Detector setting

Taking into account that it is necessary to make vary the flaw detector settings during the main part of the verifications, the total number of verifications is rather important. So, Technical Center for Mechanical Industries (CETIM) began the development of an electronic system enabling to benefit of the current possibilities of generation of synthesised radio frequency signals and help of personal computer for operator assistance and calculation. 

The prototype of verification system of ultrasonic flaw detector developed is described in the scheme given in figure 2. The verification operators performed with the system are as much automated as possible. The level of automatization is limited by the necessity of human reading of information on flaw detector screen, or other operations as manual adjustment of flaw detector settings. 

The concentrations of benzoic acid, aspartame, caffeine, and saccharin in a variety of beverages are determined in this experiment. A Gig column and a mobile phase of 80% v/v acetic acid (pH = 4.2) and 20% v/v methanol are used to effect the separation. A UV detector set to 254 nm is used to measure the eluent s absorbance. The ability to adjust retention times by changing the mobile phase s pH is also explored. 

This experiment describes the quantitative analysis of the asthma medication Quadrinal for the active ingredients theophylline, salicylic acid, phenobarbital, ephedrine HGl, and potassium iodide. Separations are carried out using a Gi8 column with a mobile phase of 19% v/v acetonitrile, 80% v/v water, and 1% acetic acid. A small amount of triethylamine (0.03% v/v) is included to ensure the elution of ephedrine HGl. A UV detector set to 254 nm is used to record the chromatogram. 

R-propranolol), Tenormim (oL-atenolol) and Lopressor (oL-metaprolol). The mobile phase was 90 10 (v/v) acetonitrile and water. A UV detector set to 254 nm is used to obtain the chromatogram. 

Caffeine in tea and coffee is determined by CZE using nicotine as an internal standard. The buffer solution is 50 mM sodium borate adjusted to pH 8.5 with H3PO4. A UV detector set to 214 nm is used to record the electropherograms. 

In hplc, detection and quantitation have been limited by availabiHty of detectors. Using a uv detector set at 254 nm, the lower limit of detection is 3.5 X 10 g/mL for a compound such as phenanthrene. A fluorescence detector can increase the detectabiHty to 8 x 10 g/mL. The same order of detectabiHty can be achieved using amperometric, electron-capture, or photoioni2ation detectors. 

Optimum detector settings may vary from instrument to instrument therefore, minor adjustments may be made to optimize performance. 

MS detector settings Segment 1 Segment 2 Segment 3 MS run time... 

It is convenient to use test solutes with a strong absorbance at 254 nm. A solute giving 50-1004 FSD with a detector setting of 0.05 or 1.0 AUFS is convenient. 

HPLC has been used, with an ultraviolet absorption detector set for 254 nm, for the determination of aromatic hydrocarbons and with a flow calorimeter for the detection of all hydrocarbons. Increased sensitivity and decreased interference can be achieved with the ultraviolet absorption detector by measuring absorption at two wavelengths and using the ratios of the absorption at those wavelengths [28]. 

Organolead and organoselenium compounds were separated satisfactorily by high-performance capillary electrophoresis, using /1-cyclodextrin-modified micellar electroki-netic chromatography with on-column UVV detector set at 210 nm130. 

Comparison of Cycle Times and Achievable Daily Sample Throughput of DAD/ToF/LC/MS System at Different Detector Settings... 

For experiments conducted in Liverpool GC was performed on a Shimadzu GC-14A gas chromatograph using a SE30 capillary column with the injector and detector set to 250 °C chiral GC was performed with chiral capillary columns (Lipodex E and C as indicated) with the injector and detector set to 250 °C. HPLC was performed on a Gilson chromatograph equipped with chiral columns Daicel Chiralpack AD and OD (wavelength 254 nm). 

Iodoethanes are separated on a glass-lined, stainless-steel column (2mx3.2mm o.d.) packed with 10% OV-101 on Chromosorb W HP (150— 190m), using flow-rates of 90ml min-1 for the carrier gas (N ) and 35 and 350ml min-1 for H and air, respectively, for the flame-ionisation detector. Set the injection port, detector and column temperatures at 140, 130 and 60°C, respectively. 

The crude product was analysed by gas chromatography on a chiral 30 m Chiraldex G-TA column (helium flow 50 kPa, evaporator and detector set at 200 °C, column temperature 90 °C for 1 min, 8 °C min to 170 °C) after addition of anisole as an internal standard. 

Because column performance decreases with age, it is important to keep good records of its performance. Entries useful to keep track of are chromatogram number, sample identification number, amount injected, volume injected, solvents used (A and B components), column characteristics (ID number, packing, size), back pressure, flow rate, detector setting (UV, absorbance units full scale at given wavelength), gradient conditions, results (retention time of desired product), remarks (baseline shifts, unusual wash profile, etc.), and date. 

Figure 2A. Dual chromatograms showing the elution of aspen AESE lignin from the HPSEC-DV system. A 250 fiL sample was injected from a freshly prepared 8 mg /mL stock solution. Viscotek A/D amplifier gain setting of 2 and RI detector setting of lx. Calculated molecular weights are also shown.

Figure 4B. Concentration chromatogram of three column loadings (1 mg, 0.2 mg, and 0.1 mg) of oganosolv aspen lignin on the HPSEC-DV system. RI detector setting was lx.

Obtained in THF at 20°C with RJ detection and Unical 2.71 software (Viscotek, Inc.). For high loadings the system was set at RJ = la and 20 PAFS, gain = 2 injections (250 /iL) made from 8 mg/mL stock solutions. For low loadings the detector settings were RJ = l/4a and 20 PAFS, gain = 2 injections (250 /iL) made from 4 mg/mL stock solutions. 

CE system equipped with a UV photodiode array detector set at 195 nm. 

For chlorothiazide and hydrochlorothiazide analysis, separation is performed on a reversed-phase polymer PRP-I column using a mobile phase consisting of a 1 1 ratio of 14% acetonitrile/tetrahydrofiiran in 0.05M potassium phosphate buffer of pH 3. Detection is carried out with a variable-wavelength detector set at 225 nm. Performance evaluation showed that recoveries were 97 and 89% for chlorothiazide and hydrochlorothiazide, respectively, with average precision of 6 and 5% for chlorothiazide and hydrochlorothiazide, respectively. The limit of detection and the limit of quantification were estimated to be 22 and 35 ppb, respectively, for both chlorothiazide and hydrochlorothiazide. 

Tocopherols can be measured simultaneously by using a diode array detector, a second UV detector set at 280 to 300 nm, or a fluorescence detector set at 296 nm excitation and 336 nm emission. 

High-performance liquid chromatograph (HPLC e.g., Waters Chromatography) equipped with column heater, solvent pump, UV detector (set at 210 nm), integrator, autosampler, and (for manual injection) a 10-pl sample loop 15 x 0.46-cm YMC-ODS-AQ analytical column (AQ12S031546WT, Waters Chromatography)... 

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