wiki:test The Merlin AutoGC Xplorer (MAX) is a cloud-based database designed to ingest data generated by chromatographic equipment deployed into EPA Photochemical Assessment Monitoring Sites (PAMS) which are collecting and analyzing hourly concentrations of up to 60 volatile organic compounds (VOC). MAX is a Structured Query Language (SQL) database of the data which includes the necessary information to allow users to view and graphically evaluate the hourly concentration data from these sites.
Orsat, LLC has developed and designed MAX to accommodate data originating from either PerkinElmer Ozone Precursor systems or Agilent systems using Markes International pre-concentration sampling system. These analytical systems incorporate a thermal desorption sampling system, a gas chromatographic system capable of separating the VOCs of interest and an chromatographic data system to integrate and quantitate the resulting chromatographic output. The format of the data from the chromatographic data system is generally an ASCII text output which has been formatted specifically for ingestion into the MAX system. Currently data formats for ingestion into MAX are available for the PerkinElmer Totalchom and Agilent OpenLab EZChrom edition chromatographic data systems.
The PAMS AutoGC systems collect not only hourly ambient air data but also have Quality Control samples which are outlined in the EPA PAMS Technical Assistance Guidance document (TAD). While most agencies have large databases capable of accumulating ambient data for review by policy makers, they do not always have the ability to review large amounts of quality control data associated with these highly technical systems. MAX was designed specifically to allow program managers, operators and data validators to review both the ambient data and the quality control samples to evaluate in near real-time the performance of their systems. Multiple QC sample types are specified by the EPA TAD to reconcile the performance of each analyzer.
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The output format for data generated by the analytical data system must adhere to a specific ASCII text format to enable MAX to be able to correctly interpret and store the data. Orsat has generated output formats for both the Totalchrom and EZChrom data systems. The user will not only need this format for the output but will need their analytical method to adhere to specific requirements such as target names, response factor format and calibration units. Orsat can assist by supplying methods for each analytical and help the user to implement any necessary changes that might be required.
MAX was designed to identify the QC control samples by using a specific file naming paradigm. Thus filenames must be specific to the sample type. Filenames are generated using a sequence generator which assigns filenames and schedules the necessary QC samples in the analytical system. This requires specific automation not generally provided as part of the original manufacturers product. Orsat offers the necessary hardware and software to generate not only the sequences with descriptive filenames but also the hardware to automate the introduction of the necessary QC samples for both the PerkinElmer and Agilent systems.
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In order to allow the evaluation of these QC samples each data set or Site has a definition which incorporates configuration parameters for the Network which defines information about incoming data such as a list of target VOCs, which targets will be in the QC samples and their concentrations and control limits. These parameters will be used by the system to calculate and display QC recoveries and threshold exceedances. A Network may have multiple sites or a single site depending on the agency and the number of PAMS sites they operate. The Network configuration also includes information about the site which is required to generate the EPA required Air Quality System (AQS) data file which is submitted for each site to incorporate the ambient data into the EPA AQS system.
Each Site also has unique information to identify it in the database. In addition to a unique site name other information is required to generate a site-specific AQS data file which will be submitted to the EPA AQS Database.
MAX allows for user-defined permissions for each user based on the users role. These roles define the activities available to that user. Users can be designated as Administrators, Validators, Operators or Guests. Each designated role provides different levels of permissions.
MAX has many ways to review data. Various data views allow users to quickly evaluate current data for a given site as well as historical data. Daily tabular data as well as graphic display of specific targets over user defined times allows users to review ambient data to compare compounds or sites. Plotting of QC data recoveries or amounts is also available.
The monthly site information page displays hourly data which has been collected. It allows a visual representation of what actual data files have been collected or lost, what QC data was collected. This is where data can be locked and unlocked and offers navigation to QuickLook tabular display of either amounts, areas, retention times or response factors for any day. It also allows navigation to the Screening QuickLook for those who have validator permissions.
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The QuickLook page is a tabular display of a single day of data. It can display either the amount (most common), area, retention time, or response factor for each target component. This page has many features designed to help operators evaluate the daily system performance. At the top of the page are navigation features allowing the user to select parameters of the displayed data such as minimum value filter, decimal point as well as any of the possible display data types. Navigation buttons are available to increment or decrement the date displayed as well. The QuickLook table is divided into two tables based on which channel of the analytical system the data originated from. Each channel represents a separate column separation. A graphic representation shows bars related to the numerical data in the table and can be used to display the target compound distribution by selecting the Chart Icon to the left of each hourly sample filename. Navigation is available in the upper right corner of each graph which allows the increment or decrement of the sample hour across the entire day. In the upper left corner a check box allows the user to fix the y-axis as sample hours are incremented. For users who do not wish to view this graphic representation a “Hide Chart” option is available under the chart on the left side. The Lock and Unlock Headers acts like a freeze pane navigation feature allowing the user to scroll through the table with the header stationary.
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In the body of the QuickLook, QC is highlighted various colors to designate the type of QC run the data in that row represents. The Status bar at the beginning of the sample hour row can be selected to show a summary of the sample status. This includes 4 tests run on each sample to determine its validity. The Valid flag indicates if at least 75% of the sample was collected within the sample hour. The Reprocessed flag will show if that sample file was reprocessed at a later date and loaded into the database. The Reupload flag shows if the same data file was reloaded. The Mismatch flag indicates that the sample filename does not match the channel or the acquisition time from the actual data.
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References
EPA Technical Assistance Document (TAD)