Sample handling storage stability

Handling, sampling and storage procedures to ensure homogeneity and stability and avoid contamination or mix-up... 

The storage and retrieval of aliquots in sealed microtubes at 20 °C ensures longterm stability of the compounds that are dissolved in the frozen DMSO matrix. This sample-handling concept also minimizes the risk of compound crystallization or... 

The Liquid Master Store at Roche uses a 96-tube version of the microtube plate described in Section 1.4 a description of the 96-tube plate is found on the web site www.remp.com. The individually accessible tubes in 96-tube plates in the Liquid Master Store hold a few definite sample volumes, e.g. 26 J,L and 140 J,L per tube. Storage and retrieval of HTS master solutions with fixed sample volumes facilitate the sample logistics considerably. Upon retrieval from the Liquid Master Store, the master solutions in the 96-tube plates are thawed and transferred to 384-well plates before they enter the downstream aliquoting process. This sample-handling concept avoids repetitive freeze-thaw cycles of HTS master solutions and thereby improves the stability and integrity of the compound samples used in HTS. 

Handling, sampling, and storage procedures should be identified in order that the homogeneity and stability are assured to the degree possible and contamination or mix-up are precluded. 

Assessment of the stability is typically performed during prestudy validation and continued during in-study validation. If changes in sample handling or storage occur, additional stability evaluations must be carried out to reflect the altered conditions. The acceptance criteria for the stability evaluations, with the exception of the whole-blood stability, will be the same acceptance criteria applied for... 

Another important quality measure is the analysis of the field-fortified samples. The field-fortified samples have been handled, shipped and stored in the same manner as the treated samples. Any loss of analyte in the field-fortified samples will be used to correct residue levels of the field treated samples. It is best practice to keep the storage interval as short as possible to minimize losses. The acceptable storage time will vary according to the stability of each compound in aqueous solution. A good guideline is to analyze the samples within 30 days of sampling. 

The chloroformate resin is readily prepared immediately before use and hence its stability to long-term storage has not been explored. However, no special precautions were needed in handling the resin and no stability problems were observed during the course of this work. The FT-IR spectrum of sampled beads showed no sign of a hydroxyl signal. 

The assay methodology selected should ensure specificity, accuracy, interday and intraday precision, linearity of standard curves, and adequate sensitivity, recovery, and stability of the samples under the storage and handling conditions associated with the analytical method. 

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