Model 6400/5 Quantitation Mode

This operating mode is only available when the instrument is fitted with a multi-position cell holder. 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 8 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 1 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.

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 three curve fits can be employed for the construction of the calibration curve.

The three possible calibration curve types are 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.

Method storage is accomplished by two calibration curves, plus associated standard values, cell holder locations and wavelength can be stored in battery backed-up memory. These can be recalled to allow measurement based on stored calibration curves. Stored calibration curves are date and time stamped. The user is prompted to confirm or abort a calibration curve save when two curves are already saved (this warning can be suppressed). Calibration curves are saved in chronological order, and are saved on a first-in-first-out basis.

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.