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C C Garber

Publications and source records attributed to C C Garber.

18 recordsLinked to original sources
PubMed1984

Quality control of electrolyte analyzers. Evaluation of the anion gap average.

The authors have shown previously that averaging at least eight patient anion gaps provides a sensitive technic for the detection of systematic error in electrolyte analysis (Am J Clin Pathol 79:688-696, 1983). They conducted a retrospective and prospective evaluation of this technic on the ASTRA 4. One month of patient and control data were studied retrospectively and showed that 17/71 abnormally low patient anion gap averages were associated with violations in a multi-rule procedure, and 41/71 low averages were associated with violations in cusum, a more sensitive procedure. In the prospective study, a total of 36 runs of eight patient specimens with low anion gap averages (less than 7.5 mmol/L) were reanalyzed after appropriate recalibration and/or maintenance. Thirty-one of the 36 groups had significant changes in either Na (nine groups, delta Na = +1.5 mmol/L), Cl (14 groups; delta Cl = -1.8 mmol/L), or in both Na and Cl (eight groups; delta Na = +1.2 mmol/L; delta Cl = -0.9 mmol/L). Because the average error detected was small, the authors recommend that the average of anion gaps be used as an early indicator of drift. It must be used, however, in conjunction with standard quality control procedures such as the multi-rule approach.

Acid-Base Equilibrium↗
PubMed1984

Monthly interlaboratory pH and blood-gas survey. Establishing accuracy based on interlaboratory performance.

The authors describe an interlaboratory survey provided by their laboratory which enables participants to establish an accuracy base for pH and blood-gas determinations. Data collected from 131 laboratories provide insight into state-of-the-art performance capabilities. The percentile ranking system presented may be used by individual laboratories to determine their need for improvement or to set intralaboratory performance goals. Data accumulated from 18 months of interlaboratory surveys are used to establish performance levels at three concentration ranges each for pH, pCO2, and pO2. By characterizing average errors on a percentile ranking basis, the authors enable participants to assess their performance compared with peer laboratory results. For samples with normal pCO2 levels, 95% of reported laboratory results have an error of 4.5 mmHg or less. Similarly, 95% of reported results for normal pO2 samples have an error of 13 mmHg or less, and 95% of the pH results, independent of level, have an error of 0.05 pH units or less.

Blood Gas Analysis↗
PubMed1981

Jendrassik--Grof analysis for total and direct bilirubin in serum with a centrifugal analyzer.

Total bilirubin is determined here with a multipoint calibration approach and with use of Standard Reference Material No. 916 bilirubin from the National Bureau of Standards. The bilirubin calibration solutions prepared in solutions of Cohn Fraction V human albumin were stable for at least one year when stored at -80 degrees C. Studies for direct bilirubin analysis show that the serum sample should be preincubated with the HCI reagent before the diazo reagent is added to minimize the false reaction with unconjugated bilirubin. With a preincubation of 15 min and a reaction interval of 15 min a 250 mg/L unconjugated bilirubin standard gave only 1 mg of apparent conjugated bilirubin per liter. Day-to-day precision studies gave CVs of 3.3% at 12.4 mg/l, 2.1% at 41.2 mg/l, and 1.0% at 197.4 mg/L for total bilirubin and 1.6% at 61.2 mg/L for direct bilirubin, the latter based on a serum pool stored at -80 degrees C. Lipemic sera caused negligible errors. Hemolysis caused slightly larger errors for total bilirubin but much smaller errors for direct bilirubin when measured at 600 nm rather than 550 nm. Comparison of results with the Rotochem (y) to those with a manual Jendrassik--Grof method (x) for total bilirubin gave y = 0.9009x - 0.04 mg/L, Sy/x = 1.3 mg/L, r = 0.9987 when different calibrators were used for each method and y = 0.9813x - 2.9 mg/L, Sy/x = 1.5 mg/L, r = 0.9997 when the same calibrators were used. For direct-bilirubin comparisons, y = 1.2762x + 0.2 mg/L, Sy/x = 1.3 mg/L, r = 0.9926.

Bilirubin↗
PubMed1981

A candidate reference method for determination of total protein in serum. II. Test for transferability.

The transferability of the candidate Reference Method for total serum protein was tested in eight laboratories in the United States and Europe. National Bureau of Standards SRM 927 (bovine serum albumin) was used in each analytical run as the calibration standard. The mean absorptivity value obtained for this material was 0.2983 L g-1 cm-1. Four serum pools prepared at the Centers for Disease Control were analyzed on each of 15 days. Within-run variation of the protein values (expressed as CV) in the eight laboratories ranged from 0.1 to 2.5% and day-to-day (total) variation in six of the laboratories ranged from 0.4 to 1%.

Biuret Reaction↗
PubMed1981

Preincubation of serum aspartate aminotransferase with pyridoxal 5'-phosphate in the SMAC: comparison with revised DuPont aca method and recommended IFCC method.

The method for continuous-flow assay of aspartate aminotransferase with the Technicon SMAC was modified to include preincubation of the serum enzyme with pyridoxal 5'-phosphate, to be consistent with the recommendations of IFCC and the Standards Committee of AACC. Preliminary estimates of the imprecision of the modified method on SMAC gave day-to-day standard deviations of 5.3 U/L at mean of 48 U/L (n = 66) and 6.2 U/L at 155 U/L (n = 61). Added bilirubin, sodium pyruvate, ascorbic acid, and endogenous lipids did not interfere. Comparison of results for 50 samples by this method with those by the manual IFCC method gave y = 1.1113x - 0.3 U/L, Sy/x = 4.4 U/L, and r = 0.997. Similar data are presented for the revised AST method for the DuPont aca discrete analyzer. Clinical data show that AST activities increase by as much as 200% when the serum is preincubated with pyridoxal 5'-phosphate.

Animals↗
PubMed1979

DuPont aca III performance as tested according to NCCLS guidelines.

We evaluated the analytical performance of 10 representative channels on the new microprocessor-controlled DuPont aca III according to the guidelines (draft documents PSEP-2, 3, and 4) proposed by the Instrument Evaluation Subcommittee of the National Committee for Clinical Laboratory Standards. These guidelines were used for the experimental design and data analysis for the precision and accuracy testing, the latter by comparison with an aca II, with results of atomic absorption spectroscopy for calcium, and with the National Glucose Reference Method. From a 20-day replication study, we estimated within-run, between-run/within-day, between-run/between-day, and total standard deviations at three concentrations for each method. From duplicate analyses of 100 samples on the aca III, aca II, and other methods, we estimated the bias from the regression line at specific concentrations and total error from a tolerance limit about the regression line. Analytical performance of the aca III was judged acceptable because these estimated errors were small.

Autoanalysis↗
PubMed1978

Albumin activation of urinary amylase as determined with the Du Pont aca.

Protein activation of urinary alpha-amylase (EC 3.2.1.1) activity was observed during an evaluation of the Du Pont aca procedure for the determination of urinary alpha-amylase. This activation effect became constant for urinary albumin concentrations exceeding 1.50 g/liter. It is recommended that urinary alpha-amylase be analyzed with sufficient albumin added to maximize this effect. The aca alpha-amylase procedure is compared to an amyloclastic method for both serum and urine analysis. Expected ranges are presented for the aca method for serum and urinary amylase, amylase clearance, and the amylase clearance/creatinine clearance ratio.

Albuminuria↗
PubMed1978

Evaluation of the co-immobilized hexokinase/glucose-6-phosphate dehydrogenase method for glucose, as adapted to the Technicon SMAC.

We assessed the analytical performance of the co-immobilized hexokinase (EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) method for D-glucose analysis on the Technicon SMAC. The enzyme-containing coils were usable for one month, or 12 000 tests. Bilirubin, hemoglobin, lipemia, creatinine, uric acid, citric acid, and ascorbic acid did not interfere. Results with this method were compared to those by the National Glucose Reference Method. The upper limits of the total error estimate (a combination of random and systematic errors) were 76, 74, and 125 mg/liter at concentrations of 500, 1200, and 3000 mg/liter, respectively. The error estimates were less than allowable errors based on medical usefulness; thus the method was judged to perform acceptably with respect to the Reference Method. We also present performance data for the routine SMAC glucose oxidase (EC 1.1.3.4)/Peroxidase (EC 1.11.1.7) 3-methyl-2-benzothianolinone hydrazone-N,N-dimethylaniline method, the direct hexokinase method with the Du Pont aca, and the glucose oxidase oxygen-rate method with the Beckman Glucose Analyzer.

Autoanalysis↗