Sample Handling and Pre-analysis Preparation

Most samples need some form of preparation before shipping to SIRFER. This preparation can be as simple as sealing liquid sample containers for prevention of evaporation or freeze-drying fresh samples such as leaves or tissue to as complex as delipification and extraction of cellulose from plant material. In the case of solid organic materials such as plant parts or soils, the samples must be dried and ground (<40 mesh). SIRFER will grind samples upon request for a nominal fee. Fresh samples, which require water extraction, should be frozen before shipping to SIRFER. Sample preparation and preservation of gas samples usually involves leak tight storage and avoiding isotopic exchange with polymer materials. For liquid samples, avoiding evaporation by sealing or freezing the sample is usually adequate.

SIRFER will accept bulk or pre-weighed solid samples for isotope composition. If you choose to submit bulk samples, the samples should arrive at SIRFER dried and ground (<40 mesh). SIRFER technicians will then weigh the samples into the appropriate capsule. Samples are routinely weighed to 1 µg before analysis. For δ13C, δ15N, and δ34S analysis of solid samples, a 0.2-20 mg aliquot of the sample is accurately weighed into a tin capsule. If the samples are not weighed immediately, the samples are placed into a dry storage cabinet. Weighed samples are stored in a vacuum desiccator until analysis. For analysis of solid (organic or inorganic) samples for δ2H and/or δ18O analysis, a 0.1-0.2 mg aliquot of the sample is accurately weighed into a pre-baked silver capsule.

Note on the submission of pre-weighed samples: because of instrument linearity issues, the elemental composition of the sample dictates the amount of sample weighed into either tin or silver capsules. Before submitting pre-weighed samples, contact the SIRFER laboratory manager for information on the appropriate weight.

Special requirements for soil analysis: SIRFER is an approved lab that can receive and process soils regulated by the USDA and APHIS PPQ. Because of specific handling and treatment requirements for regulated soils (both domestic and foreign) of the USDA, before shipping of any soils to SIRFER please complete the Soil Form.

SIRFER will accept fresh samples (prior to optional water extraction) or water for δ2H and/or δ18O isotope composition. Water samples can also be sent to SIRFER preloaded in 1.8 mL glass gas chromatography crimpseal vials. Per-loaded vials should contain a minimum of 400 µL of the sample. Upon arrival, SIRFER stores liquid samples in a cold room or freezer. Fresh samples are frozen until optional water extraction.

Optional SIRFER Services (per sample)

Soil acidification
Sample grinding
Sample weighing
Water extraction