Determination of volatile bases in seafood using the ammonia ion selective electrode: collaborative study.

Nine collaborating laboratories tested a combination of 23 seafood samples for volatile bases using an ammonia ion selective electrode. Results were reported as mg NH3/100 g fish, but the method reflected levels of both ammonia and trimethylamine, which permeated the ammonia membrane. The 23 samples were broken down into 8 blind duplicate pairs, 2 Youden matched pairs, and 3 single samples covering fresh to spoiled product ranging from 8 to 82 mg NH3/100 g. Seven species were evaluated: Atlantic cod, squid, Atlantic halibut, gray sole, monkfish, dogfish, and Atlantic mackerel. The ammonia electrode assay was performed on an aqueous homogenate consisting of 95 mL distilled water and 5.0 g sample tissue. Alkaline ion strength adjusting solution (2 mL) was added to the homogenate to liberate ammonia that was sensed by the ion specific electrode and measured on a precalibrated portable meter. Repeatability standard deviations (RSDr) ranged from 4.2 to 17%; reproducibility standard deviations (RSDR) ranged from 8.8 to 21%. A standard ammonium chloride solution was provided to all laboratories to spike 3 different samples at 10 mg NH3/100 g. Recoveries of added ammonia as ammonium chloride for fresh, borderline, and spoiled samples were 88.6, 107, and 128%, respectively.

Elder abuse and neglect: the emergency medicine perspective.

The diagnosis of elder abuse and neglect is difficult to accomplish, making intervention elusive, primarily because to date there is no set definition of either abuse or neglect. This paper, written primarily from the American viewpoint, addresses definitions; assessment and diagnosis; aetiology of abuse; intervention; prevention and management; ethical and legal considerations; elder abuse and the emergency physician; and future goals.

Rapid determination of volatile bases in fish by using an ammonia ion-selective electrode.

A simple and rapid method using an ammonia ion-selective electrode (ISE) to measure volatile bases in fish is proposed. Accuracy and precision were determined with 5, 10, 20, and 30 ppm NH3 standard solutions. Ammonia values obtained with the method correlate strongly with total volatile basic nitrogen (r2 = 0.88). Recoveries of added ammonia to homogenized fish samples ranged from 83.7 to 96.0%. Responses of the probe to trimethylamine (TMA), calculated as NH3 (mg/100 mL), ranged from 74.9 to 91.7%. These findings indicate that the probe measured TMA as well as ammonia. Storage trials on 8 fish species illustrated that the results obtained with the ISE method reflected nitrogen concentrations based on total volatile base (TVB) analysis. This procedure may be used in lieu of the traditional TVB method for on-site rapid screening of fish.

Statistical classification of seafood quality.

Discriminant function analysis (DFA) was used to classify the freshness quality of lean fish, fatty fish, and shrimp as either acceptable (Class 1), marginal (Class 2), or unacceptable (Class 3). Fresh and frozen survey samples were statistically classified following an initial precategorization using sensory, chemical, and microbiological indices as predictor variables. Computer elimination of nonsignificant predictor tests, p > 0.05, was used to optimize the test protocol. DFA correctly classified 98.5% of 67 preclassed lean fish samples (34 Class 1; 13 Class 2; 20 Class 3), 86.2% of 58 preclassed fatty fish samples (22 Class 1; 16 Class 2; 20 Class 3), and 98.7% of 79 preclassed shrimp samples (45 Class 1; 18 Class 2; 16 Class 3) by using all the quality indices. Computer selection of significant predictor indices at p < 0.05 yielded correct predicted classifications of 95.5, 81.0, and 97.5%, respectively. The number of tests required to effectively categorize quality were reduced from 15 to 3 for lean fish, from 13 to 3 for fatty fish, and from 11 to 6 for shrimp, with minimal losses in prediction accuracy and a substantial reduction in analysis time.

Comparison of microwave digestion with conventional wet ashing and dry ashing digestion for analysis of lead, cadmium, chromium, copper, and zinc in shellfish by flame atomic absorption spectroscopy.

A closed vessel microwave digestion procedure was developed for shellfish samples. This procedure was compared with wet and dry ash procedures for levels of lead, cadmium, chromium, copper, and zinc. Results obtained for microwave and conventional wet ash digestion were comparable. The dry ashing procedure produced results consistently lower than either of the other methods. Recoveries ranged from 80-92% for microwave and wet ashing procedures and 54-72% for the dry ashing procedure. Accuracy was also determined by analyzing lobster hepatopancreas marine reference material. Values for Pb, Cd, and Cr fell within the range specified for the reference material for all 3 digestion procedures; however, values were lower for Cu and Zn. Results of this study show that microwave digestion is comparable to wet ashing.

Comparison of volatile acid number test with enzymatic acetic acid assay for assessment of seafood quality.

Volatile acid number, an official AOAC method for assessing seafood quality, was compared with an enzymatic method for measuring acetic acid. Thirty-eight samples of fresh fish and 23 samples of canned fish were evaluated. The data showed high positive correlations between volatile acid number and enzymatic acetic acid methods; the correlation coefficient was 0.98 for fresh fish and 0.95 for canned fish. Positive correlation coefficients of 0.93 and 0.96 were also associated with samples of fish divided into 2 groups on the basis of acceptable or unacceptable quality, respectively. There was no significant difference between the means for the volatile acid number and enzymatic acetic acid procedures at the 5% level of significance. Decomposition studies on cod and mackerel, representing a lean and fatty fish, respectively, were monitored over 9 days by using the following analyses: volatile acid number, acetic acid, total volatile bases, and thiobarbituric acid. Results of the decomposition studies showed that enzymatic acetic acid levels closely paralleled volatile acid number values in both lean and fatty fish. Total volatile bases was a reliable supplemental measure for evaluating lean seafood quality, whereas thiobarbituric acid was more appropriate for further assessment of fatty fish quality.

Comparison of the Limulus amoebocyte lysate test with plate counts and chemical analyses for assessment of the quality of lean fish.

The quality of lean fish was assessed simply and rapidly with Limulus amoebocyte lysate. The endotoxin levels agreed with aerobic plate counts and chemical indices of spoilage. Correlation between level of endotoxin and level of total volatile bases was found to be highly significant (r = 0.8579; P less than 0.001).