For successful harvest, each new batch of hypotonic solution should be evaluated by?

In the context of cytogenetic harvest procedures, the evaluation of a new batch of hypotonic solution is essential to ensure optimal conditions for cell swelling and chromosome visualization. Comparing the new batch to a lot already in use is crucial because it helps confirm that the new solution has similar characteristics to the previously validated batch. This step ensures consistency in performance and effectiveness, as variations in formulation could affect the results of chromosome analysis.

The other options, while potentially relevant in different contexts, do not specifically address the primary concern of maintaining consistent and effective experimental conditions. For instance, a pH test is important for many laboratory reagents, but hypotonic solutions are generally formulated to be isotonic with specific parameters, making direct comparison a more reliable method. Checking for color change may help identify contamination, but it does not ensure the solution's functional efficacy. Lastly, assessing viscosity does not directly contribute to the assessment of the hypotonic solution's suitability for cytogenetic work, as the main focus remains on the osmotic properties rather than its physical viscosity. Thus, comparing the new hypotonic solution to a validated lot provides the best assurance of consistency and reliability in cytogenetic procedures.