5
Figure 1: Value Stream Map of preliminary GC Process. Areas highlighted in red are identified as wasteful activities; areas highlighted in orange are identified as business value activities; areas highlighted in green are identified as value adding activities. a
Required only when second person is performing analysis. b
isn’t standardised and (iii) results turnaround time is slow. As this occurs every time a user wants to perform an analysis, staff avoid using the technique.
The business opportunity identified was to deliver data quicker and exploit the use of GC. Based on a questionnaire, a value stream map of the current GC analytical process was produced (details in Figure 1). This investigation reviewed the existing process and addressed the root causes of why staff were underutilising the technique.
Measure Data gathered indicated that project demand for GC analysis was far in excess of the instrument capacity available. Low instrument availability lead to long result turn around times through high waiting times, which in turn introduced additional wasteful activities that also contributed to increased result turn around time:
• Customers typically requested additional analysis to avoid extra waiting times (over- processing)
• Analysis was often left in an unfinished state because projects had moved on before results were available or additional analysis requested was no longer needed (inventory and over-production)
• Local instruments were not available, staff had to move between buildings to perform analysis (motion)
• Extra columns were ordered to anticipate future demands (over-processing)
• High base level training resulted with people being re-trained to perform the analysis (defects)
Activities that contribute to waste can be split into seven categories; transport, inventory, motion, waiting, over-processing, over-production and defects (TIMWOOD), details in Table 2. The wasteful activities identified above were applied to the value stream map to identify where they affected the process (as shown in Figure 1).
Figure 2. A Pareto chart of the preliminary GC process. Areas highlighted in red are identified as wasteful activities; areas highlighted in orange are identified as business value activities; areas highlighted in green are identified as value adding activities.
spectrum of columns used meant there was no direct alignment with GC-MS platforms. Standardisation of column choice was identified as the main proposal to reduce the waste in the process.
Analyse
Data collated in the measure stage were displayed in a Pareto chart details are in Figure 2. The Pareto chart identified less than 5% of activities were associated with the actual analysis. Approximately 90% of the total process time was due to unavailability of instruments, analyst/expert and consumables.
The broad-spectrum of columns in use was identified as one of the root causes of unavailability of instruments and consumables. Additionally the broad-
10 minute total run time. cIndicates wait times (delays). The seven categories of waste are highlighted by the letters T I M W O O’ D, definitions are detailed in Table 2
Choice of Traditional Columns To understand why so many columns were in use we reviewed the columns available to project analysts when developing a new method. These were;
• Standard low polarity stationary phases (1, 5 and 17, shown in Figure 3). These are robust and have high maximum operating temperatures (~300°C); however they give poor peak shape for polar compounds.
This is a good choice for low to mid-range polarity and semi-volatile compounds that are thermally stable
• Polar stationary phases (1701, 624 and WAX, shown in Figure 3) introduce selectivity and improve peak shape for polar compounds; however they have a low maximum operating temperature (~240 °C) and are less robust.
This is a good choice for high polarity compounds and complex volatile samples
• High capacity columns are suitable for strong solution concentrations; however they are unsuited to MS due to column bleed.
This is a good choice for routine analysis when strong sample concentrations are needed to obtain sufficient sensitivity when looking for impurities
• Low capacity columns are suitable for MS; but are easily overloaded.
• Wide bore columns are typically chosen for thermally sensitive compounds; however they are unsuited to MS due to flow incompatibility.
Based on 6 samples with
`Figure 3. Column Chemistry
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