Bromocresol Purple Method Research Articles

Laboratory Performance in Albumin and Total Protein Measurement Using a Commutable Specimen: Results of a College of American Pathologists Study

Discrepant results for serum constituents were observed among peer groups in the College of American Pathologists Comprehensive Chemistry Survey. To assess the performance of serum albumin and total protein measurement procedures and to evaluate the commutability of the conventional survey specimens. A fresh frozen, off-the-clot serum sample was included along with 4 conventional survey specimens. The fresh frozen, off-the-clot serum sample was prepared in a manner expected to confer commutability with native clinical samples. For the fresh frozen, off-the-clot serum sample, the mean values for 17 peer-groups were -0.07 to 0.32 g/dL from the bromocresol green albumin designated comparison method, whereas 4 VITROS (Ortho Clinical Diagnostics, Rochester, New York) peer groups differed by -0.29 to -0.37 g/dL (15 of 21 differences [71%] had P < .001). For bromocresol purple albumin methods, the mean differences from the designated comparison method from 8 peer groups were 0.25 to 0.47 g/dL (all had P < .001). For total protein methods, 23 peer group mean values were -0.07 to 0.15 g/dL from the reference measurement procedure (12 of 24 [50%] had P < .001). The Beckman (Fullerton, California) Synchron LX20 had a bias of -0.30 g/dL (P <.001). The commutability of the conventional specimens was acceptable for 23 of 24 bromocresol green method-material combinations (96%) and 13 of 16 bromocresol purple albumin method-material combinations (81%). All (100%) of the 36 method-material combinations had acceptable commutability for total protein. One (2.2%) of the instrument systems (Synchron) using bromocresol green and none (0%) of the instrument systems using bromocresol purple had satisfactory total-error performance for albumin measurement. Differences in results between bromocresol green and bromocresol purple methods precluded using common reference intervals for interpreting results for serum albumin. Eight of 9 instrument systems (86.5%) had satisfactory total-error performance for total protein measurement.

Comparison of different methods of measuring albumin concentration in ring-necked pheasants

The purpose of this study was to compare albumin concentrations in ring-necked pheasants (Phasianus colchicus) using two different dye-binding methods: the bromocresol green (BCG) and bromocresol purple (BCP). High positive correlation was observed for albumin in BCG and BCP methods. Compared to BCP, the BCG-binding method yielded significantly higher (p < 0.0001) albumin values for adult female ring-necked pheasants.

Sensitive and selective spectrophotometric assay of rizatriptan benzoate in pharmaceuticals using three sulphonphthalein dyes

Three simple, rapid, selective and sensitive spectrophotometric methods are described for the determination of rizatriptan benzoate (RTB) in bulk drug and in tablets. The methods are based on the formation of intense yellow colored ion–pair complexes between RTB and sulphonphthalein acid dyes, namely, bromophenol blue (BPB), bromocresol purple (BCP), bromothymol blue (BTB) in chloroform medium. The colored products are measured at 425nm (RTB–BPB complex, RTB–BCP complex) and 420nm (RTB–BTB complex). The reactions were extremely rapid at room temperature and the absorbance values remained constant for 90min (methods A and B) and over 12h (method C). Beer’s law was obeyed in the concentration ranges of 0.8–16.0, 1.0–20.0 and 1.2–24μgml−1 with molar absorptivity values of 1.76×104, 1.96×104 and 1.63×104lmol−1cm−1 for BPB, BCP and BTB methods, respectively. The limits of quantification (LOQ) were 0.39, 0.34 and 0.27μgml−1 for BPB, BCP and BTB methods, respectively. Other method validation parameters, such as precision, accuracy, robustness, ruggedness and selectivity, were satisfactory. The composition of the ion–pair was found to be 1:1 by Job’s method. The proposed methods were successfully applied to the determination of RTB in commercial tablets. No interference was observed from common tablet adjuvants. Statistical comparison of the results with the reference method showed excellent agreement and indicated no significant difference in accuracy and precision.

Effects of atorvastatin on progression of diabetic nephropathy and local RAGE and soluble RAGE expressions in rats

Advanced glycation end-products (AGEs) exert inflammatory and oxidative stress insults to produce diabetic nephropathy mainly through the receptor for AGEs (RAGE). This study aimed to assess the effect of atorvastatin on diabetic nephropathy via soluble RAGE (sRAGE) and RAGE expressions in the rat kidney. Thirty-two male Sprague-Dawley rats were divided into four groups based on the presence or absence of streptozotocin-induced diabetes with or without atorvastatin treatment (10 mg/kg for 24 weeks). Serum sRAGE and glycated albumin (GA) levels were measured with enzyme-linked immunosorbent assay (ELISA) and improved bromocresol purple methods. Renal AGEs, RAGE, endogenous secretory RAGE (esRAGE), and sRAGE were determined with reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. Mesangial expansion and microalbuminuria were aggravated in diabetic rats, and improved with atorvastatin treatment. Serum sRAGE levels were lower in diabetic than in normal rats. After atorvastatin treatment, serum and renal sRAGE levels were up-regulated, while renal RAGE expression was decreased in diabetic rats, associated with a reduction in accumulation of AGEs, though renal esRAGE mRNA expression was not significantly increased. Atorvastatin exerted a beneficial effect on diabetic nephropathy with reduced AGE accumulation, down-regulating RAGE expression and up-regulating sRAGE in the kidney.

E080 Speech perception difficulties in CI patients and demonstration of their solution to normal hearing persons

To evaluate if severe jaundice is associated with acute auditory neuropathy spectrum disorder in otherwise healthy late preterm and term neonates.In a prospective observational study, all neonates who were admitted with severe jaundice at which exchange transfusion may be indicated as per American Academy of Pediatrics guidelines had comprehensive auditory evaluation performed before discharge to home. Neonates with infection, perinatal asphyxia, chromosomal disorders, cranio-facial malformations, or family history of childhood hearing loss were excluded. Comprehensive auditory evaluations (tympanometry, oto-acoustic emission tests, and auditory brainstem evoked responses) were performed by an audiologist unaware of the severity of jaundice. Total serum bilirubin and serum albumin were measured at the institutional chemistry laboratory using the Diazo and Bromocresol purple method, respectively.A total of 13 neonates with total serum bilirubin concentration at which exchange transfusion is indicated as per American Academy of Pediatrics were admitted to the Neonatal Intensive Care Unit over 3 month period. Six out of 13 neonates (46%) had audiological findings of acute auditory neuropathy spectrum disorder. There was no significant difference in gestational age, birth weight, hemolysis, serum albumin concentration, peak total serum bilirubin concentrations, and peak bilirubin:albumin molar ratio between six neonates who developed acute auditory neuropathy and seven neonates who had normal audiological findings. Only two out of six infants with auditory neuropathy spectrum disorder had clinical signs and symptoms of acute bilirubin encephalopathy.Our findings strongly suggest that auditory neuropathy spectrum disorder is a common manifestation of acute bilirubin-induced neurotoxicity in late preterm and term infants with severe jaundice. Our findings also suggest that comprehensive auditory evaluations should be routinely performed in neonates with severe jaundice irrespective of the presence of clinical findings of acute bilirubin encephalopathy.

Use of two sulfonthalein dyes in the extraction‐free spectrophotometric assay of tramadol in dosage forms and in spiked human urine based on ion‐pair reaction

Tramadol is a centrally acting analgesic used in the prevention and treatment of moderate to severe pain. Two sensitive, selective, and rapid spectrophotometric methods are described for the determination of tramadol in its dosage forms and in spiked human urine. The methods are based on formation of yellow ion-pairs between tramadol and two sulfonthalein dyes; bromocresol purple (BCP) and bromocresol green (BCG) in dichloromethane medium followed by absorbance measurement at 400 and 410 nm, respectively. Under the optimum conditions, tramadol could be assayed in the concentration ranges, 1-15 and 1-16 µg ml(-1) with correlation coefficient greater than 0.999 in both cases. The molar absorptivity values are calculated to be 1.84 × 10(4) and 1.97 × 10(4) l mol(-1) cm(-1) for BCP and BCG methods, respectively; and the corresponding Sandell sensitivity values are 0.0143 and 0.0134 µg cm(-2). The limits of detection (LOD) and quantification (LOQ) have also been reported. The stoichiometry of the reaction was found to be 1:1 in both cases and the conditional stability constant (K(f)) values of the ion pairs have been calculated. The within-day and between-day RSD were 0.9-1.96% and 1.56-3.21%, respectively. The methods were successfully applied to the determination of tramadol in tablets and injections and also in spiked human urine with good recoveries. The procedures are simple, accurate, and suitable for quality control application.

Auditory neuropathy spectrum disorder in late preterm and term infants with severe jaundice

Objective To evaluate if severe jaundice is associated with acute auditory neuropathy spectrum disorder in otherwise healthy late preterm and term neonates. Methods In a prospective observational study, all neonates who were admitted with severe jaundice at which exchange transfusion may be indicated as per American Academy of Pediatrics guidelines had comprehensive auditory evaluation performed before discharge to home. Neonates with infection, perinatal asphyxia, chromosomal disorders, cranio-facial malformations, or family history of childhood hearing loss were excluded. Comprehensive auditory evaluations (tympanometry, oto-acoustic emission tests, and auditory brainstem evoked responses) were performed by an audiologist unaware of the severity of jaundice. Total serum bilirubin and serum albumin were measured at the institutional chemistry laboratory using the Diazo and Bromocresol purple method, respectively. Results A total of 13 neonates with total serum bilirubin concentration at which exchange transfusion is indicated as per American Academy of Pediatrics were admitted to the Neonatal Intensive Care Unit over 3 month period. Six out of 13 neonates (46%) had audiological findings of acute auditory neuropathy spectrum disorder. There was no significant difference in gestational age, birth weight, hemolysis, serum albumin concentration, peak total serum bilirubin concentrations, and peak bilirubin:albumin molar ratio between six neonates who developed acute auditory neuropathy and seven neonates who had normal audiological findings. Only two out of six infants with auditory neuropathy spectrum disorder had clinical signs and symptoms of acute bilirubin encephalopathy. Conclusions Our findings strongly suggest that auditory neuropathy spectrum disorder is a common manifestation of acute bilirubin-induced neurotoxicity in late preterm and term infants with severe jaundice. Our findings also suggest that comprehensive auditory evaluations should be routinely performed in neonates with severe jaundice irrespective of the presence of clinical findings of acute bilirubin encephalopathy.

Spectrophotometric determination of diphenhydramine hydrochloride in pharmaceutical preparations and biological fluids via ion-pair formation

A simple, sensitive and accurate spectrophotometric method has been described for the assay of diphenhydramine hydrochloride (DPH) in raw material and in biological samples. The method is based on extraction of DPH into dichloromethane as ion-pair complexes with patent blue (PB), eriochrome black T (EBT), methyl orange (MO) and bromocresol purple (BCP) in acidic medium. The coloured species exhibited absorption maxima at 632, 514, 428 and 414nm for PB, EBT, MO and BCP, with molar absorptivity values of 1.32×105, 2.36×104, 3.68×104 and 3.07×104lmol−1cm−1, respectively. The reaction conditions were optimized to obtain the maximum colour intensity. Beer’s law was obeyed with a good correlation coefficient (0.9982–0.9993) in the concentration ranges 0.5–3, 2.0–16, 2.0–10 and 1.0–10μgml−1 for PB, EBT, MO and BCP methods, respectively. The composition ratio of the ion-association complexes was found to be 1:1 in all cases as established by Job’s method. The conditional stability constant (Kf) and the free energy changes (ΔG°) were determined for all complexes formed. The proposed method was successfully applied for the determination of DPH in tablets and human urine with good accuracy and precision. Statistical comparison of the results with those obtained by the official method showed good agreement and indicated no significant difference in accuracy and precision.

Ischemia‐Modified albumin levels in patients with end‐stage renal disease patients on hemodialysis: does albumin analysis method affect albumin‐adjusted Ischemia‐Modified albumin levels?

Ischemia-Modified albumin (IMA) has been used as an early marker in the evaluation of the patients with acute coronary syndrome. We aimed to evaluate IMA in end-stage renal disease (ESRD) patients on hemodialysis and the effect of albumin methods on albumin-adjusted IMA levels. A total of 30 ESRD patients were included in this study. Serum IMA and albumin levels were measured before and after a hemodialysis session. Albumin concentrations were determined with bromocresol green and bromocresol purple methods. Postdialysis IMA and albumin-adjusted IMA levels with two different albumin methods were significantly increased compared with the predialysis levels (P<0.05). However, we did not find any difference in albumin-adjusted IMA levels in either at the beginning or at the end of the dialysis session. IMA levels increase after hemodialysis, whereas albumin method has no effect on albumin-adjusted IMA levels.

Two cases of severe hypoalbuminemia (

Objective Hypoalbuminemia is known to occur in critically ill patients and is associated with increased mortality. Severe hypoalbuminemia is defined in the literature as serum albumin levels lower than 24 g/L. Methods Albumin levels were measured in our laboratory using the bromocresol purple method on the Synchron CX9 (Beckman Coulter); the lower detection limit on this apparatus is 10 g/L. Results We report two cases of severe hypoalbuminemia with levels lower than 10 g/L—one in a complete paraplegic patient with severe pressure ulcers and the other in a patient positive for the human immunodeficiency virus with chronic renal failure. Conclusion Although cases of severe hypoalbuminemia (<10 g/L) are very rare in the literature, chemical pathologists should be aware of the causes of serum albumin levels of this magnitude. These cases describe two different disease states that lead to severe hypoalbuminemia by means of a similar underlying cause, namely severe inflammation or infection.

Spectrophotometric Determination of Doxazosin Mesylate in Tablets by Ion-Pair and Charge-Transfer Complexation Reactions

Two accurate, easy spectrophotometric methods for the determination of doxazosin mesylate were described. The first method was based on the formation of ion-pair complexes with the acidic sulfophthalein dyes bromocresol purple (BCP) and bromophenol blue (BPB) in pH 3.3 and 4.5 citrate-phosphate buffer, respectively. The formed complexes were extracted into dichloromethane, and their absorbance was measured at 403 and 410 nm for BCP and BPB, respectively. The second method was based on the charge transfer reaction of the drug as an n-electron donor with either 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or 7,7,8,8-tetracyanoquinodimethane (TCNQ) as pi-acceptors, to give colored radical anions. The absorbances of products were measured at 457 nm in acetonitrile and 838 nm in methanol for DDQ and TCNQ, respectively. Under the optimum reaction conditions, Beer's law was obeyed with a good correlation coefficient (r = 0.9997-0.9999) in the concentration ranges 3.0-18.0, 3.0-20.0, 15.0-95.0, and 10.0-100.0 microg/mL for the BCP, BPB, DDQ, and TCNQ methods, respectively. Limits of detection of the BCP, BPB, DDQ, and TCNQ methods were 0.314, 0.408, 1.935, and 1.610 microg/mL, respectively. The limits of quantification were 1.045, 1.360, 6.449, and 5.367 microg/mL, respectively. The parameters molar absorptivity, precision, accuracy, recovery, robustness, and stability constant were studied. The proposed methods were successfully applied for determination of the drug in tablets with good accuracy and precision. Statistical comparison of the results with those obtained by a reported method showed good agreement and indicated no significant difference in accuracy and precision.

Comparison of glycated albumin and hemoglobin A1c levels in diabetic subjects on hemodialysis

Glycated albumin is thought to more accurately reflect glycemic control in diabetic hemodialysis patients than hemoglobin A(1c) because of shortened red cell survival. To test this, glycated hemoglobin and albumin levels were measured in blood samples collected from 307 diabetic subjects of whom 258 were on hemodialysis and 49 were without overt renal disease. In diabetic subjects with renal disease, relative to those without, the mean serum glucose and glycated albumin concentrations were significantly higher while hemoglobin A(1c) tended to be lower. The glycated albumin to hemoglobin A(1c) ratio was significantly increased in dialysis patients compared with the controls. Hemoglobin A(1c) was positively associated with hemoglobin and negatively associated with the erythropoietin dose in hemodialysis patients, whereas these factors and serum albumin did not significantly impact glycated albumin levels. Using best-fit multivariate models, dialysis status significantly impacted hemoglobin A(1c) levels without a significant effect on glycated albumin. Our results show that in diabetic hemodialysis patients, hemoglobin A(1c) levels significantly underestimate glycemic control while those of glycated albumin more accurately reflect this control.

Ontogeny of Bilirubin-Binding Capacity and the Effect of Clinical Status in Premature Infants Born at Less Than 1300 Grams

Bilirubin is toxic to the brain and enters the brain in unbound form. Serum unconjugated, unbound bilirubin may be a good predictor of bilirubin encephalopathy. Unbound bilirubin levels may depend on the bilirubin-binding capacity of albumin, which has not been described for neonates of <28 weeks' gestation. The purpose of this work was to determine the ontogeny of bilirubin-binding capacity and the effect of clinical status in very preterm neonates. A total of 152 neonates (23-31 weeks' gestational age; 440-1300 g) were enrolled prospectively. At 5 days of age, total serum bilirubin and unbound bilirubin were measured with the unbound bilirubin-A1 analyzer (Arrows Co, Osaka, Japan) and albumin with the Bromocresol-purple method. Scatchard plots were used to estimate bilirubin-binding affinity and capacity. Clinical status for each infant was rated as high, moderate, or low risk by using a modified Score for Neonatal Acute Physiology model. Low risk was considered clinically stable. Unbound bilirubin has a significant, direct correlation to total bilirubin and is greater in unstable than in stable neonates. For the entire cohort, bilirubin-binding capacity had a direct relationship to gestational age. The bilirubin-binding capacities of infants in the low- and high-risk groups also had a direct relationship to gestational age. Bilirubin-binding capacity was greater in the low-risk group (20.8 +/- 4.6 mg/dL; 356 +/- 79 micromol/L) than in the moderate- (17.8 +/- 3.5 mg/dL; 304 +/- 60 micromol/L) or high- (17.3 +/- 3.4 mg/dL; 296 +/- 58 micromol/L) risk groups. Bilirubin-binding affinity did not differ by clinical risk status or gestational age. In very preterm, very low birth weight infants, bilirubin-binding capacity is directly proportional to gestational age. Bilirubin-binding capacity is lower and unbound bilirubin higher in unstable than in stable neonates. These data may be useful in guiding the management of hyperbilirubinemia in very low birth weight infants.

Extractive Spectrophotometric Methods for the Determination of Oxomemazine Hydrochloride in Bulk and Pharmaceutical Formulations Using Bromocresol Green, Bromocresol Purple and Bromophenol Blue

Three simple, sensitive and accurate spectrophotometric methods have been developed for the determination of oxomemazine hydrochloride in bulk and pharmaceutical formulations. These methods are based on the formation of yellow ion-pair complexes between the examined drug and bromocresol green (BCG), bromocresol purple (BCP), and bromophenol blue (BPB) as sulphophthalein dyes in acetate-HCl buffer of pH 3.6, 3.4, and 4.0, respectively. The formed complexes were extracted with dichloromethane and measured at 405 nm for all three systems. The best conditions of the reactions were studied and optimized. Beer's law was obeyed in the concentration ranges 2.0-12, 2.0-13, and 2.0-14 microg mL(-1) with molar absorptivities of 3.2 x 10(4), 3.7 x 10(4), and 3.1 x 10(4) L mol(-1) cm(-1) for the BCG, BCP, and BPB methods, respectively. Sandell's sensitivity, correlation coefficient, detection and quantification limits are also calculated. The proposed methods have been applied successfully for the analysis of the drug in pure form and in its dosage forms. No interference was observed from common pharmaceutical excipients. Statistical comparison of the results with those obtained by HPLC method shows excellent agreement and indicates no significant difference in accuracy and precision.

Study of glycated amino acid elimination reaction for an improved enzymatic glycated albumin measurement method

Background: In order to improve enzymatic glycated albumin measurement, we studied the endogenous glycated amino acid elimination reaction and the new bromocresolpurple (BCP) method for albumin measurement. Methods: In the assay, endogenous glycated amino acids are first eliminated by oxidation by ketoamine oxidase. Second, glycated albumin is hydrolyzed to glycated amino acids by proteinase digestion, and glycated amino acids are oxidized to produce hydrogen peroxide, which is quantitatively measured. Third, albumin is measured by the new BCP method. Finally, glycated albumin value is calculated as the percentage of glycated albumin in total albumin. Results: Glycated amino acid concentrations in prepared total parenteral nutrition products were increased in direct proportion to storage time and temperature. The glycated amino acid elimination reaction using ketoamine oxidase may be able to eliminate more than 15 mmol/l glycated amino acids. The glycated albumin values of samples calculated from the albumin concentrations using the new BCP method accorded with those calculated with the HPLC method. Fundamental performances (linearity, dilution test, analytical recovery, within-run and between-run CVs, interference study) of the present method were good. Detection of glycated albumin by the present method was significantly correlated with detection of glycated albumin by the high-performance liquid chromatography method ( r p=0.995). Conclusions: This new improved method is free of interference by endogenous glycated amino acids and is unaffected by albumin concentration, and enables more accurate analysis of glycated albumin.

Determination method of serum albumin using a Bromocresol Green solution and a Bromocresol Purple solution containing no detergent as a color reagent.

Various detergents have been used in the dye-binding method for the determination of human serum albumin to prevent precipitation of the serum protein. However, there is problem that some detergents contained in the color reagent cause water pollution. Thus, the author studied the dye-binding method for determining human serum albumin using a Bromocresol Green (BCG) solution and a Bromocresol Purple (BCP) solution containing no detergent as a color reagent. The precipitation of serum protein occurred in the pH range of 3.8 to 4.2 for BCG, and 4.2 to 4.6 for BCP. Thus, pH 3.4 and pH 5.2 were selected for the pH of the BCG and BCP color reagents, respectively. In measuring a number of patients’ sera, the precipitaion of serum protein was not observed at all in both BCG and BCP color reagents containing no detergent. The measurement values obtained by the proposed BCG method correlated very well with those by the conventional BCG method (r = 0.997, y = 0.983x−0.807, n = 90) and the conventional BCP method (r = 0.984, y = 0.849x + 5.57, n = 90). The measurement values obtained by the proposed BCP method correlated well with those by the conventional BCP method (r = 0.961, y = 0.809x + 7.55, n = 90) and the conventional BCG method (r = 0.948, y = 0.913x + 2.39, n = 90). The mean values of the proposed BCG and BCP methods and the conventional BCG and BCP methods were 36.6, 37.2, 38.1 and 36.6 g/l, respectively.

Reaction between pH indicators with a large pKa value and human serum albumin and its application to the determination of the serum albumin concentration

The reaction between four pH indicators with a large pKa value and human serum albumin and its application to the determination of the serum albumin concentration were studied. In the reaction of Bromothymol Blue (BTB), Phenol Red, Cresol Red and Thymol Blue with serum albumin, although a change in the color shade did not occur, the absorbance of the reaction mixture decreased. Since this absorbance decrease was largest in the reaction of BTB(the molar absorbance decrease at pH 7.4 was 7.59×104 l mol−1 cm−1), which was sufficiently sensitive to measure the serum albumin concentration, the BTB color reagent at pH 7.4 was applied to its determination. The measurement values by the BTB method correlated with those by the dye-binding method using the Bromocresol Green method(r = 0.965, y = 1.21x−4.25, n = 90) and with those by a method using Bromocresol Purple(r = 0.953, y = 1.04x + 3.56, n = 90). The mean value of the BTB method (41.8 g/l) was higher than those of the Bromocresol Green method (38.1 g/l) and the Bromocresol Purple method(36.6 g/l). Since the reaction of BTB was carried out at pH 7.4, where serum protein does not precipitate, the addition of a detergent for preventing the precipitation of serum protein is not required. Therefore, the use of this color reagent contributes to decreasing water pollution by the detergent and acid used in the conventional methods.

Albumin as an outcome measure in haemodialysis in patients: the effect of variation in assay method

Serum/plasma albumin is an important predictor of future mortality/morbidity in haemodialysis (HD) patients and has been proposed as an important audit measure. Different methods of albumin assay give different results and the bias between methods may be greater in renal failure patients. Albumin concentration in plasma was measured by three methods, two dye-binding methods (bromocresol green (BCG) and bromocresol purple (BCP)) and an immuno-turbidimetric (ITM) method, in 143 HD patients (group I) and 49 non-renal patients (group II). Comparisons were made between means, variation in differences across a range of albumin concentrations and on the percentage of patients within the normal range. In HD patients (group I), BCG over-estimated plasma albumin compared with the other two methods. The difference could be as much as 10 g/l and was more marked in hypoalbuminaemic patients. The BCP method gave results closer to the ITM method, particularly in HD patients. These differences were less marked in group II patients but both methods overestimated albumin compared with the ITM method. Using the BCG local laboratory normal range, 84% of HD patients had plasma albumin concentrations within the normal range but this fell to 57% if the BCP results were used. The method for determining albumin concentration has a marked effect on the results particularly in HD patients. BCG, the most commonly used method, gives higher results than other methods and correlates poorly with an immunological method. These differences make comparative audit between nephrology units difficult and have implications for other biochemical variables and other specialties.

A comparison of two dye-binding methods for the determination of dog, rat and human plasma albumins

Plasma albumin was determined in human, rat and dog samples by bromocresol green and bromocresol purple dye-binding methods. The bromocresol purple method produced significantly lower values in dog and rat plasma samples, although the use of homologous standards reduced the differences between the two methods. These observations reflect differing affinities of the two dyes for albumins of different species.

Evaluation of a bromocresol purple method for the determination of albumin adapted to the DuPont aca discrete clinical analyzer

We evaluated a new method for the determination of albumin on the DuPont aca discrete clinical analyzer that utilized an albumin selective dye, bromocresol purple (BCP). This dye minimizes globulin interference that occurs with bromocresol green (BCG) methods that have long (greater than 30 s) incubation times. Good correlation was observed between the new BCP method and two methods which do not show significant globulin interference: an immunological method and a rapid BCG method. Comparisons with alternate BCG methods (SMA 12/60, SMAC, and the aca) were generally not as good. The albumin results by the BCP method on specimens with elevated globulins were similar to results from the immunological and rapid BCG methods. The reference interval was 34-50 g/L. The between-day coefficient of variation ranged from 0.9 to 3.5% at three evaluation sites on 2 levels of 8 different control materials. The method was linear between 6-70 g/L. No interference was observed from hemoglobin at levels less than or equal to 5.00 g/L or from bilirubin at levels less than 342 mumol/L. Also, no interference was observed from nine common drugs that are known to bind to albumin. These studies show that accuracy, reproducibility and linearity of the BCP albumin method on the aca are acceptable for clinical use.