On-line procedures

The analyte must be converted into a volatile compound suitable for mass-spectrometric analysis. Procedures for C, N, and O follow those developed for conventional organic microanalysis— oxidation of organic C to COj, reduction of organic N to N2, and conversion of O2 into CO or COj. In most procedures, cryogenic purification of the products is carried out before mass spectrometry, and both off-line and on-line procedures have been developed. 

The QA unit should have written procedures (SOPs) for the conduct of inspections and audits. These procedures should incorporate all considerations for the review of electronic data systems. The QA unit SOPs should address the role and responsibilities of the QA unit in software development, purchase, and validation activities, in-process audit procedures for data collected on line, procedures for on-line review of data (i.e., what will be verified and how much data will be reviewed), and the procedure for auditing reports using on-line data. 

Current practices in analytical SFE are organized into off-line and on-line procedures, despite their common physicochemical basis. Off-line SFE, the current method in fashion, offers more flexibility with respect to extracting different sample sizes and types, as well as in the choice of the final analytical method. On-line procedures are usually combinations of SFE with ancillary techniques such as GC, LC, supercritical fluid, or gel permeation chromatography. 

For the on-line procedures there are numerous combinations of sorbe-1 nts and mobile phases. The primary objective is to partially separate the component(s) of interest on one column, followed by diversion of those j fractions of interest onto a second column. The sorbents used for each 5... 

On-line Procedures The growing trend toward automation in industry has resulted in many studies of rapid procedures for generating size information so that feedback loops can be instituted as an integral part of a process. Many of these techniques are modifications of more traditional methods. The problems associated with on-line methods include allocation and preparation of a representative sam-... 

Most on-line procedures involving microwaves that are conducted with a view to coupling a microwave treatment (usually digestion) with a detector (usually of the atomic type) for the determination of analytes use either a domestic oven [37-40] or a commercial focused system [41-43] plus appropriate connections. Usually, the coupling is done by inserting a Teflon coil in the oven in order to circulate the suspended solid sample to be subjected to the microwaves [44]. Some systems use domestic or commercial focused systems where the solid sample is directly placed in the sample vessel [45] and an aspiration system is used after the microwave treatment to transfer the extract to the determinative instrument used [37,46] or to an apparatus employed in some other step of the analytical process [40,43]. 

Historically, pyrolysis-mass spectrometry (Py-MS) was applied to the analysis of biopolymers before Py-GC [45]. However, the first application utilized an off-line setup. In time, several on-line procedures were developed and they became more common. In Py-MS the pyrolysate is directly transferred to the mass spectrometer and analyzed, generating a complex spectrum (sometimes also called a pyrogram, although this should not be confused with the chromatogram of a pyrolysate, also called pyrogram). The ionization process that takes place in the ion source of the mass spectrometer can... 

In this connection, the on-line procedure that has been developed by Johnson et al. [36] for the simultaneous analysis of mineral acids and silicate is very interesting. As depicted in Fig. 8-47, the sample is passed through two different concentrator columns. The first one, the TAC-1, retains the mineral acids, which are separated on a conventional anion exchanger by using a carbonate/bicarbonate-mixture after switching the respective injection valve detection is carried out conductometrically. Silicate is not retained at this concentrator column, since the capacity of a TAC-1 in the carbonate/ bicarbonate-form is too low. Therefore, after passing the TAC-1, the analyte sample is... 

Sample preparation procedures are determined by target analytes, their concentrations, the sample matrix, and the analytical instrumentation used for measurement. Procedures can range from a simple filtration to a sequence of steps which may include filtration, centrifugation, extraction, concentration, removal of interfering compounds, and derivatization. Simple uncomphcated sample preparation procedures are preferred since they are less prone to errors, less susceptible to contamination, and less time consuming. Sample preparation can be quite labor-intensive although on-line procedures have also been developed." ... 

The potential success of this kind of combination of therapeutic device and on-line procedures will be based on improvements in mainstream sensors to produce reliable results of clinical significance. 

Strategies for controlling the copolymer composition and MWD of latices based on linear and non-linear copolymers, such as styrene/butyl acrylate copolymers and methyl methacrylate/n-butyl acrylate copolymers, are described. These strategies involve on-line procedures based on calorimetric measurements and open-loop processes employing a mathematical model for determining the trajectories of the manipulated variables, such as monomer feed flow rates and chain transfer agent. 35 refs. (3rd lUPAC-Sponsored International Symposium on Free-Radical Polymerization Kinetics and Mechanism, II Ciocco (Lucca), Tuscany, Italy, 3rd-9th June, 2001)... 

Details of an on-line procedure for colour control during compounding have been given... 

On-line procedures based on UV-photolysis or microwave-assisted dissolution have been established during recent years for the rapid digestion of relatively simple matrices such as water and waste water samples [130], [131 j. In 1124] on-line UV digestion with a segmented-flow device was applied for the determination of total cyanide prior to amperometric detection. The detection limit was found to be 0.2 pg/L. The throughput is about 30 analyses per hour. 

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