Standard urines

The standard urine immunoassay for detection of cocaine (23a) abuse during the gestation period of newborn babies was frequently found to yield negative results in cases where positive results were shown by extraction of meconium with a solvent, followed by HPLC. The drug and metabolites such as norcocaine (23b) and cocaethyline (23c) were detected140. See Section IV.C for an alternative analysis of cocaine. 

Add 1 ml of DMB reagent to 100 pi of demineralized water (blank) or 100 pi of urine in a cuvette. In addition, 100 pi of each urine should be added to 1 ml of formiate buffer to assess the absorbance of the pure sample (sample blank). Each sample should be measured against pure formiate buffer (buffer blank, when measured separately). The color of the GAG-DMB complex is not stable over time, so that assay conditions have to be strictly standardized. Urine, standard, or water is added to all cuvettes first. The DMB reagent must then be added swiftly. All cuvettes are mixed with a spatula (10 x) and after 3 min samples are measured at 520 nm. When the absorbance exceeds the linear range, the urine has to be diluted. It is also recommended to measure all samples in duplicate using 50 and 100 pi of urine. This allows an evaluation of the plausibility of results. 

No adverse effects on renal function or standard urine tests have been noted in humans following intermediate-duration inhalation exposure to aluminum fumes or dust (Mussi et al. 1984) or chronic-duration inhalation exposure to metallic aluminum powder (De Vuyst et al. 1987 McLaughlin et al. 

Despite these difficulties the use of the silica gel technique for the solid probe/quadrupole mass spectrometer system holds promise for the analysis of some nutritionally important metals Both zinc and copper have been extracted successfully from serurn and zinc has also been extracted from urine and feces by using an anion exchange purification Biorad A61X8 (100-200 mesh) chloride form) anion exchange resin has been used to separate copper and zinc from acidic solutions (6) We have adapted this method to the separation of these two metals from acidic solutions of AAS standards urine serum and deproteinated fecal homogenate by elution with sucessively dilute acid solutions Recovery of an isotopic spike ai subsequent mass spectral analysis has been demonstrated with a Zn spike added to 1ml aliquots of a Fisher Certified AA Standard (zinc concentration Img/ml) Results of this experiment are shown in Table III ... 

External calibration and checking with standard urine from the company Biorad... 

Checking of the system using methanolic standards and standard urines. 

Before starting any analyses, it is, of course, essential to perform a blank run in order to condition the column, and, if drug analyses are to be carried out, a methanolic drug standard or a prepared (derivatized) standard urine should also be measured to check the sensitivity of the equipment and the separating power of the column. Figure 13-1 shows a standard that can be used in the clinical laboratory. The substances present in the standard should correspond to the type of analyses required in the laboratory. However, they should cover the whole range of possible retention times. 

The preparation of a standard is not always easy, and standard urine samples are therefore prepared and supplied commercially. These standard urines have the advantage that they provide a check of the sample preparation procedure, while supporting the accuracy and precision of the analytical determinations. They thus enable the quality of the analyses performed in the laboratory to be assessed in the most effective manner possible. 

Standard urine samples of various compositions can be obtained in various concentrations. 

Suppliers of such samples include BIO-RAD and DRG Instruments. Three examples of standard urines are described below. 

The Lyphocheck urine has been optimized such that the drug concentrations lie above the recommended cut-offs for screening determinations recommended by the Substance Abuse and Mental Health Services Administration (formerly the National Institute of Drug Abuse, NIDA) and the United States Nuclear Regulatory Commission (NRC). This standard urine is prepared from human urine to which no preservative is added and is lyophilized to improve its stability. 

Table 13-1. Substances present in standard urine Toxicology Screen Lyphocheck BIO-RAD (acetylated)...

Figure 13-3 shows the chromatogram of the non-acetylated standard urine. THC could not be determined, as a special sample preparation is necessary for its determination. Benzoylecgonine can only be determined after derivatization. 

This is a qualitative standard urine. Sodium azide is added to improve its storage properties. Table 13-3 lists the concentrations of the components present [8]. 

Table 13-3. Substances present in standard urine Toxi-Control No. 19, DRG Instruments...

Fig. 13-3. Total ion chromatogram of the standard urine Toxicology Confirm Control Lyphocheck BIO-RAD.

The type of biological specimen and form of collection is important in lEM. Although this statement appears obvious, there are a large number of considerations and implications of their use. Urine specimens are characterized primarily by hydrophilic metabolites that are often extensively modified from the original endogenous metabolite that accumulated in a metabolic disorder. As discussed previously, which compounds are present in the form of a metabolic profile is important in diagnosing a disorder but determination of concentration requires many assumptions. Because higher or lower urinary output affects the dilution of various metabolites, an indication is required to standardize urine concentration. Hence, creatinine is used as an indicator of urinary... 

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