Metrohm 746 VA Trace Analyzer - Manual (Page 467)

6 Data processing and evaluation
746 VA Trace Analyzer / 747 VA Stand
6-4
6.2.2 Definition of the sample size
Before the start of a determination, it is mandatory to enter the sample size as a
volume or weight in the parameter Sample size/S0 , either on the dialog page
"MONITORING" or (with automatic sample data transfer) on the "SAMPLES" page.
You will find a detailed description of the parameter
Sample size/S0 in section
5.4.4. The most important points which must be considered in the entry of the sam-
ple size are listed again below:
– With undiluted samples and entry of S0 as a volume, S0 is used as
addition volume for the SMPL instruction. The substance content of the
sample in g/L is identical to the calculated mass concentration MC: .
– With undiluted samples and entry of S0 as a weight, the quantity S0/S2 is
used as addition volume for the SMPL instruction with mandatory entry of the
density in g/mL for S2 . To obtain the substance content of the sample in g/g,
the calculated mass concentration MC: must be divided by S2*1000 .
– With diluted samples, S0 designates the original sample size before the
dilution. The dilution must be defined by the two parameters V.fraction and
V.total of the SMPL instruction. V.fraction is then used as the addition
volume for the SMPL instruction. The calculation mass concentration
MC: refers to this volume. To obtain the substance content of the
original sample in g/L or g/g, this value must be multiplied by the factor
V.total/S0 .
The terms "undiluted samples" and "diluted samples" refer only to dilutions during
the sample preparation. Dilutions which are initiated during the program run by dis-
pensing or transfer instructions are automatically taken into consideration in the
volume bookkeeping.
The following is an overview of the various possibilities to enter
S0 and their con-
sequences for the definition of the addition volume and the calculation of the final
results:
Sample S0 S2 SMPL instr.
Parameter
SMPL instr.
Add. volume
Formula for
final result
Result
unit
undiluted L – – S0 MC: g/L
undiluted g d – S0/S2 MC:/
(S2*1000)
g/g
diluted L – V.fraction > 0
V.total
≥≥ V.fraction
V.fraction MC:*
(V.total/S0)
g/L
diluted g – V.fraction > 0
V.total
≥≥ V.fraction
V.fraction MC:*
(V.total/S0)
g/g