Model 6500/5 Quantitation Mode

Concentration is measured at a single wavelength, and is calculated from absorbance or transmittance using a calibration curve constructed from the calibration standards. Two to seven calibration standards are loaded into the cell holder in positions 1 to 7 with position 0 being reserved for zero absorbance calibration or for subsequent sample measurement. Concentration is displayed in the range 0 to 9999, auto ranging to a maximum of three decimal places.

A calibration curve is constructed and displayed using the concentration standards held in cell locations 2 to 7 as an automatic sequence initiated by selecting the appropriate menu option. The calibration procedure includes a zero absorbance calibration (utilizing cell position 8) and dark calibration. This can be repeated by pressing the calibrate key. Concentration calculated from absorbance or transmittance using a calibration curve constructed from 2 to 20.

A calibration curve can be constructed by selecting the number of calibration points to be performed and entering the calibration standard values in the respective cell locations. When the calibration sequence is initiated, the instrument automatically calibrates zero absorbance before constructing a calibration curve by measuring the absorbance or transmittance of each standard. The calibration points are displayed during the calibration procedure. On completion of the calibration procedure one of eight curve fits can be employed for the construction of the calibration curve.

Three of the possible calibration curve types include Linear Interpolation (straight lines between calibration points), Line of Best Fit between calibration points (using least squares linear regression) and line of best fit through zero and the calibration points.

Calibration curves are contained within a method which can be stored to either the internal storage area of 1Mb, or can be stored to an external PCMCIA Card.

The user can preset the y axis limits or automatically re-scale on completion of a calibration sequence.

If an internal printer is fitted, the user can print a calibration curve after performing a calibration or recalling a saved curve. The printout includes the absorbance or transmittance and concentration standards from which the calibration curve was generated, the curve construction method, plus the header information.