Further modification of flame photometer. Dual-channel circuit for convenient determination of sodium and potassium.

S PART OF A CONTINUING PROGRAM in this laboratory directed toward the improvement of clinical laboratory procedures and instruments, additional modifications (1) of the flame photometer have been devised to obtain the benefits of modern components and circuits. Flame photometers using self-generating photocells have proved to be stable and reliable instruments in hundreds of clinical laboratories over the past decade. During this period advances have been made in the design of photoelectric devices, some of which are incorporated into new flame photometers just now becoming available. While it may be argued with some merit that any instrument should be replaced as soon as a more economical one is available to do its work, use of the modifications described herein can inexpensively convert an internal standard flame photometer of older design into an improved instrument without sacrifice of advantages possessed by the earlier models. Such modifications have been incorporated into the Baird flame photometer (Model DB-2). With suitable changes in detail, the basic design can be applied to any flame photometer using self-generating selenium cells. The novel features to be described in this article, include: a threechannel circuit for measurement of both sodium and potassium without resetting controls; increased thermal stability through use of