BECKMAN COULTER DU-800 SPECTROPHOTOMETER:

Faculty incharge-Dr.K.Lily Therese / Dr.Sripriya

The BECKMANN XL 80 –PREPARATIVE ULTRACENTRIFUGE is a vacuum ultracentrifuge with a dynamic temperature regulation system, a convenient operating height for most users due to a shallow recess that holds the sample rotor. They can include several different rotor types ranging from fixed-angle, near-vertical angle, to swinging-bucket rotors.

Operation of the BECKMANN XL 80 –PREPARATIVE ULTRACENTRIFUGE is convenient and controlled through a touch screen interface which allows the operator to select RPM settings up to 80,000 RPM, temperatures between 0°C and 40°C, time settings, and even acceleration and deceleration rates for the ultracentrifuge. After the sample tubes are carefully balanced and loaded, they can be transferred directly to the rotor to spin the sample tubes. Importantly, the instrument is equipped with a rotor safety function- “Dynamic Rotor Inertia Check” (DRIC), which can sense imbalances in the rotor that may lead to catastrophic failure and equipment damage before the ultracentrifuge is allowed to run at critical revolutions per minute.

The Optima L-XP is marketed with an accessory set which includes a variety of sample tubes designed to fit the rotors. While samples can be loaded into the tubes with some care, it is entirely possible that the tube and the rotor wells themselves will accumulate sample matter.

Optical Principle

The DU 800 Spectrophotometer is a single beam instrument. Light from both sources enters the monochromator where it is dispersed by a concave holographic grating. Monochromatic light exits the monochromator and illuminates the sample. The amount of light that passes through the sample is measured by a single photodiode detector.

The focal point of the beam in the sample compartment is on the right-hand side. All sampling accessories position the sample at the focal point for best performance with regular samples and micro-samples.

The following applications are available with the software installation. More information is available in System Software and Standard Applications.

Fixed Wavelength :-

Performs Absorbance or %Transmittance readings for up to 12 wavelengths simultaneously. A factor or custom formula may be applied to calculate final results.

Wavelength Scan :-

Performs wavelength scans in Absorbance or %Transmittance. Acquired scan data are stored and may be used for various manipulations and calculations. Includes the calculation mode to add, subtract, multiply and divide spectra.

Kinetics/Time :-

Simultaneously measures and analyses up to 12 rate reactions. Data can be reviewed in real time and automatically calculated and printed. The rate of the kinetic reaction is reported using a linear regression.

Nucleic Acid Analysis :-

Determines protein impurity in nucleic acid samples based upon the ratio of readings at two wavelengths with a choice of background correction. Protein and nucleic acid concentrations can also be calculated using the Warburg and Christian1 coefficients.

Single Component Analysis :-

Determines the concentration of unknowns by either linear or non-linear (quadratic) regression and provides statistical analysis for the standard curve. The standard curve can have up to 30 standards. The operator can re-run any standard, remove or add standards, and have the instrument re-calculate the curve.

Performance Validation :-

Provides a simple procedure to verify the performance of the instrument without standards or samples. Tests include: wavelength accuracy and repeatability, resolution, baseline flatness, noise, and stability.
In addition, the "rapid" modes RediRead™ and RediScan™ are available. These provide the user with a fast and easy way to take readings at fixed wavelengths or to make wavelength scans.

Optional Applications

Wavelength Scan II :-

Extends the functionality of Wavelength Scan with the following modes: Derivatives (1st, 2nd, 3rd, and 4th), NetA Calculations, Scatter Correction, Point Picker, and Peak/Valley Picker. Also included is the display of spectra in LogA.

Nucleic Acid Analysis II :-

Extends the functionality of Nucleic Acid Analysis with multiple ratios and other concentration calculations. Also included are DNA/RNA Oligo Quantitation modes to determine molecular weight, absorptivity (extinction coefficient), concentration, and the theoretical melting point for oligonucleotide DNA samples.

Protein Analysis :-

Calculates protein concentrations using the Bradford, Lowry, Biuret, Direct UV, Colloidal Gold, or Bicinchoninate (BCA) methods. The user may choose to add, delete, or re-run individual standards based upon the statistical analysis of the standard curve.

Enzyme Mechanism :-

Provides for rapid and easy characterization of a wide variety of enzyme reactions. The software calculates and reports Km, Vmax, kcat and Ki as well as the Hill constant. The following functions are available: Michaelis-Menten, Lineweaver-Burk, Eadie-Hofstee, Hanes-Woolf, Hill, and Inhibitor plots.

Enzyme Activity :-

Calculates the enzyme activity of large numbers of samples from chromatography fractions (endpoint kinetics).

Experimental Tm Analysis :-

Allows the study of denaturation and renaturation of DNA samples. The thermal melting point (Tm) is determined quickly and efficiently using the First Derivative, 2-Point Average, or a Non-Linear Curve Fit algorithm. Up to six micro-volume samples with 325 µL can be processed automatically, applying up to three temperature ramps.