Firma:              Spark Holland

Modell:            Marathon 810

Kommentar:   Dokumente engl.

INTRODUCTION

The MARATHON autosampler is dedicated to routine analysis of (arge series of samples in an environment where zero sample loss and injection flexibility are of Iittle significance but where reliability, stability and reproducibility is mandatory.The MARATHON therefore makes use of flushed loop injection only, guaranteeing reproducibility of injection better than 0.5 %.

For optimum stability and reproducibility of analysis, column temperature control is performed by the MARATHON itself with its unique feature: the built-in column oven!

Sample tray cooling

Sample tray cooling down to 3-4°C is provided as an option and uses a regular cryobath (not included in the option) to recirculate cooling water through the sample tray cooling device.

Large sample volumes

A special sample trag for 48 large sample vials (5 ml) can be obtained as an option. Loopfilling on a time base by sample headspace pressure can be selected for quick filling of (arge sample loops as an alternative to regular dispenser controlled Ioopfilling on a volume basis.

SPECIFICATIONS

Analytical

Sample capacity                     : 96 samples

                                               (92, when needle wash is used)

Injection volume                      : flushed loop:

                                               5 - 500 pl (dispenser controlled),

                                               5 - >5000 pl (by headspace pressure).

Injections/vial                           : max 9

Analysis time                           max 99 min/59 sec

Needle wash                           : selectable

Reproducibility                         : better than 0.5%

Memory effect                         : less than 0.2%

Electrical

Power requirernents               : 110 VAC ± 20% / 220 VAC ± 20%,

                                               50/60 Hz, 50 VA (nominal).

                                               Selectable an rear panel.

Control I/O                               : outputs:

(ref. also 3.2.2)                        - injectmarker (TTL + Contacts NO/NC)

                                               - vial number BCD output (TTL) - stop I/O (TTL)

                                               - auxiliary 1 (open collector)

                                               - auxiliary 1 inverted (open collector)

                                               - auxiliary 2 (open collector)

                                               - auxiliary 2 inverted (open collector)

                                               - 24 Volt DC (0.5 A max.)

                                               inputs:

                                               - stop I/O (TTL)

                                               - freeze runtime (TTL) - next vial (TTL)

-                                               next injection (TTL)

AIR supply                               : 4-6 bar clean and dry air.

                                               (air dust filter standard in shipment kit)

Column thermostat

Temperature range                 : (ambient +5)°C - 80°

                                               * time programmable second oven temperature

Temp. accuracy                      : ± 1 °C

Temp. stability                         : better than 0.5 °C

Options

Sample cooling                       : by external cryobath

                                               via tray cooling, min. 3-4 °C

                                               Temp. readout an display.

King Size tray                          : 48 positions for 5 ml vials

Micro injector                           : 0.5, 1, 2, 5 µl loop (RHEODYNE)

                                                 0.06, 0.1, 0.2 µl loop (VALCO)

PC control                               : SPARKLINK software for autosampler control.

INJECTION PRINCIPLE

A six-port high pressure switching valve performs the injections based on the flushed loop principle. Loopfilling can be done on a volume basis, controlled by the digital dispenser System or on a time basis by headspace pressure on the sample (ref. SYSTEM SETTINGS, 5.3.1) to shorten filling time for larger loop volumes. The switching patterns of the valve in "LOAD" and "INJECT" Position are shown in fig.1. An injection is performed as follows:

DISPENSER CONTROLLED INJECTION

1.         Dispenser sucks approximately 10 µl air bubble in sample needle for more efficient removal of previous sample.

2.         With injection valve in inject position, the coaxial needle pair is inserted into the sample. Air pressure, applied to the sample through the outer air needle, ensures that no air or vapour bubbles are formed during sample withdrawal.

3.         Dispenser withdraws "preflush volume" from sample vial to fill sample line with sample and to remove previous sample. (30 - 999 µl, programmable)

4.         Injection valve switches into Ioad position; dispenser transports 2 or 3 x loopvolume through the loop to fill the loop quantitatively.

2 x loopvolume for loop equal to or larger than 100 µl,

3 x loopvolume for loop smaller than 100 µl.

5.          Injection valve switches into inject position. Sample loop is now patt of the HPLC mobile phase flow path: sample is transported to the column. Analysis time starts.

If one injection is to be made out of each sample vial, the needle pair withdraws after analysis time and sequence 1-5 starts anew for the next vial. If more than one injection is to be made out of the same sample vial, the needles remain in the vial and after analysis time the next injection is made starting the sequence at 3 with a fixed preflush of 4 µl.

PRESSURE CONTROLLED INJECTION

1.          With the injection valve in load position, the coaxial needle pair is inserted into the sample. Air pressure, applied an the sample through the outer (air-) needle, will force the sample via the inner (sample-) needle through the sample loop. The duration of the headspace pressure is programmable; appropriate duration has to be determined experimentally.

NOTE: A SPEC/AL SAMPLE DRAIN MUST BE CONNECTED TO THE INJECTION

VAL VE (REPLACING THE DISPENSER CONNECTIONI, REFER TO 4.2.4.3.

2.          Injection valve switches into inject position. Sample loop is now part of the HPLC mobile phase flow path: sample is transported to the column. Analysis time starts.

If one injection is to be made out of each sample vial, the needle pair withdraws after analysis time and sequence 1-2 starts anew for the next vial. If more than one injection is to be made out of the same sample vial, the needles remain in the vial.

DIGITAL DISPENSER SYSTEM (DDS)

Working principle

The DDS is a miniature "finger pump". The operating principle is shown in Fig.3: Fingers 1 and 3 act as inlet and outlet pinch valve respectively, finger 2 provides the fluid displacement. The stroke of finger 2 is factory adjusted to provide 2 µl per stroke. Since the volume dispensed is always a multiple of one stroke volume (digital dispensing), i.e. 2, 4, 6 µl etc., odd values for volumes will be round down to even values.

Figure 4. Operating principle of digital dispensing System (DDS)

INSTRUMENT DESCRIPTION

GENERAL DESCRIPTION

1.          Sample tray, consisting of 4 removable segments

2.          Keyboard and display

3.          Needle cover

4.          Needle cover locking screw

5.          Dispenser cover

6.          Injection valve with sample loop

7.          Dispenser drain tubing

8.          Tubing outlet groove for column outlet tubing

9.          Column oven cover

10.        Common leakage/condensation water drain for injection valve, oven, sample

tray and DDS

INJECTION SYSTEM

1. Side-port sample needle

2. Air needle

3. Air tubing to provide sample headspace pressure

4. Needle penetration depth adjustment screw

5. Injection valve

6. Digital Dispenser System

7. Pump tubing Cassette

8. Dispenser drain

9. Sample tubing needle --> valve (port 2)

10. Sample tubing valve (port 3) --> dispenser

11. Sample loop

12. Sample drain for loopfilling by sample headspace pressure. Replaces sample tubing (10)

13. Vial stripper (part of the needle cover, make sure that cover is closed AND LOCKED

      before operating the MARATHON!)

14. The silicon tubing connector with air inlet hole must be approximately at the same level

      as the liquid in the sample vial to prevent hydrostatic sample flow during analysis time.

15. Air inlet hole in connector to prevent emptying of sample vial by hydrostatic suction.

16. Needle connection nut

17. Ferrule (PTFE)

18. Sample needle connection hub

19. Air seal