Urine analysis sample preparation

For urine analysis sample aliquots are diluted 1 1 with distilled water before application to the AAS stabilized temperature platform (Leung and Henderson, 1982). Fecal analysis require considerably more complicated preparation steps than serum or urine. The procedure developed in the author s laboratory (Brown et al., manuscript in preparation) is summarized as follows Frozen specimens are thawed and distilled water is added (1 mL per 2 g feces) and the sample is homogenized in a sealed container on a paint shaker. A 10 mL aliquot is ashed at 550°C in a muffle furnace, dissolved in dilute HNO3 snd analyzed by GF-AAS. 

Several methods are available for the analysis of trichloroethylene in biological media. The method of choice depends on the nature of the sample matrix cost of analysis required precision, accuracy, and detection limit and turnaround time of the method. The main analytical method used to analyze for the presence of trichloroethylene and its metabolites, trichloroethanol and TCA, in biological samples is separation by gas chromatography (GC) combined with detection by mass spectrometry (MS) or electron capture detection (ECD). Trichloroethylene and/or its metabolites have been detected in exhaled air, blood, urine, breast milk, and tissues. Details on sample preparation, analytical method, and sensitivity and accuracy of selected methods are provided in Table 6-1. 

An alternative system proved to be both simpler and more user friendly (Unger et al., 2004 Machtejevas et al., 2006). Thus far we have used this configuration to analyze human plasma, sputum, urine, cerebrospinal fluid, and rat plasma. For each particular analysis we set up an analytical system based on a simple but specific strategy (Figure 9.5). The analysis concept is based on an online sample preparation and a two-dimensional LC system preseparating the majority of the matrix components from the analytes that are retained on a RAM-SCX column followed by a solvent switch and transfer of the trapped peptides. The SCX elution used five salt steps created by mixing 20 mM phosphate buffer (pH 2.5) (eluent Al) and 20 mM phosphate buffer with 1.5 M sodium chloride (eluent Bl) in the following proportions 85/15 70/30 65/45 45/55 0/100 with at the constant 0.1 mL/min flow rate. Desorption of the... 

Probably the most effective use of XRF and TXRF continues to be in the analysis of samples of biological origin. For instance, TXRF has been used without a significant amount of sample preparation to determine the metal cofactors in enzyme complexes [86]. The protein content in a number of enzymes has been deduced through a TXRF of the sulfur content of the component methionine and cysteine [87]. It was found that for enzymes with low molecular weights and minor amounts of buffer components that a reliable determination of sulfur was possible. In other works, TXRF was used to determine trace elements in serum and homogenized brain samples [88], selenium and other trace elements in serum and urine [89], lead in whole human blood [90], and the Zn/Cu ratio in serum as a means to aid cancer diagnosis [91]. 

Sample preparation is rather involved. A sample of urine or fecal matter is obtained and treated with calcium phosphate to precipitate the plutonium from solution. This mixture is then centrifuged, and the solids that separate are dissolved in 8 M nitric acid and heated to convert the plutonium to the +4 oxidation state. This nitric acid solution is passed through an anion exchange column, and the plutonium is eluted from the column with a hydrochloric-hydroiodic acid solution. The solution is evaporated to dryness, and the sample is redissolved in a sodium sulfate solution and electroplated onto a stainless steel planchette. The alpha particles emitted from this electroplated material are measured by the alpha spectroscopy system, and the quantity of radioactive plutonium ingested is calculated. Approximately 2000 samples per year are prepared for alpha spectroscopy analysis. The work is performed in a clean room environment like that described in Workplace Scene 1.2. 

Rule G, Henion J. 1999. High-throughput sample preparation and analysis using 96-weU membrane solid-phase extraction and liquid chromatography—tandem mass spectrometry for the determination of steroids in human urine. J Am... 

For high reproducibility of migration times and peak areas the sample matrix should be identical for all samples analyzed together. While this is challenging for forensic applications where analytes in whole blood or urine are determined, this requirement can be fulfilled easily in pharmaceutical analysis. After sample preparation of the drug product, the sample matrix is similar in most cases. The composition of blood or urine depends on its source. Thus, the changing sample matrix has more impact on the quality of the CE analysis. 

Heptachlor, heptachlor epoxide, and their metabolites have been measured in urine and feces using GC/ECD (Tashiro and Matsumura 1978). Sample preparation steps involve extraction with acetone and hexane, clean-up on Florisil and silicic acid columns, and extraction of the derivatized metabolites into hexane for GLC analysis. Precision, accuracy, and sensitivity were not reported (Tashiro and Matsumura 1978). 

Recently, turbulent flow chromatography (TFC) has shown a great potential for online sample pre-treatment in the analysis of PFCs. Up to now, the use of this technique in food and environmental analysis is scarce, but some successful applications have been developed. Among them, the analysis of PFCs has been carried out in cord blood and also in less invasive human samples, hair and urine. In these works, the main advantages presented were the simplified sample preparation, robustness and sensitivity. In addition in the case of cord blood, a low volume of sample was required. 

Lester et al. [24] have described a robotic system for the analysis of arsenic and selenium in human urine samples which demonstrates how robotics has been used to integrate sample preparations and instrument analysis of a biological matrix for trace elements. The robot is used to control the ashing, digestion, sample injection and operation of a hydride system and atomic absorption instrument, including the instrument calibration. The system, which routinely analyses both As and Se at ppb levels, is estimated to require only... 

Nitrite and nitrate may also be determined by HPLC using anion-exchange columns with either UV absorption or electrochemical detection. These methods are generally used for environmental samples and urine where fewer interfering compounds exist. The more extensive sample preparation and analysis time have limited its use for biological samples. 

Acylcarnitine analysis was first performed in urine specimens in the evaluation of patients with organic acidemias. However, because it was found that acylcarnitine analysis of plasma is more informative for the diagnosis of FAO disorders than analysis of urine specimens, plasma has become the preferred specimen [17]. It is only recently that it was shown that urine acylcarnitine analysis still has a role in the diagnostic evaluation of patients with organic acidurias but uninformative or borderline abnormal results of plasma acylcarnitine and urine organic acid analysis [18-21]. In our laboratory, sample preparation and analysis is identical to that of plasma once a urine aliquot has been prepared that is based on the creatinine concentration. 

Diethylstilbestrol is particularly difficult to quantitate below 1.0 ppb in bovine tissues, especially in liver, which is among the last tissues to contain diethystilbestrol after cattle are withdrawn from receiving tire drug (101, 102). Interferences from tissue matrix constitute a major problem that might be due to nonspecific interference of lipids and fatty compounds (103, 104). In addition, problems with false-positive results often appear in urine analysis unless a chromatographic step such as a solid-phase extraction cleanup (105, 106) is introduced. Simple sample preparation procedures such as those based on solvent extraction and liquid-liquid partitioning do not usually give satisfactory results (107, 108). 

Traditionally HPLC methods were used for isoflavone analysis from foods [Wang et al., 1990], and gas chromatography/mass spectrometry (GC/MS) to determine isoflavones and their metabolites in human biological fluids including urine [Adlercreutz et al., 1991 Kelly et al., 1993], plasma [Adlercreutz et al., 1993], and feces [Adlercreutz et al., 1995 Kurzer et al., 1995]. HPLC with photodiode array (PDA) detection was introduced in 1994 to measure these analytes in human urine [Franke and Custer, 1994 Xu et al., 1994]. Compared to GC/MS, HPLC methods require fewer steps for sample preparation and analysis and demand less technician time and less expensive instrumentation. 

The sample for analysis was prepared by solid-phase extraction of 5 ml of 0-24 h urine obtained from rats after dosing with 800 mg/kg of efavirenz. The extract was dried and reconstituted with 100 ml of 80% D2O and 20% acetonitrile-d3. 

Arce et al. [39] developed a flow injection analysis (F1A) system (Fig. 5.3) for online filtration of water samples prior to CE analysis. They also constructed a pump-driven unit for extraction and filtration of soil samples combined with CE in an online mode (automated sample transfer between pre-CE sample preparation step and the CE) [40]. The method was precise and four times faster than conventional methods of sample preparation with an off-line unit. Blood samples are centrifuged immediately to remove red blood cells and the serum is stored as discussed above. Sometimes, urine samples also contain precipitates which are removed by centrifuge. 

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