The Japanese company JASCO has been collecting its experience in the field of CD spectrometers, the most important chiroptical instruments used for the measurement of circular dichroism phenomenon since 1961. This instrument, also known as dichrograph, spectropolarimeter, circular dichroism spectrometer (CD) or electronic circular dichroism spectrometer (ECD) is capable of both the qualitative and quantitative testing of compounds in whose molecules chromophore groups can be found near the chiralty centers. The CD spectrometers are the basic instruments for measuring the absolute configuration and conformation of the organic compounds. It can be used for monitoring the stereoselective processes and for studying the conformational changes caused by temperature, pH and chemical reactions. With these instruments the kinetics of enzyme and organic reactions, the DNA/RNA interactions, the structure and conformation of proteins can also be examined.
The J-1100 and J-1500 instruments are considered as the successors of the JASCO J-815 CD spectrometers. The J-1100 compact instrument is recommended primarily for those who wish to use it to characterize bio and organic molecules as a routine task. The J-1500 can be beneficial for those who are
involved in research, because of its extensive expandability options. Both instruments, in their basic configuration, can be used for the examination of the circular (CD) and linear (LD) dichroism phenomena, as well as a single-beam spectrophotometer. With the help of the automatic accessory recognition system, the specific measuring parameters belonging to the sample holders can be easily configured by the control software. In the optical system of the instruments a shutter has been transferred to a new position. Therefore, in the case of prolonged measurements both the sample and the optical elements can be protected from the continuous high-energy radiations. Also, the protection of the optics and the feasibility of the measurements in the UV range is facilitated by the restructured, efficient and low-consumption nitrogen purge system. A built-in mercury lamp within the J-1000 is available for the simpler, faster and well-documented control of the wavelength accuracy. The instruments are connected to the computer via a USB port, while the control and the collection of the measured data is done by the Spectra Manager II software package, also controlling all the JASCO spectroscopic instruments.
The J-1100 CD spectrometer uses an air-cooled lamp of 150 W as a light source and the standard measurement range is between 180-600 nm. In its cell compartment cylindrical and rectangular cuvettes of maximum 20 cm length can be placed. The Peltier-type cuvette holder, also capable of transmission measurements, can be used to examine the temperature dependence of the sample structure. The sample of a small quantity can be measured with the Micro-Sampling Disk accessory, which is able to determine the circular dichroism characteristics of even 2 μl samples.
The J-1500 CD spectrometer, with its extensive expandability, can be of great interest for research laboratories engaged in chiroptical spectroscopy. The instrument, in its standard configuration, uses a 150W air-cooled lamp. However, in the supply, the configuration with the water-cooled 450W xenon lamp is also available. The standard measurement range is between 163-950 nm, which can be optionally extended to 1600 nm. Due to the ”Simultaneous Multi-Probe Measurement” (SMP) method, 4 signals from the CD, LD, UV, FL, FDCD, FDLD etc. measurements can be acquired simultaneously. With various sample holders and accessories it is possible:
- to follow chemical reactions or conformational changes caused by pH changes
- to examine color samples within the NIR range
- to record the CD/Abs (or LD/Abs) and fluorescence (FL) signals simultaneously by building fluorescence measurement possibilities
- to detect selectively the fluorescence circular dichroism signal (FDCD) of fluorescing chromophores
- to measure the CD and FDCD simultaneously
- to carry out fluorescence anisotropy studies
- to carry out transmission and reflection studies of solid samples
- to study the orientation of longitudinal molecules
- the HPLC-CD coupling
- to examine chiral molecules without chromophores (ORD)
- to measure magnetic CD/LD signals etc.
Spectra Manager II
The JASCO Spectra Manager II software controls the CD spectrometers and their accessories, including the setting of system configuration and spectra measurement parameters and the running of self diagnostic. This
software is available for the pharmaceutical industry in the 21 CFR Part 11 compatible version, as well. It is able to acquire the data of 4 channels simultaneously. Among standard circumstances the CD/LD/Abs signals are processed. Yet, other signals e.g. CD/fuorescence, temperature or pH can also be collected. The analysis program module is a comprehensive program package for processing the spectral data with the following functions:spectrum display in overlay mode; add/subtract/divide; baseline correction and x/y axis conversion; derivation; peak-height/area/half-value width computation; smoothing/enlargement/reduction; peak detection; data conversion (ASCII and JCAMP-DX); file search with spectrum and parameter display. The Spectra Manager II supplied with the spectropolarimeter contains the module capable of converting the CD and ORD spectra into each other, calculating absorbance from the HT voltage, determining the g-factor from CD and absorbance spectra, calculating specific ellipticity, magnetic specific ellipticity, molar ellipticity, magnetic molar ellipticity etc. from the CD signal. The JASCO Canvas report publishing editor is part of the software package and provides tools for the user to produce publication quality layouts of data, texts, graphics, photographs and logos to meet their own requirements.
The optional softwares include modules for:
- calculating the secondary structure of proteins from the CD spectrum
- determining the thermodynamic parameters of the denaturated proteins
- software calculating the thermodynamic parameters of the protein-ligand interaction
- curve fitting
- ”Macro Command” program, which provides software-writing access for the user
- CFR 21 Part 11 compliance
Vibrational Circular Dichroism (VCD) instruments are also available, please ask our office for further information!
Accessories for J -1100 CD spectrometer:
Water thermostattable cell holders for cylindrical and rectangular cuvettes, for the latter ones with magnetic stirrer
Peltier thermostatted transmission-type cuvette holder
Special sample holders for the measurement of samples volumes of 2-100 μl
Flow-through cell for HPLC coupling; the J-1100 CD spectrometer can be used as a HPLC detector. The JASCO ChromNav or any other software for HPLC are capable of processing the analog CD signal provided by the spectropolarimeter directly.
Accessories for J -1500 CD spectrometer:
Due to the outstanding optics and the large sample compartment the use of numerous accessories is possible:
PMT detector for the extended 450-1250 nm wavelength range
InGaAs detector and halogen lamp for the extended 800-1600 nm wavelength range
Unit capable of Optical Rotatory Dispersion (ORD) measurement used also for analyzing chiral samples without chromophores
- optical ORD accessory – usable spectral range 185 -700 nm , measurement range ± 45°
- electronic ORD accessory – usable spectral range 185 -700 nm measurement range ± 1°
Specially designed sample holders for measuring microliters of samples; for samples of 2 or 10 μl a ”Micro-Sampling Disk is available.
Automatic titration system controlled by the Spectra Manager II software, which also controls the CD spectrometer.
Integrating spheres for measuring solid samples using diffuse reflectance and diffuse transmittance measurement methods.
- integrating sphere ID: 60 mm
- coating: barium-sulfate or Spectralon®
- wavelength range: from 240 or 250 nm up to the measurement range of the detector
Flow-through cell for connecting to the HPLC. The J-1500 CD spectrometer can be used as a HPLC detector. The JASCO ChromNav or any other HPLC software are capable of direct processing of the analog CD signal provided by the spectropolarimeter.
Water thermostattable cell holders for cylindrical and rectangular cuvettes, for the latter ones with magnetic stirrer.
The Peltier thermostatted cuvette holders help to measure solutions at controlled temperature and to studycharacteristics depending on temperature changes. The temperature can be controlled via a sensor built in the cell holder or immersed into the cell. With the Spectra Manager II software it is possible to measure the temperature dependency of the signal acquired at selected wavelength or in the whole spectra range. The heating speed, the desired accuracy and the back and forth direction can be set, as well. The whole three-dimensional data set (detector signal/wavelength/temperature) can be displayed and processed in different ways.
- Peltier thermostatted one-position cell holder for transmission and fluorescence measurements
- Peltier thermostatted 6-position cell holder for transmission mode
- Peltier thermostatted 6-position cell holder for transmission and fluorescence measurements
- temperature range: from -40° up to +130°C
- setting by 0.1°C
- temperature accuracy: 0.2°C
- stirring: built-in magnetic stirrer, stirring speed is adjustable
All units require water cooling.
To maintain the samples at a temperature above 100°C a high-pressure cell can be used up to 170°C; in order to achieve an extreme low temperature, cryostats are available.
Sample holders capable of measuring total fluorescence (FL) or carrying out FDCD measurements. By using the standard PMT, CD or FDCD measurements can be carried out. With the simultaneous use of the standard PMT and a non-modulated detector the simultaneous measurement of the CD/FL or the UV/FDCD signals is possible. Alternatively, the simultaneous use of two modulated PMT detectors is also possible and with them the simultaneous measurement of the CD and FDCD signals can be carried out. With the use of a fluorescence monochromator the measurement of the excitation and emission spectra can be measured. For the fluorescence polarization measurements linear polarizers can be ordered.
Permanent and electromagnets for MCD signal measurements. For the electromagnets optional liquid and solid sample holders cooled with fluid nitrogen are also available .
Depending on the model, systems containing 2, 3 or 4 syringes with high-efficiency special mixing chamber. The syringes are operated by independent stepper motors. Optionally, it is possible the thermostating of the syringe part and the cell part with a Peltier thermostat.
- Cell pathlengths: 2 mm (standard), 0.5, 1, 10 mm optional
- syringe volume: 10 ml standard, 1, 2.5, 5 ml optional
- mixing ratio: from 1:1 up to 1:20 settable by software
- Min. dead time: 2.1 msec with 0.5 mm cell
- max. flow speed 5 ml/sec per syringe (with 10 ml syringe)
- Peltier-thermostat (optional): cell part: 5 – 80°C ± 0.5°C, syringe part: 5 – 60°C ± 0.5°C
Couette-type water thermostable cell for examining the orientation change of the molecules in solution with linear dichroism (LD).
- material of rotating and fixed cylinder: quartz
- sample volume: 100 μl
- lightpath length: 0.5 mm
- rotation speed: 0-7000 rpm
Beam splitter, detector and sample holder for converting the CD spectrometer into a double-beam spectrophotometer.