Sequential Injection-flow Reversal Mixing (Si-frm) Untuk Penentuan Kreatinin Dalam Urin

Jumlah kreatinin yang diekskresikan melalui urin menunjukkan keadaan ginjal seseorang. Dalam penelitian ini, dikembangkan metode untuk penentuan kreatinin secara otomatis yaitu sequential injection-flow reversal mixing (SI-FRM). Pendeteksian kreatinin didasarkan pada pembentukan senyawa berwarna (merah-orange) yang dihasilkan dari reaksi antara kreatinin dan asam pikrat dalam suasana basa dan diukur pada panjang gelombang 530 nm. Reaksi pembentukan senyawa kreatinin-pikrat dilakukan melalui pembentukan segmen antara sampel dan reagen di-holding coil dan selanjutnya dilakukan proses flow reversal di-mixing coil. Parameter-parameter yang mempengaruhi metode ini diuji secara detail. Hasil penelitian menunjukkan bahwa kondisi optimum pengukuran kreatinin yaitu menggunakan konsentrasi asam pikrat 0,035 M dan NaOH 3,5%, laju alir flow reversal 5 µL/detik, laju alir produk reaksi 20 µL/detik, jumlah flow reversal empat kali dan menggunakan tiga segmen (pikrat-kreatinin-pikrat) dengan masing-masing volume segmen 100 µL. Metode SI-FRM ini telah diaplikasikan langsung untuk penentuan kadar kreatinin dalam urin dengan limit deteksi 1,7 µg/g. The amount of creatinine excreted in urine indicates kidney condition. In this experiment, the automatic determination method of determining creatinine was developed by using sequential injection-flow reversal mixing (SI-FRM). The detection of creatinine is based on the formation of a colored product (red-orange) yielded from the reaction of creatinine with picrate at alkaline medium. The absorbance is measured at wavelength of 530 nm.  The formation of creatinine-picrate complex is performed through the segment formation between sample and reagent in the holding coil and then flow reversal process in the mixing coil of SI-FRM. Several parameters affecting to this method are investigated in detail. The results show that the optimum concentrations of picric acid and NaOH are 0.035 M and 3.5%, respectively. Other optimized conditions, such as the flow reversal rate of there 5 µL/s, flow rate of product of 20 µL/s, amount of flow reversal process of four times, and segment amount of three (picrate-creatinine -picrate) with each volume of 100 µL, were obtained. This method is successfully applied to the determination of creatinine in urine with the detection limit of 1.7 µg/g

Automated injection of slurry samples in flow-injection analysis

Two types of injectors are described for introducing solid samples as slurries in flow analysis systems. A time-based and a volume-based injector based on multitube solenoid pinch valves were built, both can be characterized as hydrodynamic injectors. Reproducibility of the injections of dispersed solids ( 150 ¿m) was tested with several concentrations of slurry samples up to 30 mg/ml; the injected volume was 1 ml. For both injectors dye and slurry samples could be injected with good precision (relative standard deviation for the peak area less than 2%). Peak detection was performed turbidimetrically. Data analysis and operation of the injectors were automated. The usual peristaltic pumps in flow analysis are normally not capable of handling slurries of the type investigated, therefore a valveless piston pump was used instead

The effect of flotation cell shape on deinking behaviour

Studies were undertaken to investigate the deinking behaviour of different shaped deinking cells of the same volume. For comparative purposes, most oprational variables were kept constant, and the same injector was used throughout the study. The position of the injector, however, was varied in some cases to go along with the particular cell shape being studied. Three types of cell shapes were studied, (1) cylindrical with tangential air injection, (2) rectanular with vertical injection, and (3) rectangular with horizontal injection. Eucalyptus/toner slurries and news/mag wastepaper slurries were deinked. Flow patterns in the cells and the corresponding deinking efficiencies were measured. It was found that strong and excessive re-circulatory flows within the cells could under certain conditions be a major factor in reducing brightness lift. Vertical injection into a rectangular cell gave stable flow patterns, non-wavy froth removal and sustained brightness lift for a wide range of feed and airflow rates. Horizontal injection into a similar rectangular shaped cell exhibited quite different characteristics. High brightness lift was possible for certain conditions and not for others. Wavy froth and excessive recirculation flow patterns varied with feed and airflow. The cylindrical cell with tangential injection gave stable circulatory flow and stable froth removal at low flow rates but was unable to deink at high flows

Variable-area nozzle automatically controls fluid flow

Simple, passive nozzle requires no active control system to vary injection area. Injection area changes with changing pressure, thereby allowing greater flow as pressure increases. As pressure drop across nozzle is decreased, spring action of segments causes them to move inward, decreasing the flow area

Skin friction reduction by slot injection at Mach 0.8

Surface skin friction, boundary layer profiles and turbulent intensity due to axially symmetric tangential slot injection into a transonic boundary layer were measured. Effects of slot height, multiple slot injection, and injection mass flow rate on the surface skin friction downstream of the the slot have been investigated. Surface skin friction was a function of the injection mass flow rate for x/s 40. Large normal pressure gradient and relatively large turbulent intensity were found near the slot with small injection mass flow rate; the region the high turbulent intensity moved downstream with increasing injection mass flow rate. The results with two slot injections indicated that the distance between slots should be less than 30 slot heights in order to achieve some benefits from the first slot. Of significant importance in the present investigation is that the skin friction reduction obtained at transonic speed is of the same order as obtained in the hypersonic regime. Additional work is required in order to formulate a correlation between the turbulent intensity and the injection mass flow rate that may be used in future analysis

Analysis of rheological behaviour of titanium feedstocks formulated with a water-soluble binder system for powder injection moulding

Binder selection and formulation are critical in powder injection moulding. Binders play a key role in controlling the rheological properties of a feedstock and influence whether the resulting feedstock can be successfully injection moulded, debound and sintered without defects. A four-step process was used to mix hydride-dehydride titanium alloy (processed) powder (Ti-6Al-4 V) with a polyethylene glycol (PEG) based water soluble binder system. The rheological properties, including flow behaviour index, flow activation energy, fluidity and melt flow index of the homogeneous feedstock, were determined with a capillary rheometer. All feedstock formulations exhibited shear thinning flow behaviour. The optimum feedstock consisting of 60 vol.% powder content, 32 vol.% PEG, 6 vol.% polyvinyl butyryl and 2 vol.% stearic acid was suitable for titanium injection moulding

Method for continuous variation of propellant flow and thrust in propulsive devices Patent

Continuous variation of propellant flow and thrust by application of liquid foam flow theory to injection orific