[0025] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.
[0026] The automatic measurement system of the present invention can replace the traditional manual process of pipetting, filtering and drying the sample solution containing total dissolved solids. The whole process is automated through software, and the drying cup after drying can be directly used for constant weight weighing measuring. During operation, first use deionized water to self-clean the system pipeline, stir the water sample and wait for it to stand, quantitatively remove the water sample, filter it through the filtration system, and let the filtered water sample dry in a drying cup.
[0027] More specifically, the present invention discloses an automatic measurement system for total dissolved solids content, including:
[0028] Sample pretreatment container, which holds the sample solution waiting for pretreatment;
[0029] The stirring device is fixedly or movably installed in the sample pretreatment container to stir the sample solution waiting for pretreatment in the sample pretreatment container;
[0030] The sample transfer device is fixedly or movably arranged in the sample pretreatment container, and transfers the pretreated sample solution in the sample pretreatment container to the sample heating container by suction;
[0031] The sample heating container contains the sample solution waiting to be heated and dried;
[0032] The filter device is located on the pipe that transfers the liquid from the sample transfer device to the sample heating container;
[0033] The drying device is located around the sample heating container or inside the sample heating container; and
[0034] The control device automatically controls the actions of the stirring device, the sample transfer device and the drying device, such as start and stop actions.
[0035] Preferably, the automatic measurement system further includes a constant volume device for constant volume of the sample solution in the sample pretreatment container; further preferably, the constant volume device adopts an infrared detection device for constant volume.
[0036] Preferably, the sample transfer device may include a peristaltic pump that can be accurately metered; further preferably, the flow rate of the peristaltic pump is controlled between 10 and 100 ml/min.
[0037] Preferably, the sample transfer device includes a liquid delivery pipeline, and the liquid delivery pipeline preferably adopts a polytetrafluoroethylene tube to adapt to different sample solutions and avoid corrosion by the sample solution or introduce soluble impurities into the sample solution.
[0038] Preferably, the drying device includes a plurality of heating units, each heating unit corresponds to a sample heating container, and each heating unit independently controls the temperature, so that simultaneous measurement of multiple sets of samples can be realized.
[0039] Among them, the heating power of the drying device is preferably selected between 800 and 1500W.
[0040] Preferably, the automatic measurement system further includes a cleaning device, which is connected to the liquid delivery pipeline of the sample transfer device through a three-way valve; the cleaning device includes a container for storing purified water, and after the sample solution is transferred, the purified water is used Flush the liquid delivery pipeline of the sample transfer device, usually for 15-40s, to ensure the cleanliness of the liquid delivery pipeline.
[0041] Preferably, the filter device is detachable, divided into upper and lower parts, and assembled together by threads. Among them, the 0.45 micron standard filter membrane is used in the filter device.
[0042] The present invention also discloses an automatic measurement method of total dissolved solid content, which adopts the above-mentioned automatic measurement system to perform measurement, including the following steps:
[0043] Put the water sample solution to be tested into the sample pretreatment container and start the power supply of the control device;
[0044] The control device controls the stirring device to stir, and the stirring time is 20 seconds to 1 minute;
[0045] After the stirring in the sample pretreatment container is stopped, let it stand for 5-10 minutes, and the control device controls the sample transfer device to transfer the water sample solution to the sample heating container; wherein the dry and empty sample heating container is weighed in advance ;
[0046] The control device starts the drying device to heat and dry the water sample solution in the sample heating container;
[0047] Weigh the dried sample heating container again;
[0048] Based on the volume of the water sample solution transferred by the sample transfer device and the weight difference between the two weighings of the sample heating container, the total soluble solid content is calculated.
[0049] Preferably, after the sample solution is transferred, pure water is used to rinse the liquid delivery pipe of the sample transfer device for 15-40 seconds.
[0050] In actual operation, as a preferred embodiment, the operation process of the automatic measurement system is as follows:
[0051] 1. Put the collected water sample (left side) into the sample position, and the instrument will perform the stirring function, and the stirring time is 30 seconds. After the stirring stops, let it stand for 5 minutes, and transfer the sample to the drying cup by the sampler. The transfer function is realized by a peristaltic pump. The flow rate of the peristaltic pump is adjustable from 10 ml/min to 100 ml/min to adapt to the filtration speed of different water quality. The pipe materials for the stirring rod and sample transfer are all polytetrafluoroethylene pipes with an inner diameter of 2mm and an outer diameter of 3mm. The joint with the peristaltic pump is made of rubber. This automatic measurement system determines the sampling volume of the sample by setting the infrared constant volume device to achieve the automatic constant volume function. When all the samples are transferred to the drying cup, the heating plate heating function is activated, and the heating power can be selected from 800 to 1500W. Each heating cup cavity can realize independent temperature control and heating function, and there is insulation cotton between each heating cavity to isolate the temperature. Each drying cup sinks 5 cm to meet the uniform and rapid heating effect. The sample cup is made of heat-resistant quartz, and the insulation layer is filled with quartz wool. The gap between the drying cup and the heating module is less than 0.5 mm, and the heating module is made of stainless steel.
[0052] 2. When the transfer of a sample is completed, the instrument starts the pipe cleaning function. The three-way valve is switched to the cleaning liquid (deionized water or ultrapure water) in the cleaning barrel, the cleaning liquid is filled with the entire pipeline by the peristaltic pump, and the other three-way valve is switched to the waste liquid pipeline and discharged into the waste liquid barrel.
[0053] 3. When the next sample is transferred, the three-way valve is switched to the sample cup, the peristaltic pump takes samples, and the other three-way valve is still switched to the waste liquid state. After setting for 30 seconds, the pipette is deemed to be completely rinsed with sample water After the passage, the waste three-way valve is switched to the first stage of the filter to realize the sample transfer function.
[0054] 4. The above-mentioned sampling pipeline adopts a removable filter. The removable filter is composed of upper and lower parts, and the combination relies on an internal and external threaded fixing frame.
[0055] The thread width of the inner threaded fixing frame is 1 mm and the material is stainless steel. The inner threaded fixing frame is equipped with a filter membrane holder, which can be replaced manually according to the turbidity of the water sample. The filter membrane holder is made of PTFE, with a height of 1 cm and a thickness of 2 mm. The 0.45 micron filter membrane can effectively filter the suspended matter larger than 0.45 microns in the water sample. The filtered water sample enters the collection port and is finally transferred to the drying cup for heating.
[0056] The thread width of the outer threaded fixing frame is 1 mm and the material is stainless steel. The outer threaded fixing frame has a fixed ring of PTFE filter membrane made of PTFE with a length of 4 cm and a width of 5 mm. The gap between the filter membrane fixing ring and the filter membrane fixing frame is less than 0.1 mm to prevent the sample from overflowing when the liquid is added too fast.
[0057] The gap of the filter membrane is 0.45 microns, and the filter membrane is fixed by a hard plastic mold around it. When the inner and outer threaded fixing frames are airtight, the filter membrane fixing ring presses the 0.45 micron filter membrane, and the gap is less than 0.1 mm.
[0058] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in further detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Within the spirit and principle of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.
