provide powerful analog signal pro- cessing capability in simple integrated circuit packages. In particular, the tapped analog delay line is uniquely applicable to filtering in the most gen- eral sense. The devices now available represent only the first generation (31). Device complexity and charac- teristics are sure to improve in the fu- ture, which will extend even further the power and utility of these devices.

References (1) H. E. Kallmann, Proc. IRE, 28,302 (1940).

(2jA:Savitzky and M.J.E. Golay, Anal.

(3) K. R. Bettv and Garv Horlick, Appl . Chem., 36,1627 (1964).

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337 (1955). (6) Yair Talmi, Anal. Chem., 47,697A

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Puckette, IEEE J. Solid State Circuits,

(10) P. K. Weimer, M. G. Kovac, F. V. Shallcross, and W. S. Pike, IEEE Trans. Electron Deuices, ED-l8,996 (1971).

(11) D. D. Buss, W. H. Bailey, and D. R. Collins, Electron. Le t t , 8, 106 (1972).

(12) D. D. Buss, D. R. Collins, W. H. Bai- ley, and C. R. Reeves, IEEE J . Solid State Circuits, SC-8,138 (1972).

(13) D. A. Smith, C. M. Puckette, and W. J. Butler, ibid., SC-7,421 (1975).

(14) W. N. Waggener, IEEE Trans. Com- mun., COM-23,394 (1975).

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~ - - .-

(28) P.J:W. Noble, ibid., p 202. (29) Gary Horlick and E. G. Codding, in

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Model 70-10 with actuator

Model 7120 Type 50

Our valves, sample injectors and accessories give liquid chromatography practitioners the best trip. They offer an optimum combination of perform- ance, precision and price. Here’s what we give you for a better LC trip.

Type 50 Teflon Rotary Valves For half the cost you’re used to paying, Rheodyne offers you the same performance. Our valves are chemically inert Only Teflon touches the stream. They feature zero dead volume and can be used in manual or automatic modes Three, four and six way valves in 0 8 mm and 1 5 mm bores are available in prices ranging from $70 to $87

Easy to turn HPLC valve, 8290 Rheodyne’s 70-10 is a conventional 6 port removable sample loop valve capable of withstanding 7 0 0 0 psi. Valve construction features a flat face rotor to reduce operating torque and simplify service. An accessory loop filler port can be used to minimize wastage. Basic unit comes with 20 $ sample loop IO, 50, 100, 200, 500 and 1000 d loops available.

Go two ways with this valve Use the Rheodyne Model 7120 Syringe Loading Sample Injector Valve to fill loops conventionally for maximum precision or in the partial loop variable volume mode with only 0 5 p sample loss.

You have maximum versatility in HPLC sample injection Load the sample by syringe through the built-in needle port Works up to 7000 psi. Price of the Model 7120 with a 20 ;d sample loop is $490 Sample loops of 10 IJ1 to 1 ml are offered

And accessories too Accessories include a pneumatic actuator for HPLC valves, high pressure switching valves, tube fittings and valve mounting plates.

Reason enough to make the Rheodyne trip? Just to be sure, ask us for our new series of data sheets together with full ordering information Call or write Rheodyne, 2809 - 10th St., Berkeley, California 94710 Phone (41 5) 548-5374

RWODYNC CIRCLE 183 ON READER SERVICE CARD

ANALYTICAL CHEMISTRY, VOL. 48, NO. 9, AUGUST 1976 7 8 7 A