The anion gap in the serum is useful in the interpretation of acid-base disorders and in the diagnosis of other conditions. In the early 1980s, ion-selective electrodes for specific ionic species were introduced for the measurement of serum electrolytes. This new method has caused a shift of the anion gap from 12+/-4 mEq/L down 6+/-3 mEq/L. It is worthy for clinicians to understand the range of normal anion gap and the measuring methods for serum sodium and chloride in the laboratories that support their practice. While an increase in the anion gap is almost always caused by retained unmeasured anions, a decrease in the anion gap can be generated by multiple mechanisms.
Acid-Base Equilibrium* ; Anions ; Diagnosis ; Electrolytes ; Ion-Selective Electrodes ; Sodium

Air ; analysis ; Hydrobromic Acid ; analysis ; Ion-Selective Electrodes ; Workplace

To develop optimal shift systems for an improvement of work schedule satisfaction, health and work productivity, the effects of the direction of the rotational work shifting on the circadian rhythm and adaptation of physiological components and work mistakes were investigated in nursing students. Two groups of seven volunteers participated as experimental subjects, apd seven to twenty nursing students participated as a control group. The directions of rotation work shift were as follows CW(clockwise)-shift system rotation in the direction of day shift(3 days), evening shift(3 days), off duty(l day) and night shift(5 days), and CCW (counterclockwise) -shift system rotation in the reverse direction. Urinary Na, K, and Cl levels were measured with ion-selective electrodes. The levels of performance were measured by a questionnaire to determine the number of mistakes in 12 specific items during duty. The disturbance of Na the circadian rhythm was seen on day and night shifts, especially in the CCW-rotation shift system, and the magnitude of the daily variation was greatest in the CCW-rotation system. The daily rhythms of K and Cl shifted to the right on the evening shift, and the rhythms were reversed on the night shift, which suggests that they adapted to the altered shift work. However, the levels of Cl were higher in day and night shift workers, especially in CCW-shift system. In the ease of urine salts, it seems that the students in CW-shift system more easily adapted to the altered shift. The incidence of mistakes during work were more frequent on the CCW shift than in the CW shift. These data indicate that the direction of rotation effects the worker's health and work performance. These results indicate that the CCW rotation of shift work makes it more difficult for the workers to adapt to the shift on a physiological level, and has many more negative effects on the shift workers' health when compared with the CW rotation. Thus, a clockwise rotating shift system seems to be more desirable for the optimal health and performance of nurses.
Appointments and Schedules ; Circadian Rhythm* ; Efficiency ; Humans ; Incidence ; Ion-Selective Electrodes ; Salts ; Students, Nursing ; Volunteers ; Surveys and Questionnaires

BACKGROUND: Calcium status is more accurately determined by measuring free calcium, the tightly regulated biologically active form. The concentration of ionized calcium is strongly dependent on different preanalytic factors. In this study the influence of several methodological factors on the concentration of ionized calcium in blood is investigated. METHODS: Authors selected 127 persons of health care management center & comparatively healthy-look, out-patients of our hospital. When serum was needed, blood was anaerobically withdrawn in vacutainers, the serum was separated after standing at room temperature. For the plasma sample blood was anaerobically drawn into the tube with dry sodium heparin 143 IU/10ml blood in the same patient. And then, to avoid CO2 loss, the samples were left unopened and centrifuged anaerobically at 900g for 15 min; the serum and plasma were then pipetted as quickly as possible into 2ml plastic eppendorf-tube, which were completely filled and sealed off immediately and keeping it in refrigeration before testing. For the studies of calcium binding effect by different volume of sodium heparin. blood was collected into two type of tube, each containing 30IU heparin/whole blood ml or 125 IU/ml. Ioniged calcium were measured by ion-selective electrodes. RESULTS: 1. The reference value of ionized calcium in serum and plasma was 4.9+/- 0.19, 4.9+/-0.17 mg/ml(serum versus plasma, p>0.05) respectively. 2. The concentration change of ionized calcium according to heparin volume shows no significant difference until heparin 14.3 IU/blood 1 ml compared with serum. 3. The concentration of ionized calcium of serum and plasma was stable until 4 hours and 4 days after serum and plasma separation. CONCLUSIONS: Above shows that the concentration of ionized calcium have the same reference range on both serum and plasma. But each laboratory should have their own reference range according to heparin volume, ionized calcium in serum and plasma samples kept at -4degrees C remains stable within few days, provided the proposed conditions for storage.
Calcium* ; Delivery of Health Care ; Heparin ; Humans ; Ion-Selective Electrodes ; Outpatients ; Plasma ; Plastics ; Reference Values ; Refrigeration

In the method for lithium (Li) analysis, flame emission photometry and atomic absorption spectrophotometry (AAS) have been used most frequently. In addition, lithium can be analyzed by ion-selective electrode (ISE) or fluorscence polarization immunoassay. We evaluated the comparison between AAS method based on the principle of absorption of light at 670.8 nm by Li and ISE method based on the principle of voliage difference generated by Li in contact with lithium ionophore. We compared with those obtained by AAS (AA/AE Spectrophotometer 551, Instrumentation Laboratory Co.) and ISE (SYNCHRON EL-ISE, Beckman Co.) in the serum and urine of 6 pati,,:nts- and evaluated time-related changes of serum lithium concentration after dosing in both methods. The results are summarized-as follows: 1. In within-run precision study for lithium concentration, coefficient variations (CVs, %) ranged from 1.34 to 2.17 for AAS and from 0.34 to 0.85 for ISE method. In between-run precision study for lithium concentration, CVs ranged from 1.23 to 1.72 for AAS and from 0.61 to 1.38 for ISE method. 2. The correlation study between AAS and ISE method resulted in Y= 0.946X+ 0.137 (N = 32, r= 0. 933, X= AAS, Y= ISE) for serum lithium and Y= 1. 092X+ 0. 977 (N= 28, r= 0.943, X= AAS, Y= ISE) for urine lithium. 3. Time-related changes of serum lithium concentration in both AAS and ISE method resulted in peak serum levels about 2 hours after dosing and then rapidly decreased after the peak serum level and finally arrived at nearly initial levels about 9 hours after dosing. 4. The reference range of serum lithium was found as undetectable level for both AAS and ISE method and the reference range of urine lithium to the urine creatinine was 0 0.00014 mmol/mg(mean 0.00002 mmol/mg) for AAS method.
Absorption ; Creatinine ; Immunoassay ; Ion-Selective Electrodes ; Lithium* ; Photometry ; Reference Values ; Spectrophotometry, Atomic ; Statistics as Topic

OBJECTIVES: The aims of this study were to determine the total fluoride concentration and bioavailable fluoride concentration in different toothpastes, based on a newly suggested method by the International Organization for Standardization (ISO), and to compare the measured concentrations with the concentrations written on the packaging. METHODS: The concentrations of total fluoride (TF) and bioavailable fluoride (BF) were measured in six toothpastes. For the TF measurement, 1 g of each toothpaste was mixed with dipotassium hydrogen phosphate (K2HPO4), and hydrogen chloride (HCl) was placed. After 24 hours, the samples were centrifuged and total ionic strength adjustment buffer (TISAB) solution was added. For the BF measurement, the toothpaste was mixed with K2HPO4 for only 1 minute. The samples were centrifuged, and then HCl was placed and allowed to stand for 24 hours. The TISAB solution was added subsequently. The concentration of fluoride ions was measured using a fluoride ion-selective electrode and calculated against a standard curve. RESULTS: The six toothpastes were composed of different fluoride compounds and abrasives. The measured TF concentration ranged from 624.99 ppm to 1,353.00 ppm, and the similarity to the declared fluoride concentration ranged from 53.48% to 93.31%. The measured BF concentration ranged from 587.61 ppm to 1,360.05 ppm, and the similarity to the expected fluoride concentration ranged from 41.97% to 93.80%. Two samples were clearly separated when the samples were centrifuged, whereas the remaining four samples had unclear supernatants. The clearly separated toothpastes (i.e., toothpastes 5 and 6) had BF concentrations that were similar to or lower than the declared fluoride concentrations and the measured TF concentrations. However, the unclearly separated toothpastes showed inconsistent relationships between the measured TF and BF concentrations. CONCLUSIONS: The measured TF and BF concentrations of the six toothpastes did not reach the expected fluoride concentration. This finding resulted from the different compositions and forms of the toothpastes. Therefore, the properties of toothpastes need to be considered when measuring their fluoride concentrations.
Biological Availability* ; Fluorides* ; Hydrochloric Acid ; Hydrogen ; Ion-Selective Electrodes ; Ions ; Osmolar Concentration ; Product Packaging ; Toothpastes*

OBJECTIVETo evaluate the uncertainty of measurement result of urinary fluoride and to provide quality assurance for determinations.

METHODThe investigation was conducted, according with principles and methods for uncertainty evaluation.

RESULTSThe uncertainty of the combined standard of present method was 2.86 %. For the sample containing 4.47 mg/L urinary fluoride, the expanded uncertainty was 0.26 mg/L.

CONCLUSIONThe uncertainty of the present method was mainly from the sample repeatability, the preparation of standard solution, the linearity of the calibration curve and instruments and so on.

Animals ; Boron ; analysis ; urine ; Ion-Selective Electrodes ; Minerals ; chemistry ; Urine ; chemistry

BACKGROUND: Direct measurements of ionized magnesium (iMg) in serum by ion-selective electrodes have recently become available in clinical practice, and its usefulness needs to be investigated in dialysis patients because chronic renal failure is associated with disturbances in magnesium metabolism. METHODS: We measured serum iMg in 29 hemodialysis (HD) patients and 24 peritoneal dialysis (CAPD) patients using an ion-selective electrode. The results were compared with those from 30 age- matched control patients who were admitted due to non-renal diseases and were confirmed to have normal serum total magnesium (tMg) levels. RESULTS: Serum tMg was significantly higher in both HD (0.95 [0.81-1.06] mmol/L) and CAPD (0.86 [0.74-0.99] mmol/L) patients compared with the controls (0.74 [0.70-0.78] mmol/L). Serum iMg was significantly higher in HD patients (0.65 [0.60-0.72] mmol/L) compared with the controls (0.55 [0.51-0.57] mmol/L), but was not higher in CAPD patients (0.54 [0.50-0.60] mmol/L). Thus, the ionized fraction of serum magnesium (iMg/tMg) was significantly lower in CAPD patients (65.3 [58.8-68.2]%), but not in HD patients (68.7 [63.6-77.0]%), compared with the controls (72.2 [67.2-78.3]%). In dialysis patients, iMg/ tMg was significantly lower in those with residual renal function than in anuric patients (67.5 [63.6-74.8]% vs. 61.4 [56.4-70.7]%). CONCLUSION: In current practice, true hypermagnesemia may exist frequently in HD patients (at predialysis), but not in CAPD patients. The ionized fraction of serum magnesium may be reduced in CAPD patients, but not in HD patients.
Dialysis* ; Humans ; Ion-Selective Electrodes ; Kidney Failure, Chronic ; Magnesium* ; Metabolism ; Peritoneal Dialysis ; Peritoneal Dialysis, Continuous Ambulatory ; Renal Dialysis

OBJECTIVE: Traumatic brain injury has been shown to result in a decrease of the brain-free magnesium concentration that is associated with the development of neurologic deficits. However, changes in free magnesium homeostasis have not been characterized in other fluid compartments. We examine the ionized serum magnesium(Mg2+) and ionized serum calcium(Ca2+) in the moderate diffuse axonal injury of rat model. METHODS: We designed a study to determine whether ionized serum magnesium(Mg2+) and / or ionized serum calcium(Ca2+) levels correlate with moderate diffuse axonal injury(mDAI). A new ion-selective electrode was used to determine Mg2+ and Ca2+ level in the serum, prior to and following weight-drop induced mDAI. RESULTS: Serum Mg2+ remained significantly depressed to about 76% of preinjury values for 3 hours (0.73+/-0.01 mg/dL, 0.79+/-0.03 mg/dL, 0.84+/-0.03 mg/dL at 1, 2, 3 hours after trauma, respectively) compared to control group (1.07+/-0.03 mg/dL, p<0.05), but not in total serum magnesium(tMg). Mg2+/ tMg was shown a significant decrease for first 3 hours (49%, 53.4%, 56.4% at 1, 2, 3 hours after trauma respectively) compared to control group (70.9%, p<0.05). Head trauma resulted in small decrease of Ca2+, but there was a significant increase in the amount of Ca2+/ Mg2+(mean value in control group: in injured group for 3 hours after trauma = 4.65+/-0.012: 5.71+/-0.015, p<0.05). Apoptotic change was shown at 3 hours after mDAI and apoptotic index(AI) was significantly increased at 12 and 24 hours after trauma (54.8+/-1.7, 51.5+/-3.2 at 12, 24 hours, p<0.05). CONCLUSION: These findings suggest that the early decline in serum Mg2+ and increase in the amount of Ca2+/ Mg2+ following brain trauma may be a critical factor in the development of irreVersible tissue injury and early treatment with magnesium salt may be effective in histological changes following experimental traumatic brain injury in the rat.
Animals ; Apoptosis ; Axons ; Brain Injuries ; Calcium* ; Craniocerebral Trauma ; Diffuse Axonal Injury* ; Homeostasis ; Ion-Selective Electrodes ; Ions* ; Magnesium* ; Models, Animal ; Neurologic Manifestations ; Rats*