Charm detection

To our knowledge only one work has been reported on the use of a commercial immunochemical test to detect penicillins (penicillin G, penicillin V, ampicillin, cloxacillin, and oxacillin) in several environmental compartments. Thus, Campagnolo et al. [84] measured penicillin using the Charm IIRIA test in water samples proximal to a US farm. The LOD of the technique was 2 pg L L... 

As occurred with the other antibiotics, commercial immunoassay formats, also available as kits for tetracyclines and penicillins such as the Parallux, the LacTek, or the Charm II, have also been placed on the market for the analysis of sulfonamides (see Table 4). Thus, the Parallux detects sulfamethazine and sulfadimethoxine in raw milk with a LOD of 10 pg L1. The Charm II detects almost all sulfonamides in honey and milk with a LOD in the range from 1 to 10 pg L, whereas LacTek is able to detect sulfamethazine. Moreover, the 5101SULlp and 5101SUDAlp tests reach LOD values for sulfamethazine and sulfadiazine of around 0.2 pg L 1 and they have been applied to the analysis of urine, milk, and plasma. These tests have proved to be efficient as a point of care for on-site applications on farms. Moreover, commercially available antibodies can be found from several sources such as Silver Lake Research, US Biological, Cortex Biochem. Inc., Accurate Chemical Scientific, Fitzgerald Industries International Inc., and Biotrend Chemikalien GmbH. 

We have found only one attempt to use immunoassays to detect sulfonamides in environmental samples. As in the case of penicillins and tetracyclines and also for fluoroquinolones (see below), Campagnolo et al. [84] measured sulfonamides in water samples proximal to a farm in Iowa using a commercial Charm II RIA test, accomplishing a LOD of 5 pg L 1 for sulfamethazine. 

Regarding commercially available immunochemical kits, we could mention the Charm ROSA Enrofloxacin Test that detects ciprofloxacin and enrofloxacin equally (see Table 4) and the 5101ERFXlp test. This last one is a direct competitive ELISA, which uses MAbs and has a LOD of 3 ng g1 in tissues. Some other companies do have antibodies available as reagents for different applications such as Biodesign International and QED Bioscience Inc. 

The Charm II 6600/7600 system is the only commercial immunoassay test available for the detection of several macrolides in different matrices (see Table 4). The LOD of erythromycin in milk is 40 pg L 1 and 100 pg L 1 in tissues. 

Several common methods for the detection of these compounds in environmental media have been proposed such as microbiological assay and conventional chromatographic methods. However, only one example of the application of immunochemical methods to the analysis of environmental samples has been reported [84]. In this case, erythromycin could be measured at concentrations higher than 10 pg L 1 using the Charm II6600/7600 assay in water samples proximal to livestock farms. 

Results showed a total of 2.8% of the samples (n 2972) to be inhibitor positive by the Delvotest SP test further examination identified 1.7% as -lactam antibiotics, and 1.1 % as sulfonamides and dapsone. The percentage of chloramphenicol suspicious samples determined by the Charm II test was amazingly high however, tests for confirmation were not available and contamination of the samples by residues of the chloramphenicol-based preservative azidiol could not be excluded with certainty. Low concentrations of streptomycins were also detected in 5.7% of the samples (n 1221), but the MRL was not exceeded. Macrolide and tetracycline residues were not found in significant levels. Model trials with commercially applied yoghurt cultures confirmed how important the compliance to MRLs can be to dairy industry compared to antibiotic-free milk, a pH of 5.0 was reached with a delay of 15 min in the case of contamination with cloxacillin 30 min in the case of penicillin, spiramycin, and tylosin and 45 min in the case of oxytetracycline contamination. 

The HPLC-receptorgram assay combined the advantages of HPLC separation with the multiresidue detection of the Charm II tests. The procedure was tested for identification and quantitation of the most common veterinary drugs at regulatory levels or lower. It was validated for 40 individual drugs from seven antibiotic families 10 /3-lactams, 13 sulphonamides, 8 tetracyclines, 4 macrolides, 3 amphenicols, and other miscellaneous antimicrobials. This procedure combined a simple aqueous extraction and SPE with HPLC fractionation of individual drugs. Final identification and quantitation was achieved with the Charm II test. A drug contaminant could be identified in less then 3 hours (50). 

WA Moats, KL Anderson, JE Rushing, DP Wesen. Comparison of a radioimmunoassay (Charm-II) test with high-performance liquid chromatography for detection of oxytetracycline residues in milk samples from lactating cattle. Amer J Vet Res 56 795-800, 1995. 

Gas chromatography/olfactometry (GCO) methods have been developed as screening procedures to detect potent odorants in food extracts. The FD-factors or CHARM values determined in food extracts are not consequently an exact measure for the contribution of a single odorant to the overall food flavor for the following reasons. During GCO the complete amount of every odorant present in the extract is volatilized. However, the amount of an odorant present in the headspace above the food depends on its volatility from the food matrix. Furthermore, by AEDA or CHARM analysis the odorants are ranked according to their odor thresholds in air, whereas in a food the relative contribution of an odorant is strongly affected by its odor threshold in the food matrix. The importance of odor thresholds in aroma research has been recently emphazised by Teranishi et al. [58],... 

Carlsson, A., Bjorck, L. 1992. Liquid chromatography verification of tetracycline residues in milk and influence of milk fat lipolysis on the detection of antibiotic residues by microbial assays and the Charm II test. J. Food Prot. 55, 374-378. 

Odor-active components in cheese flavor, many of which are derived from milk lipids, can be detected using GC-olfactometry (GC-O). GC-0 is defined as a collection of techniques that combine olfactometry, or the use of the human nose, as a detector to assess odor activity in a defined air stream post-separation using a GC (Friedich and Acree, 1988). The data generated by GC-0 are evaluated primarily by aroma extract dilution analysis or Charm analysis. Both involve evaluating the odor activity of individual compounds by sniffing the GC outlet of a series of dilutions of the original aroma extract and therefore both methods are based on the odor detection threshold of compounds. The key odourants in dairy products and in various types of cheese have been reviewed by Friedich and Acree (1988) and Curioni and Bosset (2002). 

These methods were developed to quantify and visualize the intensity of aroma as a chromatogram. A specific system named combined hedonic and response measurement (CHARM) was initially developed. Later on, aroma extract dilution analysis (AEDA) (Figure 3), a new method using a conventional GC-O system, was proposed. They share the same strategy aroma extract is diluted to a certain extent and then GC—O methodology is applied. In an AEDA procedure, if such a maximum extent of a dilution that allows the detection of a certain component is times diluted from the original sample, this component is referred to have a flavor dilution (FD) factor of . CHARM value corresponds to FD factor in a CHARM procedure. These values represent the contribution of the volatile the larger these values are, the more important they are considered as key components. 

Fig. 8E.1 Scheme showing the basics of AEDA and Charm analysis. Different sequential dilutions of the sample extract are analyzed in the GC-O system. In AEDA the judge simply marks the retention times and the odor descriptions. The FD value is R , where p is the p-th dilution of the extract at which the odor was last detected and R is the dilution rate (3 in the figure). In Charm, he/she presses the space bar of the computer during the odor detection, and the outputs are combined to form the Charm chromatogram... 

The Candesartan in Heart Failure Assessment of Reduction in Mortahty and Morbidity (CHARM) trials were designed as three studies to compare candesartan with placebo in patients with symptomatic heart failure (Table 14-7). Both the CHARM-Added and the CHARM-Alternative trials found significant reductions in the primary end point of cardiovascular death or hospitalization for heart failure in patients receiving candesartan, although the benefit was modest in CHARM-Added. By the end of the CHARM-Added trial, over 60% of patients were receiving /S-blocker therapy, but unhke the Val-HeET trial, no adverse interaction with /S-blockers was detected. No significant benefit of candesartan was observed in the CHARM-Preserved trial. Overall, candesartan was weU tolerated, but its use was associated with an increased risk of hypotension, hyperkalemia, and renal dysfunction. 

The CHARM 11 and AEDA analyses based on odor detection thresholds (measurement of the odor potency) have been criticized. The conclusions as to the relative contribution of odorants to a flavor may be limited, the responses for a given compound being dependent on the concentration. The relative intensity of two odorants with the same threshold does not necessarily correspond to their relative concentrations in a mixture (Abbott et al., 1993). For these authors, the contribution of a compound to an odor is probably better determined by CHARM analysis than by AEDA, which does not take into account the duration of the smell. Other methods have been proposed for a better determination of potent odorants. 

A wide variety of commercial LFIA kits for the detection of antibiotic residues is available and the most well-characterised of these are summarized in Table 5.4, including the rapid one-step assay (ROSA) range from Charm Sciences Inc., and the Tetrasensor, Twinsensor, Trisensor, and Sulfasensor from Unisensor SA and the Betastar from Neogen Corporation. Other LFIA assays have been reported in the scientific literature for the detection of antimicrobial residues, including a lateral-flow device for nicarbazin detection in animal feedstuffs. However, at present these are not commercially available. These LFIA tests incorporate either a receptor protein or an antibody as the specific capture molecule and operate in the competitive assay format (most applicable for small-molecule detection). The sample preparation protocols are based on either direct analysis of the liquid sample (e.g., milk) or a simple extraction step for solid or complex matrices using buffer(s) supplied in the test kit. In general, the time required to perform these tests is less than 30 min with only basic laboratory equipment, if any, required. 

Figure 5.5 The Charm II detection system for receptor-based radioimmunoassays. (Schematic diagram provided courtesy of Charm Sciences Inc.)...

The range of kits currently available for the Charm II system and their applications are given in Table 5.5. The test manufacturer claims that the Charm II tests are capable of detecting compounds belonging to the antimicrobial class at or below their defined MRLs (or USFDA tolerances, as indicated) within the relevant matrix, including, milk, urine, serum, animal tissue, honey, and other substances at concentrations of interest to regulatory agencies. 

Charm II Tests for Antibiotics Test Kits Available (number of individual compounds for which detection concentration are quoted) Application(s) Sample Preparation Time (minutes) Assay Time (minutes)... 

---