vide ut supra. Manual insertion of the glass injection port liners eventually results in chipping and cracking. This annoyance is compounded by the difficulty in finding glass tubing of the exact dimensions for insertion into the injection block, as glass tubing often varies in diameter several hundredths of a mm even along the same length of tubing. Elimination of operator manipulation of the sample collection and injection steps and replacement with complete control of all timed events by a digital processor greatly enhances the reproducibility in analyses. The unique data treatment capabilities of this instrument, modified as shown, are notable: 1)retention times on all peaks are printed directly above the peak on the chromatogram; 2) an event marker signaling the beginning and end of integration of each peak is made on the chromatogram; 3) integration of peak areas is performed and the data can be expressed in terms of area percentage evaluations, or internal/external standard calculations can be made. Figure 2 illustrates several types of samples which are analyzed for volatile components to which the automated process has been applied. As can be seen, approximately 170 lowmolecular-weight constituents were resolved in the urine sample. This resolution is significantly better than has been previously reported in the literature. Rather than attribute this improved resolution to the chromatographic column employed in the study, it is more likely that the expanded range of temperature programming (-20 to 170 "C) produced the resultant improvement. Table I shows the repeatability of retention times of key peaks obtained from replicate analyses. In summary, automation of a volatile analysis procedure by modification of a commercially available gas chromatograph has resulted in enhanced reproducibility, elimination
of the inconvenience and loss of time due to manipulation and breakage of injection port liners, and improved chromatographic resolution as a result of expanded temperature programming capabilities. The procedure is now standardized to such a degree that it can be performed routinely in any laboratory.
ACKNOWLEDGMENT The authors thank K. Patchel for instrument modifications and N. Foster and K. Geer for technical assistance. LITERATURE CITED (1) B. Dowty, R. Gonzalez, and J. L. Laseter, Biomed. Mass Spectrom., 2, 142 (1975). (2) I. R. Politzer, S. Githens. B. Dowty, and J. L. Laseter, J. Chromatogr. Sci., 13, 378 (1975). (3) B. Dowty, J. Storer. and J. L. Laseter, J. Ped. Res., in press. (4) A . Zlatkis. H. A. Lichtenstein, and A. Tishbee, Chromatographia, 6 (2). 67 (1973). (5) A . Zlatkis, W. Bertsch, H. A. Lichtenstein, A. Tishbee, F. Shunbo, H. M. Liebich, A. M. Coscia, and N. Fieischer. Anal. Chem., 45, 763 (1973). (6) R. A. Flath, R. R. Forrey. and R. Teranishi, J. Food Sci., 34, 382 (1969). (7) R. Teranishi, T. R. Mon, A. B. Robinson, P. Cary, and L. Pauling, Anal. Cbem., 44, 18 (1972). (8) K. E. Matsumoto, D. H. Partridge, A. B. Robinson, L. Pauling, R. A. Flath, T. R. Mon. and R. Teranishi, J. Chromatogr., 85, 31 (1973). (9) B. Dowty, D. Carlisle, J. L. Laseter, and J. Storer, Science, 187, 75 (1975). (10) B. Dowtyand J. L. Laseter. Anal. Lett., 8 ( l ) ,25 (1975). (11) B. Dowty, D. Carlisle, and J. L. Laseter, Environ. Sci. Techno/., 9, 8 (1975). (12) B. Dowty and J. L. Laseter, J. Am. Water Works Assoc., submitted (1975). (13) T. A. Beliar and J. J. Lichtenberg, J. Am. Water Works Assoc., 66, 739-744 (1974). (14) T. A. Bellar J. J. Lichtenberg, and R. C. Kroner, J. Am. Water Works Assoc., 66, 703-706 (1974).
RECEIVEDfor review November 25,1975. Accepted February 12, 1976.
Remote Terminal Compatible Magnetic Tape Cassette Data Recording Device Arden W. Forrey" and Walter R. Baker' Clinical Research Center, Harborview Medical Center, School of Medicine, University of Washington, 325 Ninth A venue, Seattle, Wash. 98 104
The process of collection of data from instruments is one important step in the subsequent activities of reduction and analysis of data, and the development of quality control procedures within either the research laboratory or the small clinical-analytical laboratory. The use of computers provides one method for these laboratories to manage these data. One of the most highly advertised of the computer approaches is the laboratory minicomputer, though programmable desktop calculators may also be employed'. Minicomputers, however, are best used in situations where a high volume of data, fast sampling times, or control loops are required. Many procedures in the laboratory cannot justify the expenditures for dedicated minicomputers because of the wide variety and infrequency of the procedures which they use. A number of devices have been on the market for the logging and/or storage of data, several of which are minicomputer based. Before the latest of these devices came on the market, there was no device selling for less than $3000 which was easily configured or easy to use in the laboratory for collecting data directly from laboratory instruments. Present address, M e d i t e k Labs, Inc., 2852 F a i r v i e w Avenue
East, Seattle, Wash. 98104.
The sole availability of suitable digital components is not a satisfactory answer to this problem for the many laboratories which have no facility for assembling instrumentation. The use of remote terminals and telecommunications input, however, allows the laboratory access to that power and speed of computation which is proportionate to the task for a large segment of these laboratories; another very useful and complementary method is to process laboratory data by programmable desktop calculators. One of the obstacles to wide use of a flexible approach to data calculation using these resources is the unavailability of a device which collects data easily, accurately, and rapidly, and yet is completely plug compatible with both standard remote terminals and common desktop calculators. This account reports the development of such a device which collects data from a wide variety of laboratory devices, formats it flexibly, and records it onto standard magnetic tape cassettes. When the cassette device is plugged into a standard interface on standard remote terminals, it is then able to transmit the stored data under the control of the laboratory-located remote terminal into a data file in a telecommunications-equipped computer system for later analysis. The data on the cassette can, alternatively, be read into a programmable calculator for local data reducANALYTICAL CHEMISTRY, VOL. 48, NO. 6, MAY 1976
949
Optional input boards (switch selectible)
WRITE TAPE
READ TAPE
4 bit charoclor
Optional output boards (switch selectible)
Srlal ASCII
&Ip r d U
ASCII dewcar
Words/ line
switch,brd Flgure 1. Block diagram of the tape cassette unit. Each block is a functional unit constructed from standard integrated circuit chips
tion (if the computation algorithm is within its power) by a simple plug change.
EXPERIMENTAL We consider that a data collection device for general laboratory use must have the following capabilities. 1. It must collect data from both analog sources and from digital sources of up to six 4-bit BCD digits. The analog data must be either converted internally into at least three 4-bit BCD digits or be supplied in that form by an external A-D converter (1 mV to 10 V range). The output from the external device and the internal board must be compatible with the BCD-parallel input function board within the tape unit. 2. It must be usable with instruments usually found in the laboratory; therefore, it not only must accept analog output from these instruments, as noted above, but also must connect with the various styles of digital output plugs (specifically: 14 line [0-9, decimal point, execute, minus, end-of-line signals from listers and typewriters] and T T L 4-bit BCD serial and/or parallel information from multichannel analyzers, digital voltmeters, etc.), and must use optical isolator techniques for tape unit isolation. 3. It must be capable of accepting digital input from a modular multiplexer for simultaneous recording of data from several sensors. 4. It must possess its own internal clock for the usual output data transmission speeds used in remote terminals (10, 30,120 cps, switch selectable), and in addition, it must allow external synchronization in the data collection modes. 5. It must have a selectable number of data fields per logical record, and at least three selectable end-of-record characters for print format and system monitor compatibility with time-sharing computers. It must delimit data fields by using either a blank or another selectable character. 6. Optionally, it must be able to record an end-of-file character after all data in a block has been recorded. 7. It must be capable of converting all internal digital data into USASCII when used for data transmission, and it must be able to convert USASCII input into internal format. It must be interfaceable and usable in output mode while in parallel with any standard remote terminal or calculator which uses USASCII and the RS232B or C standard interface. 8. Minimally, it must be plug compatible in output mode with programmable calculators (H-P 9800 series, Monroe 1860, Wang Model 500, 600, 700, 2200 and Tektronics TEK-31). T o do this, it should utilize a 12-line optically isolated interface, which may (if required) parallel the keyboard of programmable desktop calculators for those calculators not having input connectors (which currently may be unique for each model of calculator). It must also have full duplex capacity, using either a clear-to-send line or control codes. Specifications. In order to meet these requirements, the device reported here was designed to the following specifications. 950
ANALYTICAL CHEMISTRY, VOL. 48, NO. 6, MAY 1976
Tape Unit. A Computer Access Systems Model 250 cassette drive uses a Phillips type cassette, 300 ft, computer grade, with 1600 FCI on track 2. The tape speed is at least 10 ips forward, 40 ips rewind, constant tape speed reel to reel. Tape drive servos are the only moving parts. Controls. It has the following controls in addition to main power: 1. An operation mode switch with the following positions. a. Write data-records data using the number of fields designated by the words per line switch. b. File read-with each push of the start button, reads entire file (up to end-of-file mark) without stopping, inserting end of logical record, carriage return, and line-feed characters in the data stream after transmission of the number of fields set by the words per line switch. c. Line read-with each push of the start button, reads the number of fields designated by the words per line switch, placing the above triad of characters at the end of the line. d. Word read-reads only one field up to the field delimiter per depression of the start button. 2. A words per line switch which determines, in write mode, the number of fields per logical and physical record (line) written before an end-of-record character is written. In read mode, the switch determines the number of fields read before either a carriage return, line-feed (when in ASCII), or an end-of-record character is produced by the tape unit. 3. A start button which initiates the function of the mode switch. 4. A rewind button which rewinds the tape until either the beginning of the tape is reached or the stop button is depressed. 5 . A reset/stop button which stops current function and resets all registers to the setting indicated by the mode and words per line switches. 6. An end of file button which, (a) in write mode, initiates the writing of a read-mechanism-recognizable end-of-file character in the last position of the current buffer and then writes the contents of the buffer to the tape, and (b) In read mode, is nonfunctional. 7. An ASCII data line switch which isolates the cassette unit from the terminal or calculator, allowing either keyboard communication with the line or independent calculator function. 8. An analyzer voltage-range switch (when an A-D board is inserted). Display: 1. power light-instrument power on/off; 2. ready light-indicates that the function of the mode switch is in process; 3. holding light-indicates that the function of the mode switch has been completed; 4. error light-indicates that a buffer overflow has occurred which would cause erroneous data to be written to the tape; tape unit function has been stopped until reset. Implementation. A block diagram of the design resulting from the above specifications is shown in Figure 1. The device constructed from the detailed design is shown in Figure 2. The cassette tape drive is a Computer Access Systems Model 250 tape drive. The diagram depicts the independent handling of various forms of input and output data between internal 4-bit BCD numeric form on tape and external form. The conversion and han-
1
..................
..............
. . , . o : ., . . . .. . .. . . . . . . . . . . . .. . .‘. . . . .. ’.. :.. . . .. .. . .. .. . .. .. . .. .. . . . . . . 3. . ..
.
I
.
.
.
“I
.
......
I , ,
..
I
iia:
I
............
I
t , ,
1
.
I
Figure 2. A photograph of the unit in front view shows the position of the controls while the back view shows the input connections dling of the data internally in this manner via B common buffer provides the flexibility leading to the wide range of plug eompatibilities with input and output devices. The internal A-D board is not shown as its output enem a t the parallel BCD interface board, and its design is conventional; alternatively, an external A-D eonversion device would also enter a t this point. Instrument Test. The device was tested for data capture by inputting data from the following instruments: 1. interfaced with a Paekard Model 930 “Spectrazoom” multichannel analyzer (BCD parallel); 2. interfaced with a Searle Analytic “Autogamma” type gamma well counter (BCD serial): 3. interfaced with a Paekard Model 3315 Liquid Scintillation spectrometer (BCD serial); 4. interfaced with a Gilford Model 2000 spectrophotometer using a Model 209 Digital Absorbance Unit (and using 4-hit BCD parallel directly from this unit); 5. interfaced with an optical punched paper tape reader using a Meditek Model 650 punched tape read head (operated a t 500 BPS, 4-bit BCD parallel). Analog data are presently accepted, after analog to digital conversion, both from independent devices such as the Gilford Model 209 digital display unit and from a similar hut internally packaged A-D conversion board which has been built using conventional circuitry. The principles of tape cassette data capture, nevertheless, are adequately demonstrated by the present implementations. Data collected from the above noted instruments was read and printed by the following devices: 1. a Terminet-300 data communications terminal (General Electric): 2. Monroe Model 1860 calculato< 3. Hewlett-Packard Model 9830 programmable calculator using B 11205A serial interface card snd No. 11272B R O M 4. a Tektroniv Model TEK-31 programmable calculator: 5. Wang Model 2200 calculator. Instrument Operation Procedures. The instrument setup for interfacing with either the Searle “Autogamma” instrument or the Packard liquid scintillation counter requires plugging one end of the input cable, fitted with a 25 pin connector, into the rear of the modified instrument which has had the digital output from a selected channel directed to a connector on the rear of each counting instrument. The other end of this cable is plugged into the input connector of the tape unit and the unit power is turned on. The cassette is then inserted into the drive unit and the “Rewind” button pushed. The words per line switch which, for example, is set,at “8” when the automatic external standardization on the liquid scintillation counter is used and ‘tS” when it is not enabled is next set. The readlwrite switch is set a t “Write,” and then the ”Reset”.
4 Figure 4. The apbearance of the output collected from a liquid scintillation counter with automatic external standardization (AES) is shown after it has been read from the tape cassettes (described for Figure 3) and subsequently composed into a complete data file for processing (the first number is a text editor line number) and “Start” buttons are pushed. This act resets all registers and starts the run. At the end of the run, the “End-of-file” button is pushed, whereupon the Stop function is executed and the remaining buffer contents (and an end-of-file mark) are written onto the tape. Another run can now be commenced, or the tape may be rewound. The cassette may then either be removed from the unit or the unit may be disconnected from the counting instrument and reconnected either to a programmable calculator or t o a remote terminal using the output jack on the rear panel of the tape unit. Alternately, the input and output devices may both be left eontinuously connected to the unit or the cassette unit may be unplugged, carried to another site, and replugged into other devices. In either case, for data readout, the readlwrite switch is set to either “line-read”, “word-read”, or “file-read”, and then any changes in the settings of the words per line can be made. The “reset” and “rewind” buttons are next pushed. The data read from the tape now appear a t the printer of the terminal (when set a t half duplex or a t full duplex with echo-mode by the computer) or on the calculator. When the data communication terminal is used, the computer monitor is placed in “tape” mode first with the data line switch set to “off’, and then, with the cassette unit mode switch set to “read” and the data line switch, ”on”, the data are read singly, in groups, or continuously. Turning the data line switch “off” again allows regular communication with the eomputer monitor. Whenever the calculator is used, the reads are always under program control.
RESULTS This i n s t r u m e n t was designed to meet the data c a p t u r e needs of the Clinical Research Center at Harborview Medical Center of this university, but is now available in several models commercially from Meditek Labs at $2750 for the write-only model and $3500 for t h e readlwrite model. Various laboratory instruments listed ahove have been used to ANALYTiCAL CHEMISTRY, VOL. 48. NO. 6, MAY 1976 * 951
supply data; the captured data were output for printing on several calculators and a data communications terminal. Instrument Test. A sample listing created during data entry is shown in Figure 3; the file was created from a Terminet-300. The data shown was collected on a Packard Model 930 multichannel analyzer (MCA) in pulse height analysis mode (or optionally in multiscale mode with different instrument settings) and was read out of the MCA into the tape cassette unit with the words per line switch set a t 14 and the mode switch set a t “write”. The data from the cassette was entered into a standard Burroughs B5500 text editor disk file in cassette “Read” mode under the control of the editor in “Sequence” mode with the system communications handler in “Tape” mode (no feedback response). A t the completion of data entry, the handler was placed in “Key” mode, the editor in “Nonsequence” mode, and the file “Typed” as shown. The file can then be readily edited to insert additional lines of information as exemplified in the upper portion of Figure 4. In the format shown, channel number is followed by channel counts as produced by the multichannel analyzer readout procedure. Sample output listings of data from a Monroe Model 1860, a Tektronix Model TEK-31, a Wang 2200, and a Hewlett-Packard Model 9830 programmable calculator were compatible to those shown in Figure 4. Data from a Packard Model 3315 liquid scintillation counter, which was listed on a Terminet-300 after composition of a data file for processing a quench correction calculation, is shown in the upper half of Figure 4; the calculation itself is irrelevant here and is discussed in Ref 1. Also shown in the lower half of Figure 4 is the conversion of punched paper tape format from a Searle Analytic Autogamma automatic well counter into magnetic cassette form by reading the data from a tape reader into the cassette unit, followed by readout into the terminal. In this case, the data was automatically edited by the reader unit to remove nonnumeric characters and extra spaces for better data formatting. Once entered properly from the cassette into either a calculator or a computer file through the data communications terminal, the data can be manipulated programmatically, as desired, in a wide variety of ways which are not a t issue here. The most important point demonstrated with this instrument is that by using one self-contained unit with minimal controls and common plugs, it is possible to capture major amounts of the data produced in most laboratories and communicate it simply to the computing instrument of desired complexity. Since the instrument is operated either in an input or in an output state, the advantage of using a common buffer for both functions lies in the fact that data (always numeric) can be read either from or into the tape deck a t a clocked rate in exactly the same way via this buffer. The mode of input into or out of the buffer depends upon the circuitry activated, which is itself modularly designed to be plug compatible with the most prevalent voltages and connectors. Since the cassette is optically isolated from the instrument supplying the data, there is no instrument loading, and any unique interface conditions can be remedied by specifying these unique conditions when the interface circuit board is initially constructed. Another mode of possible use of the cassette unit with clinical laboratory computer systems capitalizes on the use by those systems of video displays into which “manual” inputs are displayed. T o display and verify data in this way, the cassette unit would be placed either in word mode (to enter single fields) or in line mode with words per line set a t one in order to obtain single field entry. For constella-
952
ANALYTICAL CHEMISTRY, VOL. 48, NO. 6, M A Y 1976
tions of sequential fields (e.g., counting position, counting time, counts from a nuclear counting device), the words per line switch would be set a t greater than one. In this way, data from virtually every “manual” procedure in a laboratory requiring these procedures could be captured on tape cassettes a t the time of measurement and subsequently entered into the video display, either under manual (by pushing the start button) or programmatic control (with certain easily accomplished circuit modifications) for data verification. Ater verification in this way, the data may be subsequently subjected to computation without the need of using any written data sheets followed by keyboard entry with the attendant error from this procedure. The above results demonstrate, however, that it is now possible to capture data easily and flexibly a t instruments and then conveniently, inexpensively, and reliably transmit that data to a calculating instrument without the intervention of human recording activities. By using the vehicle of relatively inexpensive digital tape cassettes, the data can be recorded on one device connected either permanently or temporarily to a laboratory instrument and then read in a variety of ways from either the same or different unit into a number of different calculating devices, as appropriate, for further computation. The original data may also be stored on the cassettes as long as needed and recalculated many times if necessary. The wide range of plug compatibilities also makes it possible to record the data from a wide variety of laboratory instruments as procedures or projects within the laboratory change. This capability is very important to a smaller laboratory which can afford only a limited number of data capture and calculating devices. A major function of this device in our laboratory has been to capture liquid scintillation data for quench correction by a procedure reported earlier ( I ) and for radioenzymatic assay of aminoglycosides (2). Other functions include capture of radioimmunoassay counting data, and radio-xenon washout for renal blood flow distribution using the Packard Model 930 multichannel analyzer in multiscale mode ( 3 ) .
LITERATURE CITED (1) A. W. Forrey, “Organic Scintillators and Liquid Scintillation Counting”, Academic Press, New York, N. Y., 1971, p 835. (2) A. W. Forrey, A. D. Blair, M. A. O’Neill. T. G. Christopher, and R. E. Cutler, Clin Res., 22, 114A (1974). (3) R. A. Gutman. A. W. Forrey, W. P. Fleet, and R. E. Cutler, Clin. Sci. Mol. Med., 45, 19 (1973).
RECEIVEDfor review April 23, 1975. Resubmitted November 6, 1975. Accepted February 6, 1976. This work was supported in part by a grant from the General Clinical &search Centers Program (RR-133) of the Division of Research Resources, National Institutes of Health, and by a research contract (72-2219) from the Artificial KidneyChronic Uremia of the National Institute of Arthritis, Metabolism and Digestive Diseases, National Institutes of Health.
CORRECTION
Micro, Ultramicro, and Trace Determination of Fluorine
Tungsten trioxide, which is used for the expulsion of fluorine, W. J. Kirsten, Anal. Chem., 48, 84 (1976), has earlier been proposed for use with inorganic compounds by R. H. Powell and Oscar Menis, Anal. Chem., 30, 1546 (1958). This reference should be added.
