Metrohm 746 VA Trace Analyzer User Manual

Page 305

5.6 Method Specifications

746 VA Trace Analyzer / 747 VA Stand

5-154

Parameter

Range; Default value / Meaning

The proportionality factor is determined by means of a linear function
of type

0/linear

, i.e. a straight line of type y = bx passed through the

origin, where

Ratio of the evaluation values of analyte
and reference substance

eff,a

eff,r

Ratio of the effective mass concentrations
of analyte and reference substance in the
analysis solution

Prop.fact.

Proportionality factor

The curve "

" vs "

eff,a

eff,r

" is displayed and plotted.

0/linear

int.std.

Slope = Prop.fact.

Determinations with the aid of an internal standard are normally
programmed with the following basic structure:

:
D SMPL>M or SMPL/M

Sample addition to measuring vessel

C (CAL

Loop start for calibration

C CSOLN>M

Addition of calibration solution to meas. vessel

RADD>M

Addition of internal standard to meas. vessel

(REP

Loop start for replication

SEGMENT

Call-up of segment (with sweep)

ØMEAS

Switch off voltage (solution change)

REP)n

Loop end, n = number of replications

C RINSE

Resetting of the volume bookkeeping to 0

C CAL)n

Loop end, n = number of calibration solutions – 1

First, this program is used to record a calibration curve for determina-
tion of the proportionality factor. For this, the run mode on the
"MONITORING" page must be set to

Run mode = calibration

Instructions marked by

are ignored. Internal standard is added to

the calibration solutions (max. 10) in sequence and the measure-
ments performed.

To store the proportionality factor calculated from the calibration curve
permanently in the method, the method must then be copied from the
working memory into the method memory. This occurs automatically
with

Auto.batch = on

; an unsecured method with the same name in

the method memory will be overwritten.

The run mode is then switched to

Run mode = determination

. In-

structions marked by

are ignored. Internal standard is added to the

analysis solution and the measurement performed.

eff,a

eff,r