Dilute-and-shoot is only effective when you are working with relatively clean matrices—complex biological samples, such as whole blood, require a cleanup step or your results may be inaccurate. Matrix components, such as proteins, phospholipids, and salts, introduce interferences and suppression/enhancement effects that compromise data integrity. Solid phase extraction (SPE) and liquid-liquid extraction are excellent ways to produce clean extracts, but they are time-consuming and not always necessary. Your first step in developing a sample preparation procedure should be supported liquid extraction (SLE); if your samples do not require extensive treatment, SLE cleanup is a quick, efficient, and fully automatable solution.
Volume guidelines: Selecting an SLE format with sufficient loading capacity (1 mg sorbent to 1µL diluted sample) is very important because the entire sample volume (including 1:1 dilution in buffer) is absorbed into the diatomaceous earth sorbent. For example, a 100 µL sample should be diluted 1:1 with buffer for a total volume of 200 µL, which requires use of a 200 mg SLE product.