Gow-mac Gow-mac Gas Chromatograph 580-200 Isothermal Unit 115vac 1100w: Refurbished: 2: 90128194: Gow-mac Gow-mac Instrument Isothermal Did Gas Chromatograph M/n 590-3-v: Refurbished: 2: 90128195: Gow-mac Gow-mac Instrument Mini Gas Leak Detector Model 21-070: Refurbished: 2: 90128196: Gow-mac. Gow-Mac Gas Chromatograph Series 580 Model 50. Location: National City Skid 80.PLEASE READ. Due to the nature of the items we sell, we may only have one in stock. Because many items are genuine manufacture's new old stock, they are in limited supply. Once it's sold, its gone, and we may never get another item exactly like it.

These are the older GCs used in the organic labs. They can accept a wider range of compounds than the Vernier Mini GCs, but are more finicky and require the use of helium as a carrier gas.

Key parts of the Gow-Macs

The septum

The inside of the injector port

The column. On the outside, all you see is a long stainless steel tube, 1/8 to 1/4 inch in diameter and 4-5 feet long, which is coiled to fit inside the instrument. Inside the column is the important component: the stationary phase composed of the high-boiling liquid. The liquid is usually impregnated on a high surface area solid support like diatomaceous earth, crushed firebrick, or alumina. The liquid can be applied in various concentrations: the more liquid, the more sites it has to interact with the compounds. The labs at CU use a methyl silicone polymer liquid phase (OV-101, 1.5%) on a diatomaceous earth support (chromosorb G). Methyl silicone is a liquid phase of intermediate polarity, and non-polar compounds will separate according to their respective boiling points.

The detector inside the housing. Detection of the compounds is achieved with a thermal conductivity (TC or hot wire) detector.

The gas input port. This is where the carrier gas enters the GCs and where the gas flow rate can be adjusted. The carrier gas used by the Gow-Macs is an inert gas, helium. The flow rate of the gas influences how fast a compound will travel through the column; the faster the flowrate, the lower the retention time. Generally, the flow rate is held constant throughout a run. (The GCs at CU Boulder are set at a flow rate of 55 mL/min.)

Canon 580 Manual

Procedure for Using the Gow-Macs

Pull the sample to be injected into the syringe. A 25µL glass Hamilton syringe is used to inject the GC samples. Only 2-4 µL of sample is injected onto the column, which means that you fill only a small part of the barrel with sample. Examine the syringe carefully before you fill it. The divisions are marked '5 - 10 - 15 - 20 - 25'. Place the tip of the needle in the liquid. Slowly draw up a small amount of liquid by raising the plunger, then press on the plunger to expel the liquid back into the liquid. This serves to rinse the syringe with your sample, ensuring that what you will measure in the GC run is the composition of your mixture. Repeat the rinse process one or two times. Then, draw up the plunger slowly again while the needle is in the liquid and carefully fill the syringe with liquid about halfway to the 5 mark.

It is often hard to see the liquid in the syringe. If the syringe is clogged, the plunger will be in the correct position but the barrel of the syringe will be filled with only air, as in the bottom syringe in this photo. The best thing to do is to carefully examing the syringe after you think that you have filled it. Hold it up to the light to get a better view. Small air bubbles in the syringe will not affect the GC run (middle syringe in the photo to the left). As long as there is enough liquid in the syringe, the GC run will work fine. If you keep getting bubbles, just pull the plunger up a bit past the 'halfway to the 5' mark to compensate. If you have a VERY large air bubble, you will not have enough liquid to show a reading on the GC (e.g., the bottom syringe in the photo).

Inject the sample into the injector port. You will need to do two things sequentially and quickly, so make sure you know where the injection port is and where the start button on the recorder is. Push the needle of the syringe through the injection port and immediately press the plunger to inject the sample, then immediately press the start button on the recorder. You will feel a bit of resistance from the rubber septum in the injection port; this is to be expected and you should be prepared to apply some pressure to the syringe as you force the needle into the instrument all the way to the base of the needle.

Observe the recorder. Within several minutes, it should record several peaks. When you have seen all of the peaks which you suspect are in the mixture, or when the recorder has shown a flat baseline for a few minutes or so, press stop on the recorder. When you press stop, the recorder will print out the peaks, the retention times, and the areas under the peaks. When it is done printing, you can press enter a couple of times to advance the paper.

Carefully tear the paper off the recorder. The paper is not perforated, so do not try to pull up and expect it to pop out of the recorder. Instead, pull it down to start a tear from one edge, and then continue the tear until the paper is cut and free. Yanking the paper can result in the paper being torn below the plastic cutting surface on the recorder, and the paper gets jammed down inside the recorder. If this happens, the entire recorder has to be dis-assembled, a process which takes about 15 minutes, thus putting the entire GC out of service until it can be fixed.

Gow-mac Chromatograph 580 Manualquotesdigital

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