Limit of detection range

The amounts of analytes are compiled in Table 2.74. The results indicated that the concentration of polyphenols in red wines depends on both the grape variety and on the exogenous factors. The validation parameters of the method were good, the recoveries were in each case over 98 per cent, the coefficients of variation were between 1.3 per cent and 4.3 per cent, and the limit of detection ranged from 10/rg/l to 0.1mg/l. It was stated that the method is suitable for the determination of silbene compounds and quercetin in red wines [194],... 

Sample cleanup with an NP-HPLC column has been shown to be an efficient, robust way to separate triglycerides from organochlorine compounds for analysis in a wide range of fatty samples, such as milk, pork fat, animal feed, and cod liver (67). Complete fat-OCP separation is obtained in a small fraction volume. The method showed average recoveries of 80-110% in the concentration range of 1-510 /zg/kg, with relative standard deviations of less than 10%. The limits of detection ranged from 0.5 to 50 /ug/kg. The process can be monitored online with a UV detector. 

The conversion of several biogenic amines into their acetyl derivatives has been attempted [26] for their analysis by HPLC with UV detection. The calibration graphs are linear within the tested range and the limits of detection range from 30 to 250 ng depending on the amine. 

Method. The coating of the stationary phase on the support material is carried out in situ as described above in order to achieve a loading of 27% w/w. The stationary phase consists of 0.1 M tetrabutylammonium hydrogen sulfate in borate buffer (pH 9.2). The mobile phase is butanol-hexane (1 3). The HPLC separation of 12 sulfa drugs with the system described is shown in Fig.4.24. The distribution ratios of some drugs are listed in Table 4.8. The limits of detection range from ca. 10 to 100 ng per injection. 

TLC separation is carried out on silica gel G (containing 14% binder) with benzene-methanol (3 1). An example of the separation of DNS derivatives of some alkaloids is shown in Fig.4.57. The limits of detection range from 0.12 to 0.44 nmole with in situ quantitation. Spot removal and quantitation in solution results in a lowering of the limits of detection to 0.02 nmole. 

The hydrolysis reaction is carried out in a sealed test-tube in 1 N hydrochloric acid at 150 °C for 8-16 h. The resulting solution is made basic and the mixture is then dansylated [156]. Triazines such as atrazine, simazine and propazine yield different combinations of free amines on hydrolysis, thus enabling their characterization using the fluorogenic labeling technique. The limits of detection range from 5 to 10 ng per spot. Concentrations of 0.05 ppm in food crops may be determined. 

The derivatives are extracted by adding 0.5 ml of hexane and shaking. An aliquot portion of the clear hexane layer is then spotted on to a TLC plate (silica gel) and eluted with solvents such as benzene-chloroform (1 1) or hexane-acetone (7 3). After separation, the plate is dried and sprayed until moist with 20% triethanolamine in isopropanol. The plate is dried and observed under UV light at long wavelength. The limit of detection is ca. 5 ng per spot. For HPLC, an aliquot portion of the hexane extract is injected into a system consisting of small-particle silica gel (7-18 fan) as stationary phase and hexane-chloroform (9 1) as the mobile phase. The limits of detection range from 1 to 5 ng per injection. 

The alkylphosphonic acids, MPA, EPA, and PPA, have been determined by direct fluorescence after derivatization with 4-(9-anthroxyloxy)phenacyl bromide (panacyl bromide) (18). The 325-nm line of the HeCd laser was used for excitation. The neutral derivatives required MEKC for the separation and 50 mM sodium cholate was used as the pseudo-stationary phase. Separation was achieved in 33 min and limits of detection ranged from 0.13-0.14 xM (12-17ppb). 

The compounds were separated on a strong anion exchange (SAX) HPLC column with a pH 4.5 ammonium formate-acetonitrile mobile phase. Molecular ions were not obtained for any of the conjugate structures due to decomposition, but the phenols were detected in all cases as the M or [M+H] ion. The phenol formed from each conjugate as a decomposition product could usually be identified by computerized library search. In SIM mode, limits of detection ranged from 0.25 ng for 4-nitrophenyl glucuronide to 51 ng for phenol. 

The limits of detection were less then 200 fmol and the concentrations of nitrite and nitrate were typically 2 and 12 mM, respectively. A more recent report involved CE separations of arginine, citmllene, nitrate, and nitrite with LIE and conductivity detection Contrary to previous results, it was determined that nitrates are not always reliable indicators of NO synthase activity. Similarly, other metabolites associated with NO—arginine, citmllene, arginosuccinate, ornithine, and arginine phosphate—were quantified in Pleurobranchaea and Aplysia with limits of detection ranging from 5 nM to 17... 

Figure 7 shows the channel design and typical electropherograms for a microchip device used to determine taurine and amino acids in individual fibrosarcoma cells from mice. The device enabled cell loading and lysis, electrophoretic separation, and detection based on the enhancing effect of these analytes on the chemiluminescent reaction of luminol with hydrogen peroxide and Cu ". The limits of detection ranged from 0.068 fmol (0.26 pM) for Glu to 0.16 fmol (0.61 pM) for Tau. 

Identification and quantification were performed by using MRM with one parent ion, one daughter ion for each analyte, and ESI in positive ion scan mode. Under these conditions, a chromatographic separation within 10 min was achieved. Recoveries at three concentration levels (low, medium, and high) for all analytes ranged between 81.8% and 106.1%. The limit of detection ranged between 0.0042 ng/mL for riboflavin and 28.872 ng/mL for ascorbic acid, with an RSD of 1.17% to 5.09% for intraday and 2.61% to 7.43% for interday analysis [91]. 

There are no official guidelines on the sequence of validation experiments and the optimal sequence can depend on the method itself. A potentially useful sequence for a liquid chromatographic method is 1) Selectivity of standards (optimizing separation and detection of standard mixtures) 2) precision of retention times and peak areas 3) linearity, limit of quantitation, limit of detection, range 4) selectivity with real samples 5) trueness or accuracy, at different concentrations 6) ruggedness. 

The analysis results for all five anesthetics show excellent linear relationships (r > 0.999) within certain concentration ranges of the calibration standard. Both precision and accuracy results. The pharmacological concentrations of inhalational anesthetics are about 100 Xg/mL. The lowest limit of detection range from 0.6 Xg/mL for enflurane to 2.3 xg/mL for desflurane. 

Separation and identification of 14 different antibiotic residues in milk (which are used for mastitis control) by means of TLC were described by Bossuyt et al. The limits of detection ranged from 0.1 to 3 jag/ml except for neomycin which had a minimum detectable level of 15 jag/ml. 

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