Laboratory operations sample handling

Flow NMR has recently been eclipsed by the advent of robotic sample handling systems capable of dealing with very small sample quantities and volumes. We now have a system operating in our laboratory that makes up samples directly into 1 mm NMR tubes, using only about 8 ul of solvent. These can be run under automation and the tubes emptied back into the plate wells by the same robot. This technology offers superior performance and largely gets around the problems of contamination and recovery. 

Flow injection analysis is based on the injection of a liquid sample into a continuously flowing liquid carrier stream, where it is usually made to react to give reaction products that may be detected. FIA offers the possibility in an on-line manifold of sample handling including separation, preconcentration, masking and color reaction, and even microwave dissolution, all of which can be readily automated. The most common advantages of FIA include reduced manpower cost of laboratory operations, increased sample throughput, improved precision of results, reduced sample volumes, and the elimination of many interferences. Fully automated flow injection analysers are based on spectrophotometric detection but are readily adapted as sample preparation units for atomic spectrometric techniques. Flow injection as a sample introduction technique has been discussed previously, whereas here its full potential is briefly surveyed. In addition to a few books on FIA [168,169], several critical reviews of FIA methods for FAAS, GF AAS, and ICP-AES methods have been published [170,171]. 

Synchrotron beam time remains a scarce resource world-wide, however wiA over 30 synchrotron raAation centers eiAer operational or under construction, most prospective users can obtain access to Ae facilities (11). In most cases, beam time is available free of charge for non-proprietary research. Access to a facAty is often by means of a peer reviewed proposal. Adequate equipment for sample handling and data collection is available at most synchrotron raAation laboratories. Many laboratories also provide software for data analysis. 

The Association of Biomolecular Resource Facilities (ABRP) Protein Sequence Research Committee was established in 1988 in order to provide individual laboratories with a means of self-evaluation. Each year test samples have been distributed, enabling laboratories an opportunity to monitor their performance in areas such as sample handling, insuument operation/optimization, and data interpretation. In previous years these samples have focused on sensitivity of protein sequencing (1, 6), sample heterogeneity (2, 8), protein-bound peptides on PVDF membrane or in solution (3, 4), post-translational modifications (5), identification of cysteine and tryptophan (7), and length of sequence assignment (8). 

All operations (cleaning, filtration, acidification and sample handling) were carried out in a specially designed Class 100 room, either fitted in a standard 20 ft transport container which was fully equipped as a chemical laboratory or in a room transformed as such on board of the research ship. All operations with the sample were performed in a closed system, except for the sample acidification and the filling of the bottles, which were performed in a laminar flow clean bench inside the clean room. All personnel working in the clean area used polythene gloves, dust-free garments and shoe-covers. 

The drawbacks of discrete analyzers are their mechanical complexity and high cost of operation. Sample cups, disposable cuvettes, rotors, and prepacked reagents increase the cost of individual assays above the acceptable limit for the strained budgets of most clinical laboratories. In addition, these machines are seldom used outside the clinical laboratory, because they are designed to handle three dozen of the most frequently required clinical tests. The advantages of the discrete approach are the ability of some of these instruments to perform assays via random access—which allows sequential assay of diverse analytes at will—and the capability of stat operation, which yields the analytical readout within 5-10 min after the machine has been switched on and a sample has been inserted by a technician. 

As the laboratory based sulfur by combustion and UVF technology was placed in the at process application environment, the associated design constraints and operational concerns of any high temperature analysis technique were realized. Application specific solutions were developed for concerns ranging fiom specialized flammable sample handling of multiple streams to various explosion proof apparatus enclosure requirements. Figures 2 and 3 illustrate a typical at process sulfur by combustion and UVF analyzer. 

Sloppy analytical technique can also lead to widespread laboratory contamination, so it is imperative that any analyst working at trace levels has a demonstrated expertise when it comes to general sample handling and analytical techniques, including the operation and maintenance of apparatus used in the laboratory. This is especially true for methods that use automated liquid handling devices that could be prone to dripping or other phenomena that cause cross-contamination. Extraction schemes and formats in which extracts are arranged in close proximity to one another, e.g. 96-well or other similar formats, can be especially problematic in this respect (an example is described in Section 9.7.1b). 

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