Abstract: A device for warning when a low fluid level is reached is provided in which a levelness detecting switch is encapsulated in a conically shaped inert material (such as TEFLON.TM.), sized appropriately to the predetermined fluid limit, and coupled to an alarm device (such as an audible alarm, a frequency signal or a light).

Abstract: This invention involves the elution of macromolecules such as proteins, deoxyribonucleic acid(DNA), ribonucleic acid(RNA) from solid phase matrix such as polyacrylamide, agarose and membranes such as polyvinyl difluoride (PVDF) in an electric field. The elution chamber shown in FIG. 1 consists of two separate screws 9, 9a and attachable chamber 1. The screw well 8 holds the gel matrix containing the macromolecules and is separated by the bottom chamber 1 with a membrane 5 with a nominal molecular weight cutoff higher than the macromolecule. On the other hand, the macromolecule is retained in the well 1 by introducing another membrane 6 having a molecular weight cutoff lower than the molecular weight of the macromolecule. Alternatively, macromolecules separated on membrane, e.g. PVDF, are held in a Teflon or plastic membrane holder 11. This holder can fit inside well 8 in screw 9. In addition, chamber 1 contains a well 7.