6 Quality Management
spectral interference. The sample injection unit and interface
where ionized atoms pass through are easy to remove and
Shimadzu’s proprietary Development Assistant as well as
Diagnosis Assistant functions reduce users' burden and improve
reliability of data by setting automatically the most suitable analysis
conditions and performing checks for spectral interferences.
These functions reduce the amount of work significantly in
checking data and improving reliability of measurement results.
Low running costs
The ICPMS-2030 can achieve extremely low running costs due
to reduced argon gas flow rate (mini torch) which can be minimized
even more by applying the “eco mode” during standby,
also cutting RF-power output and stopping all aspiration. In
addition, the use of 99.95 % pure argon gas is possible. Analysis
can therefore be performed with reasonably priced technical
argon gas for industrial purposes instead of the expensive
99.999 % high purity argon gas generally used.
To demonstrate the capability for high sample throughput,
the long-term stability of the instrument over a typical session
was assessed by analyzing a series of known samples repeatedly
to ensure minimal deviation of signal intensities over time. The
ICPMS-2030 demonstrates stable signals over a 10-hour analytical
period, indicating that the instrument will provide robust
results in high-throughput laboratories.
Monitoring provides confidence
During water treatment, other problems can be present although
not actively searched for. To highlight such problems, the
so-called indicator parameters are used. One of these parameters
is TOC (Total Organic Carbon), for which no limit value or criterion
has been defined, but which can be considered as a cautionary
warning for action under unusual circumstances.
Another indicator is the oxidizability parameter, as a measure
of the sum of all chemically oxidizable organically bound
compounds present in water. While not a direct cause for concern,
it can lead to re-germination or undesirable disinfection
by-products. Oxidizability is proportional to the sum of organically
bound carbon that are determined as DOC (Dissolved
Organic Carbon) and can therefore be replaced by TOC measurement.
When examining carbon compounds in drinking water, it
is apparent that the amount of inorganic carbon (IC) such as
carbonates and hydrogen carbonates is much higher than the
organic fraction which is only 1 % of total carbon (TC).
A TOC determination via the differential method (TOC = TC
- IC) will not be appropriate in this case, as the TOC value calculated
is prone to large statistical errors. According to EN 1484
(instruction for the determination of total organic carbon and
dissolved organic carbon), the differential method can only be
applied when the TIC (Total Inorganic Carbon value) is lower
than the TOC value.
Identification of organic carbon in water
For drinking water analysis, the NPOC (Non-Purgeable Organic
Carbon) method is used. The drinking water sample is first acidified
to a pH value of 2. This way, the carbonates and hydrogen
Figure 2: TOC-L analyzer
carbonates are transformed into carbon dioxide. The CO2 is then
removed via sparging with carrier gas. The amount of volatile
and therefore purgeable organic carbon can be disregarded
in drinking water. What remains is a solution of non-volatile
organic carbon compounds. These can be oxidized to CO2 and
detected via NDIR.
Sample preparation for the NPOC method (acidification and
sparging) is done automatically in the TOC-L analyzer, a series of
instruments used in laboratory applications. Removing the TIC
can be performed either in the syringe of the ISP module or in
the autosampler with the external spare kit.
The ISP (Integrated Sample Preparation) module consists of
an 8-port valve and a syringe with sparging gas connection. In
addition to acidification and sparging in the syringe, the ISP also
enables automatic dilution. This feature facilitates an extended
measuring range, dilution of highly contaminated samples and
the preparation of a series of calibration samples from a stock
solution. The robust ISP module therefore considerably reduces
time-consuming sample handling steps.
Shimadzu’s ICPMS-2030 and TOC-L analyzers meet all analytical
requirements for effective drinking water control with top
performance and easy-to-use concepts, while providing an
economical solution for the modern laboratory. Furthermore,
Shimadzu provides solutions for other parameters such as pesticides
(GC-MS/MS, LC-MS/MS), PAHs (HPLC), trace pharmaceuticals
(LC-MS/ MS), various chemical parameters by UV-spectrophotometers
and much more.
One of those methods will be discussed in Episode 2 of
the drinking water trilogy in Shimadzu NEWS 2/2020.