Channels calibration with standards

HIAC device.An HIAC/ROYCO model size 3000, 6 channels (Pacific Scientific Co., USA - Silver Spring, MD.) fitted with an HR60H sensor, with standard size range of 1-120 im, flow rate 10 ml min and supplied by the manifacturer already calibrated with standard spherical materials was employed. 

FFF calibrations are universal in the sense that calibration constants apply to all other FFF setups under a wide range of experimental conditions [113] which are somewhat different from SEC as explained below. For characterizing molecular mass distributions with SEC, the calibration constants must be determined empirically for a whole set of standard samples. FFF channels are also calibrated empirically with standards for polymer-solvent systems where the Mark-Hou-wink coefficients for the dependence of the transport coefficients on M are un-... 

Fig. 3b. It provides a low-cost amperometric sensor for detection of electrolyte concentration with self-calibration. One channel is injected with standard solutions for calibration, while the others are for the injection of solutions with unknown concentration which remains to be detected.

The chemiluminescence method is accepted as the most reliable and precise method currently available for the analysis of oxides of nitrogen. The basis of the method is the reaction between atmospheric NO and O3 (generated within the instrument). This reaction generates light (chemiluminescence), which is detected by a photomultiplier and converted to a concentration by calibration of the instrument with standard gas mixtures. To determine the NO2 content of the air, NO2 must be converted by thermal decomposition to NO and the instrument then measures NO. NO2 is then determined by difference between the NO and NO channels. 

The standard calibration of the MicroCount 05 is based on uniform polystyrene beads traceable to NIST. This provides accurate sizing for a broad range of materials in the ranges above roughly lOpm. At smaUer sizes, the optical properties of the sample influence the sensor response significantly. Tliis is especially true for the smallest particles measured in the scattering channel. When calibrated with polystyrene, the sensor may be used as a comparison instrument. If additional applications information is available, a calibration curve specific to the material can be developed. 

Cahbration spectra must be measured at defined temperamres (ambient temperature for a-iron) because of the influence of second-order Doppler shift (see Sect. 4.2.1) for the standard absorber. After folding, the experimental spectrum should be simulated with Lorentzian lines to obtain the exact line positions in units of channel numbers which for calibration can be related to the hteramre values of the hyperfine splitting. As shown in Fig. 3.4, the velocity increment per channel, Ostep, is then obtained from the equation Ustep = D,(mm s )/D,(channel numbers). Different... 

The hematite with adsorbed Co-57 or Sb-119 along with the solution was subjected to emission Mossbauer measurement at 24 1°C with the experimental setup shown in Figure 2. The absorber, Fe-57-enriched potassium ferrocyanide (0.5 mg Fe-57/cm2) or barium stannate (0.9 mg Sn-119/cm2), was driven by a Hanger 700-series Mossbauer spectrometer connected to a Tracor-Northern TN-7200 multi-channel analyzer. The Mosssbauer gamma-rays of Co-57 and Sb-119 were detected respectively with a Kr(+3% carbon dioxide)-filled proportional counter and with a 2 mm-thick Nal(Tl) scintillation counter through 65 pm-thick Pd critical absorber for Sn K X-rays. The integral errors in the relative velocity were estimated to be of the order of 0.05 mm/s by repeated calibration measurements using standard absorbers. 

The calibration of a chemiluminescent analyzer using these standards is verified when both the nitrogen dioxide and nitric oxide channels respond similarly to charges from the (ylinder of diluted nitric oxide. Agreement with the response of the nitric oxide channel should also be obtained when the standard nitric oxide mixture is titrated with a previously established source of ozone. Chemiluminescent instruments have simplified monitoring of nitrogen oxides, but accurate calibration requires well-trained personnel. 

With known analyte concentrations, the processed data provide calibration points, and Immusoft comprises fitting procedures to deduce the corresponding calibration curve that can be stored in the program for further experiments. Different calibration curves can be stored depending for instance on the assay protocol, on the specific features of the chip used or on the medium in which the assay is performed. In most cases, the calibration is performed with six independent chips of eight channels and cumulated in order to get a stable batch calibration. Then the results can be referred to this internal batch calibration. For routine control, one calibration each week is recommended to be sure that the chemistry is still in the specifications (e.g. + 10% of inter-assay standard deviation). 

The enzymatic reaction occurring in the various micro-channels during the detection step is followed by chrono-amperometry as presented in Fig. 50.2A. The measured currents result from the oxidation of the p-aminophenol produced by the enzymes, and it is thus increasing with the reaction time. Finally, the values of the slopes of these current versus time curves (in A/s) are reported as a function of the known concentrations of the IL-1B standards, thereby providing a calibration curve as shown in Fig. 50.2B. 

The FIA system consisted of TMI modules (Tecniques Mesura Instrumentacio), a five-channel peristaltic pump, an eight-channel injection valve, an eight-channel distributed valve, and a colorimeter connected to an interface and to an IBM-PC microcomputer. A specific application software, Qcontroll , was used for data acquisition, with a continuous historical trend, and a scheduled control program for sequential analysis. In a previous scheme as in Fig. 1, free enzymes were used and the whole system was calibrated for a linear range of 0.05-1.0 g of ethanol/ L of standard ethanol solutions, and the product of the reaction was passed through the colorimeter. 

Upon calibration of the optical unit with the standard white and black reflectance plates, the correction coefficients allowing to correlate the measured reflectivities and with the known standard values and R are determined for each of the 6 measuring channels and each of the S available wavelengths, and stored in the instrument memory. 

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for the determination of most major and trace elements. The samples are fused in a Claisse semi-automatic fusion device in Pt-Au crucibles with lithium metaborate (4). The fusion product is dissolved in diluted HNO and brought to volume. For trace elements determination the sample is decomposed by HF, HNOg and HCIO. Scandium serves as an internal standard and is added to all samples and solutions. The instrument (product of Jobin Yvon, France)is calibrated using multi-element synthetic standards. The aqueous solutions are nebulized and injected into the heart of a plasma fire ball. A computerized multi-channel vacuum spectrometer has been programmed for multi-element analysis. 

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