Samples for nutrient analysis should be filtered through a 0.4um polycarbonate filter. Unfiltered, turbid, or samples with widely varying concentrations within a batch of samples may require dilutions or manipulations. These samples fall in the 'Other' category as found on the rate schedule. Samples should be collected in clean, pre-rinsed glass or plastic HDPE 20ml scintillation vials. Samples being analyzed for Si(OH)4 must be collected in plastic HDPE vials. For all other analytes, glass or plastic HDPE containers are acceptable. Some adsorption of PO4 during storage in plastic containers has been noted, so glass may be preferred if PO4 is to be determined. Caps should have a plastic liner. All foil lined lids should be avoided.

Storage blanks are required if NH4 is to be measured. Storage blanks are recommended for all other analytes to detect possible contamination.

A minimum of 5mL of sample is required for the determination of a single nutrient species. 12-17mL of sample is necessary for simultaneous determination of all analytes. It is entirely unnecessary to submit more than 20mL of sample. If you must submit more than 20mL of sample or have other volume concerns, please contact the Analytical Lab.

Mark all samples clearly and directly on the sample container, as well as the lid. If you plan on shipping samples, any masking tape or colored lab-style tape placed on sample vials will fall off during shipment if in the presence of dry ice. Do not use these types of tape to label samples if you plan on shipping samples on dry ice.

Biological samples typically require 2-3mg of sample per analysis. For materials with low organic content, a larger amount of material will be analyzed to obtain a signal within the optimal range. We ask that 10-100mg of sample be provided. If less than 10mg of material is available, or if you have other concerns, please contact the Analytical Lab.

Samples must be thoroughly dried and finely ground to a powder. Sample homogeneity is usually the limiting factor for analytical precision.

Biological materials submitted to the Analytical Lab for Organic Carbon analysis (TOC) should be treated with acid (H2SO3) to remove inorganic carbonates. It is best to weigh samples into silver capsules first, then acidify gently with multiple aliquots of H2SO3. After acidification, samples should be placed in a 60°C drying oven to dry completely before closing the sliver capsule. The Analytical Lab can provide the acidification service upon request.

Screw-cap glass vials are the preferred containers.