CHALLENGE As microsampling technique gets more and more attractive in supporting the animal PK/TK studies, Sponsor transferred a typical microsampling procedure using the glass capillary microsampling (CMS) for plasma sample collection to Frontage to support the GLP toxicity studies. During the method transfer and validation, the advantages and disadvantages of the typical CMS procedure using glass capillary tube were realized. Some of the disadvantages include frangibility of the glass tube, required sample dilution on site and potential over dilution issue, and the compliance concern using diluted samples for reassay and ISR test, etc. SOLUTION Frontage bioanalytical scientists develop a novel procedure for the collection and isolation of microvolumes of plasma using plastic instead of glass capability tubes to order to overcome those issues associated with the typical glass CMS technique. RESULTS A technique has been developed wherein a flexible plastic capillary tube, lined with K¬2EDTA, is used for the collection of 35-40 µL of blood. This tube is then spun down and approximately 15-20 µL of plasma is available. Small metered sections of the plasma section of the capillary are then cut into multiple sections and stored for the initial analysis, reassay, and ISR. Each section of the capillary is placed into a secondary container, diluted with a washout solution and extracted using protein precipitation. The container is then spun down, the supernatant further diluted with mobile phase, and analyzed using LC-MS/MS. In mouse plasma, this method was demonstrated to be accurate and precise in a curve range of 1-1000 ng/mL for midazolam using the cut tube of 5 mm length (~ 3.3 uL sample volume) (see data below in Table 1 and 2). With this method a complete PK curve can be determined from a single mouse thereby reducing the number of animals in each study. More importantly, in pediatric models, a heal, or finger, stick can be used to extract very small volumes of blood for testing. Table 1: Performance of the calibration curves of midazolan in mouse K2EDTA plasma CASE STUDY: A Capillary Microsampling (CMS) Technique for Low Volume Bioanalytical Plasma Analysis in Support of a Regulated Study FOR MORE INFORMATION, CONTACT US AT: sales @ frontagelab.com OR VISIT US AT: frontagelab.com