Firma:                DionexDionex

Modell:              ED 40ED 40

Kommentar:      Dokumente engl.Dokumente engl.

Overview

The ED40 Electrochemical Detector measures current resulting from the application of potential (voltage) across electrodes in flow­through cells. Depending an the method by which the potential is applied and the current measured, several different properties of the flowing solution can be determined. These measurements help answer the major questions analytical chemists ask: What's in it, and how muck is there?

Of course, other detectors are used in high performance liquid chromatography (HPLC). The UV-visible absorbance detector dominates all other forms of detection. Sensitivity is excellent for mang analytes, especially aromatic species, and transparent mobile phases are readily available. However, there are numerous analytes that haue very poor absorbance and are not detected with sufficient sensitivity by UV absorbance. Most of these nonchromophoric molecules are aliphatic organic molecules and inorganic ions. Low wavelength UV detection can be used, but at a loss in selectivity. Refractive Index detection can also be used. However, maintaining a stable baseline can be difficult, and RI detection is less sensitive and substantially less selective than UV detection.

Fortunately, a wide variety of nonchromophoric molecules can be detected with good or excellent sensitivity by one of several forms of electrochemical detection. These molecules include carboxylic, sulfonic and phosphonic acids; alcohols, glycols, aldehydes, and carbohydrates, primary, secondary, tertiary, and quaternary amines; sulfates, sulfoxides, thiols, sulfides, and mercaptans; and inorganic anions and cations. In addition, when compared to UV absorbance detection, electrochemical detection provides substantial improvements in sensitivity and selectivity for amine and hydroxy-substituted aromatics such as catecholamines.

The ED40 Electrochemical Detector is housed in a single-unit DX 500 enclosure (sec Figure 2-1). The detector is designed to be stacked an top of other DX 500 units, up to a maximum height of four units. Figure B-1 in Appendix B illustrates the recommended stacking configuration for DX 500 systems.

ED40 Enclosure

Electrical

Main Power        85 to 270 Vac, 47/63 Hz; 40 W Max, 25 W typical. The ED40 power supply is auto-sensing and requires no voltage adjustment.

Fuse                   Two 3.15 amp fast-blow IEC127 fuses (P/N 954745)

Analog Output    User-selectable full-scale Output of 10, 100, or 1000 mV

Environmental

Operating          

Temperature      4 °C to 40 °C (40 °F to 104 °F)

Operating          

Humidity             5 to 95% relative humidity, non-condensing

Physical

Dimensions        22.5 cm wide x 17.0 cm high x 42.0 cm dep

                          (8.8 in wide x 6.6 in high x 16.4 in deep)

                          6 cm (2.4 in) clearance required behind the detector

Weight                8.2 kg (18 lb)

Display and Keypad

Display               Liquid crystal display with adjustable backlighting

Keypad               26-button keypad for entering commands and numerical values for screen parameters

Detector

Range                0.01 µS to 3000 µS, full scale (Conductivity)

                          50 pC to 200 µC (Integrated Amperometry)

                          50 pA to 300 µA (DC Amperometry)

Temperature     

Compensation   0.0 to 3.0% per °C (Conductivity)

Cell Drive           Variable 8 kHz square wave (Conductivity)

                          ±2.04 V (DC and Integrated Amperometry)

Local                 

Operation          Front panel controls and display Status of all functions.

Remote             

Operation          Control of 4 of 7 functions via TTL or Relay contacts.

DX LAN              All functions controlled by PeakNet Software an a PC

Operation           connected to the ED40 via the DX LAN Interface (optional).

Conductivity Cell

Cell Body           PEEK
Active Volume    1.0 µL

Maximum          

Pressure            2.0 mPa (300 psi)

Electrodes          316 stainless steel

Amperometry Cell

Cell Body            Titanium (counterelectrode)

Active volume     ~ 0.2 µL

Maximum          

Pressure            0.7 mPa (100 psi)

Working             

Electrodes         Gold, Silver, Platinum, Glassy Carbon

Reference         

Electrode            Combination pH–Ag/AgC1

SRS Power Supply

Supply Current   50, 100, 300, 500 mA @ 1.5 to 7.5 V

Over-Voltage     
Alarm                  8.5 V

Over-Tempera-

ture Alarm          40 °C

DS3 Detection Stabilizer

Operating           25 °C to 40 °C (50 °F to 104 °F)

Temperature

Warm-up Time 10 minutes (typical)

Under- or            Message displayed when not at set temperature

Over-Tempera‑

ture Alarms