Turbidity photometer

This section deals with the experimental determination of the rate of oil solubilization in aqueous solutions of AOS and IOS [70]. The experimental method [71] consists of injecting 25 pi of n-hexadecane (containing 5 wt % Dobanol 45-3 as an emulsifier) into 50 ml water this produces a turbid macroemulsion upon vigorous stirring. At the start of the experiment, a concentrated solution of the surfactant under test is injected and the decrease in turbidity is followed with a photometer. The time elapsed to reach 90% of the initial turbidity is recorded (t ) and the pseudo rate constant of oil solubilization is calculated from... 

It is possible to relate observed scattered intensity to turbidity through knowledge of the geometry of the photometer but calibration with substance of known turbidity is common by practice. These substances include reflecting standards, colloidal suspensions, and simple liquids. Tungstosilicic acid, H4SiW12O40,... 

Hence c(g/ml) is the concentration of colloidal suspension G90 is the reading on the LS photometer at 6 = 90°, 2 is the path length, which equals the cell diameter when using a cylindrical cell t is the turbidity obtained from measurements of optical density. Table 4 gives the results of calibrating a Sofica instrument with colloidal... 

Prepare a calibration curve by plotting turbidity (in NTU if a nephelometer is used) or absorbance or transmittance (if a spectrophotometer or filter photometer is used) of BaS04 formed against the corresponding concentrations of S042 standards. Determine the concentration of S042 in the sample from the standard calibration curve. 

To measure turbidities according to the method of attenuation of the incident radiation, any photometer of minimum (400-900) nm wavelength range and maximum 60 nm bandwidth can be used. 

The light that emerges from the sample is then directed to a photometer that measures the light absorbed. The readout is calibrated in terms of turbidity. 

On the other hand, a Mutascreen assay platform is a fully automated instrument for mutagenicity assessment12. It is suitable for experiments involving all bacterial tester strains. Its major advantages are streamlined protocol and elimination of agar plates. The assay exploits the turbidity measurements of liquid bacterial cultures for the detection of bacterial growth. Small volumes of cultures are treated in multiwell plates, and the turbidity in each well is monitored intermittently over a 24-h period by using a vertical pathway photometer. 

Turbidity is measured at 180° from the incident beam, or more simply, in the same manner as absorbance measurements are made in a spectrophotometer. Turbidity can be measured on most spectrophotometers and automated clinical chemistry analyzers. The stability and resolution of modern microprocessor-driven spectrophotometers and photometers have greatly improved the ability to measure turbidity with accuracy and precision. 

Turbidimetric measurements are easily performed on photometers or spectrophotometers and require little optimization. The principal concern of turbidimetric measurements is signal-to-noise ratio. Photometric systems with electro-optical noise in the range of 0.0002 absorbance unit or less are useful for turbidity measurements. ... 

The method involves comparing the turbidity formed when silver nitrate is added to an acidified (HNO3) sample solution containing chloride, with the turbidity formed in standard solutions. The method is simple but has rather low precision. Instead of visual comparison of the turbidities in colorimetric cylinders, the absorbance can be measured with a photometer. 

Because measurements dependent upon time always disturb laboratory routine, the hemoglobin derivative to be used for the determination of the Hb concentration in blood must be formed rapidly, all hemoglobins present in the sample must be converted, and the end product formed must be stable. Stability is an essential requisite for the use of standard solutions to calibrate the photometer to be used. The measurement itself should not be disturbed by plasma proteins (globulins) or erythroc3rte stromata, either through the introduction of a so-called protein error (C3) or because of turbidity. Only HiCN properly prepared fulfills all requirements mentioned. 

An important and rapidly expanding detector group is that of the derivatization devices in which the sample components are reacted or interacted with appropriate substance so that the specific groups, e.g., chromophores, are introduced into their molecules and, consequently, they can be detected by the specific detectors (e.g. by photometers). Turbidimeters, in which the precipitate is formed by the controlled addition of a nonsolvent for the sample to the effluent, also belong to the group of derivatization detectors. Naturally, the nephelometers measuring turbidity can also... 

The electrical conductivity of the foam was measured on-line to control the steady state of the process. Results were only accepted if they had been obtained under steady state conditions. The protein concentrations were determined by a photometer at 275.5 and 320 nm and the difference was used for to correct for the error due to the turbidity of the solution. 

Fig. 84. Schematic diagram of laboratory turbidity photometer LTP 3 1) = Stabilizer for lamp 2) = Optical system 3) = Lamp 4) = Particles causing turbidity 5) = Cuvette 6) = Optical system 7) = Measuring cell 8) = Compensating amplifier 9) = Data display, recording and control unit 10) = Data output...

The draft versions of ISO norms (1983) describe both simple techniques for on-the-spot turbidity measurement and optical turbidity meters. The diagram below illustrates the principle of a turbidity photometer for laboratory use (Dr, Lange, model LTP 3). 

Fig. 85. Precision turbidity photometer TK 3 1) = Outlet 2) = Lamp 3) = Optical system 4) = Tubular cuvette 5) = Cleaning access cap 6) = Reference cell 7) = Interference filter 8) = Measuring cell 9) = Inlet...

Correction for color or turbidity Prepare a special blank for every sample that needs such correction. Carry two identical portions of each such sample through the procedme, including NaHCOa treatment if this is used. To one portion add all reagents. To the other portion add HCl and oxalic acid but no molybdate. Adjust photometer to zero absorbance with the blank containing no molybdate before reading absorbance of molybdate-treated sample. 

The tubes are shaken and the turbidity is read in a photometer (e. g., Lumetron 402 E, Photovolt Corporation, 95 Madison Avenue, New York 16) X = 650 m . The cuvettes are filled with a pipet and emptied with a piece of plastic tubing connected to a suction piunp. 

Turbidimetric—The sulfate is predpitated as barium sulfate and the turbidity of a suspension of the precipitate is measured with a photometer. 

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