Human serum SRM

The problem of developing accurate data for chromium in biological samples is further complicated by the lack of Standard Reference Materials (SRM). Only recently have chromium certified materials, such as brewer s yeast (SRM-1569), bovine liver (SRM-1577), human serum (SRM-909), urine (SRM-2670), orchard leaves (SRM-1571), spinach leaves (SRM-1570), pine needles (SRM-1575), oyster tissue (SRM-1566), and tomato leaves (SRM-1573) been issued by the National Institute of Standards and Technology (formerly the National Bureau of Standards). Because of the lack of SRMs, the less recent data should be interpreted with caution (EPA 1984a), unless the data are verified by interlaboratory studies. 

Recovery experiments were carried out with spiked blood serum samples and were in the range 94 3 to 96 5%. To determine the accuracy of the method, two level certified reference materials were analyzed fat-soluble vitamins, carotenoids and cholesterol in human serum (SRM 968c, from NIST, Gaithersburg, MD). Values of 11.21 0.47 and 18.15 0.8 pg/mL (levels I and II, respectively) were obtained for vitamin E, which were in good agreement with certified values of 11.501 0.618 and 18.887 0.931 pg/mL. 

Other than NIST SRM 1589, PCBs in human serum, there are no reference materials for these compounds in urine or serum. A number of reference materials are available for environmental samples, food and agriculture. 

The development and validation of the bioanalysis of atorvastatin, its two hydroxy metabolites, and their lactone forms in human serum was reported, using a [Zljl-ILIS [51], Samples were extracted at pH 5.0 with MTBE. The analytes were separated on a 50x2-mm-lD YMC Basic column (5 pm) and an aqueous formic acid-methanol gradient, and analysed in positive-ion ESI-MS in SRM mode. The LOQ was 0.5 ng/ml. 

The simultaneous determination of 3TC and AZT in human serum and seminal plasma was reported [41-42]. The sample pretreatment consisted of an automated ultrafiltration step. For isocratic LC, a 150x2-mm-ID Cig colunrn was used and 15% acetonitrile in water at 0.3 ml/min. The eluate of the first 2 min after injection were directed to waste. ESI-MS in SRM mode was apphed in the positive-ion mode for 3TC and negative-ion mode for AZT. Polarity switching was done in between the two peaks. The LOQ was 2.5 ng/ml. 

The determination of ddl [44] and d4T [45] in human serum was reported by online SPE-LC-MS with positive-ion ESI-MS. 3TC and ddl were applied as IS. The analysis time was less than 5 min for both methods. The LOQ was 10 ng/ml for both compounds. Another group described the determination of ddl and d4T in human plasma, bronchoalveolar lavage fluid (BALE), alveolar cells, PBMC, seminal plasma, cerebrospinal fluid (CSF), and tonsil tissue [57]. Depending on the matrix, either isocratic or gradient LC was applied after SPE sample pretreatment. Positive-ion ESI-MS in SRM mode was applied. The LOQ for both compounds were 2.0 ng/ml in plasma, 0.5 ng/ml in CSF, 0.4 ng/ml in alveolar cells, BALF, and PBMC, 1 ng/ml in seminal plasma, and 0.01 ng/mg in tonsil tissue. 

Go to http //chemistry.brookscole.com/skoogfac/. From the Chapter Resources menu, choose Web Works. Locate the Chapter 34 section, click on the link for NIST, and find the pages dealing with Standard Reference Materials (SRMs). Look under Health Care and Nutrition. Find the Clinical Laboratory Materials available as SRMs. Find the information on glucose in frozen human serum and look up the Certificate of Analysis. Determine the relative uncertainties (as defined by NIST) of the glucose concentrations in mg/dL for the three different levels available. 

Nishiyama et al. (2004) set out to quantitate DHT in human serum and prostate biopsy tissue using LC-MS with charged derivatization to the A-methylpyridinium derivative. Prostate tissue DHT was dissolved in alkaline solution, extracted by SPE and derivatized before LC-MS analysis [ESI, positive ion mode, selected reaction monitoring (SRM)]. Pretreatment values in patients with N = 69) or without N = 34) prostate cancer were, for serum DHT, 423.9 pg mL ( 1.46 nmol L ) with SD 243.2 pg mL (< 0.84 nmol L ) or... 

Use of Complex Standards for Cell Proteins and Two-Dimensional Electrophoresis. One of the more widely-used cell lines chosen as a reference standard is the lymphoblastoid cell line GM607, derived from a normal individual and available from the Human Genetic Mutant Cell Depository, Camden, NJ 08103. This cell line may be grown in defined media, labeled with a radioactive tracer, and reproducibly separated in a 2-DE system. Heat shock proteins may readily be isolated and visualized from this cell line, as shown by Anderson et al. (42). For serum, a reference preparation for serum proteins is available as a certified reference material prepared and assayed by the College of American Pathologists (CAP) and by the U. S. Centers for Disease Control. A widely available human serum standard is that provided by the National Bureau of Standards as SRM 909. If sufficient interest from the user community is evident, a full electrophoretic characterization of this material can be included in the documentation. If the amount of selected standard proteins loaded on a gel is known, "relative" quantification of similar proteins could be obtained. In addition, the National Bureau of Standards could serve as an impartial evaluator of potential national standards (e.g. molecular weight standards, "tie-point" proteins, and Isoelectric point standards) to assess suitability and stability. 

College of American Pathologists proficiency test samples, Human Serum NIST SRMs Na Acidify, spike with Mg [N/MT] Determine Na with ICP-MSr from Na/ Mg ratio in a manner similar to that used in IDMS [ICP-MS] [N/MT-ICP- MS[ Long and Vetter (2002)... 

Table 9.11 Precision of laboratory standard and precision and accuracy of SRM 909 human serum (Lugowski et al., 1990)...

The requirements for, preparation of, and application of enzyme reference materials have been discussed extensively (134, 135, 151, 152, 153, 154, 155, 156, 157, 158). Cooperation among clinical enzvmologists in Europe and the United States over the last several years has resulted in the availability of only a few enzyme reference materials. SRM 8430 from NIST is a preparation of human erythrocyte aspartate aminotransferase in a human albumin matrix (144) certified reference material (CRM) 319 from the Community Bureau of Reference (BCR) of the Commission of the European Communities is a preparation of porcine y-glutamvltransferase in a bovine serum matrix (159). The working group of the BCR is in the process of establishing protocols and evaluating... 

Greenberg et al. [86] employed a preirradiation chemical separation involving retention of the vanadium moiety on Chelex-100 resin. Tlie vanadium recovery was 97.6 3%. These authors report a vanadium value of 0.055 0.035 ng/g for bovine semm SRM 1598 and a value of 0.028 0.02 ng/g for random samples of human blood serum. While these values are more in line with those of Versieck et al. in different serum matrices ( l ng), there remains the question of how meaningful are quoted values less than 1 ng for physiological interpretation in clinical chemistry. We conclude, based on serum values from different laboratories, that the vanadium concentration in serum is s 1 ppb. 

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