Minimum reportable concentration

Minimum reportable concentration. The lower concentration limit for a method is usually measured by determining the detection limit. This is basically an instrument signal to noise ratio, and it does not include calibration effects. At low concentrations the calibration process often has a major adverse effect on precision. Detection limits are useful for comparing the inherent sensitivity of methods, but they are not realistic indexes of measurable concentrations in routine analysis. 

We suggest using a new parameter, the minimum reportable concentration, defined as the concentration whose confidence band just includes zero (5.). This parameter is obtained by reducing the value of signal Yo, figure 4, until the band around predicted concentration, Xo, just touches zero. For example, for the determination of iron in water by AAS, (data given in Table III) the detection limit, defined as the concentration at which the... 

Confidence bands are direct precision data, and the maximum reportable concentration can be defined as the maximum concentration at which the method yields adequate precision ( ) (excluding measurements near the minimum reportable concentration, where poor precision is unavoidable). Table III shows RCB for the determination of iron in water by AAS. The analyst may consider a RCB of say, 15% to be adequate. The maximum reportable concentration would be 15 pg/ml from a single, weighted least-squares curve, and 20 pg/ml by the multiple-curve method. Samples containing > 20 pg/ml should be diluted to 1-10 pg/ml and analyzed using standards containing 0.05 - 15 pg/mL. (Note that it is always better to include a standard above the maximum desired concentration. The precision of this standard measurement will be poor, but poor data at this level are better than none.)... 

The values reported In Table III represent readings taken after incubation times of 24 hr for all organisms except M. smegmatis. which was read at 72 hr. The concentration of the tube of highest dilution that was free from growth was recorded as the minimum inhibitory concentration (micrograms per milliliter). 

Minimum explosive concentration for explosive and pyrotechnic dusts have been reported in the range of 40 to 1000 gm/mm, (40 to 1000 oz/ft ). With the exception of location 5 in Building 1619 at Louisiana AAP, all the dust concentrations determined for the various plants were below the maximum average concentrations. 

A series of DCE-based formulations containing Igepal CO-630 Special (N9) and dextran sulfate (DS) were evaluated for in vitro contraceptive testing. Also included in the screening tests were placebos, N9, two commercial spermicidal products (Conceptrol and KY Plus), vaginal moisturizer products (KY Jelly and Replens ), and saline. Test results are summarized in Table 6. The N9-containing products exhibited similar spermicidal activity, as illustrated by the minimum effective concentration (MEC). Samples without N9 did not have spermicidal activity. DCE placebo vehicle inhibits sperm penetration into the cervical mucus, illustrated by the very low MOET values after 1 10 and 1 160 dilutions. This activity has not been reported for anionic or nonionic polymer vehicles. There are no striking differences... 

The absorption and excretion of carbenicillin in man has been reported [396]. The antibiotic is not absorbed intact from the gut intramuscular injection (which is painful) often provides adequate serum levels (approximately 20 Mg/ntl) but infections with Pseudomonas strains having minimum inhibitory concentrations up to, or higher than, 100 Mg/ml require intravenous thbrapy to achieve such levels. No evidence of active metabolite formation has been obtained. Marked reductions in the half-life (and serum levels) of carbenicillin follow extracorporeal dialysis or peritoneal dialysis, the former producing the most striking effect [397]. These results were, of course, obtained in patients with severe renal failure. Patients with normal renal function rapidly eliminate the drug but, as with all penicillins, renal tubular secretion can be retarded by concurrent administration of probenecid. 

Table 9. Antimicrobial activity of compounds 11 and 49-53 Minimum Inhibitory Concentration, Minimum Bactericidal Concentration is reported in parentheses (fig/ml)...

The first marine bacterial metabolite to be reported was pentabromopseudiline (89) which is composed of more than 70% bromine by weight. It shows antibiotic properties against Gram-positive bacteria with minimum inhibitory concentrations from 0.0063 to 0.2 pg/ml [80]... 

Table I presents calculated minimal concentrations of contrast agents that would give visible enhancements in MR images. These concentrations are to be compared with typical receptor concentrations of about 10 9-10 13 mol/g of tissue [5]. Several MRI contrast agents reported in table I are characterized by minimum detectable concentrations that are included in this range. Some have indeed been shown to allow receptor detection in MR contrast enhanced images.

Not detected concentrations were replaced by one-half the limit of detection. b The minimum concentration is less than the minimum reported limit of detection... 

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