cyclic voltammogram of glucose in eluent (black CV) by comparison with pure eluent (red CV). Intelligent measuring cells as the key to success 08 Intelligent IC stands for self-monitoring measuring sys-The measuring cells are easy to use and equipped with tems, minimization of operating errors, and traceability three electrodes: working, reference, and auxiliary elec-of the measurement results from sample preparation, trodes. As the working electrode, a number of 2-mm-through separation and on to detection. In practice, that and 3-mm-versions are available in the usual materials, means reliable and simple operation. The intelligent mea s-nam ely gold, silver, platinum, copper, and glassy carbon, uring cells of the amperometric detector are a perfect depending on the particular application. The working example. The systems offer the following advantages: electrode can be replaced at any time and is so rugged that it can be used for months or even years. The preci- • Automatic recognition of the cells in the system sion and repeatability of the meas urements are impres- • Traceability of data to the measuring cell used sive. Maintenance-free auxiliary and reference electrodes • Monitoring of the working and reference electrodes complete the detection system. Solid-phase palladium on the basis of operating hours electrodes with long-term stability and Ag/AgCl gel electrodes (filled with saturated KCl) are available as refer-The intelligent measuring cells are resistant to pressure, ence electrodes. A stainless steel auxiliary electrode is a require little maintenance, and are optimized for ion standard component of every cell. chro matography applications. Depending on the application, users can choose between wall-jet cell or thin-layer cel . The closed cell compartment, the electrical shielding, and the thermostatic control also minimize the signal noise. Moreover, the cell compartment is equipped with a leak sensor, so the analytical system is shut down immediately in the event of any escape of liquids. Each cell has a purge connection that ensures easy venting. The intelligent measuring cells and their working and reference electrodes − a perfect team for your application Typical applications of the different working electrodes Working electrode Application Au • Mono-, di-, oligo-, and polysaccharides, sugar alcohols, sugar amines, sugar acids • Amino acids • Antibiotics Ag • Halogen anions, e.g., bromide, iodide • Cyanide and sulfide • Thiosulfate • Pharmaceuticals Pt • Alcohols and glycols • Hydrazines • Arsenite and hypochlorite Cu • Mono-, di-, oligo-, and polysaccharides, sugar alcohols GC • Inorganic anions, e.g., nitrite, sulfite, iodide • Phenols • Catecholamines and aromatic amines • Vitamins The right system for every challenge Metrohm offers the amperometric detector in the form Due to the wide variety of possible configurations with 09 of a detector block (IC Amperometric Detector) and as a the IC Amperometric Detector and the 945 Pro fessional stand-alone detector (945 Professional Detector Vario). Detector Vario it is not only possible to equip IC systems These two instruments can be used both with 940 Pro-with additional analytical features, but also to up grade fessional IC Vario or with 930 Compact IC Flex. De pend-HPLC systems to an ion chromatograph. ing on the task at hand, measurement can be performed in series or in parallel with other analytical channels. Sys tem configurations with gra dient elution, with inline eluent preparation, with mi cro bore columns, and inline sample preparation techniques (MISP) are also possible. Such systems are controlled and the data are collected and evaluated by MagIC Net ion chromatography software. The stand-alone detector 945 Professional Detector Vario is a versatile instrument that is offered in three different versions: only as an amperometric detector (945 Pro fessional Detector Vario – Amperometry), only as a conductivity de tec tor (945 Professional Detector Vario – Conducti vity), and as a combination of both detectors in a single instrument (945 Professional Detector Vario Conductivity & Amperometry). The 945 Professional Detektor Vario is the in terface for a number of optional peripheral de vices As a detector block or as a stand-alone detector − as for example, 942 Extension Module Vario, 800 Dosino, ampe rometric detection provides the solution for both selective 891 Professional Detector Out, or USB devices. and sensitive analytical tasks. Technical information 10 945 Professional Detector Vario – IC Amperometric Detector Amperometry 2.850.9110 2.945.0020 Design Detector block Stand-alone detector Type of detector Microprocessor-controlled digital signal processing Detection modes DC, PAD, flexIPAD, CV Potential range -5.0 to +5.0 V in 0.001 V steps DC mode: 1 potential Potential profile PAD mode: 40 potentials flexIPAD mode: 40 potentials (steps and ramps) Data output channels Current and charge DC mode: 0.00012 pA to 2 mA, autorange PAD mode: 0.012 pA to 2 mA Digital signal range flexIPAD mode: 0.12 pC to 200 µC CV mode: 0.12 pA to 20 mA DC mode: < 5 pA Electronic noise PAD mode: < 10 pA flexIPAD mode: < 30 pC Control, data collection, MagIC Net 3.1 Compact, Professional and Multi and data evaluation Temperature stability better than 0.05 °C Detector temperature Temperature range: ambient temperature +8 °C to 80 °C Liquid-carrying parts Free of metal • Automatic function test upon startup System readiness • Leak sensor • Monitoring of temperature stability Can be installed in 940, 930 Can be combined with Peripheral devices standard component of 940, 930, 883, 944, and 945 2.945.0020 and 2.945.0030 Installation Dedicated and multiple detection (parallel and in series) possible Sample preparation and Can be combined with all inline sample preparation techniques (MISP) and liquid handling injection techniques (full-loop, internal loop, MiPT, MiPuT) Possible directly with Analog data output Via peripheral devices 891 Professional Analog Out Measuring cell management Intelligent measuring cells with automatic recognition and monitoring functions Cell geometry Wall-jet cell and thin-layer cell Cell housing PEEK body purge outlet Replaceable gold, silver, platinum, copper, and glassy carbon working electrodes Working electrodes (2 and 3 mm diameter) Reference electrodes Replaceable solid-phase Pd electrode and Ag/AgCl reference electrodes Auxiliary electrode Stainless steel auxiliary electrode incorporated in the measuring cell Cell volume < 0.1 µL wall-jet cell (with 2 mm working electrode and 25 µm spacer) 11 Ordering information Detectors 2.850.9110 IC Amperometric Detector 2.945.0010 945 Professional Detector Vario – Conductivity 2.945.0020 945 Professional Detector Vario – Amperometry 2.945.0030 945 Professional Detector Vario – Conductivity & Amperometry Equipment with intelligent cell, 25 and 50 µm spacers and accessories 6.5337.000 IC equipment wall-jet cell 6.5337.010 IC equipment wall-jet cell for carbohydrate analysis* 6.5337.020 IC equipment wall-jet cell for cyanide analysis** 6.5337.030 IC equipment wall-jet cell for anion analysis*** 6.5337.200 IC equipment thin-layer cell Cells and electrodes 6.1257.010 Wall-jet cell (without accessories) 6.1257.100 Thin-layer cell (without accessories) 6.1257.210 Au working electrode (3 mm) 6.1257.220 GC working electrode (3 mm) 6.1257.230 Pt working electrode (3 mm) 6.1257.240 Ag working electrode (3 mm) 6.1257.260 Au working electrode (2 mm) 6.1257.270 Cu working electrode (2 mm) 6.1257.720 Ag/AgCl reference electrode 6.1257.740 Pd reference electrode Other accessories 6.1257.810 50 µm spacers for wall-jet cell (3 pieces) 6.1257.820 50 µm spacer for thin-layer cell (3 pieces) 6.1257.830 25 µm spacers for wall-jet cell (3 pieces) 6.1257.840 25 µm spacer for thin-layer cell (3 pieces) 6.1257.500 Connecting cable for cell (set with 3 cables) 6.2061.100 Bottle holder for Professional IC instruments 6.2061.110 Tray with leak sensor for Professional IC instruments 6.2802.200 Maintenance set for 6.1257.2XX working electrodes 6.2802.210 Polishing disks for 6.2802.200 maintenance set 6.2813.040 Dummy cell * with Au working electrode (3 mm) and Pd reference electrode ** with Ag working electrode (3 mm) and Pd reference electrode *** with GC working electrode (3 mm) and Ag/AgCl reference electrode www.metrohm.com witzerland G, CH-9100 Herisau, S ohm A , printed by Metr SW Subject to change without prior notice Layout by Ecknauer+Schoch A 8.945.5001EN – 2016-01