Firma:              Milton Roy

Modell:            LDC 200

Kommentar:   Dokumente engl.

General

The spectroMonitor® D variable wave­length detector is designed for applications requiring the measurement of ultraviolet light absorption through a column effluent. Small cell volumes and high sensitivity make it well-suited for use as a detector in high perfor­mance column liquid chromatography, although it is not necessarily limited_

to this application. This instrument is designed for years of trouble-free service. If difficulty is experienced, please write or call LDC/Milton Roy, Riviera Beach, Fla. or your nearest regional office for assistance. See page IV-3 for locations and telephone numbers.

FUNCTIONAL CHARACTERISTICS

The spectroMonitor® D provides wave­length coverage in the UV/visible wave­length range of 190 to 700 nm. The cell has a zero dead volume, dual path, flow type configuration. A dual beam (sample reference) optical system is used to compensate for source energy variation and as the reference cell is a flow thru type, it may also be used for solvent absorbance compensation. Minimum spac­ing of sample and reference beams is achieved by a precision quartz fiber optic beam splitter which focuses both beams on their respective cell paths.

Wavelength dispersion is accomplished by means of a concave holographic diffraction grating. Entrance and exit slits are defined by the source and beam splitter geometry rather than by discrete slits. The concave nature of the grating focuses the entrance slit on the exit slit without the usual two concave mirrors The simplicity of this type of monochromator enhances stability and reliability, maximizes energy throughput, and simplifies adjustments.

SPECIFICATIONS    

...for LDC/Milton Roy spectroMonitor® D, when equipped with the standard maxN"" Series LS-23 cell, and operating at 25°C:

POWER REQUIREMENTS : 100, 120, 220 or 240 VAC + 10%, 50/60 Hz, 100W.

Integral filter supresses external line noise.

FUSES: 100, 120 VAC, 1.5 Amps ; 220, 240 VAC, 0.75 Amps (Slo-Blo).

WEIGHT: 20.75 lbs. (9.41 Kg).

DIMENSIONS: 11" (27.44 cm) W x 18" (45.7 cm) D x 5 3/4" (14.6 cm) H.

FLUID CELL TYPE: maxNn" Series high efficiency, 1000 psig. 10 mm pathlength, with flowing reference, 316 stainless steel, removable from front of instrument. Zero dead volume high flow efficiency design (suitable for microparticulate column packing materials).

FLUID CELL VOLUME: 14 uL sample and reference cells (f ul l 10 mm path lengt h) .

FLUID CELL PRESSURE: 1000 psi, designed to eliminate cross contamination (recycle and series detection compatible).

SPECTRAL BANIMI DTH: 5 nm. 1.4.9 WAVELENGTH RANGE : 190-700 nm.

ABSORBANCE RANGES: Eleven steps from .001 to 2.0 absorbance units full scale (AUFS) as follows:

            .001      .100

            .002      .200

            .005      .500

            .010      1.000

            .020      2.000

.050

RESPONSE TIME: Switch selectable active filter, 0.05, 0.1, 0.5, 1.0 and 5.0 seconds (1.0 second specification setting).

ENERGY SOURCE: 35-Watt deuteriun lamp (incorporating a window with high UV transmittance). The lamp filament heater current can be switched off or reduced by one-half during normal opera­tion. Single energy source for both UV and visible ranges.

MONOCHROMATOR: Concave hologra­phic grating.

OPTICAL SYSTEM: Double beam, polished quartz fiber optic beam splitter.

DETECTION: Dual UV enhanced silicon photovoltaic cell.

NOISE: Noise levels may vary at wavelength extremes. Short term noise, dry cell, (peak-to-peak) at 1 second response time is typically less than:

2x10 ^-5 AU@200-300 nm

3 x 10 ^-5 AU @ 350 nm

3 x 10 ^-4 AU @ 550 nm

3 x 1,0 ^-4 AU @ 650 nm

The new LDC/Milton Roy spectroMonitor® D variable wavelength detector sets the new industry standard for high perform­ance liquid chromatography (HPLC) spec­trophotolnetric detectors. Differential absorbance measurements can now be made in the UV/VIS wavelength range of 190 through 700 nm without lamp changes. Plus, the new maxN'" Series high effi­ciency, high pressure fluid cell Fea­tures the lowest noise specification available only 2.0 x 10-5 AU. An integral very low volume heat exchanger

insures temperature equilibration and low baseline drift - less than 1 x 10 ^-4 AU per hour.

LDC/Milton Roy has achieved these remarkable noise and drift levels with a true 10 mm pathlength cell. Detectors which achieve low noise through the use of

short pathlength cells are not as senstive. For example, a detector having mm path cells will produce peaks (sign only one half as large as the spectro--, Monitor® D variable wavelength detector

DRIFT: Less than 1 x 10 ^-4 A.U. per hour (after warm up) in the UV ran,

LINEARITY RANGE : Linear to 2.0 AUFS 1% deviation (typical).

ZERO SUPPRESSION: Front panel and remote automatic zeroing for a ran; of +.75 AU.

RECORDER OUTPUT: 0 to 10 mV, 5 maximum source impedance.

COMPUTER OUTPUT: 1.0V per A.U.: 1K source impedance.

MATERIALS OF CONSTRUCTION

(Wetted surfaces only) : 316 stainless steel, Teflon® and quartz.

FLUID CONNECTION: .010" ID x

1/16" OD 316 stainless steel tubing accepts all 1/16" standard zero dead volume fittings.

OPERATING TEMPERATURE : 15-38°e

FRONT PANEL DIAGNOSTICS:

A. Direct Reading of Absorbance Units.

B. Direct Reading of Sample and Reference Energy.

C. Direct Reading of Source Lamp filament current.

D. Direct Reading of Zero correction

E. LED Indicators for supply voltage (+ 15VDC).

FRONT PANEL SIGNAL POLARITY REVERSAL.

FRONT PANEL EVE NT MARK BUTTON.

OPTIONAL FLUID CELLS: Prep, and Semi-Prep/maxN®, 3mm/ 1 uL/microCelln'.

SPECIAL DESIGN FEATURES

Dual beam configuration provides excellent long term baseline stability and allows the use of a reference cell to compensate for mobile phase back­ground absorbance. This makes it possible to find the peak absorbance wavelength by scanning manually .

Optical components common to the dual beam utilize optical and mechanical components which function symmetrically with both beams, thus noise and drift are held to a minimum. Additionally advantageous is the fact that aging of components is in common with both sides, as are wavelength-dependent character­istics.

Alignment of the optical system is greatly simplified by using the source lamp aperture as the entrance slit to the monochromator (easy replace­ment of lamp) and by incorporating the exit slit and beam splitter into one component.

Events such as time of sample injection can be recorded by pressing the MARK button.

Optics simplicity provides ease of maintenance, and minimum transmission and reflecting surfaces.

Integral heat exchange fluid cell reduces flow sensitivity.

Solvents contact materials of 316 SS, Tefloe and fused silica only.

A maxN'" Series LS-23 Fluid Cell has been incorporated in the spectro-Monitor® D, and is available for all previous spectroMonitor® III's as a factory or retrofit option. Some advantage s of the maxN"" cell are:

A. Optimized plate count in micro­particulate column s without sacrificing detector sensitivity (signal/noise).

B. Improvement of bubble clearing by enabling slight back pressure to be added to the fluid cell (1000 psig mal

NOTE: Back pressure regulators are 1 commercially available for adjusting the exact back pressure required.

C. Additional detectors can be added downstream without exceeding detector pressure rating (1000 psig).

D. Recycle chromatography is possible with the appropriate pump or valve arrangement.

E. The cell will accept higher flaw rates without leakage.

Holographie grating reduces spurious wavelengths and allows high levels of usable throughput energy.,

A computer output signal of 1V/ is provided for data reduction, and an output signal of 10 millivolts, full scale, is provided for recording absorbance.

This ins t rumen t is configure d into a single unit housing the cell, optics, and measurement electronics. The unit contains output signal ports for recording purposes, electronic controls, and power supplies.

The sample stream and a reference stream (if desired) are connected to t measurement cell at the inlet tubes (labeled SAMPLE IN and REF IN). Separate outlet tubes near their respective inlets are provided for connection for further processing or sample collection.

The new LED Diagnostic Circuitry, introduced in the spectro Monitor D, provides the chromatographer with a switch selectable digital display to indicate the follwing:

A. AU: Direct reading of absorbance units.

B. ENERGY (S and R): Direct Sample and Reference readings in mV. Record the mV readings at various wavelengths with the clean, new cell for future reference. A decreased reading at a later time may indicate a contaminated cell or lamp deterioration.

C. DACE: Direct reading of filament current at the deuterium source lamp. Typical display with a healty lamp is approximately 300 mA.

D. ZERO: Displays (in absorbance units) amount of zero correction applied.

E. +15V: Proper operating voltages are indicated by a separate two-color LED. When green, it indicates proper supply voltages (+15V) are present in the signal processing circuits. When red, either the positive (+), the negative (-), or both supplies are abnormal.

A single pushbutton on the front panel automatically zeroes the detector, signal. The autozero function will compensate for +0.75 AU of background. This helps to eliminate the often tedious adjustments normally associated, with the initial setting of detector baseline. The autozero function is also valuable tool in resetting baseline, after wavelength, solvent or temperature changes.

An offset adjustment on the front panel allows the user to shift the recorder baseline and still maintain automatic zeroing.