High Performance Liquid Chromotography (HPLC)
Data Processing & Analysis
NASA has a continuing requirement to collect high-quality in situ data for the vicarious calibration of ocean color satellite sensors and to validate the algorithms for which the remotely-sensed observations are used as input parameters. Within this context, "high quality" refers to measurements with a documented uncertainty in keeping with established performance metrics for producing a climate-quality data record (CDR). The concept of pigment oceanography has become important in mapping global community structure in response to climate change and understanding current and future global CO2 budgets. Phytoplankton are a major part of the food web, and can influence global chemical and CO2 budgets through uptake of atmospheric CO2 and the production of volatile compounds, e.g., dimethylsulfide (DMS).
One of the objectives for the Field Support Group (FSG) of the Ocean Ecology Laboratory (OEL) is to provide analyses of algal pigment samples collected by NASA principal investigators (PIs) supported by the Ocean Biology and Biogeochemistry (OBB) program. The pigment products cover a suite of chlorophylls and carotenoids useful to ocean color research, in particular the validation of data products from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the Moderate Resolution Imaging Spectroradiometer (MODIS). High performance liquid chromatography (HPLC) pigment analysis is a complicated procedure requiring expert analysis and substantial costs for purchasing, maintaining, and calibrating the equipment. A centralized laboratory can be a cost-effective mechanism for providing consistently high-quality data to multiple PIs and databases, if the facility is vigilant in the pursuit of excellence, maintains rigorous quality assurance and control (QA and QC, respectively) procedures as part of a well-documented quality assurance plan (QAP), adheres to stated performance metrics to minimize uncertainties, and is evaluated independently (to detect biases and problems).
Data Products and Reporting Practices
Samples are analyzed for a suite of chorophylls, xanthophylls, and carotenoids, and classified as primary, secondary, tertiary or ancillary. These classifications, defined originally in Hooker et al.(2005) and summarized below, were developed during SeaHARRE HPLC pigment analysis round-robin exercises and categorize pigments according to two primary criteria: a) their utility with respect to biogeochemical investigations, and b) how many laboratories quantified them.
- The primary pigments (PPg) are the total chlorophylls and the carotenoids most commonly used in chemotaxonomic or photophysiological studies in the open ocean or in coastal waters. They include: TChl a, TChl b, TChl c, Perid, But fuco, Fuco, Hex fuco, Diadino, Diato, Allo, Zea, and Caro. The primary pigments are reported by all SeaHARRE laboratories, so their uncertainties are better characterized than other pigment categories.
- The secondary pigments are the individual pigments used to create a primary pigment composed of separate contributions (e.g., TChl a). Secondary pigments reported by the OEL are Chl a, DV Chl a, Chlide a, Chl b, DV Chl b, Chl c12 and Chl c3.
- tertiary pigments are those pigments not included in the composition of the primary and secondary pigments for which three or more laboratories involved in SeaHARRE provided quantitations. Tertiary pigments reported by the OEL are Lut, Neo, Phytin a, Phide a, Pras, and Viola.
- The ancillary pigments are those remaining pigments only analyzed by one or two laboratories during SeaHARRE. The ancillary pigment reported by the OEL is Gyroxanthin diester.
Individual pigment results are also used to construct various higher order data products-sums and ratios, also originally defined in Hooker et al.(2005).
Please contact Crystal Thomas when you know you will have samples to send for analysis. If you have any questions, please do not hesitate to contact Crystal. In the interest of time and record keeping, email is the preferred method of contact.
Crystal Thomas Science Systems & Applications, Inc. NASA Goddard Space Flight Center Ocean Ecology Laboratory Greenbelt, MD 20771 email@example.com lab: 301-286-6790 office: 301-286-7299
The address for shipping is:
Crystal Thomas NASA-GSFC Bldg. 22, Room C197 8800 Greenbelt Rd. Greenbelt, MD 20771 301-286-7299
Please contact the lab BEFORE shipping. When it is time to ship, tracking information is always helpful! Please send Crystal tracking information when sending samples, so that the lab knows exactly when the samples were sent and can keep track of shipment progress and monitor any delays. A liquid nitrogen dry shipper is the preferred method of transport for samples. If you do not have a dry shipper, the lab has a few that are available to borrow for sample transfer.
Please include the HPLC sample information form with each sample set.
Loading a dry shipper: When loading your samples into the basket(s), it can be useful to put them into nylons or stockings first. Alternatively, aluminum foil or paper can be stuffed into the top of the baskets to contain the samples. Otherwise, samples can get jostled out of the baskets during shipping, and they can become stuck under the plate in the bottom of the dewar.Information needed to return your shipper:
In order to return your shipper, the following information is needed:
- Contact name
- Shipping address
- Contact phone number
- Shipping account number (FedEx or UPS) to which to charge return shipping
- Internal reference number you want referenced (if any)
- Specific deadline by which you need your shipper returned (if any)
- Preferred shipping option (i.e. overnight, super saver, etc.)
As before, PIs are expected to have prior approval for their samples.
Please remember to incorporate replicate filters into your sampling protocols. Calibration and validation procedures dictate that replicate filters should be collected at a rate of >5% of total samples, or a minimum of three sets of replicate filters per sample set received. Replicates are an important and necessary component of our Quality Assurance Plan. This Quality Assurance Plan is for your benefit as well as ours.