Specimen quality

A universial anticoagulant does not exist, and it is therefore necessary to use, in clinical chemical analysis, serum or plasma prepared with a variety of anticoagulants. The role of the anticoagulant and preservatives on the observed value has been reviewed by Caraway (C2, C4) and by Winsten (Wll). 

The importance of the antiglycolytic agent is accentuated in the busy laboratory, where several hours may elapse between collection of the specimen and laboratory processing, and even longer when specimens are mailed to central laboratories some distance from the hospital or doctor s office where the specimen was collected (R4). In one study, mean glucose values determined in serum obtained and analyzed within 30 minutes after collection were 96 mg/100 ml but they were 86 mg/100 ml in 

Oxalate does not interfere with glucose assays, but insulin values determined in oxalate-plasma are lower than those obtained with lithium heparin-plasma or serum (L6). Specimens collected in EDTA demonstrate lower carbon dioxide combining power than those observed with serum or heparin or potassium oxalate plasma (Zl). 

Enzymes activities are particularly sensitive to the anticoagulant used in collecting the specimen. Heparin inhibits acid phosphatase (W16) and muramidase (Z5). Amylase activity is inhibited by oxalate or citrate (MIO), and lactic dehydrogenase and acid phosphatase lose activity in oxalate (C2). Alkaline phosphatase is stable in oxalate, oxalate-fluoride, or heparin, but 25 mAf citrate inhibits 50% of the activity, and as little as 50 mlf EDTA is completely inhibitory (B19). Leucine aminopeptidase is inhibited by EDTA, as is creatine phosphokinase (F3). Amylase activity has been reported to be only 83% of that in serum when oxalate or citrate-plasma is used (MIO). Heparin plasma appears to have no inhibitory effect. Despite the fact that clotting factor V is not stable in oxalate or EDTA, these are often used as anticoagulants to obtain plasma for prothrombin determinations (Z2, Z4). 

Glucose Values in Blood Collected with and without Fluoride 

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The production of quality specimens is critically dependent upon the initial steps in the process treatment before transport, transport, grossing, and fixation before processing.4 Nothing about this is profound or even new, yet many specimens, perhaps a large majority of them, show evidence that some basic rule has been ignored. The quest for ever-shorter turnaround time has taken us down a very undesirable path. It has become such a hot topic that an acronym for turnaround time, TAT, has been coined for it. Specimen quality has suffered, putting diagnostic conclusions in doubt. This is well-known, but... 

Whole blood is the most likely specimen for a clinical laboratory to receive for gas analysis and may be obtained from any site accessible to vascular catheterization or entry. These sites commonly are the vessels of the extremities, but special studies may require access to the chambers of the heart and great vessels of the chest. Analysts should recognize that some specimens are difficult to obtain and should be handled with utmost care. Sometimes the volume of the specimen collected for analysis, particularly from premature neonates, has to be as small as possible without sacrificing specimen quality and analytical accuracy. 

In practice, specimen quality usually limits d ui to a value greater than this theoretical lower limit. The best horizontal resolution typically attained via confocal microscopy is approximately 0.2 pm, while the best vertical resolution is 0.5 pm [1]. This Encyclopedia focuses on fluorescence detection using confocal microscopy as adapted for micro-/nanofluidics research. 

Description of the sample processing and storage requirements for a biomarker is an opportunity to proactively avoid contamination and maintain specimen quality and... 

Standard practices must be modified for conducting laboratory or field tests on zirconium, hafnium, and their alloys. Emphasis must be placed on specimen quality and preparation, galvanic corrosion, test duration, contamination resulting from the corrosion of other metals, and handling of corroded specimens. The procedures recommended herein should be used in conjunction with the applicable ASTM and NACE standards previously mentioned. Additional information is available in Ref 3. 

Specimen Quality. The surface quality of the test specimen significantly affects the test results. For example, a notch in the test specimen will alter the impact values (42). 

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