Abstract:
High-speed, automated analyzers for analyzes of biological fluids, such as whole blood or blood-derived components, include specialized analyzer and sample transfer features permitting injection-to-injection analysis times on the order of one minute. The analyzers are particularly designed for HPLC analysis for glycated and nonglycated proteinaceous species in blood samples.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is broadly concerned with automated chromatographic analyzer apparatus which can be used to analyze a variety of biological samples, such as whole blood and blood-derived components. More particularly, the invention is concerned with such apparatus which is especially designed for high-speed, accurate analyses of blood samples in order to quantitatively determine glycated and nonglycated proteinaceous fractions therein. Such analyses are valuable to determine diabetes conditions in patients. 
     2. Description of the Prior Art 
     The measurement of glycated protein in the blood of a patient suffering from diabetes mellitus provides an attending physician with a means for assessing blood sugar control over different periods of time. As a consequence, considerable research has been done in the past to develop accurate, rapid analyses for glycated proteins. In order to be truly effective, however, such methods should also be capable of measuring the glycated protein content of both hemoglobin and plasma (serum) proteins. This stems from the fact that the percentage of glycated hemoglobin in a sample is a measure of mean blood sugar concentrations for the preceding 45 to 60 days, whereas the percentage of glycated plasma protein reflects blood sugar concentrations over a shorter period, approximately 1-3 weeks prior to analysis. 
     It is known that non-enzymatically glycated proteins such as hemoglobins and circulating plasma or serum proteins differ from nonglycated species by the attachment of sugar moieties to the proteins at various binding sites by means of a ketoamine bond. Glycated proteins thus contain functional groups (sometimes reported as 1,2-cis-diol groups) not found in nonglycated proteins. The presence of such functional groups thus provides a basis for separation of glycated and nonglycated proteins. 
     One prior technique for separating glycated and nonglycated protein fractions is known as boronate affinity chromatography. This analysis relies on the fact that borates or boronates, such as m-aminophenylboronic acid (PBA), can under certain conditions, bond with the functional groups in glycated proteins. The bonds in the resulting complex are reversible in aqueous solution. In the typical chromatographic system, the boronate is immobilized on a support medium in a chromatographic column. A solution containing the substance under analysis, such as hemoglobin or plasma (serum), is applied to the column, wherein the glycated components bond with the boronate. Nonglycated components are washed out of the column with a suitable buffer solution, then eluated from the column and collected separately. Eluation of the glycated components is achieved by means of either: 1) a buffer solution containing a competing polyol, which replaces the protein in the boronate complex, or 2) a buffer or acid solution of low (below neutrality) pH. 
     A number of secondary factors, such as interactions between boronates and amines or carboxyls, influence the chromatographic separation. Complex molecules such as proteins also engage in hydrophobic, ionic, hydrogen-bond, and charge-transfer interactions. The need to design chromatographic systems which maximize the specific binding of boronates with diol-containing glycated proteins is therefore complicated by the need to also minimize the binding of nonglycated proteins through nonspecific interactions. Many factors such as buffer composition, molarity, ion content, ligand concentration and pH are known to influence the boronate affinity chromatographic separation of glycated and nonglycated proteins. 
     Glycated and nonglycated proteins separated chromatographically are commonly quantitated spectrophotometrically. For hemoglobin quantitation, the spectrophotometer is set to measure the absorbance of light in or near the “Soret region” (413-415 nanometers), which is the range of peak absorbance for hemoglobin. For plasma (serum) protein quantitation, the spectrophotometer is set to measure the absorbance of light in the 280 nanometer range, at which the proteins show peak absorbance. Of course, other wavelength determinations can also be maintained using known chromagens in the eluates. The buffer solution used to elute the non-glycated components is first placed in the light path of the spectrophotometer. The spectrophotometer is then adjusted so that zero absorbance is displayed on the scale or readout. This procedure, called a “blank”, corrects for the background absorbance of the contents of the buffer solution. The next step is to place the non-glycated protein-containing buffer solution in the light path of the spectrophotometer and record the absorbance of light. By virtue of the “blanking” procedure, any increase in the absorbance of light by the protein-containing solution is due entirely to the protein content. 
     The same procedure is used for the eluate containing the glycated components; that is, the spectrophotometer is first “blanked” with the elution buffer solution in the light path, after which the increase in absorbance of the protein-containing buffer is recorded. Quantitation is then achieved by calculation. The increase in absorbance over the “blank” solutions of the protein-containing solutions is directly proportional to the protein content. The calculation also takes into account the dilution of the proteins by the buffer solutions. The result of this calculation is the expression of the glycated components as a percentage of the whole, e.g., “10% glycated hemoglobin” or “14% glycated plasma proteins.” 
     The above procedure, although somewhat effective in yielding accurate hemoglobin protein analyses, is generally inaccurate or imprecise in serum protein analyses, and moreover is less suited for commercial laboratories because the protocol is very time consuming and costly. Thus, the need to individually collect and subsequently blank each of the eluates presents a significant drawback in the context of multiple analyses in a large laboratory. 
     U.S. Pat. No. 6,020,203 describes significant improvement in the art and is capable of short sample injection-to-injection times on the order of 8 minutes. In this technique, use is made of “spectrophotometrically balanced” reagents to transfer the sample through the PBA column and spectrophotometer, and to regenerate the column after each sample separation. However, the preferred apparatus described in the &#39;203 patent is rather large and cumbersome, and has a significant footprint. Moreover, the equipment is not modularized for optimal operation and servicing. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the problems outlined above and provides a greatly improved analyzers having a number of features which provide high-speed, continuous analyses of biological samples, such as blood, blood components, or other body fluids, extracts, or emulsions. A particular utility of the invention is provision of HPLC analyzers for quantitatively and/or qualitatively determining glycated and nonglycated protein fractions within samples. The preferred analyzers are of modular design, including respective modules which may be individually removed for service or replacement. 
     Generally speaking, the analyzers of the invention are operable to handle individual racks of sample tubes where each tube contains a respective biological fluid sample, a pierceable septum, and an external, uniquely identifying bar code. The analyzers serially analyze each sample during the handling of the racks. To this end, the analyzers of the invention include a shiftable needle operable to pierce the septum of each sample tube and to take a sample aliquot from each tube, and to inject the aliquots for downstream analysis thereof, typically by column separation and spectrophotometric analysis. As such, it is important that the racks and sample tubes be identified and optimally handled during the course of sample analysis. 
     Accordingly, the analyzers of the invention include structure operably supporting the analysis needle in order to selectively axially rotate the needle, and to selectively axially shift the needle. The preferred needle-supporting structure comprises a needle body presenting a non-round surface portion (preferably a pair of opposed, flattened surfaces), and a rotatable spindle receiving the non-round surface portion, with the needle support being axially rotatable in response to rotation of the spindle. This overall structure further includes apparatus operably coupled with the needle support for selective vertical shifting movement of the needle support and the needle. In this fashion, when the needle pierces the septum of each sample, the frictional engagement between the needle and the septum causes rotation of the sample tube in response to rotation of the needle. This tube rotation continues until the analyzer bar code reader detects the external identifying bar code on the sample tube. At the same time, the vertical reciprocation of the needle is maintained. 
     In addition, a specialized apparatus is provided for selective shifting of the racks containing the sample tubes. This apparatus includes a generally quadrate, elongated base plate presenting a pair of opposed side margins and a pair of opposed end margins. A fore-and-aft shifting assembly is also provided which is operable to individually shift each of the racks in a first direction adjacent one of the side margins, and in the opposite direction along the other of the side margins, along with a lateral shifting mechanism operable to shift each of the racks in a first lateral direction adjacent one of the end margins, and in the opposite lateral direction adjacent the other of the end margins. Accordingly, each of the racks follows a quadrate path of travel around the base plate. After all of the samples in all of the racks have been analyzed, fresh racks are installed in the analyzer, and the analysis process is repeated. 
     Preferably, the fore-and-aft shifting assembly including a pair of elongated, shiftable belts respectively located adjacent and outboard of the side margins of the base plate and shiftable in opposite directions, respectively, each of the belts supporting a rack shifter operable to engage and axially shift a respective rack. The lateral shifting mechanism comprises a first pair of axially spaced apart, laterally extending rack-supporting belts proximal to one of the base plate end margins, and a second pair of axially spaced apart, laterally extending rack-supporting belts proximal to the other of the base plate end margins, the first pair of belts shiftable in one direction, and the other pair of belts shiftable in the opposite direction. 
     In particularly preferred forms, the belts of the first and second belt pairs are each supported on a pair of eccentric pulleys, the pulleys operable to withdraw end sections of the belts below the base plate in order to prevent interference between the belts and the fore-and-aft shifting of the racks along the base plate. Additionally, one pulley of each of the sets thereof includes a rack-engaging lug operable during rotation of the pulley to engage an adjacent rack to assist in lateral movement thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an analyzer in accordance with the invention; 
         FIG. 2  is another perspective view of the analyzer, with protective covers removed to illustrate the modules of the analyzer. 
         FIG. 3  is another perspective view of the analyzer, illustrated with the conveyor module extended for loading or service; 
         FIG. 4  is a plan view of the sample conveyor forming a part of the conveyor module, with the upper frame removed and parts broken away to illustrate details of construction; 
         FIG. 5  is a bottom perspective view of the conveyor module, illustrating the fore-and-aft rack shifting drive and the lateral rack moving belts; 
         FIG. 6  is a vertical sectional view taken along line  6 - 6  of  FIG. 4 , and depicting the lateral rack moving belts with the eccentric belt pulleys shown in the belts-down position permitting movement of a sample rack in a fore-and-aft direction without belt interference; 
         FIG. 7  is a sectional view similar to that of  FIG. 6 , but showing the belt-supporting eccentric pulleys in the belts-up position to laterally move the racks; 
         FIG. 8  is a fragmentary vertical sectional view illustrating one of the eccentric pulley lugs engaging a sample rack; 
         FIG. 9  is a fragmentary central sectional view depicting the drive for the calibrated sample rack; 
         FIG. 10  is an exploded perspective view of the different analyzer modules and their relationship; 
         FIG. 11  is a perspective view of the syringe module; 
         FIG. 12  is a vertical view of the syringe module; 
         FIG. 13  is a horizontal sectional view taken along line  13 - 13  of  FIG. 12 ; 
         FIG. 14  is a perspective view of the probe module; 
         FIG. 15  is a vertical sectional view of the probe module; 
         FIG. 16  is a fragmentary perspective view of the rotary drive used to rotate the probe and align each sample tube bar code with the bar code reader; 
         FIG. 17  is a perspective view of the probe module carrier; 
         FIG. 18  is a schematic view illustrating the probe module in its sample dilution/extraction position; 
         FIG. 19  is a schematic view illustrating the probe module in its sample injection position; 
         FIG. 20  is a schematic view illustrating the probe module in its needle wash position; 
         FIG. 21  is a schematic view illustrating the probe module in position to sample a tube in the static holder; 
         FIG. 22  is a perspective view of the oven module; 
         FIG. 23  is a perspective view of the oven module, with the door thereof open to reveal the HPLC column and oven coil; 
         FIG. 24  illustrates the interconnection between the oven coil and column; 
         FIG. 25  is a partial sectional view of the oven coil; 
         FIG. 26  is a schematic fluid flow block diagram illustrating the operation of the analyzer; and 
         FIG. 27  is a perspective view illustrating one of the sample racks loaded with tubes with bar codes for identification of the rack and the individual sample tubes therein. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings, and particularly  FIGS. 1 ,  2 ,  10 , and  26 , the analyzer  30  include covers  34 ,  36 , and  38 , and a detachable, forwardly extending, generally U-shaped cover  44 . The apparatus further includes a monitor  46  and would also have an input keyboard (not shown).  FIG. 2  illustrates the analyzer  30  with the covers  36 - 38  removed to depict the modules of the analyzer, namely the conveyor module  48 , motherboard module  50 , syringe module  52 , probe module  54 , detector module  56 , oven module  58 , injector module  60 , and pump module  62 . A bar code scanner assembly  63  is also provided forwardly of the syringe module  52  ( FIGS. 1-3 ). The aforementioned chassis is equipped with guide rails and stops permitting easy removal and replacement of the modules, as may be necessary during the course of operation of the analyzer  30 . 
     As best seen in  FIG. 2 , a liquids tray  64  is located above the modules  56  and  58  and supports a series of liquid bottles including ( FIG. 1 ) bottle  66  containing cleaning reagent, bottle  68  containing reagent A, bottle  70  containing reagent B, bottle  72  containing water, and bottles  74  and  76  containing aqueous diluent. 
     A principal feature of the present invention is the provision of an analyzer which is fully modular, in that the respective modules  48 - 62  may be individually removed from the overall analyzer for service or replacement. This also creates an analyzer having a relatively small footprint, as compared with analyzers of the prior art. 
     The analyzer  30  is designed to receive a series of sample racks  78  ( FIG. 27 ) each containing a number of identical sample tubes  80  therein, and to individually analyze the contents thereof. The rack  78  has a base plate  82  and a series of upstanding tube-receiving compartments  84  defined by upwardly extending, laterally spaced apart segments  86 . One segment  86   a  carries a bar code  88  which uniquely identifies the respective rack. Each of the sample tubes  80  includes an elongated tube section  90  with an uppermost septum  92 . Furthermore, each tube section  90  carries a bar code  94  which uniquely identifies the individual tube  80 . 
     Conveyor Module  48   
     The conveyor module  48  is supported by tray  96  which is in turn supported by a drawer assembly  49 . The module  48  has a rack-shifting assembly  97  including a frame assembly  98 , a fore-and-aft rack transport mechanism  100 , two lateral rack transport mechanisms  102  and  104 , and a bridge assembly  106 . The purpose of conveyor module  48  is to efficiently handle a plurality of racks  78  each carrying loaded sample tubes  80  so as to sequentially move each rack  78  into a test station adjacent bar code reader assembly  63 , and to thereupon index the so-positioned rack, so that each tube  80  thereof is successively moved to a fixed test position beneath probe module  54 . After all of the tubes  80  within the rack  78  are tested, the rack is then moved to a rearward storage location and a fresh rack is moved into the test station. After all of the sample tubes of all of the racks within the assembly  97  are analyzed, the in-place assembly  97  may be reloaded with new racks  78 , or the assembly  97  may be bodily removed from tray  96  to allow installation of a fresh, loaded assembly  97 . 
     The frame assembly  98  includes two generally L-shaped, fore-and-aft extending side rails  108 ,  110  and spaced apart cross rails  112 ,  114 ,  116 , and  118 . The side rails  108 ,  110  ( FIG. 5 ) have positioning apertures  108   a ,  108   b  and  110   a ,  110   b  adjacent the ends thereof ( FIG. 5 ). The conveyor assembly  48  is mounted by means of four locating pins mounted on a drawer assembly  49  which extend though corresponding tubular tray-mounted grommets (not shown) and into the apertures  108   a ,  108   b  and  110   a ,  110   b . The overall frame assembly  48  further has a slotted base plate  120  supported by the cross rails  112 - 118  between the side rails  108 ,  110 . The base plate  120  includes two pairs of spaced apart lateral belt slots  122 , each including a relatively wide slot  122   a  and an opposed, narrower slot  122   b  ( FIG. 4 ). A series of belt rollers  124  are secured to the underside of base plate  120  closely adjacent the inner margin of each slot  122   a ,  122   b . It will be observed that the base plate  120  is substantially quadrate in plan configuration, presenting a pair of opposed fore-and-aft extending side margins, and a pair of opposed end margins. 
     The transport mechanism  100  includes a pair of continuous belts  126 ,  128  respectively support on endmost rollers  130  and  132 . The belt  126  is driven by motor  134 , whereas belt  128  is driven by  136 . An elongated rack shifter  138  having endmost, inwardly extending, rack-engaging ears  138   a  which cooperatively define a rack-receiving recess  140  is supported by the side rail and is attached to belt  130  by means of belt couplers  142  ( FIG. 5 ); similarly, an identical rack shifter  144  having ears  144   a  defining a rack-receiving recess  145  is supported by side rail  110  to belt  128  via couplers  142 . 
     The lateral rack transport mechanism  102  includes a pair of laterally extending continuous belts  146  and  148 , each supported by a pair of endmost eccentric pulleys  150  secured to common cross shafts  152 . As illustrated, the upper runs of each of the belts  146 ,  148  pass around the pulleys  150  and through the slots  122   a ,  122   b  to move along the upper surface of base plate  120 . Moreover ( FIG. 6 ), the pulleys  150  adjacent the slots  122   a  are equipped with rotary lug plates  154 , which are important for purposes to be described. The belts  146 ,  148  are driven via a motor  156  member  112  having an output shaft  158  supporting a drive pulley  160 . A drive belt  162  passes around pulley  160  and the small concentric pulley  160   a  adjacent the slot  122   b . The lateral transport mechanism  104  is identical with the mechanism  102  and accordingly like reference numerals are used to identify the components thereof. 
     The bridge assembly  106  includes an uppermost bridge plate  164  which spans the distance between the side  108 ,  110  and is equipped with a slot  166  and a test opening  168 . The plate  164  is supported by an upper rectangular channel frame  170  by means of oblique legs  171 . A rotary calibration rack  172  carrying a plurality of tubes  174  having calibrated samples therein is positioned below the bridge plate  164 . The rack  172  is mounted for rotation about an upright axis on a rotary support  176 , and is selectively rotated by means of a motor  178  secured to the upper face of base plate  120 , and a drive belt  180 . The motor  178  is within a housing  182 , as best seen in  FIG. 9 . A latch pin  184  is located on bridge plate  164  and operates in conjunction with a latching assembly (not shown) to releasably secure the rack shifting assembly  97  to cabinet  32 . 
     Motherboard Module  50   
     This module houses conventional digital processing equipment and has an electronic memory for storing sample analysis programs and data. The motherboard assembly is operably coupled with the other modules and controls the operation thereof. It also is coupled with monitor  46  so as to generate a real-time output of the ongoing sample analyses during operation of the analyzer  30 . A keyboard, mouse, and/or other input device is used to load the necessary data within the electronic memory to allow functioning of the module  50 . 
     Syringe Module  52   
     The syringe module  52  is operably coupled with the probe module  54  described below in order to dilute and collect samples to be analyzed. To this end, the syringe module  52  includes a generally L-shaped housing  186  including a front plate  188  having an elongated slot  190  formed therein. Internally, the module  52  has a vertical drive screw  192  in alignment with the slot  190 , and supported by upper and lower stationary blocks  193   a ,  193   b . The screw  192  is driven by means of a motor  194  mounted on upper block  193   a  and a belt and pulley drive assembly  196 . 
     An external, generally U-shaped fixed block  198  is secured to upper block  193   a  and has aqueous diluent and output ports  200 ,  202 . The block  198  supports a vertically extending tubular sleeve  204  equipped with an internal plunger rod  206  having an enlarged, liquid-tight head  208 . An internally threaded, vertically reciprocal shifter  210  is threaded onto drive screw  192  so as to move the shifter upwardly or downwardly depending upon the direction of rotation of the drive screw. Such movement of the shifter  210  is guided by a stationary guide block  212  mounted to the supports  193   a ,  193   b . The shifter  210  also carries a sensor probe  214  which mates with position sensor  216  within housing  186 ; this arrangement allows sensing of the vertical position of the shifter  210 . The shifter  210  also carries a forwardly extending block  218  which receives the lower end of plunger rod  206 , as best seen in  FIG. 12 . It will be appreciated that vertical movement of the shifter  210  effects corresponding movement of the plunger rod  206 . 
     Probe Module  54   
     The probe module  54  is positioned adjacent the syringe module  52  and includes a housing  220  including an upwardly extending section  222  and a rearwardly extending section  224 . The section  222  has an internal, vertically extending drive screw  226  supported by upper and lower stationary mounts  228 ,  230 . The screw  226  is rotationally driven by means of a motor  232  secured to mount  228 , and a belt and pulley drive assembly  234 . The section  222  includes a face plate  236  having an elongated, vertical slot  238  in alignment with drive screw  226 . The screw supports a shifter  240  which moves vertically upwardly or downwardly depending upon the direction of rotation of screw  226 , and is maintained in alignment by means of a stationary guide  241 . The shifter  240  carries an external block  242 , which in turn supports an axially rotatable, vertically shiftable needle support  244  having an enlarged spindle  246  received within a bore  247  through the mount  230  ( FIG. 16 ), and an upper connection nipple  248 . The fitting  246  includes an enlarged lower section  246   a  equipped with external teeth. 
     The needle support  244  has a non-round surface portion which mates with spindle  246 , in this instance a pair of opposed flattened surfaces  244   a  which extend through the spindle  246 , so as to permit vertical shifting of the support  244  relative to the spindle, and also to allow rotation of the support  244  via rotation of the spindle  246 . The lowermost end of needle support  244  below spindle  246  threadably supports a sharpened sample injection needle  250 . The injection needle  250  is protected in its ready position by means of a transparent cover  251 . The needle support  244  and injection needle  250  are selectively rotatable by means of a motor  252  supported on mount  230  and a belt drive assembly  254  operably interconnecting the output of motor  252  and the rotational fitting  246 . 
     The rearwardly extending section  224  of housing  220  has an elongated, horizontally extending drive screw  256  supported by fore-and-aft stationary mounts  258 ,  260 . The screw  256  is selectively rotatable by means of a motor  262  secured to mount  258  and a belt and pulley drive assembly  264 . The screw  256  carries a pair of spaced apart shifters  266 ,  268  which are guided by a stationary rail  270 . The shifters  266 ,  268  support an elongated, fore-and-aft reciprocal carrier block  272  ( FIG. 17 ). The carrier block  272  has a depending, tubular needle guide  274 , an injection port  276  including a depending delivery tube  277 , and a wash fitting  278  equipped with an upper port  280 , a vertical passageway  281 , and a wash liquid input nipple  281   a . The injection port  276  and port  280  are positioned within a recess  282  formed in carrier block  272 , the latter communicating with a drainage slot  284  leading to a waste liquid outlet tube  286 . 
     The carrier block  272  supports a tube holder  288  used to manually test a single sample tube  80 , as may be necessary from time to time. The tube holder  288  is secured to the carrier block  272  by means of a hanger component  289  having through apertures  289   a ,  289   b  respectively above the holder  288  and the open end of needle guide  274 . Additionally, a wash pump  290  is mounted on the sidewall of housing  220  and includes a tubular input  292  and an output  294  operably coupled with nipple  281   a.    
     During normal automated operation of analyzer  30  described in detail below, the carrier block  272  is shifted laterally to individual positions, and the needle support  244  carrying needle  250  is correspondingly adjusted vertically. These automated operation positions are depicted in  FIGS. 18-20 , and are referred to as the diluted sample extraction, diluted sample injection, and needle wash positions. 
     Turning first to  FIG. 18 , it will be observed that the carrier block  272  is shifted laterally to a point where the needle guide  274  is in alignment with injection needle  250 . The latter is then shifted downwardly until the needle  250  passes through the test opening  168  and pierces the septum of a sample tube  80 . This permits dilution and extraction of a sample from the tube  80 . After the needle is fully withdrawn from the guide  274 , the carrier block  272  is shifted rightwardly, as viewed in  FIG. 20 , until the injection port  276  comes into alignment with needle  250 . At this point, the needle  250  is lowered into the port  276  and the diluted sample is injected through tube  177 . Then ( FIG. 20 ), the needle  250  is moved to the wash fitting  278  and is lowered to allow the needle to be washed for reuse. 
     In certain instances, it may be desired to test a single sample using the tube holder  288 . In such case ( FIG. 21 ), the sample tube  280  is positioned within the holder  288 , and the carrier block  272  is positioned so that needle  250  is directly above opening  289   a . The needle  250  is then moved downwardly into the holder-mounted tube  80  and a sample is taken. The remaining steps are then identical to those used during automated operation of the analyzer  30 . 
     Injector Module  60   
     This module is itself entirely conventional, and serves to inject buffering reagents A or B, or mixtures of the reagents A or B and the diluted samples from the injector into the oven module  58 , depending upon the stage of operation of the analyzer  30 . 
     Oven Module  58   
     The oven module  58  ( FIGS. 22-25 ) has a housing  296  having a hingedly mounted front access door  298 . Internally, the module  58  includes a heating coil assembly  300  in series with a HPLC column  302 , usually an aminophenylboronic acid (PBA) column of known design. The coil assembly  300  includes a shell  304  and an coil  306  forming a part of the line  308  which is wound about an inner spool which also houses a central heating element (not shown). The assembly  300  serves to heat liquid passing through the coil  306 , delivering the heated liquid via output line  310  to the HPLC column  302 . As the analysis proceeds, the components separated within the column  302  pass through column output  312  for analysis within detector module  56 . 
     Detector Module  56   
     The detector module  56  is itself conventional and provides spectrophotometric absorbance analyses of the liquid fractions delivered from column  302 . The operation and data output from the module  56  are controlled by means of the motherboard module  50 , in order to generate an output which can be stored in memory, viewed in real time on monitor  46 , or printed in hard copy. 
     In the case of analyses to qualitatively and/or quantitatively determine levels of glycated and nonglycated proteinaceous fractions within a blood or serum sample, the detector module  56  would typically generate a chromatogram illustrating peaks for nonglycated and glycated proteins at characteristic absorbances, which can be integrated to quantitate the detected species. 
     Pump Module  62   
     This module is designed to move all of the liquids involved in operation of analyzer  30  in properly timed, pressurized, and mixed sequences. The module  62  operates in conjunction with a valve assembly  314  and syringe module  52  for these purposes. The valve assembly  314  has input lines  316 ,  318 ,  320 ,  322 , respectively from detector module  56 , reagent bottle  66 , buffer reagent A bottle  68 , and buffer reagent B bottle  70 . The assembly  314  has reagent A and B output lines  324  and  326 , and a waste output line  328 . 
     The module  62  includes pumps  330 ,  332  for reagents A and B, a syringe prime  334 , and a pressure dampener  336 . As depicted, the output line  324  from valve assembly  314  is directed to the input of pump A, and the output thereof in line  338  is directed to a tee  340 . Similarly, the output line  326  from valve assembly  314  is directed to pump B, and the output from the latter is directed to pressure dampener  336 . A return line  341  extends from the output of pump A to wash bottle  72 . A separate line  342  extends from the output of pump B to the inlet of pump A. Also, a line  344  extends from wash water bottle  72  to the input of pump B. The output from pressure dampener  336  is conveyed via line  346  to a tee  348 , where it may alternately be delivered to syringe prime  334  or to the tee  340 . The output from syringe prime  334  passes from line  350  and join with waste line  328 . 
     The pumps A and B are each piston pumps driven by associated cams which rotate 360° during each pump cycle. The cams are powered by stepper motors that divide each 360° cam rotation into 1600 equal steps, with each step corresponding to a fixed amount of rotation of the cam. However, each step does not generate the same positive displacement of the pump piston, meaning that as the cam approaches top dead center, the displacement of the piston approaches zero. In order to overcome this issue, the time between the respective steps is altered so that the displacement of the piston is substantially constant for each step. This linearizes the liquid flow from the pumps during each pump cycle to yield an essentially even flow from each pump during the course of each pump cycle. This operation of the pumps A and B is controlled by the software resident on the motherboard module  50 . 
     Bar Code Assembly  63   
     The assembly  63  includes a rectangular housing  352  having an observation slot  354  therein. The housing  352  supports a conventional bar code scanner  356  and also has an opening  358  to receive a manual bar code scanner wand  360 . The purpose of assembly  63  is to sequentially read the identifying bar codes  86   a  and  94 , respectively, on the racks  78  and the individual sample tubes  80 , as the latter pass through the test position of the analyzer  30  and the bar codes come into view through the slot  354 . 
     Operation 
     1. Initial Conditions 
     In the ensuing discussion, the continuous operation of analyzer  30  will be described during HPLC spectrophotometric analysis of whole blood samples to qualitatively and quantitatively determine glycated and nonglycated proteinaceous fractions within the samples. The separation column  302  is a standard PBA column used in such analyses. As an initial matter, the column  302  is conventionally equilibrated using reagent B. 
     Reagent A is designed to enhance the binding of glycated species to the boronate matrix of the column by converting the hydroxylated moieties thereof to the tetrahedryl anionic form. This reagent also serves as a transport medium for the nonglycated proteins initially passing through the column during the analyses. Common reagent A buffers include ammonium salts, phosphates, glycines, morpholine, taurine, and HEPES (N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid). The ionic strength and pH of reagent A may be adjusted to minimize secondary interactions between the boronate column packing and proteins. Magnesium ions, usually in the form of magnesium chloride (MgCl2), may be added to reduce ionic effects without causing hydrophobic bonding. A common reagent A buffer contains, per liter, 250 mmol ammonium acetate, 50 mmol MgCl2 at a pH adjusted to between 8.0-9.0. Sodium azide or other preservatives may be employed to enhance shelf life. 
     Reagent B is designed to elute the glycated components from the column, most frequently by means of a competing polyol which displaces the glycated components from the column binding sites. The preferred reagent B is a mixture of polyol and buffering compound. The most common reagent B consists of, per liter, 100 mmol TRIS (tris(hydroxymethyl)aminomethane), 200 mmol sorbitol, 50 mmol EDTA (ethylenediaminetetraacetic acid), pH 8.0-8.5. Trace amounts of preservatives may also be present. 
     Venous blood samples, typically collected via venipuncture or finger stick, are mixed with sufficient anticoagulant (e.g., EDTA or heparin) to prevent clotting, and placed within individual tubes  80 , which are uniquely identified with a bar code  94 , and loaded into racks  78 , which are also identified by a separate bar code  86   a . The racks  78  are then loaded into a rack shifting assembly  97  to present two banks of side-by-side racks respectively located above the lateral rack transport mechanisms  102  and  104  and between the rack shifters  138  and  144  allowing unimpeded fore-and-aft shifting of the latter ( FIG. 4 ). The loaded assembly  97  is then positioned within tray  96  using the locating pins and apertures  108   a ,  108   b ,  110   a ,  110   b , and the latch pin  184 . 
     2. Sequential Rack Shifting 
     Initially, the mechanisms  102  and  104  are operated in order to shift the racks within the latter, rightwardly in the case of mechanism  102  and leftwardly in the case of mechanism  104  as viewed in  FIG. 4 , so that the leading loaded racks are moved into the shifters  138  and  144 , respectively (e.g., rack  78   a ). This lateral rack movement is accomplished by energizing the motors  156  and  158   a  to thereby shift the lateral belts  146  and  148  rightwardly or leftwardly, as the case may be. In addition, during such belt rotation, the lug plates  154  engage the base plates of the adjacent racks  78  to positively shift the abutting racks so that the remote leading racks are fully positioned within the corresponding shifters ( FIGS. 7 and 8 ). Further rotation of the common shafts  152  causes the eccentric pulleys  150  to move to the over-center positions illustrated in  FIG. 6 , thereby drawing the transverse belts  146 ,  148  downwardly beneath the axial belts  126  and  128 . This in turn permits the racks  78  to be shifted along base plate  120  in a fore-and-aft direction by the belts  126 ,  128  and the shifters  138  and  144  of the fore-and-aft rack transport mechanism  100 , without interference from the belts  146 ,  148  of the lateral rack transport mechanisms  102  and  104 . 
     In order to move the leading tube  80   a  of rack  78   a  into the test station adjacent bar code assembly  63 , it is necessary to shift belts  126  and  128  by appropriate activation of the motors  134  and  136  until the leading sample tube  80   a  of rack  78   a  comes into alignment with the test opening  168  of bridge  164 . The belt  128  is also shifted so as to move shifter  144  as appropriate.\. At this point, the tube  80   a  is analyzed as described below, and identified by its unique bar code  94 . Next, the rack  78   a  is indexed by additional shifting of belt  126  and shifter  138  until the next succeeding sample tube  80  is aligned with test opening  168 , and these steps are repeated. This indexing movement is continued until the last sample tube  80  within the rack  78   a  is tested. The shifter  144  is also independently moved amount as needed to maintain the sequential movement of the racks  78 . 
     When all of the samples tubes  80  with rack  78   a  have been analyzed, the rack  78   a  is now in a position opposite to that illustrated in  FIG. 4 , i.e., the rack  78   a  is positioned adjacent the mechanism  104 . Also, the loaded and the leading rack within shifter  144  is now positioned adjacent mechanism  102 . The mechanisms  102  and  104  are then operated to move the racks from the shifters  138 ,  144  so as to allow the shifters to be again moved back to the starting positions thereof illustrated in  FIG. 4 . The mechanisms  102 ,  104  are again operated to load each of the shifters  138 ,  144  with a fresh loaded rack  78 . This process continues during the course of operation of the analyzer  30  until each sample  80  of each rack  78  passes into the test position above opening  168 . Thereupon, rack shifting assembly  97  may be removed from tray  96  (or the original assembly  97  may be reloaded with fresh racks), and the procedure is repeated. 
     In essence, it will be seen that each rack  78  follows a quadrate path of travel around and through the assembly  97  until the contents of each tube  80  of each rack  78  is analyzed. That is, as depicted in  FIG. 4 , each rack is conveyed axially rearwardly adjacent the lefthand margin of base plate  120  by belt  128 , then laterally (rightwardly) adjacent the rear transverse margin by means of mechanism  102 , then axially forwardly adjacent the right-hand margin of base plate  120  by belt  126 , and finally laterally (leftwardly) adjacent the front transverse margin by means of mechanism  104 . 
     3. Analysis of Samples 
     The analysis of samples using an analyzer  30  follows the technique described in U.S. Pat. No. 6,020,203 in terms of the preferred reagents, HPLC column, and processing steps. Accordingly, the disclosure of this patent is incorporated by reference herein in its entirety. 
     When a sample tube  80  is moved by conveyor module  48  into the test position, a number of steps are followed in order to identify the tube  80 , to appropriately mix the contents of the tube  80  with aqueous diluent, to withdraw an aliquot of the diluted sample from the tube  80 , to separate the glycated and nonglycated proteinaceous fractions in the sample in HPLC column  302 , and to spectrophotometrically analyze the separated species within detector module  56 . Those skilled in the art will appreciate that a variety of specific steps may be followed in order to accomplish the analyses; the following discussion represents one preferred procedure. 
     Specifically, in this procedure, the carrier block  272  is shifted to the  FIG. 18  position thereof where needle  250  is in alignment with the guide  274 . Thereupon, the needle  250  is shifted downwardly to pierce the septum  92  of the tube  80  to a level permitting withdrawal of the sample aliquot. The frictional engagement between needle  250  and septum  92  allows the sample tube  80  to be rotated by corresponding rotation of the needle support  244  via actuation of motor  252 , and in this fashion the tube  80  is rotated until the bar code  94  thereon comes into the view of bar code reader  356 . During this sequence, diluent is withdrawn from bottles  74 ,  76  by operation of syringe module  52  (i.e., the plunger rod  206  is shifted downwardly to draw diluent), which is then injected through needle  250  by upward shifting of the rod  206 ; appropriate valving with the module  52  permits these operations. Once the sample has been diluted, an aliquot is withdrawn into needle  250 , again by operation of syringe module  52 . 
     Next, the needle  250  is fully withdrawn from the sample tube  80 . The presence of bridge  164  ensures that there is a clean separation between the needle  250  and the septum  92  of the tube  80 , because the upper end of the tube  80  engages the underside of bridge  164  as the needle  250  is withdrawn. 
     Thereupon, the carrier block  272  is shifted rightwardly, as viewed in  FIG. 19 , until the injection port  276  is beneath the needle  250 . At this point, the latter, containing the diluted and withdrawn aliquot, is injected through the delivery tube  277  to the injector module  60 . As this is occurring, reagent A is directed through injector module  60  into and through the column  302  in order to equilibrate and condition the column. The leading reagent A then passes through detector module  56  and is ultimately sent to waste. When the diluted sample enters module  60 , it is in-line mixed with the flowing reagent A and ultimately passes through module  58  for separation in column  302 . The nonglycated fraction within the sample is thus bound to the PBA matrix within column  302 , allowing the glycated fraction to pass therethrough. This glycated fraction is then analyzed in detector module  56  and the effluent is passed to waste. After an appropriate time, passage of reagent A is terminated and reagent B is directed to module  60  for ultimate passage through the column  302  and detector module  56 . As reagent B passes through the column, the bound nonglycated proteins are detached from the column and thereupon pass through detector module  56  for quantitation thereof. 
     After injection, the needle  250  is withdrawn from injection port  276  and the carrier block  272  is moved to the wash position ( FIG. 20 ) where the port is directly beneath the needle. The needle  250  is then moved downwardly within the confines of fitting  278 , and wash pump  290  is actuated in order to direct aqueous diluent through nipple  281   a  and into the interior of fitting  278  to wash the needle for the next analysis. The liquid overflow from fitting  278  passes through drainage slot  284  and outlet tube  286  to waste. 
     The analyzer  30  is capable of a total analysis time one the order of one minute for each sample within each tube  80 , i.e., the injection-to-injection time between individual samples is about one minute, and in preferred forms approximately 66 seconds. These extremely rapid analyses are obtained using the combination of features described above. 
     During the course of analyses, it may be necessary or helpful to calibrate the analyzer  30  using the rotary calibration rack  172 . In this operation, the rack  78  within the testing station is withdrawn by appropriate movement of the rack shifter  138 , and the calibration rack  172  is rotated by actuation of the motor  178  until a selected one of the calibrated sample tubes  80  within the rack move into the test position beneath opening  168 . At this point, the calibrated sample may be subjected to the same sequence of steps described previously, and the analyzed output is compared with the known characteristics of the calibrated sample; the analyzer  30  may then be adjusted as necessary to calibrate the overall instrument. 
     In some instances, it may be helpful or necessary to individually analyze the contents of a given sample tube. As illustrated in  FIG. 21 , use is made of the stationary tube holder  288 . Specifically, a single sample tube is manually placed within the holder  288 , and the manual scanner wand  360  is used to scan the bar code associated with the single sample tube. The carrier block  272  is then moved to the  FIG. 21  position above opening  289   a  and the sample dilution/withdrawal, injection, and wash steps described previously are followed.