BAS 100B/W - Page 99

10-31
The other advantage of
OSWV
compared to
DPV/P
is its speed. Scan rates of up to
80 V/s are available on the BAS 100B/W, although scan rates of 100s mV/s to a few
V/s are typically used (note that the scan rate for
OSWV
depends on the square wave
frequency). This is significantly faster than the scan rate for
DPV/P
(ca. 10 -20
mV/s). In addition, the sensitivity of
OSWV
(compared with
DPP/V
) increases with
increasing scan rate, even for irreversible processes. The greater sensitivity and faster
speed of
OSWV
has increased the popularity of this technique for quantitative
determination of electroactive species in solution. The detection limit can be further
lowered by using stripping methods, which are discussed in section 10.6.
Mode = OSWV
General Parameters
Initial E (mV) = 0 -3276 to 3276
Final E (mV) = 0 -3276 to 3276
Sensitivity = 1
µ
A/V 100 mA/V to 100 nA/V (10 pA/V with the
Low Current Module)
Specific Parameters
Step E (mV) = 4 1 to 40
S.W. Amplitude (mV) = 25 1 to 250
S.W. Frequency (Hz) = 15 1 to 2000
Sampling Points = 256 1, 16, 256
Quiet Time (sec) = 2 0 to 65535
Comments
a) The
S.W. Amplitude
must be greater than
Step E
(which is the potential step
height for the staircase potential wave form).
b)
Sampling Points
is the number of current samples taken and averaged at the
end of each half-cycle. The 3 current sampling options are:
i) 256 samples taken and averaged over 1 line cycle (maximum
S.W.
Frequency
= 15 Hz).
ii) 16 samples taken and averaged over 1 msec (maximum
S.W. Frequency
= 250 Hz)
iii) 1 sample taken (maximum
S.W. Frequency
= 2000 Hz).
The maximum frequency for each option is such that the sampling time is no
longer than 1/2 of each half-cycle. The option is selected by the software.
c) The scan rate (mV/s) is the product of the
S.W. Frequency
and
Step E
.
d) The sample interval is equal to
Step E
.
e) Maximum data file length is 1279 points.